optimize check function

fix bugs found by LLVM assertions
fix incorrect typing of globals bitmap
2026-07-28 23:58:40 +00:00 · 2019-09-15 19:58:23 +02:00 · 2019-09-15 12:51:54 -04:00 · 2019-09-12 16:42:37 -04:00
456 changed files with 9941 additions and 30028 deletions
@@ -14,16 +14,19 @@ commands:
      - run:
          name: "Install apt dependencies"
          command: |
-            echo 'deb https://apt.llvm.org/buster/ llvm-toolchain-buster-<<parameters.llvm>> main' | sudo tee /etc/apt/sources.list.d/llvm.list
+            echo 'deb http://apt.llvm.org/stretch/ llvm-toolchain-stretch<<parameters.llvm>> main' | sudo tee /etc/apt/sources.list.d/llvm.list
            wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
            sudo apt-get update
            sudo apt-get install \
-                llvm-<<parameters.llvm>>-dev \
-                clang-<<parameters.llvm>> \
-                libclang-<<parameters.llvm>>-dev \
-                lld-<<parameters.llvm>> \
+                python3 \
+                llvm<<parameters.llvm>>-dev \
+                clang<<parameters.llvm>> \
+                libclang<<parameters.llvm>>-dev \
+                lld<<parameters.llvm>> \
                gcc-arm-linux-gnueabihf \
+                libc6-dev-armel-cross \
                gcc-aarch64-linux-gnu \
+                libc6-dev-arm64-cross \
                qemu-system-arm \
                qemu-user \
                gcc-avr \
@@ -41,119 +44,36 @@ commands:
    steps:
      - restore_cache:
          keys:
-            - llvm-source-10-v0
+            - llvm-source-8-v5
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-10-v0
+          key: llvm-source-8-v5
          paths:
            - llvm-project
-  build-wasi-libc:
-    steps:
-      - restore_cache:
-          keys:
-            - wasi-libc-sysroot-v2
-      - run:
-          name: "Build wasi-libc"
-          command: make wasi-libc
-      - save_cache:
-          key: wasi-libc-sysroot-v2
-          paths:
-            - lib/wasi-libc/sysroot
  test-linux:
-    parameters:
-      llvm:
-        type: string
    steps:
      - checkout
      - submodules
      - apt-dependencies:
-          llvm: "<<parameters.llvm>>"
+          llvm: "-8"
      - install-node
      - restore_cache:
          keys:
-            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
-            - go-cache-v2-{{ checksum "go.mod" }}
+            - go-cache-{{ checksum "Gopkg.lock" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
+            - go-cache-{{ checksum "Gopkg.lock" }}
      - llvm-source-linux
-      - run: go install -tags=llvm<<parameters.llvm>> .
-      - restore_cache:
-          keys:
-            - wasi-libc-sysroot-systemclang-v1
-      - run: make wasi-libc
-      - save_cache:
-          key: wasi-libc-sysroot-systemclang-v1
-          paths:
-            - lib/wasi-libc/sysroot
-      - run: go test -v -tags=llvm<<parameters.llvm>> ./cgo ./compileopts ./interp ./transform .
+      - run: go install .
+      - run: go test -v
      - run: make gen-device -j4
-      - run: make smoketest
+      - run: make smoketest RISCV=0
      - save_cache:
-          key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
+          key: go-cache-{{ checksum "Gopkg.lock" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
          paths:
            - ~/.cache/go-build
            - ~/.cache/tinygo
-            - /go/pkg/mod
      - run: make fmt-check
-  assert-test-linux:
-    steps:
-      - checkout
-      - submodules
-      - run:
-          name: "Install apt dependencies"
-          command: |
-            sudo apt-get install \
-                gcc-arm-linux-gnueabihf \
-                binutils-arm-none-eabi \
-                libc6-dev-armel-cross \
-                gcc-aarch64-linux-gnu \
-                libc6-dev-arm64-cross \
-                qemu-system-arm \
-                qemu-user \
-                gcc-avr \
-                avr-libc
-      - install-node
-      - restore_cache:
-          keys:
-            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
-            - go-cache-v2-{{ checksum "go.mod" }}
-      - llvm-source-linux
-      - restore_cache:
-          keys:
-            - llvm-build-10-linux-v0-assert
-      - run:
-          name: "Build LLVM"
-          command: |
-            if [ ! -f llvm-build/lib/liblldELF.a ]
-            then
-              # install dependencies
-              sudo apt-get install cmake clang ninja-build
-              # make build faster
-              export CC=clang
-              export CXX=clang++
-              # hack ninja to use less jobs
-              echo -e '#!/bin/sh\n/usr/bin/ninja -j3 "$@"' > /go/bin/ninja
-              chmod +x /go/bin/ninja
-              # build!
-              make ASSERT=1 llvm-build
-            fi
-      - save_cache:
-          key: llvm-build-10-linux-v0-assert
-          paths:
-            llvm-build
-      - run: make ASSERT=1
-      - build-wasi-libc
-      - run:
-          name: "Test TinyGo"
-          command: make ASSERT=1 test
-      - save_cache:
-          key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
-          paths:
-            - ~/.cache/go-build
-            - ~/.cache/tinygo
-            - /go/pkg/mod
-      - run: make gen-device -j4
-      - run: make smoketest TINYGO=build/tinygo
  build-linux:
    steps:
      - checkout
@@ -162,6 +82,7 @@ commands:
          name: "Install apt dependencies"
          command: |
            sudo apt-get install \
+                python3 \
                gcc-arm-linux-gnueabihf \
                binutils-arm-none-eabi \
                libc6-dev-armel-cross \
@@ -174,12 +95,12 @@ commands:
      - install-node
      - restore_cache:
          keys:
-            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
-            - go-cache-v2-{{ checksum "go.mod" }}
+            - go-cache-{{ checksum "Gopkg.lock" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
+            - go-cache-{{ checksum "Gopkg.lock" }}
      - llvm-source-linux
      - restore_cache:
          keys:
-            - llvm-build-10-linux-v0
+            - llvm-build-8-linux-v7
      - run:
          name: "Build LLVM"
          command: |
@@ -197,10 +118,15 @@ commands:
              make llvm-build
            fi
      - save_cache:
-          key: llvm-build-10-linux-v0
+          key: llvm-build-8-linux-v7
          paths:
            llvm-build
-      - build-wasi-libc
+      - run:
+          name: "Create LLVM symlinks"
+          command: |
+            ln -s $PWD/llvm-build/bin/clang-8 /go/bin/clang-8
+            ln -s $PWD/llvm-build/bin/ld.lld  /go/bin/ld.lld-8
+            ln -s $PWD/llvm-build/bin/wasm-ld /go/bin/wasm-ld-8
      - run:
          name: "Test TinyGo"
          command: make test
@@ -212,11 +138,10 @@ commands:
      - store_artifacts:
          path: /tmp/tinygo.linux-amd64.tar.gz
      - save_cache:
-          key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
+          key: go-cache-{{ checksum "Gopkg.lock" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
          paths:
            - ~/.cache/go-build
            - ~/.cache/tinygo
-            - /go/pkg/mod
      - run:
          name: "Extract release tarball"
          command: |
@@ -224,6 +149,11 @@ commands:
            tar -C ~/lib -xf /tmp/tinygo.linux-amd64.tar.gz
            ln -s ~/lib/tinygo/bin/tinygo /go/bin/tinygo
            tinygo version
+      - run:
+          name: "Download SiFive GNU toolchain"
+          command: |
+            curl -O https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.2.0-2019.05.3-x86_64-linux-ubuntu14.tar.gz
+            sudo tar -C /usr/local --strip-components=1 -xf riscv64-unknown-elf-gcc-8.2.0-2019.05.3-x86_64-linux-ubuntu14.tar.gz
      - run: make smoketest
  build-macos:
    steps:
@@ -232,27 +162,23 @@ commands:
      - run:
          name: "Install dependencies"
          command: |
-            curl https://dl.google.com/go/go1.14.darwin-amd64.tar.gz -o go1.14.darwin-amd64.tar.gz
-            sudo tar -C /usr/local -xzf go1.14.darwin-amd64.tar.gz
+            curl https://dl.google.com/go/go1.12.5.darwin-amd64.tar.gz -o go1.12.5.darwin-amd64.tar.gz
+            sudo tar -C /usr/local -xzf go1.12.5.darwin-amd64.tar.gz
            ln -s /usr/local/go/bin/go /usr/local/bin/go
            HOMEBREW_NO_AUTO_UPDATE=1 brew install qemu
      - restore_cache:
          keys:
-            - go-cache-macos-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
-            - go-cache-macos-v2-{{ checksum "go.mod" }}
-      - restore_cache:
-          keys:
-            - llvm-source-10-macos-v0
+            - llvm-source-8-macos-v5
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-10-macos-v0
+          key: llvm-source-8-macos-v5
          paths:
            - llvm-project
      - restore_cache:
          keys:
-            - llvm-build-10-macos-v0
+            - llvm-build-8-macos-v6
      - run:
          name: "Build LLVM"
          command: |
@@ -264,19 +190,13 @@ commands:
              make llvm-build
            fi
      - save_cache:
-          key: llvm-build-10-macos-v0
+          key: llvm-build-8-macos-v6
          paths:
            llvm-build
-      - restore_cache:
-          keys:
-            - wasi-libc-sysroot-macos-v1
      - run:
-          name: "Build wasi-libc"
-          command: make wasi-libc
-      - save_cache:
-          key: wasi-libc-sysroot-macos-v1
-          paths:
-            - lib/wasi-libc/sysroot
+          name: "Create LLVM symlinks"
+          command: |
+            ln -s $PWD/llvm-build/bin/clang-8 /usr/local/bin/clang-8
      - run:
          name: "Test TinyGo"
          command: make test
@@ -300,47 +220,22 @@ commands:
            curl -O https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.2.0-2019.05.3-x86_64-apple-darwin.tar.gz
            sudo tar -C /usr/local --strip-components=1 -xf riscv64-unknown-elf-gcc-8.2.0-2019.05.3-x86_64-apple-darwin.tar.gz
      - run: make smoketest AVR=0
-      - save_cache:
-          key: go-cache-macos-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
-          paths:
-            - ~/.cache/go-build
-            - ~/.cache/tinygo
-            - /go/pkg/mod


 jobs:
-  test-llvm9-go111:
+  test-llvm8-go111:
    docker:
-      - image: circleci/golang:1.11-buster
+      - image: circleci/golang:1.11-stretch
    steps:
-      - test-linux:
-          llvm: "9"
-  test-llvm10-go112:
+      - test-linux
+  test-llvm8-go112:
    docker:
-      - image: circleci/golang:1.12-buster
+      - image: circleci/golang:1.12-stretch
    steps:
-      - test-linux:
-          llvm: "10"
-  test-llvm10-go113:
-    docker:
-      - image: circleci/golang:1.13-buster
-    steps:
-      - test-linux:
-          llvm: "10"
-  test-llvm10-go114:
-    docker:
-      - image: circleci/golang:1.14-buster
-    steps:
-      - test-linux:
-          llvm: "10"
-  assert-test-linux:
-    docker:
-      - image: circleci/golang:1.14-stretch
-    steps:
-      - assert-test-linux
+      - test-linux
  build-linux:
    docker:
-      - image: circleci/golang:1.14-stretch
+      - image: circleci/golang:1.12-stretch
    steps:
      - build-linux
  build-macos:
@@ -355,10 +250,7 @@ jobs:
 workflows:
  test-all:
    jobs:
-      - test-llvm9-go111
-      - test-llvm10-go112
-      - test-llvm10-go113
-      - test-llvm10-go114
+      - test-llvm8-go111
+      - test-llvm8-go112
      - build-linux
      - build-macos
-      - assert-test-linux
@@ -12,5 +12,5 @@ src/device/sifive/*.s
 src/device/stm32/*.go
 src/device/stm32/*.s
 vendor
+llvm
 llvm-build
-llvm-project
@@ -9,14 +9,8 @@
 	url = https://github.com/avr-rust/avr-mcu.git
 [submodule "lib/cmsis-svd"]
 	path = lib/cmsis-svd
-	url = https://github.com/posborne/cmsis-svd
+	url = https://github.com/tinygo-org/cmsis-svd
 [submodule "lib/compiler-rt"]
 	path = lib/compiler-rt
 	url = https://github.com/llvm-mirror/compiler-rt.git
 	branch = release_80
-[submodule "lib/wasi-libc"]
-	path = lib/wasi-libc
-	url = https://github.com/CraneStation/wasi-libc
-[submodule "lib/picolibc"]
-	path = lib/picolibc
-	url = https://github.com/keith-packard/picolibc.git
@@ -16,6 +16,7 @@ LLVM, Clang and LLD are quite light on dependencies, requiring only standard
 build tools to be built. Go is of course necessary to build TinyGo itself.

  * Go (1.11+)
+  * [dep](https://golang.github.io/dep/)
  * Standard build tools (gcc/clang)
  * git
  * CMake
@@ -27,19 +28,15 @@ on a different system like Mac.
 ## Download the source

 The first step is to download the TinyGo sources (use `--recursive` if you clone
-the git repository). Then, inside the directory, download the LLVM source:
+the git repository). Then, inside the directory, perform these steps:

-    make llvm-source
+    dep ensure -vendor-only # download Go dependencies
+    make llvm-source        # download LLVM

 You can also store LLVM outside of the TinyGo root directory by setting the
 `LLVM_BUILDDIR`, `CLANG_SRC` and `LLD_SRC` make variables, but that is not
 covered by this guide.

-TinyGo uses Go modules, so if you clone TinyGo inside your GOPATH (and are using
-Go below 1.13), make sure that Go modules are enabled:
-
-    export GO111MODULE=on
-
 ## Build LLVM, Clang, LLD

 Before starting the build, you may want to set the following environment
@@ -1,332 +1,3 @@
-0.13.1
---
-* **standard library**
-  - `runtime`: do not put scheduler and GC code in the same section
-  - `runtime`: copy stack scan assembly for GBA
-* **boards**
-  - `gameboy-advance`: always use ARM mode instead of Thumb mode
-
-
-0.13.0
---
-* **command line**
-  - use `gdb-multiarch` for debugging Cortex-M chips
-  - support `tinygo run` with simavr
-  - support LLVM 10
-  - support Go 1.14
-  - retry 3 times when attempting to do a 1200-baud reset
-* **compiler**
-  - mark the `abort` function as noreturn
-  - fix deferred calls to exported functions
-  - add debug info for local variables
-  - check for channel size limit
-  - refactor coroutine lowering
-  - add `dereferenceable_or_null` attribute to pointer parameters
-  - do not perform nil checking when indexing slices and on `unsafe.Pointer`
-  - remove `runtime.isnil` hack
-  - use LLVM builtins for runtime `memcpy`/`memmove`/`memzero` functions
-  - implement spec-compliant shifts on negative/overflow
-  - support anonymous type asserts
-  - track pointer result of string concatenation for GC
-  - track PHI nodes for GC
-  - add debug info to goroutine start wrappers
-  - optimize comparing interface values against nil
-  - fix miscompilation when deferring an interface call
-  - builder: include picolibc for most baremetal targets
-  - builder: run tools (clang, lld) as separate processes
-  - builder: use `-fshort-enums` consistently
-  - interp: add support for constant type asserts
-  - interp: better support for interface operations
-  - interp: include backtrace with error
-  - transform: do not track const globals for GC
-  - transform: replace panics with source locations
-  - transform: fix error in interface lowering pass
-  - transform: make coroutine lowering deterministic
-  - transform: fix miscompilation in func lowering
-* **cgo**
-  - make `-I` and `-L` paths absolute
-* **standard library**
-  - `machine`: set the USB VID and PID to the manufacturer values
-  - `machine`: correct USB CDC composite descriptors
-  - `machine`: move `errors.New` calls to globals
-  - `runtime`: support operations on nil maps
-  - `runtime`: fix copy builtin return value on AVR
-  - `runtime`: refactor goroutines
-  - `runtime`: support `-scheduler=none` on most platforms
-  - `runtime`: run package initialization in the main goroutine
-  - `runtime`: export `malloc` / `free` for use from C
-  - `runtime`: add garbage collector that uses an external allocator
-  - `runtime`: scan callee-saved registers while marking the stack
-  - `runtime`: remove recursion from conservative GC
-  - `runtime`: fix blocking select on nil channel
-  - `runtime/volatile`: include `ReplaceBits` method
-  - `sync`: implement trivial `sync.Map`
-* **targets**
-  - `arm`: use `-fomit-frame-pointer`
-  - `atmega1284`: support this chip for testing purposes
-  - `atsamd51`: make QSPI available on all boards
-  - `atsamd51`: add support for ADC1
-  - `atsamd51`: use new interrupt registration in UART code
-  - `attiny`: clean up pin definitions
-  - `avr`: use the correct RAM start address
-  - `avr`: pass the correct `-mmcu` flag to the linker
-  - `avr`: add support for tasks scheduler (disabled by default)
-  - `avr`: fix linker problem with overlapping program/data areas
-  - `nrf`: fix typo in pin configuration options
-  - `nrf`: add lib/nrfx/mdk to include dirs
-  - `nrf52840`: implement USB-CDC
-  - `riscv`: implement VirtIO target and add RISC-V integration test
-  - `riscv`: add I2C support for the HiFive1 rev B board
-  - `stm32`: refactor GPIO pin handling
-  - `stm32`: refactor UART code
-  - `stm32f4`: add SPI
-  - `wasm`: support Go 1.14 (breaking previous versions)
-  - `wasm`: support `syscall/js.CopyBytesToJS`
-  - `wasm`: sync polyfills from Go 1.14.
-* **boards**
-  - `arduino-mega2560`: add the Arduino Mega 2560
-  - `clue-alpha`: add the Adafruit CLUE Alpha
-  - `gameboy-advance`: enable debugging with GDB
-  - `particle-argon`: add the Particle Argon board
-  - `particle-boron`: add the Particle Boron board
-  - `particle-xenon`: add the Particle Xenon board
-  - `reelboard`: add `reelboard-s140v7` SoftDevice target
-
-0.12.0
---
-* **command line**
-  - add initial FreeBSD support
-  - remove getting a serial port in gdb subcommand
-  - add support for debugging through JLinkGDBServer
-  - fix CGo when cross compiling
-  - remove default port check for Digispark as micronucleus communicates directly using HID
-  - differentiate between various serial/USB error messages
-* **builder**
-  - improve detection of Clang headers
-* **compiler**
-  - fix assertion on empty interface
-  - don't crash when encountering `types.Invalid`
-  - revise defer to use heap allocations when running a variable number of times
-  - improve error messages for failed imports
-  - improve "function redeclared" error
-  - add globaldce pass to start of optimization pipeline
-  - add support for debugging globals
-  - implement RISC-V CSR operations as intrinsics
-  - add support for CGO_ENABLED environment variable
-  - do not emit debug info for extern globals (bugfix)
-  - add support for interrupts
-  - implement maps for arbitrary keys
-  - interp: error location for "unknown GEP" error
-  - wasm-abi: create temporary allocas in the entry block
-* **cgo**
-  - add support for symbols in `#define`
-  - fix a bug in number tokenization
-* **standard library**
-  - `machine`: avoid bytes package in USB logic
-  - `runtime`: fix external address declarations
-  - `runtime`: provide implementation for `internal/bytealg.IndexByte`
-* **targets**
-  - `atsamd51`: fix volatile usage
-  - `atsamd51`: fix ADC, updating to 12-bits precision
-  - `atsamd51`: refactor SPI pin configuration to only look at pin numbers
-  - `atsamd51`: switch UART to use new pin configuration
-  - `atsamd51`: fix obvious bug in I2C code
-  - `atsamd51`: use only the necessary UART interrupts
-  - `atsamd51`: refactor I2C pin handling to auto-detect pin mode
-  - `avr`: use a garbage collector
-  - `fe310`: use CLINT peripheral for timekeeping
-  - `fe310`: add support for PLIC interrupts
-  - `fe310`: implement UART receive interrupts
-  - `riscv`: support sleeping in QEMU
-  - `riscv`: add bare-bones interrupt support
-  - `riscv`: print exception PC and code
-  - `wasm`: implement memcpy and memset
-  - `wasm`: include wasi-libc
-  - `wasm`: use wasi ABI for basic startup/stdout
-* **boards**
-  - `arduino`: make avrdude command line compatible with Windows
-  - `arduino-nano`: add this board
-  - `arduino-nano33`: fix UART1 and UART2
-  - `circuitplay-bluefruit`: add this board
-  - `digispark`: add clock speed and pin mappings
-  - `gameboy-advance`: include compiler-rt in build
-  - `gameboy-advance`: implement interrupt handler
-  - `hifive1b`: add support for gdb subcommand
-  - `pyportal`: add this board
-  - `pyportal`: remove manual SPI pin mapping as now handled by default
-
-
-0.11.0
---
-* **command line**
-  - add support for QEMU in `gdb` subcommand
-  - use builtin Clang when building statically, dropping the clang-9 dependency
-  - search for default serial port on both macOS and Linux
-  - windows: support `tinygo flash` directly by using win32 wmi
-* **compiler**
-  - add location information to the IR checker
-  - make reflection sidetables constant globals
-  - improve error locations in goroutine lowering
-  - interp: improve support for maps with string keys
-  - interp: add runtime fallback for mapassign operations
-* **standard library**
-  - `machine`: add support for `SPI.Tx()` on play.tinygo.org
-  - `machine`: rename `CPU_FREQUENCY` to `CPUFrequency()`
-* **targets**
-  - `adafruit-pybadge`: add Adafruit Pybadge
-  - `arduino-nano33`: allow simulation on play.tinygo.org
-  - `arduino-nano33`: fix default SPI pin numbers to be D13/D11/D12
-  - `circuitplay-express`: allow simulation on play.tinygo.org
-  - `hifive1-qemu`: add target for testing RISC-V bare metal in QEMU
-  - `riscv`: fix heap corruption due to changes in LLVM 9
-  - `riscv`: add support for compiler-rt
-  - `qemu`: rename to `cortex-m-qemu`
-
-0.10.0
---
-* **command line**
-  - halt GDB after flashing with `gdb` subcommand
-  - fix a crash when using `-ocd-output`
-  - add `info` subcommand
-  - add `-programmer` flag
-* **builder**
-  - macos: use llvm@8 instead of just llvm in paths
-  - add `linkerscript` key to target JSON files
-  - write a symbol table when writing out the compiler-rt lib
-  - make Clang header detection more robust
-  - switch to LLVM 9
-* **compiler**
-  - fix interface miscompilation with reflect
-  - fix miscompile of static goroutine calls to closures
-  - fix `todo: store` panic
-  - fix incorrect starting value for optimized allocations in a loop
-  - optimize coroutines on non-Cortex-M targets
-  - fix crash for programs which have heap allocations but never hit the GC
-  - add support for async interface calls
-  - fix inserting non-const values in a const global
-  - interp: improve error reporting
-  - interp: implement comparing ptrtoint to 0
-* **cgo**
-  - improve diagnostics
-  - implement the constant parser (for `#define`) as a real parser
-  - rename reserved field names such as `type`
-  - avoid `"unsafe" imported but not used` error
-  - include all enums in the CGo Go AST
-  - add support for nested structs and unions
-  - implement `#cgo CFLAGS`
-* **standard library**
-  - `reflect`: add implementation of array alignment
-  - `runtime`: improve scheduler performance when no goroutines are queued
-  - `runtime`: add blocking select
-  - `runtime`: implement interface equality in non-trivial cases
-  - `runtime`: add AdjustTimeOffset to update current time
-  - `runtime`: only implement CountString for required platforms
-  - `runtime`: use MSP/PSP registers for scheduling on Cortex-M
-* **targets**
-  - `arm`: add system timer registers
-  - `atmega`: add port C GPIO support
-  - `atsamd21`: correct handling of pins >= 32
-  - `atsamd21`: i2s initialization fixes
-  - `atsamd51`: fix clock init code
-  - `atsamd51`: correct initialization for RTC
-  - `atsamd51`: fix pin function selection
-  - `atsamd51`: pin method cleanup
-  - `atsamd51`: allow setting pin mode for each of the SPI pins
-  - `atsamd51`: correct channel init and pin map for ADC based on ItsyBitsy-M4
-  - `feather-m4`: add Adafruit Feather M4 board
-  - `hifive1b`: add support for SPI1
-  - `hifive1b`: fix compiling in simulation
-  - `linux`: fix time on arm32
-  - `metro-m4`: add support for Adafruit Metro M4 Express Airlift board
-  - `metro-m4`: fixes for UART2
-  - `pinetime-devkit0`: add support for the PineTime dev kit
-  - `x9pro`: add support for this smartwatch
-  - `pca10040-s132v6`: add support for SoftDevice
-  - `pca10056-s140v7`: add support for SoftDevice
-  - `arduino-nano33`: added SPI1 connected to NINA-W102 chip on Arduino Nano 33 IOT
-
-0.9.0
---
-* **command line**
-  - implement 1200-baud UART bootloader reset when flashing boards that support
-    it
-  - flash using mass-storage device for boards that support it
-  - implement `tinygo env`
-  - add support for Windows (but not yet producing Windows binaries)
-  - add Go version to `tinygo env`
-  - update SVD files for up-to-date peripheral interfaces
-* **compiler**
-  - add `//go:align` pragma
-  - fix bug related to type aliases
-  - add support for buffered channels
-  - remove incorrect reflect optimization
-  - implement copying slices in init interpretation
-  - add support for constant indices with a named type
-  - add support for recursive types like linked lists
-  - fix miscompile of function nil panics
-  - fix bug related to goroutines
-* **standard library**
-  - `machine`: do not check for nil slices in `SPI.Tx`
-  - `reflectlite`: add support for Go 1.13
-  - `runtime`: implement `internal/bytealg.CountString`
-  - `sync`: properly handle nil `New` func in `sync.Pool`
-* **targets**
-  - `arduino`: fix .bss section initialization
-  - `fe310`: implement `Pin.Get`
-  - `gameboy-advance`: support directly outputting .gba files
-  - `samd`: reduce code size by avoiding reflection
-  - `samd21`: do not hardcode pin numbers for peripherals
-  - `stm32f103`: avoid issue with `time.Sleep` less than 200µs
-
-0.8.0
---
-* **command line**
-  - fix parsing of beta Go versions
-  - check the major/minor installed version of Go before compiling
-  - validate `-target` flag better to not panic on an invalid target
-* **compiler**
-  - implement full slice expression: `s[:2:4]`
-  - fix a crash when storing a linked list in an interface
-  - fix comparing struct types by making type IDs more unique
-  - fix some bugs in IR generation
-  - add support for linked lists in reflect data
-  - implement `[]rune` to string conversion
-  - implement support for `go` on func values
-* **standard library**
-  - `reflect`: add support for named types
-  - `reflect`: add support for `t.Bits()`
-  - `reflect`: add basic support for `t.AssignableTo()`
-  - `reflect`: implement `t.Align()`
-  - `reflect`: add support for struct types
-  - `reflect`: fix bug in `v.IsNil` and `v.Pointer` for addressable values
-  - `reflect`: implement support for array types
-  - `reflect`: implement `t.Comparable()`
-  - `runtime`: implement stack-based scheduler
-  - `runtime`: fix bug in the sleep queue of the scheduler
-  - `runtime`: implement `memcpy` for Cortex-M
-  - `testing`: implement stub `testing.B` struct
-  - `testing`: add common test logging methods such as Errorf/Fatalf/Printf
-* **targets**
-  - `386`: add support for linux/386 syscalls
-  - `atsamd21`: make SPI pins configurable so that multiple SPI ports can be
-    used
-  - `atsamd21`: correct issue with invalid first reading coming from ADC
-  - `atsamd21`: add support for reset-to-bootloader using 1200baud over USB-CDC
-  - `atsamd21`: make pin selection more flexible for peripherals
-  - `atsamd21`: fix minimum delay in `time.Sleep`
-  - `atsamd51`: fix minimum delay in `time.Sleep`
-  - `nrf`: improve SPI write-only speed, by making use of double buffering
-  - `stm32f103`: fix SPI frequency selection
-  - `stm32f103`: add machine.Pin.Get method for reading GPIO values
-  - `stm32f103`: allow board specific UART usage
-  - `nucleo-f103rb`: add support for NUCLEO-F103RB board
-  - `itsybitsy-m4`: add support for this board with a SAMD51 family chip
-  - `cortex-m`: add support for `arm.SystemReset()`
-  - `gameboy-advance`: add initial support for the GameBoy Advance
-  - `wasm`: add `//go:wasm-module` magic comment to set the wasm module name
-  - `wasm`: add syscall/js.valueSetIndex support
-  - `wasm`: add syscall/js.valueInvoke support
-
 0.7.1
 ---
 * **targets**
@@ -1,76 +0,0 @@
-# Contributor Covenant Code of Conduct
-
-## Our Pledge
-
-In the interest of fostering an open and welcoming environment, we as
-contributors and maintainers pledge to make participation in our project and
-our community a harassment-free experience for everyone, regardless of age, body
-size, disability, ethnicity, sex characteristics, gender identity and expression,
-level of experience, education, socio-economic status, nationality, personal
-appearance, race, religion, or sexual identity and orientation.
-
-## Our Standards
-
-Examples of behavior that contributes to creating a positive environment
-include:
-
-* Using welcoming and inclusive language
-* Being respectful of differing viewpoints and experiences
-* Gracefully accepting constructive criticism
-* Focusing on what is best for the community
-* Showing empathy towards other community members
-
-Examples of unacceptable behavior by participants include:
-
-* The use of sexualized language or imagery and unwelcome sexual attention or
-  advances
-* Trolling, insulting/derogatory comments, and personal or political attacks
-* Public or private harassment
-* Publishing others' private information, such as a physical or electronic
-  address, without explicit permission
-* Other conduct which could reasonably be considered inappropriate in a
-  professional setting
-
-## Our Responsibilities
-
-Project maintainers are responsible for clarifying the standards of acceptable
-behavior and are expected to take appropriate and fair corrective action in
-response to any instances of unacceptable behavior.
-
-Project maintainers have the right and responsibility to remove, edit, or
-reject comments, commits, code, wiki edits, issues, and other contributions
-that are not aligned to this Code of Conduct, or to ban temporarily or
-permanently any contributor for other behaviors that they deem inappropriate,
-threatening, offensive, or harmful.
-
-## Scope
-
-This Code of Conduct applies within all project spaces, and it also applies when
-an individual is representing the project or its community in public spaces.
-Examples of representing a project or community include using an official
-project e-mail address, posting via an official social media account, or acting
-as an appointed representative at an online or offline event. Representation of
-a project may be further defined and clarified by project maintainers.
-
-## Enforcement
-
-Instances of abusive, harassing, or otherwise unacceptable behavior may be
-reported by contacting the project team at [conduct@tinygo.org](mailto:conduct@tinygo.org). All
-complaints will be reviewed and investigated and will result in a response that
-is deemed necessary and appropriate to the circumstances. The project team is
-obligated to maintain confidentiality with regard to the reporter of an incident.
-Further details of specific enforcement policies may be posted separately.
-
-Project maintainers who do not follow or enforce the Code of Conduct in good
-faith may face temporary or permanent repercussions as determined by other
-members of the project's leadership.
-
-## Attribution
-
-This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
-available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
-
-[homepage]: https://www.contributor-covenant.org
-
-For answers to common questions about this code of conduct, see
-https://www.contributor-covenant.org/faq
@@ -15,4 +15,3 @@ Ayke van Laethem <aykevanlaethem@gmail.com>
 Daniel Esteban <conejo@conejo.me>
 Loon, LLC.
 Ron Evans <ron@hybridgroup.com>
-Jaden Weiss <jaden@jadendw.dev>
@@ -1,51 +1,52 @@
-# TinyGo base stage installs Go 1.14, LLVM 10 and the TinyGo compiler itself.
-FROM golang:1.14 AS tinygo-base
+# TinyGo base stage just installs LLVM 8 and the TinyGo compiler itself.
+FROM golang:latest AS tinygo-base

 RUN wget -O- https://apt.llvm.org/llvm-snapshot.gpg.key| apt-key add - && \
-    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main" >> /etc/apt/sources.list && \
+    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-8 main" >> /etc/apt/sources.list && \
    apt-get update && \
-    apt-get install -y llvm-10-dev libclang-10-dev git
+    apt-get install -y llvm-8-dev libclang-8-dev git

-COPY . /tinygo
+RUN wget -O- https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
+
+COPY . /go/src/github.com/tinygo-org/tinygo

 # remove submodules directories and re-init them to fix any hard-coded paths
 # after copying the tinygo directory in the previous step.
-RUN cd /tinygo/ && \
+RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
    rm -rf ./lib/* && \
-    git submodule sync && \
    git submodule update --init --recursive --force

-COPY ./lib/picolibc-include/* /tinygo/lib/picolibc-include/
-
-RUN cd /tinygo/ && \
-    go install /tinygo/
+RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
+    dep ensure --vendor-only && \
+    go install /go/src/github.com/tinygo-org/tinygo/

 # tinygo-wasm stage installs the needed dependencies to compile TinyGo programs for WASM.
 FROM tinygo-base AS tinygo-wasm

 COPY --from=tinygo-base /go/bin/tinygo /go/bin/tinygo
-COPY --from=tinygo-base /tinygo/src /tinygo/src
-COPY --from=tinygo-base /tinygo/targets /tinygo/targets
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/src /go/src/github.com/tinygo-org/tinygo/src
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/targets /go/src/github.com/tinygo-org/tinygo/targets

 RUN wget -O- https://apt.llvm.org/llvm-snapshot.gpg.key| apt-key add - && \
-    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main" >> /etc/apt/sources.list && \
+    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-8 main" >> /etc/apt/sources.list && \
    apt-get update && \
-    apt-get install -y libllvm10 lld-10
+    apt-get install -y libllvm8 lld-8

 # tinygo-avr stage installs the needed dependencies to compile TinyGo programs for AVR microcontrollers.
 FROM tinygo-base AS tinygo-avr

 COPY --from=tinygo-base /go/bin/tinygo /go/bin/tinygo
-COPY --from=tinygo-base /tinygo/src /tinygo/src
-COPY --from=tinygo-base /tinygo/targets /tinygo/targets
-COPY --from=tinygo-base /tinygo/Makefile /tinygo/
-COPY --from=tinygo-base /tinygo/tools /tinygo/tools
-COPY --from=tinygo-base /tinygo/lib /tinygo/lib
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/src /go/src/github.com/tinygo-org/tinygo/src
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/targets /go/src/github.com/tinygo-org/tinygo/targets
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/Makefile /go/src/github.com/tinygo-org/tinygo/
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/tools /go/src/github.com/tinygo-org/tinygo/tools
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/lib /go/src/github.com/tinygo-org/tinygo/lib

-RUN cd /tinygo/ && \
+RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make binutils-avr gcc-avr avr-libc && \
+    apt-get install -y apt-utils python3 make binutils-avr gcc-avr avr-libc && \
    make gen-device-avr && \
+    apt-get remove -y python3 && \
    apt-get autoremove -y && \
    apt-get clean

@@ -53,27 +54,33 @@ RUN cd /tinygo/ && \
 FROM tinygo-base AS tinygo-arm

 COPY --from=tinygo-base /go/bin/tinygo /go/bin/tinygo
-COPY --from=tinygo-base /tinygo/src /tinygo/src
-COPY --from=tinygo-base /tinygo/targets /tinygo/targets
-COPY --from=tinygo-base /tinygo/Makefile /tinygo/
-COPY --from=tinygo-base /tinygo/tools /tinygo/tools
-COPY --from=tinygo-base /tinygo/lib /tinygo/lib
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/src /go/src/github.com/tinygo-org/tinygo/src
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/targets /go/src/github.com/tinygo-org/tinygo/targets
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/Makefile /go/src/github.com/tinygo-org/tinygo/
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/tools /go/src/github.com/tinygo-org/tinygo/tools
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/lib /go/src/github.com/tinygo-org/tinygo/lib

-RUN cd /tinygo/ && \
+RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make clang-10 && \
-    make gen-device-nrf && make gen-device-stm32
+    apt-get install -y apt-utils python3 make clang-8 && \
+    make gen-device-nrf && make gen-device-stm32 && \
+    apt-get remove -y python3 && \
+    apt-get autoremove -y && \
+    apt-get clean

 # tinygo-all stage installs the needed dependencies to compile TinyGo programs for all platforms.
 FROM tinygo-wasm AS tinygo-all

-COPY --from=tinygo-base /tinygo/Makefile /tinygo/
-COPY --from=tinygo-base /tinygo/tools /tinygo/tools
-COPY --from=tinygo-base /tinygo/lib /tinygo/lib
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/Makefile /go/src/github.com/tinygo-org/tinygo/
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/tools /go/src/github.com/tinygo-org/tinygo/tools
+COPY --from=tinygo-base /go/src/github.com/tinygo-org/tinygo/lib /go/src/github.com/tinygo-org/tinygo/lib

-RUN cd /tinygo/ && \
+RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make clang-10 binutils-avr gcc-avr avr-libc && \
-    make gen-device
+    apt-get install -y apt-utils python3 make clang-8 binutils-avr gcc-avr avr-libc && \
+    make gen-device && \
+    apt-get remove -y python3 && \
+    apt-get autoremove -y && \
+    apt-get clean

 CMD ["tinygo"]
@@ -0,0 +1,51 @@
+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  branch = "master"
+  digest = "1:06519a2ec1d59040eaccec40206f9d0b59dc662db2a032f974d6d6b9a2bcb839"
+  name = "github.com/blakesmith/ar"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "8bd4349a67f2533b078dbc524689d15dba0f4659"
+
+[[projects]]
+  branch = "master"
+  digest = "1:00b45e06c7843541372fc17d982242bd6adfc2fc382b6f2e9ef9ce53d87a50b9"
+  name = "github.com/marcinbor85/gohex"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "7a43cd876e46e0f6ddc553f10f91731a78e6e949"
+
+[[projects]]
+  branch = "master"
+  digest = "1:ba70784a3deee74c0ca3c87bcac3c2f93d3b2d27d8f237b768c358b45ba47da8"
+  name = "golang.org/x/tools"
+  packages = [
+    "go/ast/astutil",
+    "go/ssa",
+    "go/types/typeutil",
+  ]
+  pruneopts = "UT"
+  revision = "8dcc6e70cdefe9a82236b6e195e4f4e2108fcb9f"
+
+[[projects]]
+  branch = "llvm8"
+  digest = "1:bf5539bdf6b3cc3ec1e45926db05d81180da11ce722fa1edcce3f0b4e1967da5"
+  name = "tinygo.org/x/go-llvm"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "7707ae5d1261a8929edea7336c8087ca8b520d8d"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  input-imports = [
+    "github.com/blakesmith/ar",
+    "github.com/marcinbor85/gohex",
+    "golang.org/x/tools/go/ast/astutil",
+    "golang.org/x/tools/go/ssa",
+    "tinygo.org/x/go-llvm",
+  ]
+  solver-name = "gps-cdcl"
+  solver-version = 1
@@ -0,0 +1,11 @@
+[[constraint]]
+  branch = "llvm8"
+  name = "tinygo.org/x/go-llvm"
+
+[[constraint]]
+  branch = "master"
+  name = "golang.org/x/tools"
+
+[prune]
+  go-tests = true
+  unused-packages = true
@@ -1,10 +1,7 @@
-Copyright (c) 2018-2020 TinyGo Authors. All rights reserved.
+Copyright (c) 2018-2019 TinyGo Authors. All rights reserved.

 TinyGo includes portions of the Go standard library.
-Copyright (c) 2009-2020 The Go Authors. All rights reserved.
-
-TinyGo includes portions of LLVM, which is under the Apache License v2.0 with
-LLVM Exceptions. See https://llvm.org/LICENSE.txt for license information.
+Copyright (c) 2009-2019 The Go Authors. All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
@@ -1,117 +1,40 @@

 # aliases
 all: tinygo
+tinygo: build/tinygo

 # Default build and source directories, as created by `make llvm-build`.
 LLVM_BUILDDIR ?= llvm-build
-LLVM_PROJECTDIR ?= llvm-project
-CLANG_SRC ?= $(LLVM_PROJECTDIR)/clang
-LLD_SRC ?= $(LLVM_PROJECTDIR)/lld
+CLANG_SRC ?= llvm-project/clang
+LLD_SRC ?= llvm-project/lld

-# Try to autodetect LLVM build tools.
-ifneq (, $(shell command -v llvm-build/bin/clang 2> /dev/null))
-    CLANG ?= $(abspath llvm-build/bin/clang)
-else
-    CLANG ?= clang-10
-endif
-ifneq (, $(shell command -v llvm-build/bin/llvm-ar 2> /dev/null))
-    LLVM_AR ?= $(abspath llvm-build/bin/llvm-ar)
-else ifneq (, $(shell command -v llvm-ar-10 2> /dev/null))
-    LLVM_AR ?= llvm-ar-10
-else
-    LLVM_AR ?= llvm-ar
-endif
-ifneq (, $(shell command -v llvm-build/bin/llvm-nm 2> /dev/null))
-    LLVM_NM ?= $(abspath llvm-build/bin/llvm-nm)
-else ifneq (, $(shell command -v llvm-nm-10 2> /dev/null))
-    LLVM_NM ?= llvm-nm-10
-else
-    LLVM_NM ?= llvm-nm
-endif
+.PHONY: all tinygo build/tinygo test $(LLVM_BUILDDIR) llvm-source clean fmt gen-device gen-device-nrf gen-device-avr

-# Go binary and GOROOT to select
-GO ?= go
-export GOROOT = $(shell $(GO) env GOROOT)
+LLVM_COMPONENTS = all-targets analysis asmparser asmprinter bitreader bitwriter codegen core coroutines debuginfodwarf executionengine instrumentation interpreter ipo irreader linker lto mc mcjit objcarcopts option profiledata scalaropts support target

-# md5sum binary
-MD5SUM = md5sum
-
-# tinygo binary for tests
-TINYGO ?= tinygo
-
-# Use CCACHE for LLVM if possible
-ifneq (, $(shell command -v ccache 2> /dev/null))
-    LLVM_OPTION += '-DLLVM_CCACHE_BUILD=ON'
-endif
-
-# Allow enabling LLVM assertions
-ifeq (1, $(ASSERT))
-    LLVM_OPTION += '-DLLVM_ENABLE_ASSERTIONS=ON'
-else
-    LLVM_OPTION += '-DLLVM_ENABLE_ASSERTIONS=OFF'
-endif
-
-.PHONY: all tinygo test $(LLVM_BUILDDIR) llvm-source clean fmt gen-device gen-device-nrf gen-device-avr
-
-LLVM_COMPONENTS = all-targets analysis asmparser asmprinter bitreader bitwriter codegen core coroutines coverage debuginfodwarf executionengine frontendopenmp instrumentation interpreter ipo irreader linker lto mc mcjit objcarcopts option profiledata scalaropts support target
-
-ifeq ($(OS),Windows_NT)
-    EXE = .exe
-    START_GROUP = -Wl,--start-group
-    END_GROUP = -Wl,--end-group
-
-    # LLVM compiled using MinGW on Windows appears to have problems with threads.
-    # Without this flag, linking results in errors like these:
-    #     libLLVMSupport.a(Threading.cpp.obj):Threading.cpp:(.text+0x55): undefined reference to `std::thread::hardware_concurrency()'
-    LLVM_OPTION += -DLLVM_ENABLE_THREADS=OFF
-
-    CGO_LDFLAGS += -static -static-libgcc -static-libstdc++
-    CGO_LDFLAGS_EXTRA += -lversion
-
-    # Build libclang manually because the CMake-based build system on Windows
-    # doesn't allow building libclang as a static library.
-    LIBCLANG_PATH = $(abspath build/libclang-custom.a)
-    LIBCLANG_FILES = $(abspath $(wildcard $(LLVM_BUILDDIR)/tools/clang/tools/libclang/CMakeFiles/libclang.dir/*.cpp.obj))
-
-    # Add the libclang dependency to the tinygo binary target.
-tinygo: $(LIBCLANG_PATH)
-test: $(LIBCLANG_PATH)
-    # Build libclang.
-$(LIBCLANG_PATH): $(LIBCLANG_FILES)
-	@mkdir -p build
-	ar rcs $(LIBCLANG_PATH) $^
-
-else ifeq ($(shell uname -s),Darwin)
-    MD5SUM = md5
-    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
-else ifeq ($(shell uname -s),FreeBSD)
-    MD5SUM = md5
-    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
-    START_GROUP = -Wl,--start-group
-    END_GROUP = -Wl,--end-group
-else
-    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
+UNAME_S := $(shell uname -s)
+ifeq ($(UNAME_S),Linux)
    START_GROUP = -Wl,--start-group
    END_GROUP = -Wl,--end-group
 endif

-CLANG_LIBS = $(START_GROUP) -lclangAnalysis -lclangARCMigrate -lclangAST -lclangASTMatchers -lclangBasic -lclangCodeGen -lclangCrossTU -lclangDriver -lclangDynamicASTMatchers -lclangEdit -lclangFormat -lclangFrontend -lclangFrontendTool -lclangHandleCXX -lclangHandleLLVM -lclangIndex -lclangLex -lclangParse -lclangRewrite -lclangRewriteFrontend -lclangSema -lclangSerialization -lclangStaticAnalyzerCheckers -lclangStaticAnalyzerCore -lclangStaticAnalyzerFrontend -lclangTooling -lclangToolingASTDiff -lclangToolingCore -lclangToolingInclusions $(END_GROUP) -lstdc++
+CLANG_LIBS = $(START_GROUP) $(abspath $(LLVM_BUILDDIR))/lib/libclang.a -lclangAnalysis -lclangARCMigrate -lclangAST -lclangASTMatchers -lclangBasic -lclangCodeGen -lclangCrossTU -lclangDriver -lclangDynamicASTMatchers -lclangEdit -lclangFormat -lclangFrontend -lclangFrontendTool -lclangHandleCXX -lclangHandleLLVM -lclangIndex -lclangLex -lclangParse -lclangRewrite -lclangRewriteFrontend -lclangSema -lclangSerialization -lclangStaticAnalyzerCheckers -lclangStaticAnalyzerCore -lclangStaticAnalyzerFrontend -lclangTooling -lclangToolingASTDiff -lclangToolingCore -lclangToolingInclusions $(END_GROUP) -lstdc++

 LLD_LIBS = $(START_GROUP) -llldCOFF -llldCommon -llldCore -llldDriver -llldELF -llldMachO -llldMinGW -llldReaderWriter -llldWasm -llldYAML $(END_GROUP)


 # For static linking.
-ifneq ("$(wildcard $(LLVM_BUILDDIR)/bin/llvm-config*)","")
-    CGO_CPPFLAGS=$(shell $(LLVM_BUILDDIR)/bin/llvm-config --cppflags) -I$(abspath $(LLVM_BUILDDIR))/tools/clang/include -I$(abspath $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
-    CGO_CXXFLAGS=-std=c++14
-    CGO_LDFLAGS+=$(LIBCLANG_PATH) -std=c++14 -L$(abspath $(LLVM_BUILDDIR)/lib) $(CLANG_LIBS) $(LLD_LIBS) $(shell $(LLVM_BUILDDIR)/bin/llvm-config --ldflags --libs --system-libs $(LLVM_COMPONENTS)) -lstdc++ $(CGO_LDFLAGS_EXTRA)
+ifneq ("$(wildcard $(LLVM_BUILDDIR)/bin/llvm-config)","")
+    CGO_CPPFLAGS=$(shell $(LLVM_BUILDDIR)/bin/llvm-config --cppflags) -I$(abspath $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
+    CGO_CXXFLAGS=-std=c++11
+    CGO_LDFLAGS=-L$(LLVM_BUILDDIR)/lib $(CLANG_LIBS) $(LLD_LIBS) $(shell $(LLVM_BUILDDIR)/bin/llvm-config --ldflags --libs --system-libs $(LLVM_COMPONENTS))
 endif


 clean:
 	@rm -rf build

-FMT_PATHS = ./*.go builder cgo compiler interp ir loader src/device/arm src/examples src/machine src/os src/reflect src/runtime src/sync src/syscall src/internal/reflectlite transform
+FMT_PATHS = ./*.go cgo compiler interp ir loader src/device/arm src/examples src/machine src/os src/reflect src/runtime src/sync src/syscall
 fmt:
 	@gofmt -l -w $(FMT_PATHS)
 fmt-check:
@@ -121,208 +44,108 @@ fmt-check:
 gen-device: gen-device-avr gen-device-nrf gen-device-sam gen-device-sifive gen-device-stm32

 gen-device-avr:
-	$(GO) build -o ./build/gen-device-avr ./tools/gen-device-avr/
-	./build/gen-device-avr lib/avr/packs/atmega src/device/avr/
-	./build/gen-device-avr lib/avr/packs/tiny src/device/avr/
-	@GO111MODULE=off $(GO) fmt ./src/device/avr
+	./tools/gen-device-avr.py lib/avr/packs/atmega src/device/avr/
+	./tools/gen-device-avr.py lib/avr/packs/tiny src/device/avr/
+	go fmt ./src/device/avr

-build/gen-device-svd: ./tools/gen-device-svd/*.go
-	$(GO) build -o $@ ./tools/gen-device-svd/
+gen-device-nrf:
+	./tools/gen-device-svd.py lib/nrfx/mdk/ src/device/nrf/ --source=https://github.com/NordicSemiconductor/nrfx/tree/master/mdk
+	go fmt ./src/device/nrf

-gen-device-nrf: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/NordicSemiconductor/nrfx/tree/master/mdk lib/nrfx/mdk/ src/device/nrf/
-	GO111MODULE=off $(GO) fmt ./src/device/nrf
+gen-device-sam:
+	./tools/gen-device-svd.py lib/cmsis-svd/data/Atmel/ src/device/sam/ --source=https://github.com/posborne/cmsis-svd/tree/master/data/Atmel
+	go fmt ./src/device/sam

-gen-device-sam: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/Atmel lib/cmsis-svd/data/Atmel/ src/device/sam/
-	GO111MODULE=off $(GO) fmt ./src/device/sam
+gen-device-sifive:
+	./tools/gen-device-svd.py lib/cmsis-svd/data/SiFive-Community/ src/device/sifive/ --source=https://github.com/AdaCore/svd2ada/tree/master/CMSIS-SVD/SiFive-Community
+	go fmt ./src/device/sifive

-gen-device-sifive: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/SiFive-Community -interrupts=software lib/cmsis-svd/data/SiFive-Community/ src/device/sifive/
-	GO111MODULE=off $(GO) fmt ./src/device/sifive
-
-gen-device-stm32: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/STMicro lib/cmsis-svd/data/STMicro/ src/device/stm32/
-	GO111MODULE=off $(GO) fmt ./src/device/stm32
+gen-device-stm32:
+	./tools/gen-device-svd.py lib/cmsis-svd/data/STMicro/ src/device/stm32/ --source=https://github.com/posborne/cmsis-svd/tree/master/data/STMicro
+	go fmt ./src/device/stm32


 # Get LLVM sources.
-$(LLVM_PROJECTDIR)/README.md:
-	git clone -b release/10.x https://github.com/llvm/llvm-project $(LLVM_PROJECTDIR)
-llvm-source: $(LLVM_PROJECTDIR)/README.md
+llvm-project/README.md:
+	git clone -b release/8.x https://github.com/llvm/llvm-project
+llvm-source: llvm-project/README.md

 # Configure LLVM.
 TINYGO_SOURCE_DIR=$(shell pwd)
 $(LLVM_BUILDDIR)/build.ninja: llvm-source
-	mkdir -p $(LLVM_BUILDDIR); cd $(LLVM_BUILDDIR); cmake -G Ninja $(TINYGO_SOURCE_DIR)/$(LLVM_PROJECTDIR)/llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;RISCV;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR" -DCMAKE_BUILD_TYPE=Release -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF $(LLVM_OPTION)
+	mkdir -p $(LLVM_BUILDDIR); cd $(LLVM_BUILDDIR); cmake -G Ninja $(TINYGO_SOURCE_DIR)/llvm-project/llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR;RISCV" -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=OFF -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF

 # Build LLVM.
 $(LLVM_BUILDDIR): $(LLVM_BUILDDIR)/build.ninja
 	cd $(LLVM_BUILDDIR); ninja


-# Build wasi-libc sysroot
-.PHONY: wasi-libc
-wasi-libc: lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a
-lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a:
-	cd lib/wasi-libc && make -j4 WASM_CC=$(CLANG) WASM_AR=$(LLVM_AR) WASM_NM=$(LLVM_NM)
-
-
 # Build the Go compiler.
-tinygo:
+build/tinygo:
 	@if [ ! -f "$(LLVM_BUILDDIR)/bin/llvm-config" ]; then echo "Fetch and build LLVM first by running:"; echo "  make llvm-source"; echo "  make $(LLVM_BUILDDIR)"; exit 1; fi
-	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) build -o build/tinygo$(EXE) -tags byollvm .
+	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" go build -o build/tinygo -tags byollvm .

-test: wasi-libc
-	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) test -v -tags byollvm ./cgo ./compileopts ./interp ./transform .
+test:
+	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" go test -v -tags byollvm .

 tinygo-test:
 	cd tests/tinygotest && tinygo test

 .PHONY: smoketest
 smoketest:
-	$(TINYGO) version
 	# test all examples
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/adc
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/blinkm
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/blinky2
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/button
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/button2
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/echo
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/i2s
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/mcp3008
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=microbit            examples/microbit-blink
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/pwm
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/serial
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/systick
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/test
-	@$(MD5SUM) test.hex
-	# test simulated boards on play.tinygo.org
-	$(TINYGO) build             -o test.wasm -tags=arduino              examples/blinky1
-	@$(MD5SUM) test.wasm
-	$(TINYGO) build             -o test.wasm -tags=hifive1-qemu         examples/serial
-	@$(MD5SUM) test.wasm
-	$(TINYGO) build             -o test.wasm -tags=hifive1b             examples/blinky1
-	@$(MD5SUM) test.wasm
-	$(TINYGO) build             -o test.wasm -tags=reelboard            examples/blinky1
-	@$(MD5SUM) test.wasm
-	$(TINYGO) build             -o test.wasm -tags=pca10040             examples/blinky2
-	@$(MD5SUM) test.wasm
-	$(TINYGO) build             -o test.wasm -tags=pca10056             examples/blinky2
-	@$(MD5SUM) test.wasm
-	$(TINYGO) build             -o test.wasm -tags=circuitplay_express  examples/blinky1
-	@$(MD5SUM) test.wasm
+	tinygo build -size short -o test.elf -target=pca10040            examples/blinky1
+	tinygo build -size short -o test.elf -target=pca10040            examples/adc
+	tinygo build -size short -o test.elf -target=pca10040            examples/blinkm
+	tinygo build -size short -o test.elf -target=pca10040            examples/blinky2
+	tinygo build -size short -o test.elf -target=pca10040            examples/button
+	tinygo build -size short -o test.elf -target=pca10040            examples/button2
+	tinygo build -size short -o test.elf -target=pca10040            examples/echo
+	tinygo build -size short -o test.elf -target=circuitplay-express examples/i2s
+	tinygo build -size short -o test.elf -target=pca10040            examples/mcp3008
+	tinygo build -size short -o test.elf -target=microbit            examples/microbit-blink
+	tinygo build -size short -o test.elf -target=pca10040            examples/pwm
+	tinygo build -size short -o test.elf -target=pca10040            examples/serial
+	tinygo build -size short -o test.elf -target=pca10040            examples/test
 	# test all targets/boards
-	$(TINYGO) build -size short -o test.hex -target=pca10040-s132v6     examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=microbit            examples/echo
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=nrf52840-mdk        examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10031            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=bluepill            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=reelboard           examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=reelboard           examples/blinky2
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10056            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10056            examples/blinky2
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=feather-m0          examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=trinket-m0          examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=stm32f4disco        examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=stm32f4disco        examples/blinky2
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=circuitplay-bluefruit examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/i2s
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=clue_alpha          examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.gba -target=gameboy-advance     examples/gba-display
-	@$(MD5SUM) test.gba
-	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m4        examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=feather-m4          examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pybadge             examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=metro-m4-airlift    examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pyportal            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=particle-argon      examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=particle-boron      examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=particle-xenon      examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=nucleo-f103rb       examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pinetime-devkit0    examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=x9pro               examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10056-s140v7     examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=reelboard-s140v7    examples/blinky1
-	@$(MD5SUM) test.hex
+	tinygo build             -o test.wasm -tags=pca10040             examples/blinky2
+	tinygo build -size short -o test.elf -target=microbit            examples/echo
+	tinygo build -size short -o test.elf -target=nrf52840-mdk        examples/blinky1
+	tinygo build -size short -o test.elf -target=pca10031            examples/blinky1
+	tinygo build -size short -o test.elf -target=bluepill            examples/blinky1
+	tinygo build -size short -o test.elf -target=reelboard           examples/blinky1
+	tinygo build -size short -o test.elf -target=reelboard           examples/blinky2
+	tinygo build -size short -o test.elf -target=pca10056            examples/blinky1
+	tinygo build -size short -o test.elf -target=pca10056            examples/blinky2
+	tinygo build -size short -o test.elf -target=itsybitsy-m0        examples/blinky1
+	tinygo build -size short -o test.elf -target=feather-m0          examples/blinky1
+	tinygo build -size short -o test.elf -target=trinket-m0          examples/blinky1
+	tinygo build -size short -o test.elf -target=circuitplay-express examples/blinky1
+	tinygo build -size short -o test.elf -target=stm32f4disco        examples/blinky1
+	tinygo build -size short -o test.elf -target=stm32f4disco        examples/blinky2
+	tinygo build -size short -o test.elf -target=circuitplay-express examples/i2s
+	tinygo build -size short -o test.elf -target=gameboy-advance     examples/gba-display
 ifneq ($(AVR), 0)
-	$(TINYGO) build -size short -o test.hex -target=atmega1284p         examples/serial
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=arduino             examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=arduino -scheduler=tasks  examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=arduino-nano        examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=digispark           examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=digispark -gc=leaking examples/blinky1
-	@$(MD5SUM) test.hex
+	tinygo build -size short -o test.elf -target=arduino             examples/blinky1
+	tinygo build -size short -o test.elf -target=digispark           examples/blinky1
 endif
-	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/export
-	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/main
+ifneq ($(RISCV), 0)
+	tinygo build -size short -o test.elf -target=hifive1b            examples/blinky1
+endif
+	tinygo build             -o wasm.wasm -target=wasm               examples/wasm/export
+	tinygo build             -o wasm.wasm -target=wasm               examples/wasm/main

-release: tinygo gen-device wasi-libc
+release: build/tinygo gen-device
 	@mkdir -p build/release/tinygo/bin
 	@mkdir -p build/release/tinygo/lib/clang/include
 	@mkdir -p build/release/tinygo/lib/CMSIS/CMSIS
 	@mkdir -p build/release/tinygo/lib/compiler-rt/lib
 	@mkdir -p build/release/tinygo/lib/nrfx
-	@mkdir -p build/release/tinygo/lib/picolibc/newlib/libc
-	@mkdir -p build/release/tinygo/lib/wasi-libc
 	@mkdir -p build/release/tinygo/pkg/armv6m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7em-none-eabi
 	@echo copying source files
-	@cp -p  build/tinygo$(EXE)           build/release/tinygo/bin
+	@cp -p  build/tinygo                 build/release/tinygo/bin
 	@cp -p $(abspath $(CLANG_SRC))/lib/Headers/*.h build/release/tinygo/lib/clang/include
 	@cp -rp lib/CMSIS/CMSIS/Include      build/release/tinygo/lib/CMSIS/CMSIS
 	@cp -rp lib/CMSIS/README.md          build/release/tinygo/lib/CMSIS
@@ -330,19 +153,9 @@ release: tinygo gen-device wasi-libc
 	@cp -rp lib/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt
 	@cp -rp lib/compiler-rt/README.txt   build/release/tinygo/lib/compiler-rt
 	@cp -rp lib/nrfx/*                   build/release/tinygo/lib/nrfx
-	@cp -rp lib/picolibc/newlib/libc/ctype       build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/include     build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/locale      build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/string      build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/tinystdio   build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc-include         build/release/tinygo/lib
-	@cp -rp lib/wasi-libc/sysroot        build/release/tinygo/lib/wasi-libc/sysroot
 	@cp -rp src                          build/release/tinygo/src
 	@cp -rp targets                      build/release/tinygo/targets
-	./build/tinygo build-library -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/compiler-rt.a compiler-rt
-	./build/tinygo build-library -target=armv7m-none-eabi  -o build/release/tinygo/pkg/armv7m-none-eabi/compiler-rt.a compiler-rt
-	./build/tinygo build-library -target=armv7em-none-eabi -o build/release/tinygo/pkg/armv7em-none-eabi/compiler-rt.a compiler-rt
-	./build/tinygo build-library -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/picolibc.a picolibc
-	./build/tinygo build-library -target=armv7m-none-eabi  -o build/release/tinygo/pkg/armv7m-none-eabi/picolibc.a picolibc
-	./build/tinygo build-library -target=armv7em-none-eabi -o build/release/tinygo/pkg/armv7em-none-eabi/picolibc.a picolibc
+	./build/tinygo build-builtins -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/compiler-rt.a
+	./build/tinygo build-builtins -target=armv7m-none-eabi  -o build/release/tinygo/pkg/armv7m-none-eabi/compiler-rt.a
+	./build/tinygo build-builtins -target=armv7em-none-eabi -o build/release/tinygo/pkg/armv7em-none-eabi/compiler-rt.a
 	tar -czf build/release.tar.gz -C build/release tinygo
@@ -1,6 +1,6 @@
 # TinyGo - Go compiler for small places

-[![CircleCI](https://circleci.com/gh/tinygo-org/tinygo/tree/dev.svg?style=svg)](https://circleci.com/gh/tinygo-org/tinygo/tree/dev) [![Build Status](https://dev.azure.com/tinygo/tinygo/_apis/build/status/tinygo-CI?branchName=dev)](https://dev.azure.com/tinygo/tinygo/_build/latest?definitionId=1&branchName=dev)
+[![CircleCI](https://circleci.com/gh/tinygo-org/tinygo/tree/dev.svg?style=svg)](https://circleci.com/gh/tinygo-org/tinygo/tree/dev)

 TinyGo is a Go compiler intended for use in small places such as microcontrollers, WebAssembly (Wasm), and command-line tools.

@@ -43,40 +43,23 @@ See the [getting started instructions](https://tinygo.org/getting-started/) for

 You can compile TinyGo programs for microcontrollers, WebAssembly and Linux.

-The following 32 microcontroller boards are currently supported:
+The following 15 microcontroller boards are currently supported:

-* [Adafruit Circuit Playground Bluefruit](https://www.adafruit.com/product/4333)
 * [Adafruit Circuit Playground Express](https://www.adafruit.com/product/3333)
-* [Adafruit CLUE Alpha](https://www.adafruit.com/product/4500)
 * [Adafruit Feather M0](https://www.adafruit.com/product/2772)
-* [Adafruit Feather M4](https://www.adafruit.com/product/3857)
 * [Adafruit ItsyBitsy M0](https://www.adafruit.com/product/3727)
-* [Adafruit ItsyBitsy M4](https://www.adafruit.com/product/3800)
-* [Adafruit Metro M4 Express Airlift](https://www.adafruit.com/product/4000)
-* [Adafruit PyBadge](https://www.adafruit.com/product/4200)
-* [Adafruit PyPortal](https://www.adafruit.com/product/4116)
 * [Adafruit Trinket M0](https://www.adafruit.com/product/3500)
-* [Arduino Mega 2560](https://store.arduino.cc/arduino-mega-2560-rev3)
-* [Arduino Nano](https://store.arduino.cc/arduino-nano)
 * [Arduino Nano33 IoT](https://store.arduino.cc/nano-33-iot)
 * [Arduino Uno](https://store.arduino.cc/arduino-uno-rev3)
 * [BBC micro:bit](https://microbit.org/)
+* [ST Micro STM32F103XX "Bluepill"](http://wiki.stm32duino.com/index.php?title=Blue_Pill)
+* [ST Micro STM32F407 "Discovery"](https://www.st.com/en/evaluation-tools/stm32f4discovery.html)
 * [Digispark](http://digistump.com/products/1)
-* [Game Boy Advance](https://en.wikipedia.org/wiki/Game_Boy_Advance)
-* [Makerdiary nRF52840-MDK](https://wiki.makerdiary.com/nrf52840-mdk/)
 * [Nordic Semiconductor PCA10031](https://www.nordicsemi.com/eng/Products/nRF51-Dongle)
 * [Nordic Semiconductor PCA10040](https://www.nordicsemi.com/eng/Products/Bluetooth-low-energy/nRF52-DK)
 * [Nordic Semiconductor PCA10056](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-DK)
-* [Particle Argon](https://docs.particle.io/datasheets/wi-fi/argon-datasheet/)
-* [Particle Boron](https://docs.particle.io/datasheets/cellular/boron-datasheet/)
-* [Particle Xenon](https://docs.particle.io/datasheets/discontinued/xenon-datasheet/)
+* [Makerdiary nRF52840-MDK](https://wiki.makerdiary.com/nrf52840-mdk/)
 * [Phytec reel board](https://www.phytec.eu/product-eu/internet-of-things/reelboard/)
-* [PineTime DevKit](https://www.pine64.org/pinetime/)
-* [SiFIve HiFive1](https://www.sifive.com/boards/hifive1)
-* [ST Micro "Nucleo F103RB"](https://www.st.com/en/evaluation-tools/nucleo-f103rb.html)
-* [ST Micro STM32F103XX "Bluepill"](http://wiki.stm32duino.com/index.php?title=Blue_Pill)
-* [ST Micro STM32F407 "Discovery"](https://www.st.com/en/evaluation-tools/stm32f4discovery.html)
-* [X9 Pro smartwatch](https://github.com/curtpw/nRF5x-device-reverse-engineering/tree/master/X9-nrf52832-activity-tracker/)

 For more information, see [this list of boards](https://tinygo.org/microcontrollers/). Pull requests for additional support are welcome!

@@ -135,5 +118,3 @@ The original reasoning was: if [Python](https://micropython.org/) can run on mic
 ## License

 This project is licensed under the BSD 3-clause license, just like the [Go project](https://golang.org/LICENSE) itself.
-
-Some code has been copied from the LLVM project and is therefore licensed under [a variant of the Apache 2.0 license](http://releases.llvm.org/10.0.0/LICENSE.TXT). This has been clearly indicated in the header of these files.
@@ -1,83 +0,0 @@
-# Avoid lengthy LLVM rebuilds on each newly pushed branch. Pull requests will
-# be built anyway.
-trigger:
- master
- dev
-
-jobs:
- job: Build
-  timeoutInMinutes: 240 # 4h
-  pool:
-    vmImage: 'VS2017-Win2016'
-  steps:
-    - task: GoTool@0
-      inputs:
-        version: '1.14.1'
-    - checkout: self
-    - task: CacheBeta@0
-      displayName: Cache LLVM source
-      inputs:
-        key: llvm-source-10-windows-v0
-        path: llvm-project
-    - task: Bash@3
-      displayName: Download LLVM source
-      inputs:
-        targetType: inline
-        script: make llvm-source
-    - task: CacheBeta@0
-      displayName: Cache LLVM build
-      inputs:
-        key: llvm-build-10-windows-v0
-        path: llvm-build
-    - task: Bash@3
-      displayName: Build LLVM
-      inputs:
-        targetType: inline
-        script: |
-          if [ ! -f llvm-build/lib/liblldELF.a ]
-          then
-            choco install ninja
-            make llvm-build
-          fi
-    - task: Bash@3
-      displayName: Install QEMU
-      inputs:
-        targetType: inline
-        script: choco install qemu
-    - task: CacheBeta@0
-      displayName: Cache wasi-libc sysroot
-      inputs:
-        key: wasi-libc-sysroot-v2
-        path: lib/wasi-libc/sysroot
-    - task: Bash@3
-      displayName: Build wasi-libc
-      inputs:
-        targetType: inline
-        script: PATH=/usr/bin:$PATH make wasi-libc
-    - task: Bash@3
-      displayName: Test TinyGo
-      inputs:
-        targetType: inline
-        script: |
-          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
-          unset GOROOT
-          make test
-    - task: Bash@3
-      displayName: Build TinyGo release tarball
-      inputs:
-        targetType: inline
-        script: |
-          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
-          unset GOROOT
-          make release -j4
-    - publish: $(System.DefaultWorkingDirectory)/build/release/tinygo
-      displayName: Publish zip as artifact
-      artifact: tinygo
-    - task: Bash@3
-      displayName: Smoke tests
-      inputs:
-        targetType: inline
-        script: |
-          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
-          unset GOROOT
-          make smoketest TINYGO=build/tinygo AVR=0
@@ -1,4 +1,4 @@
-package builder
+package main

 import (
 	"debug/elf"
@@ -6,18 +6,18 @@ import (
 	"strings"
 )

-// programSize contains size statistics per package of a compiled program.
-type programSize struct {
-	Packages map[string]*packageSize
-	Sum      *packageSize
+// Statistics about code size in a program.
+type ProgramSize struct {
+	Packages map[string]*PackageSize
+	Sum      *PackageSize
 	Code     uint64
 	Data     uint64
 	BSS      uint64
 }

-// sortedPackageNames returns the list of package names (ProgramSize.Packages)
-// sorted alphabetically.
-func (ps *programSize) sortedPackageNames() []string {
+// Return the list of package names (ProgramSize.Packages) sorted
+// alphabetically.
+func (ps *ProgramSize) SortedPackageNames() []string {
 	names := make([]string, 0, len(ps.Packages))
 	for name := range ps.Packages {
 		names = append(names, name)
@@ -26,9 +26,8 @@ func (ps *programSize) sortedPackageNames() []string {
 	return names
 }

-// packageSize contains the size of a package, calculated from the linked object
-// file.
-type packageSize struct {
+// The size of a package, calculated from the linked object file.
+type PackageSize struct {
 	Code   uint64
 	ROData uint64
 	Data   uint64
@@ -36,12 +35,12 @@ type packageSize struct {
 }

 // Flash usage in regular microcontrollers.
-func (ps *packageSize) Flash() uint64 {
+func (ps *PackageSize) Flash() uint64 {
 	return ps.Code + ps.ROData + ps.Data
 }

 // Static RAM usage in regular microcontrollers.
-func (ps *packageSize) RAM() uint64 {
+func (ps *PackageSize) RAM() uint64 {
 	return ps.Data + ps.BSS
 }

@@ -65,9 +64,8 @@ func (l symbolList) Swap(i, j int) {
 	l[i], l[j] = l[j], l[i]
 }

-// loadProgramSize calculate a program/data size breakdown of each package for a
-// given ELF file.
-func loadProgramSize(path string) (*programSize, error) {
+// Calculate program/data size breakdown of each package for a given ELF file.
+func Sizes(path string) (*ProgramSize, error) {
 	file, err := elf.Open(path)
 	if err != nil {
 		return nil, err
@@ -84,18 +82,7 @@ func loadProgramSize(path string) (*programSize, error) {
 		if section.Type != elf.SHT_PROGBITS && section.Type != elf.SHT_NOBITS {
 			continue
 		}
-		if section.Name == ".stack" {
-			// HACK: this works around a bug in ld.lld from LLVM 10. The linker
-			// marks sections with no input symbols (such as is the case for the
-			// .stack section) as SHT_PROGBITS instead of SHT_NOBITS. While it
-			// doesn't affect the generated binaries (.hex and .bin), it does
-			// affect the reported size.
-			// https://bugs.llvm.org/show_bug.cgi?id=45336
-			// https://reviews.llvm.org/D76981
-			// It has been merged in master, but it has not (yet) been
-			// backported to the LLVM 10 release branch.
-			sumBSS += section.Size
-		} else if section.Type == elf.SHT_NOBITS {
+		if section.Type == elf.SHT_NOBITS {
 			sumBSS += section.Size
 		} else if section.Flags&elf.SHF_EXECINSTR != 0 {
 			sumCode += section.Size
@@ -128,7 +115,7 @@ func loadProgramSize(path string) (*programSize, error) {
 	}
 	sort.Sort(symbolList(symbols))

-	sizes := map[string]*packageSize{}
+	sizes := map[string]*PackageSize{}
 	var lastSymbolValue uint64
 	for _, symbol := range symbols {
 		symType := elf.ST_TYPE(symbol.Info)
@@ -142,7 +129,7 @@ func loadProgramSize(path string) (*programSize, error) {
 		}
 		pkgSize := sizes[pkgName]
 		if pkgSize == nil {
-			pkgSize = &packageSize{}
+			pkgSize = &PackageSize{}
 			sizes[pkgName] = pkgSize
 		}
 		if lastSymbolValue != symbol.Value || lastSymbolValue == 0 {
@@ -161,7 +148,7 @@ func loadProgramSize(path string) (*programSize, error) {
 		lastSymbolValue = symbol.Value
 	}

-	sum := &packageSize{}
+	sum := &PackageSize{}
 	for _, pkg := range sizes {
 		sum.Code += pkg.Code
 		sum.ROData += pkg.ROData
@@ -169,5 +156,5 @@ func loadProgramSize(path string) (*programSize, error) {
 		sum.BSS += pkg.BSS
 	}

-	return &programSize{Packages: sizes, Code: sumCode, Data: sumData, BSS: sumBSS, Sum: sum}, nil
+	return &ProgramSize{Packages: sizes, Code: sumCode, Data: sumData, BSS: sumBSS, Sum: sum}, nil
 }
@@ -1,14 +1,21 @@
-package builder
+package main

 import (
 	"io"
 	"os"
 	"path/filepath"
 	"time"
-
-	"github.com/tinygo-org/tinygo/goenv"
 )

+// Get the cache directory, usually ~/.cache/tinygo
+func cacheDir() string {
+	dir, err := os.UserCacheDir()
+	if err != nil {
+		panic("could not find cache dir: " + err.Error())
+	}
+	return filepath.Join(dir, "tinygo")
+}
+
 // Return the newest timestamp of all the file paths passed in. Used to check
 // for stale caches.
 func cacheTimestamp(paths []string) (time.Time, error) {
@@ -34,7 +41,8 @@ func cacheTimestamp(paths []string) (time.Time, error) {
 // TODO: the configKey is currently ignored. It is supposed to be used as extra
 // data for the cache key, like the compiler version and arguments.
 func cacheLoad(name, configKey string, sourceFiles []string) (string, error) {
-	cachepath := filepath.Join(goenv.Get("GOCACHE"), name)
+	dir := cacheDir()
+	cachepath := filepath.Join(dir, name)
 	cacheStat, err := os.Stat(cachepath)
 	if os.IsNotExist(err) {
 		return "", nil // does not exist
@@ -68,7 +76,7 @@ func cacheStore(tmppath, name, configKey string, sourceFiles []string) (string,

 	// TODO: check the config key

-	dir := goenv.Get("GOCACHE")
+	dir := cacheDir()
 	err := os.MkdirAll(dir, 0777)
 	if err != nil {
 		return "", err
@@ -109,10 +117,10 @@ func moveFile(src, dst string) error {
 		return err
 	}

-	err = outf.Close()
+	err = os.Rename(dst+".tmp", dst)
 	if err != nil {
 		return err
 	}

-	return os.Rename(dst+".tmp", dst)
+	return outf.Close()
 }
@@ -1,182 +0,0 @@
-package builder
-
-import (
-	"bytes"
-	"debug/elf"
-	"encoding/binary"
-	"errors"
-	"io"
-	"os"
-	"path/filepath"
-	"time"
-
-	"github.com/blakesmith/ar"
-)
-
-// makeArchive creates an arcive for static linking from a list of object files
-// given as a parameter. It is equivalent to the following command:
-//
-//     ar -rcs <archivePath> <objs...>
-func makeArchive(archivePath string, objs []string) error {
-	// Open the archive file.
-	arfile, err := os.Create(archivePath)
-	if err != nil {
-		return err
-	}
-	defer arfile.Close()
-	arwriter := ar.NewWriter(arfile)
-	err = arwriter.WriteGlobalHeader()
-	if err != nil {
-		return &os.PathError{"write ar header", archivePath, err}
-	}
-
-	// Open all object files and read the symbols for the symbol table.
-	symbolTable := []struct {
-		name      string // symbol name
-		fileIndex int    // index into objfiles
-	}{}
-	objfiles := make([]struct {
-		file          *os.File
-		archiveOffset int32
-	}, len(objs))
-	for i, objpath := range objs {
-		objfile, err := os.Open(objpath)
-		if err != nil {
-			return err
-		}
-		objfiles[i].file = objfile
-
-		// Read the symbols and add them to the symbol table.
-		dbg, err := elf.NewFile(objfile)
-		if err != nil {
-			return err
-		}
-		symbols, err := dbg.Symbols()
-		if err != nil {
-			return err
-		}
-		for _, symbol := range symbols {
-			bind := elf.ST_BIND(symbol.Info)
-			if bind != elf.STB_GLOBAL && bind != elf.STB_WEAK {
-				// Don't include local symbols (STB_LOCAL).
-				continue
-			}
-			if elf.ST_TYPE(symbol.Info) != elf.STT_FUNC {
-				// Not a function.
-				// TODO: perhaps globals variables should also be included?
-				continue
-			}
-			// Include in archive.
-			symbolTable = append(symbolTable, struct {
-				name      string
-				fileIndex int
-			}{symbol.Name, i})
-		}
-	}
-
-	// Create the symbol table buffer.
-	// For some (sparse) details on the file format:
-	// https://en.wikipedia.org/wiki/Ar_(Unix)#System_V_(or_GNU)_variant
-	buf := &bytes.Buffer{}
-	binary.Write(buf, binary.BigEndian, int32(len(symbolTable)))
-	for range symbolTable {
-		// This is a placeholder index, it will be updated after all files have
-		// been written to the archive (see the end of this function).
-		err = binary.Write(buf, binary.BigEndian, int32(0))
-		if err != nil {
-			return err
-		}
-	}
-	for _, sym := range symbolTable {
-		_, err := buf.Write([]byte(sym.name + "\x00"))
-		if err != nil {
-			return err
-		}
-	}
-	for buf.Len()%2 != 0 {
-		// The symbol table must be aligned.
-		// This appears to be required by lld.
-		buf.WriteByte(0)
-	}
-
-	// Write the symbol table.
-	err = arwriter.WriteHeader(&ar.Header{
-		Name:    "/",
-		ModTime: time.Unix(0, 0),
-		Uid:     0,
-		Gid:     0,
-		Mode:    0,
-		Size:    int64(buf.Len()),
-	})
-	if err != nil {
-		return err
-	}
-
-	// Keep track of the start of the symbol table.
-	symbolTableStart, err := arfile.Seek(0, os.SEEK_CUR)
-	if err != nil {
-		return err
-	}
-
-	// Write symbol table contents.
-	_, err = arfile.Write(buf.Bytes())
-	if err != nil {
-		return err
-	}
-
-	// Add all object files to the archive.
-	for i, objfile := range objfiles {
-		// Store the start index, for when we'll update the symbol table with
-		// the correct file start indices.
-		offset, err := arfile.Seek(0, os.SEEK_CUR)
-		if err != nil {
-			return err
-		}
-		if int64(int32(offset)) != offset {
-			return errors.New("large archives (4GB+) not supported: " + archivePath)
-		}
-		objfiles[i].archiveOffset = int32(offset)
-
-		// Write the file header.
-		st, err := objfile.file.Stat()
-		if err != nil {
-			return err
-		}
-		err = arwriter.WriteHeader(&ar.Header{
-			Name:    filepath.Base(objfile.file.Name()),
-			ModTime: time.Unix(0, 0),
-			Uid:     0,
-			Gid:     0,
-			Mode:    0644,
-			Size:    st.Size(),
-		})
-		if err != nil {
-			return err
-		}
-
-		// Copy the file contents into the archive.
-		n, err := io.Copy(arwriter, objfile.file)
-		if err != nil {
-			return err
-		}
-		if n != st.Size() {
-			return errors.New("file modified during ar creation: " + archivePath)
-		}
-
-		// File is not needed anymore.
-		objfile.file.Close()
-	}
-
-	// Create symbol indices.
-	indicesBuf := &bytes.Buffer{}
-	for _, sym := range symbolTable {
-		err = binary.Write(indicesBuf, binary.BigEndian, objfiles[sym.fileIndex].archiveOffset)
-		if err != nil {
-			return err
-		}
-	}
-
-	// Overwrite placeholder indices.
-	_, err = arfile.WriteAt(indicesBuf.Bytes(), symbolTableStart+4)
-	return err
-}
@@ -1,232 +0,0 @@
-// Package builder is the compiler driver of TinyGo. It takes in a package name
-// and an output path, and outputs an executable. It manages the entire
-// compilation pipeline in between.
-package builder
-
-import (
-	"errors"
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"strconv"
-	"strings"
-
-	"github.com/tinygo-org/tinygo/compileopts"
-	"github.com/tinygo-org/tinygo/compiler"
-	"github.com/tinygo-org/tinygo/goenv"
-	"github.com/tinygo-org/tinygo/interp"
-	"github.com/tinygo-org/tinygo/transform"
-	"tinygo.org/x/go-llvm"
-)
-
-// Build performs a single package to executable Go build. It takes in a package
-// name, an output path, and set of compile options and from that it manages the
-// whole compilation process.
-//
-// The error value may be of type *MultiError. Callers will likely want to check
-// for this case and print such errors individually.
-func Build(pkgName, outpath string, config *compileopts.Config, action func(string) error) error {
-	// Compile Go code to IR.
-	machine, err := compiler.NewTargetMachine(config)
-	if err != nil {
-		return err
-	}
-	mod, extraFiles, errs := compiler.Compile(pkgName, machine, config)
-	if errs != nil {
-		return newMultiError(errs)
-	}
-
-	if config.Options.PrintIR {
-		fmt.Println("; Generated LLVM IR:")
-		fmt.Println(mod.String())
-	}
-	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
-		return errors.New("verification error after IR construction")
-	}
-
-	err = interp.Run(mod, config.DumpSSA())
-	if err != nil {
-		return err
-	}
-	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
-		return errors.New("verification error after interpreting runtime.initAll")
-	}
-
-	if config.GOOS() != "darwin" {
-		transform.ApplyFunctionSections(mod) // -ffunction-sections
-	}
-
-	// Browsers cannot handle external functions that have type i64 because it
-	// cannot be represented exactly in JavaScript (JS only has doubles). To
-	// keep functions interoperable, pass int64 types as pointers to
-	// stack-allocated values.
-	// Use -wasm-abi=generic to disable this behaviour.
-	if config.Options.WasmAbi == "js" && strings.HasPrefix(config.Triple(), "wasm") {
-		err := transform.ExternalInt64AsPtr(mod)
-		if err != nil {
-			return err
-		}
-	}
-
-	// Optimization levels here are roughly the same as Clang, but probably not
-	// exactly.
-	errs = nil
-	switch config.Options.Opt {
-	case "none", "0":
-		errs = transform.Optimize(mod, config, 0, 0, 0) // -O0
-	case "1":
-		errs = transform.Optimize(mod, config, 1, 0, 0) // -O1
-	case "2":
-		errs = transform.Optimize(mod, config, 2, 0, 225) // -O2
-	case "s":
-		errs = transform.Optimize(mod, config, 2, 1, 225) // -Os
-	case "z":
-		errs = transform.Optimize(mod, config, 2, 2, 5) // -Oz, default
-	default:
-		errs = []error{errors.New("unknown optimization level: -opt=" + config.Options.Opt)}
-	}
-	if len(errs) > 0 {
-		return newMultiError(errs)
-	}
-	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
-		return errors.New("verification failure after LLVM optimization passes")
-	}
-
-	// On the AVR, pointers can point either to flash or to RAM, but we don't
-	// know. As a temporary fix, load all global variables in RAM.
-	// In the future, there should be a compiler pass that determines which
-	// pointers are flash and which are in RAM so that pointers can have a
-	// correct address space parameter (address space 1 is for flash).
-	if strings.HasPrefix(config.Triple(), "avr") {
-		transform.NonConstGlobals(mod)
-		if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
-			return errors.New("verification error after making all globals non-constant on AVR")
-		}
-	}
-
-	// Generate output.
-	outext := filepath.Ext(outpath)
-	switch outext {
-	case ".o":
-		llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
-		if err != nil {
-			return err
-		}
-		return ioutil.WriteFile(outpath, llvmBuf.Bytes(), 0666)
-	case ".bc":
-		data := llvm.WriteBitcodeToMemoryBuffer(mod).Bytes()
-		return ioutil.WriteFile(outpath, data, 0666)
-	case ".ll":
-		data := []byte(mod.String())
-		return ioutil.WriteFile(outpath, data, 0666)
-	default:
-		// Act as a compiler driver.
-
-		// Create a temporary directory for intermediary files.
-		dir, err := ioutil.TempDir("", "tinygo")
-		if err != nil {
-			return err
-		}
-		defer os.RemoveAll(dir)
-
-		// Write the object file.
-		objfile := filepath.Join(dir, "main.o")
-		llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
-		if err != nil {
-			return err
-		}
-		err = ioutil.WriteFile(objfile, llvmBuf.Bytes(), 0666)
-		if err != nil {
-			return err
-		}
-
-		// Prepare link command.
-		executable := filepath.Join(dir, "main")
-		tmppath := executable // final file
-		ldflags := append(config.LDFlags(), "-o", executable, objfile)
-
-		// Load builtins library from the cache, possibly compiling it on the
-		// fly.
-		if config.Target.RTLib == "compiler-rt" {
-			librt, err := CompilerRT.Load(config.Triple())
-			if err != nil {
-				return err
-			}
-			ldflags = append(ldflags, librt)
-		}
-
-		// Add libc.
-		if config.Target.Libc == "picolibc" {
-			libc, err := Picolibc.Load(config.Triple())
-			if err != nil {
-				return err
-			}
-			ldflags = append(ldflags, libc)
-		}
-
-		// Compile extra files.
-		root := goenv.Get("TINYGOROOT")
-		for i, path := range config.ExtraFiles() {
-			abspath := filepath.Join(root, path)
-			outpath := filepath.Join(dir, "extra-"+strconv.Itoa(i)+"-"+filepath.Base(path)+".o")
-			err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, abspath)...)
-			if err != nil {
-				return &commandError{"failed to build", path, err}
-			}
-			ldflags = append(ldflags, outpath)
-		}
-
-		// Compile C files in packages.
-		for i, file := range extraFiles {
-			outpath := filepath.Join(dir, "pkg"+strconv.Itoa(i)+"-"+filepath.Base(file)+".o")
-			err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, file)...)
-			if err != nil {
-				return &commandError{"failed to build", file, err}
-			}
-			ldflags = append(ldflags, outpath)
-		}
-
-		// Link the object files together.
-		err = link(config.Target.Linker, ldflags...)
-		if err != nil {
-			return &commandError{"failed to link", executable, err}
-		}
-
-		if config.Options.PrintSizes == "short" || config.Options.PrintSizes == "full" {
-			sizes, err := loadProgramSize(executable)
-			if err != nil {
-				return err
-			}
-			if config.Options.PrintSizes == "short" {
-				fmt.Printf("   code    data     bss |   flash     ram\n")
-				fmt.Printf("%7d %7d %7d | %7d %7d\n", sizes.Code, sizes.Data, sizes.BSS, sizes.Code+sizes.Data, sizes.Data+sizes.BSS)
-			} else {
-				fmt.Printf("   code  rodata    data     bss |   flash     ram | package\n")
-				for _, name := range sizes.sortedPackageNames() {
-					pkgSize := sizes.Packages[name]
-					fmt.Printf("%7d %7d %7d %7d | %7d %7d | %s\n", pkgSize.Code, pkgSize.ROData, pkgSize.Data, pkgSize.BSS, pkgSize.Flash(), pkgSize.RAM(), name)
-				}
-				fmt.Printf("%7d %7d %7d %7d | %7d %7d | (sum)\n", sizes.Sum.Code, sizes.Sum.ROData, sizes.Sum.Data, sizes.Sum.BSS, sizes.Sum.Flash(), sizes.Sum.RAM())
-				fmt.Printf("%7d       - %7d %7d | %7d %7d | (all)\n", sizes.Code, sizes.Data, sizes.BSS, sizes.Code+sizes.Data, sizes.Data+sizes.BSS)
-			}
-		}
-
-		// Get an Intel .hex file or .bin file from the .elf file.
-		if outext == ".hex" || outext == ".bin" || outext == ".gba" {
-			tmppath = filepath.Join(dir, "main"+outext)
-			err := objcopy(executable, tmppath)
-			if err != nil {
-				return err
-			}
-		} else if outext == ".uf2" {
-			// Get UF2 from the .elf file.
-			tmppath = filepath.Join(dir, "main"+outext)
-			err := convertELFFileToUF2File(executable, tmppath, config.Target.UF2FamilyID)
-			if err != nil {
-				return err
-			}
-		}
-		return action(tmppath)
-	}
-}
@@ -1,170 +0,0 @@
-package builder
-
-import (
-	"strings"
-)
-
-// These are the GENERIC_SOURCES according to CMakeList.txt.
-var genericBuiltins = []string{
-	"absvdi2.c",
-	"absvsi2.c",
-	"absvti2.c",
-	"adddf3.c",
-	"addsf3.c",
-	"addtf3.c",
-	"addvdi3.c",
-	"addvsi3.c",
-	"addvti3.c",
-	"apple_versioning.c",
-	"ashldi3.c",
-	"ashlti3.c",
-	"ashrdi3.c",
-	"ashrti3.c",
-	"bswapdi2.c",
-	"bswapsi2.c",
-	"clzdi2.c",
-	"clzsi2.c",
-	"clzti2.c",
-	"cmpdi2.c",
-	"cmpti2.c",
-	"comparedf2.c",
-	"comparesf2.c",
-	"ctzdi2.c",
-	"ctzsi2.c",
-	"ctzti2.c",
-	"divdc3.c",
-	"divdf3.c",
-	"divdi3.c",
-	"divmoddi4.c",
-	"divmodsi4.c",
-	"divsc3.c",
-	"divsf3.c",
-	"divsi3.c",
-	"divtc3.c",
-	"divti3.c",
-	"divtf3.c",
-	"extendsfdf2.c",
-	"extendhfsf2.c",
-	"ffsdi2.c",
-	"ffssi2.c",
-	"ffsti2.c",
-	"fixdfdi.c",
-	"fixdfsi.c",
-	"fixdfti.c",
-	"fixsfdi.c",
-	"fixsfsi.c",
-	"fixsfti.c",
-	"fixunsdfdi.c",
-	"fixunsdfsi.c",
-	"fixunsdfti.c",
-	"fixunssfdi.c",
-	"fixunssfsi.c",
-	"fixunssfti.c",
-	"floatdidf.c",
-	"floatdisf.c",
-	"floatsidf.c",
-	"floatsisf.c",
-	"floattidf.c",
-	"floattisf.c",
-	"floatundidf.c",
-	"floatundisf.c",
-	"floatunsidf.c",
-	"floatunsisf.c",
-	"floatuntidf.c",
-	"floatuntisf.c",
-	//"int_util.c",
-	"lshrdi3.c",
-	"lshrti3.c",
-	"moddi3.c",
-	"modsi3.c",
-	"modti3.c",
-	"muldc3.c",
-	"muldf3.c",
-	"muldi3.c",
-	"mulodi4.c",
-	"mulosi4.c",
-	"muloti4.c",
-	"mulsc3.c",
-	"mulsf3.c",
-	"multi3.c",
-	"multf3.c",
-	"mulvdi3.c",
-	"mulvsi3.c",
-	"mulvti3.c",
-	"negdf2.c",
-	"negdi2.c",
-	"negsf2.c",
-	"negti2.c",
-	"negvdi2.c",
-	"negvsi2.c",
-	"negvti2.c",
-	"os_version_check.c",
-	"paritydi2.c",
-	"paritysi2.c",
-	"parityti2.c",
-	"popcountdi2.c",
-	"popcountsi2.c",
-	"popcountti2.c",
-	"powidf2.c",
-	"powisf2.c",
-	"powitf2.c",
-	"subdf3.c",
-	"subsf3.c",
-	"subvdi3.c",
-	"subvsi3.c",
-	"subvti3.c",
-	"subtf3.c",
-	"trampoline_setup.c",
-	"truncdfhf2.c",
-	"truncdfsf2.c",
-	"truncsfhf2.c",
-	"ucmpdi2.c",
-	"ucmpti2.c",
-	"udivdi3.c",
-	"udivmoddi4.c",
-	"udivmodsi4.c",
-	"udivmodti4.c",
-	"udivsi3.c",
-	"udivti3.c",
-	"umoddi3.c",
-	"umodsi3.c",
-	"umodti3.c",
-}
-
-var aeabiBuiltins = []string{
-	"arm/aeabi_cdcmp.S",
-	"arm/aeabi_cdcmpeq_check_nan.c",
-	"arm/aeabi_cfcmp.S",
-	"arm/aeabi_cfcmpeq_check_nan.c",
-	"arm/aeabi_dcmp.S",
-	"arm/aeabi_div0.c",
-	"arm/aeabi_drsub.c",
-	"arm/aeabi_fcmp.S",
-	"arm/aeabi_frsub.c",
-	"arm/aeabi_idivmod.S",
-	"arm/aeabi_ldivmod.S",
-	"arm/aeabi_memcmp.S",
-	"arm/aeabi_memcpy.S",
-	"arm/aeabi_memmove.S",
-	"arm/aeabi_memset.S",
-	"arm/aeabi_uidivmod.S",
-	"arm/aeabi_uldivmod.S",
-}
-
-// CompilerRT is a library with symbols required by programs compiled with LLVM.
-// These symbols are for operations that cannot be emitted with a single
-// instruction or a short sequence of instructions for that target.
-//
-// For more information, see: https://compiler-rt.llvm.org/
-var CompilerRT = Library{
-	name:      "compiler-rt",
-	cflags:    func() []string { return []string{"-Werror", "-Wall", "-std=c11", "-nostdlibinc"} },
-	sourceDir: "lib/compiler-rt/lib/builtins",
-	sources: func(target string) []string {
-		builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
-		if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
-			builtins = append(builtins, aeabiBuiltins...)
-		}
-		return builtins
-	},
-}
@@ -1,510 +0,0 @@
-// +build byollvm
-
-//===-- cc1as.cpp - Clang Assembler  --------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This is the entry point to the clang -cc1as functionality, which implements
-// the direct interface to the LLVM MC based assembler.
-//
-//===----------------------------------------------------------------------===//
-
-#include "clang/Basic/Diagnostic.h"
-#include "clang/Basic/DiagnosticOptions.h"
-#include "clang/Driver/DriverDiagnostic.h"
-#include "clang/Driver/Options.h"
-#include "clang/Frontend/FrontendDiagnostic.h"
-#include "clang/Frontend/TextDiagnosticPrinter.h"
-#include "clang/Frontend/Utils.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/StringSwitch.h"
-#include "llvm/ADT/Triple.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/MC/MCAsmBackend.h"
-#include "llvm/MC/MCAsmInfo.h"
-#include "llvm/MC/MCCodeEmitter.h"
-#include "llvm/MC/MCContext.h"
-#include "llvm/MC/MCInstrInfo.h"
-#include "llvm/MC/MCObjectFileInfo.h"
-#include "llvm/MC/MCObjectWriter.h"
-#include "llvm/MC/MCParser/MCAsmParser.h"
-#include "llvm/MC/MCParser/MCTargetAsmParser.h"
-#include "llvm/MC/MCRegisterInfo.h"
-#include "llvm/MC/MCSectionMachO.h"
-#include "llvm/MC/MCStreamer.h"
-#include "llvm/MC/MCSubtargetInfo.h"
-#include "llvm/MC/MCTargetOptions.h"
-#include "llvm/Option/Arg.h"
-#include "llvm/Option/ArgList.h"
-#include "llvm/Option/OptTable.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/FileSystem.h"
-#include "llvm/Support/FormattedStream.h"
-#include "llvm/Support/Host.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/Path.h"
-#include "llvm/Support/Process.h"
-#include "llvm/Support/Signals.h"
-#include "llvm/Support/SourceMgr.h"
-#include "llvm/Support/TargetRegistry.h"
-#include "llvm/Support/TargetSelect.h"
-#include "llvm/Support/Timer.h"
-#include "llvm/Support/raw_ostream.h"
-#include <memory>
-#include <system_error>
-using namespace clang;
-using namespace clang::driver;
-using namespace clang::driver::options;
-using namespace llvm;
-using namespace llvm::opt;
-
-#include "cc1as.h"
-
-bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
-                                         ArrayRef<const char *> Argv,
-                                         DiagnosticsEngine &Diags) {
-  bool Success = true;
-
-  // Parse the arguments.
-  const OptTable &OptTbl = getDriverOptTable();
-
-  const unsigned IncludedFlagsBitmask = options::CC1AsOption;
-  unsigned MissingArgIndex, MissingArgCount;
-  InputArgList Args = OptTbl.ParseArgs(Argv, MissingArgIndex, MissingArgCount,
-                                       IncludedFlagsBitmask);
-
-  // Check for missing argument error.
-  if (MissingArgCount) {
-    Diags.Report(diag::err_drv_missing_argument)
-        << Args.getArgString(MissingArgIndex) << MissingArgCount;
-    Success = false;
-  }
-
-  // Issue errors on unknown arguments.
-  for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
-    auto ArgString = A->getAsString(Args);
-    std::string Nearest;
-    if (OptTbl.findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
-      Diags.Report(diag::err_drv_unknown_argument) << ArgString;
-    else
-      Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
-          << ArgString << Nearest;
-    Success = false;
-  }
-
-  // Construct the invocation.
-
-  // Target Options
-  Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
-  Opts.CPU = Args.getLastArgValue(OPT_target_cpu);
-  Opts.Features = Args.getAllArgValues(OPT_target_feature);
-
-  // Use the default target triple if unspecified.
-  if (Opts.Triple.empty())
-    Opts.Triple = llvm::sys::getDefaultTargetTriple();
-
-  // Language Options
-  Opts.IncludePaths = Args.getAllArgValues(OPT_I);
-  Opts.NoInitialTextSection = Args.hasArg(OPT_n);
-  Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
-  // Any DebugInfoKind implies GenDwarfForAssembly.
-  Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
-
-  if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
-                                     OPT_compress_debug_sections_EQ)) {
-    if (A->getOption().getID() == OPT_compress_debug_sections) {
-      // TODO: be more clever about the compression type auto-detection
-      Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
-    } else {
-      Opts.CompressDebugSections =
-          llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
-              .Case("none", llvm::DebugCompressionType::None)
-              .Case("zlib", llvm::DebugCompressionType::Z)
-              .Case("zlib-gnu", llvm::DebugCompressionType::GNU)
-              .Default(llvm::DebugCompressionType::None);
-    }
-  }
-
-  Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
-  Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
-  Opts.DwarfDebugFlags = Args.getLastArgValue(OPT_dwarf_debug_flags);
-  Opts.DwarfDebugProducer = Args.getLastArgValue(OPT_dwarf_debug_producer);
-  Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
-  Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
-
-  for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
-    Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));
-
-  // Frontend Options
-  if (Args.hasArg(OPT_INPUT)) {
-    bool First = true;
-    for (const Arg *A : Args.filtered(OPT_INPUT)) {
-      if (First) {
-        Opts.InputFile = A->getValue();
-        First = false;
-      } else {
-        Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
-        Success = false;
-      }
-    }
-  }
-  Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
-  Opts.OutputPath = Args.getLastArgValue(OPT_o);
-  Opts.SplitDwarfOutput = Args.getLastArgValue(OPT_split_dwarf_output);
-  if (Arg *A = Args.getLastArg(OPT_filetype)) {
-    StringRef Name = A->getValue();
-    unsigned OutputType = StringSwitch<unsigned>(Name)
-      .Case("asm", FT_Asm)
-      .Case("null", FT_Null)
-      .Case("obj", FT_Obj)
-      .Default(~0U);
-    if (OutputType == ~0U) {
-      Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
-      Success = false;
-    } else
-      Opts.OutputType = FileType(OutputType);
-  }
-  Opts.ShowHelp = Args.hasArg(OPT_help);
-  Opts.ShowVersion = Args.hasArg(OPT_version);
-
-  // Transliterate Options
-  Opts.OutputAsmVariant =
-      getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
-  Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
-  Opts.ShowInst = Args.hasArg(OPT_show_inst);
-
-  // Assemble Options
-  Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
-  Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
-  Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
-  Opts.NoWarn = Args.hasArg(OPT_massembler_no_warn);
-  Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
-  Opts.TargetABI = Args.getLastArgValue(OPT_target_abi);
-  Opts.IncrementalLinkerCompatible =
-      Args.hasArg(OPT_mincremental_linker_compatible);
-  Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
-
-  // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
-  // EmbedBitcode behaves the same for all embed options for assembly files.
-  if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
-    Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
-                            .Case("all", 1)
-                            .Case("bitcode", 1)
-                            .Case("marker", 1)
-                            .Default(0);
-  }
-
-  return Success;
-}
-
-static std::unique_ptr<raw_fd_ostream>
-getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
-  // Make sure that the Out file gets unlinked from the disk if we get a
-  // SIGINT.
-  if (Path != "-")
-    sys::RemoveFileOnSignal(Path);
-
-  std::error_code EC;
-  auto Out = std::make_unique<raw_fd_ostream>(
-      Path, EC, (Binary ? sys::fs::OF_None : sys::fs::OF_Text));
-  if (EC) {
-    Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
-    return nullptr;
-  }
-
-  return Out;
-}
-
-bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
-  // Get the target specific parser.
-  std::string Error;
-  const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
-  if (!TheTarget)
-    return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
-
-  ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
-      MemoryBuffer::getFileOrSTDIN(Opts.InputFile);
-
-  if (std::error_code EC = Buffer.getError()) {
-    Error = EC.message();
-    return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
-  }
-
-  SourceMgr SrcMgr;
-
-  // Tell SrcMgr about this buffer, which is what the parser will pick up.
-  unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
-
-  // Record the location of the include directories so that the lexer can find
-  // it later.
-  SrcMgr.setIncludeDirs(Opts.IncludePaths);
-
-  std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
-  assert(MRI && "Unable to create target register info!");
-
-  MCTargetOptions MCOptions;
-  std::unique_ptr<MCAsmInfo> MAI(
-      TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
-  assert(MAI && "Unable to create target asm info!");
-
-  // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
-  // may be created with a combination of default and explicit settings.
-  MAI->setCompressDebugSections(Opts.CompressDebugSections);
-
-  MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
-
-  bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
-  if (Opts.OutputPath.empty())
-    Opts.OutputPath = "-";
-  std::unique_ptr<raw_fd_ostream> FDOS =
-      getOutputStream(Opts.OutputPath, Diags, IsBinary);
-  if (!FDOS)
-    return true;
-  std::unique_ptr<raw_fd_ostream> DwoOS;
-  if (!Opts.SplitDwarfOutput.empty())
-    DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
-
-  // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
-  // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
-  std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());
-
-  MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr, &MCOptions);
-
-  bool PIC = false;
-  if (Opts.RelocationModel == "static") {
-    PIC = false;
-  } else if (Opts.RelocationModel == "pic") {
-    PIC = true;
-  } else {
-    assert(Opts.RelocationModel == "dynamic-no-pic" &&
-           "Invalid PIC model!");
-    PIC = false;
-  }
-
-  MOFI->InitMCObjectFileInfo(Triple(Opts.Triple), PIC, Ctx);
-  if (Opts.SaveTemporaryLabels)
-    Ctx.setAllowTemporaryLabels(false);
-  if (Opts.GenDwarfForAssembly)
-    Ctx.setGenDwarfForAssembly(true);
-  if (!Opts.DwarfDebugFlags.empty())
-    Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
-  if (!Opts.DwarfDebugProducer.empty())
-    Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
-  if (!Opts.DebugCompilationDir.empty())
-    Ctx.setCompilationDir(Opts.DebugCompilationDir);
-  else {
-    // If no compilation dir is set, try to use the current directory.
-    SmallString<128> CWD;
-    if (!sys::fs::current_path(CWD))
-      Ctx.setCompilationDir(CWD);
-  }
-  if (!Opts.DebugPrefixMap.empty())
-    for (const auto &KV : Opts.DebugPrefixMap)
-      Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
-  if (!Opts.MainFileName.empty())
-    Ctx.setMainFileName(StringRef(Opts.MainFileName));
-  Ctx.setDwarfVersion(Opts.DwarfVersion);
-  if (Opts.GenDwarfForAssembly)
-    Ctx.setGenDwarfRootFile(Opts.InputFile,
-                            SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
-
-  // Build up the feature string from the target feature list.
-  std::string FS;
-  if (!Opts.Features.empty()) {
-    FS = Opts.Features[0];
-    for (unsigned i = 1, e = Opts.Features.size(); i != e; ++i)
-      FS += "," + Opts.Features[i];
-  }
-
-  std::unique_ptr<MCStreamer> Str;
-
-  std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
-  std::unique_ptr<MCSubtargetInfo> STI(
-      TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
-
-  raw_pwrite_stream *Out = FDOS.get();
-  std::unique_ptr<buffer_ostream> BOS;
-
-  MCOptions.MCNoWarn = Opts.NoWarn;
-  MCOptions.MCFatalWarnings = Opts.FatalWarnings;
-  MCOptions.ABIName = Opts.TargetABI;
-
-  // FIXME: There is a bit of code duplication with addPassesToEmitFile.
-  if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
-    MCInstPrinter *IP = TheTarget->createMCInstPrinter(
-        llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
-
-    std::unique_ptr<MCCodeEmitter> CE;
-    if (Opts.ShowEncoding)
-      CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
-    std::unique_ptr<MCAsmBackend> MAB(
-        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
-
-    auto FOut = std::make_unique<formatted_raw_ostream>(*Out);
-    Str.reset(TheTarget->createAsmStreamer(
-        Ctx, std::move(FOut), /*asmverbose*/ true,
-        /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
-        Opts.ShowInst));
-  } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
-    Str.reset(createNullStreamer(Ctx));
-  } else {
-    assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
-           "Invalid file type!");
-    if (!FDOS->supportsSeeking()) {
-      BOS = std::make_unique<buffer_ostream>(*FDOS);
-      Out = BOS.get();
-    }
-
-    std::unique_ptr<MCCodeEmitter> CE(
-        TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
-    std::unique_ptr<MCAsmBackend> MAB(
-        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
-    std::unique_ptr<MCObjectWriter> OW =
-        DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
-              : MAB->createObjectWriter(*Out);
-
-    Triple T(Opts.Triple);
-    Str.reset(TheTarget->createMCObjectStreamer(
-        T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
-        Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
-        /*DWARFMustBeAtTheEnd*/ true));
-    Str.get()->InitSections(Opts.NoExecStack);
-  }
-
-  // When -fembed-bitcode is passed to clang_as, a 1-byte marker
-  // is emitted in __LLVM,__asm section if the object file is MachO format.
-  if (Opts.EmbedBitcode && Ctx.getObjectFileInfo()->getObjectFileType() ==
-                               MCObjectFileInfo::IsMachO) {
-    MCSection *AsmLabel = Ctx.getMachOSection(
-        "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
-    Str.get()->SwitchSection(AsmLabel);
-    Str.get()->EmitZeros(1);
-  }
-
-  // Assembly to object compilation should leverage assembly info.
-  Str->setUseAssemblerInfoForParsing(true);
-
-  bool Failed = false;
-
-  std::unique_ptr<MCAsmParser> Parser(
-      createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
-
-  // FIXME: init MCTargetOptions from sanitizer flags here.
-  std::unique_ptr<MCTargetAsmParser> TAP(
-      TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
-  if (!TAP)
-    Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
-
-  // Set values for symbols, if any.
-  for (auto &S : Opts.SymbolDefs) {
-    auto Pair = StringRef(S).split('=');
-    auto Sym = Pair.first;
-    auto Val = Pair.second;
-    int64_t Value;
-    // We have already error checked this in the driver.
-    Val.getAsInteger(0, Value);
-    Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
-  }
-
-  if (!Failed) {
-    Parser->setTargetParser(*TAP.get());
-    Failed = Parser->Run(Opts.NoInitialTextSection);
-  }
-
-  // Close Streamer first.
-  // It might have a reference to the output stream.
-  Str.reset();
-  // Close the output stream early.
-  BOS.reset();
-  FDOS.reset();
-
-  // Delete output file if there were errors.
-  if (Failed) {
-    if (Opts.OutputPath != "-")
-      sys::fs::remove(Opts.OutputPath);
-    if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
-      sys::fs::remove(Opts.SplitDwarfOutput);
-  }
-
-  return Failed;
-}
-
-static void LLVMErrorHandler(void *UserData, const std::string &Message,
-                             bool GenCrashDiag) {
-  DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
-
-  Diags.Report(diag::err_fe_error_backend) << Message;
-
-  // We cannot recover from llvm errors.
-  sys::Process::Exit(1);
-}
-
-int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
-  // Initialize targets and assembly printers/parsers.
-  InitializeAllTargetInfos();
-  InitializeAllTargetMCs();
-  InitializeAllAsmParsers();
-
-  // Construct our diagnostic client.
-  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
-  TextDiagnosticPrinter *DiagClient
-    = new TextDiagnosticPrinter(errs(), &*DiagOpts);
-  DiagClient->setPrefix("clang -cc1as");
-  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
-  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
-
-  // Set an error handler, so that any LLVM backend diagnostics go through our
-  // error handler.
-  ScopedFatalErrorHandler FatalErrorHandler
-    (LLVMErrorHandler, static_cast<void*>(&Diags));
-
-  // Parse the arguments.
-  AssemblerInvocation Asm;
-  if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
-    return 1;
-
-  if (Asm.ShowHelp) {
-    getDriverOptTable().PrintHelp(
-        llvm::outs(), "clang -cc1as [options] file...",
-        "Clang Integrated Assembler",
-        /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
-        /*ShowAllAliases=*/false);
-    return 0;
-  }
-
-  // Honor -version.
-  //
-  // FIXME: Use a better -version message?
-  if (Asm.ShowVersion) {
-    llvm::cl::PrintVersionMessage();
-    return 0;
-  }
-
-  // Honor -mllvm.
-  //
-  // FIXME: Remove this, one day.
-  if (!Asm.LLVMArgs.empty()) {
-    unsigned NumArgs = Asm.LLVMArgs.size();
-    auto Args = std::make_unique<const char*[]>(NumArgs + 2);
-    Args[0] = "clang (LLVM option parsing)";
-    for (unsigned i = 0; i != NumArgs; ++i)
-      Args[i + 1] = Asm.LLVMArgs[i].c_str();
-    Args[NumArgs + 1] = nullptr;
-    llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
-  }
-
-  // Execute the invocation, unless there were parsing errors.
-  bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
-
-  // If any timers were active but haven't been destroyed yet, print their
-  // results now.
-  TimerGroup::printAll(errs());
-  TimerGroup::clearAll();
-
-  return !!Failed;
-}
@@ -1,120 +0,0 @@
-//===-- cc1as.h - Clang Assembler  ----------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This is the entry point to the clang -cc1as functionality, which implements
-// the direct interface to the LLVM MC based assembler.
-//
-//===----------------------------------------------------------------------===//
-
-/// Helper class for representing a single invocation of the assembler.
-struct AssemblerInvocation {
-  /// @name Target Options
-  /// @{
-
-  /// The name of the target triple to assemble for.
-  std::string Triple;
-
-  /// If given, the name of the target CPU to determine which instructions
-  /// are legal.
-  std::string CPU;
-
-  /// The list of target specific features to enable or disable -- this should
-  /// be a list of strings starting with '+' or '-'.
-  std::vector<std::string> Features;
-
-  /// The list of symbol definitions.
-  std::vector<std::string> SymbolDefs;
-
-  /// @}
-  /// @name Language Options
-  /// @{
-
-  std::vector<std::string> IncludePaths;
-  unsigned NoInitialTextSection : 1;
-  unsigned SaveTemporaryLabels : 1;
-  unsigned GenDwarfForAssembly : 1;
-  unsigned RelaxELFRelocations : 1;
-  unsigned DwarfVersion;
-  std::string DwarfDebugFlags;
-  std::string DwarfDebugProducer;
-  std::string DebugCompilationDir;
-  std::map<const std::string, const std::string> DebugPrefixMap;
-  llvm::DebugCompressionType CompressDebugSections =
-      llvm::DebugCompressionType::None;
-  std::string MainFileName;
-  std::string SplitDwarfOutput;
-
-  /// @}
-  /// @name Frontend Options
-  /// @{
-
-  std::string InputFile;
-  std::vector<std::string> LLVMArgs;
-  std::string OutputPath;
-  enum FileType {
-    FT_Asm,  ///< Assembly (.s) output, transliterate mode.
-    FT_Null, ///< No output, for timing purposes.
-    FT_Obj   ///< Object file output.
-  };
-  FileType OutputType;
-  unsigned ShowHelp : 1;
-  unsigned ShowVersion : 1;
-
-  /// @}
-  /// @name Transliterate Options
-  /// @{
-
-  unsigned OutputAsmVariant;
-  unsigned ShowEncoding : 1;
-  unsigned ShowInst : 1;
-
-  /// @}
-  /// @name Assembler Options
-  /// @{
-
-  unsigned RelaxAll : 1;
-  unsigned NoExecStack : 1;
-  unsigned FatalWarnings : 1;
-  unsigned NoWarn : 1;
-  unsigned IncrementalLinkerCompatible : 1;
-  unsigned EmbedBitcode : 1;
-
-  /// The name of the relocation model to use.
-  std::string RelocationModel;
-
-  /// The ABI targeted by the backend. Specified using -target-abi. Empty
-  /// otherwise.
-  std::string TargetABI;
-
-  /// @}
-
-public:
-  AssemblerInvocation() {
-    Triple = "";
-    NoInitialTextSection = 0;
-    InputFile = "-";
-    OutputPath = "-";
-    OutputType = FT_Asm;
-    OutputAsmVariant = 0;
-    ShowInst = 0;
-    ShowEncoding = 0;
-    RelaxAll = 0;
-    NoExecStack = 0;
-    FatalWarnings = 0;
-    NoWarn = 0;
-    IncrementalLinkerCompatible = 0;
-    DwarfVersion = 0;
-    EmbedBitcode = 0;
-  }
-
-  static bool CreateFromArgs(AssemblerInvocation &Res,
-                             ArrayRef<const char *> Argv,
-                             DiagnosticsEngine &Diags);
-};
-
-bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags);
@@ -1,97 +0,0 @@
-// +build byollvm
-
-#include <clang/Basic/DiagnosticOptions.h>
-#include <clang/CodeGen/CodeGenAction.h>
-#include <clang/Driver/Compilation.h>
-#include <clang/Driver/Driver.h>
-#include <clang/Frontend/CompilerInstance.h>
-#include <clang/Frontend/CompilerInvocation.h>
-#include <clang/Frontend/FrontendDiagnostic.h>
-#include <clang/Frontend/TextDiagnosticPrinter.h>
-#include <clang/FrontendTool/Utils.h>
-#include <llvm/ADT/IntrusiveRefCntPtr.h>
-#include <llvm/Option/Option.h>
-
-using namespace llvm;
-using namespace clang;
-
-#include "cc1as.h"
-
-// This file provides C wrappers for the builtin tools cc1 and cc1as
-// provided by Clang, and calls them as the driver would call them.
-
-extern "C" {
-
-bool tinygo_clang_driver(int argc, char **argv) {
-	std::vector<const char*> args(argv, argv + argc);
-
-	// The compiler invocation needs a DiagnosticsEngine so it can report problems
-	llvm::IntrusiveRefCntPtr<clang::DiagnosticOptions> DiagOpts = new clang::DiagnosticOptions();
-	clang::TextDiagnosticPrinter DiagnosticPrinter(llvm::errs(), &*DiagOpts);
-	clang::DiagnosticsEngine Diags(llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs>(new clang::DiagnosticIDs()), &*DiagOpts, &DiagnosticPrinter, false);
-
-	// Create the clang driver
-	clang::driver::Driver TheDriver(args[0], llvm::sys::getDefaultTargetTriple(), Diags);
-
-	// Create the set of actions to perform
-	std::unique_ptr<clang::driver::Compilation> C(TheDriver.BuildCompilation(args));
-	if (!C) {
-		return false;
-	}
-	const clang::driver::JobList &Jobs = C->getJobs();
-
-	// There may be more than one job, for example for .S files
-	// (preprocessor + assembler).
-	for (auto Cmd : Jobs) {
-		// Select the tool: cc1 or cc1as.
-		const llvm::opt::ArgStringList &CCArgs = Cmd.getArguments();
-
-		if (strcmp(*CCArgs.data(), "-cc1") == 0) {
-			// This is the C frontend.
-			// Initialize a compiler invocation object from the clang (-cc1) arguments.
-			std::unique_ptr<clang::CompilerInstance> Clang(new clang::CompilerInstance());
-			bool success = clang::CompilerInvocation::CreateFromArgs(
-					Clang->getInvocation(),
-					CCArgs,
-					Diags);
-			if (!success) {
-				return false;
-			}
-
-			// Create the actual diagnostics engine.
-			Clang->createDiagnostics();
-			if (!Clang->hasDiagnostics()) {
-				return false;
-			}
-
-			// Execute the frontend actions.
-			success = ExecuteCompilerInvocation(Clang.get());
-			if (!success) {
-				return false;
-			}
-
-		} else if (strcmp(*CCArgs.data(), "-cc1as") == 0) {
-			// This is the assembler frontend. Parse the arguments.
-			AssemblerInvocation Asm;
-			ArrayRef<const char *> Argv = llvm::ArrayRef<const char*>(CCArgs);
-			if (!AssemblerInvocation::CreateFromArgs(Asm, Argv.slice(1), Diags))
-				return false;
-
-			// Execute the invocation, unless there were parsing errors.
-			bool failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
-			if (failed) {
-				return false;
-			}
-
-		} else {
-			// Unknown tool, print the tool and exit.
-			fprintf(stderr, "unknown tool: %s\n", *CCArgs.data());
-			return false;
-		}
-	}
-
-	// Commands executed successfully.
-	return true;
-}
-
-} // extern "C"
@@ -1,65 +0,0 @@
-package builder
-
-import (
-	"errors"
-	"os"
-	"os/exec"
-	"runtime"
-	"strings"
-
-	"tinygo.org/x/go-llvm"
-)
-
-// Commands lists command alternatives for various operating systems. These
-// commands may have a slightly different name across operating systems and
-// distributions or may not even exist in $PATH, in which case absolute paths
-// may be used.
-var commands = map[string][]string{}
-
-func init() {
-	llvmMajor := strings.Split(llvm.Version, ".")[0]
-	commands["clang"] = []string{"clang-" + llvmMajor}
-	commands["ld.lld"] = []string{"ld.lld-" + llvmMajor, "ld.lld"}
-	commands["wasm-ld"] = []string{"wasm-ld-" + llvmMajor, "wasm-ld"}
-	// Add the path to a Homebrew-installed LLVM for ease of use (no need to
-	// manually set $PATH).
-	if runtime.GOOS == "darwin" {
-		prefix := "/usr/local/opt/llvm@" + llvmMajor + "/bin/"
-		commands["clang"] = append(commands["clang"], prefix+"clang-"+llvmMajor)
-		commands["ld.lld"] = append(commands["ld.lld"], prefix+"ld.lld")
-		commands["wasm-ld"] = append(commands["wasm-ld"], prefix+"wasm-ld")
-	}
-	// Add the path for when LLVM was installed with the installer from
-	// llvm.org, which by default doesn't add LLVM to the $PATH environment
-	// variable.
-	if runtime.GOOS == "windows" {
-		commands["clang"] = append(commands["clang"], "clang", "C:\\Program Files\\LLVM\\bin\\clang.exe")
-		commands["ld.lld"] = append(commands["ld.lld"], "lld", "C:\\Program Files\\LLVM\\bin\\lld.exe")
-		commands["wasm-ld"] = append(commands["wasm-ld"], "C:\\Program Files\\LLVM\\bin\\wasm-ld.exe")
-	}
-	// Add the path to LLVM installed from ports.
-	if runtime.GOOS == "freebsd" {
-		prefix := "/usr/local/llvm" + llvmMajor + "/bin/"
-		commands["clang"] = append(commands["clang"], prefix+"clang-"+llvmMajor)
-		commands["ld.lld"] = append(commands["ld.lld"], prefix+"ld.lld")
-		commands["wasm-ld"] = append(commands["wasm-ld"], prefix+"wasm-ld")
-	}
-}
-
-func execCommand(cmdNames []string, args ...string) error {
-	for _, cmdName := range cmdNames {
-		cmd := exec.Command(cmdName, args...)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		err := cmd.Run()
-		if err != nil {
-			if err, ok := err.(*exec.Error); ok && (err.Err == exec.ErrNotFound || err.Err.Error() == "file does not exist") {
-				// this command was not found, try the next
-				continue
-			}
-			return err
-		}
-		return nil
-	}
-	return errors.New("none of these commands were found in your $PATH: " + strings.Join(cmdNames, " "))
-}
@@ -1,39 +0,0 @@
-package builder
-
-import (
-	"errors"
-	"fmt"
-
-	"github.com/tinygo-org/tinygo/compileopts"
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// NewConfig builds a new Config object from a set of compiler options. It also
-// loads some information from the environment while doing that. For example, it
-// uses the currently active GOPATH (from the goenv package) to determine the Go
-// version to use.
-func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
-	spec, err := compileopts.LoadTarget(options.Target)
-	if err != nil {
-		return nil, err
-	}
-	goroot := goenv.Get("GOROOT")
-	if goroot == "" {
-		return nil, errors.New("cannot locate $GOROOT, please set it manually")
-	}
-	major, minor, err := goenv.GetGorootVersion(goroot)
-	if err != nil {
-		return nil, fmt.Errorf("could not read version from GOROOT (%v): %v", goroot, err)
-	}
-	if major != 1 || minor < 11 || minor > 14 {
-		return nil, fmt.Errorf("requires go version 1.11, 1.12, 1.13, or 1.14, got go%d.%d", major, minor)
-	}
-	clangHeaderPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))
-	return &compileopts.Config{
-		Options:        options,
-		Target:         spec,
-		GoMinorVersion: minor,
-		ClangHeaders:   clangHeaderPath,
-		TestConfig:     options.TestConfig,
-	}, nil
-}
@@ -1,69 +0,0 @@
-package builder
-
-import (
-	"io/ioutil"
-	"os"
-	"os/exec"
-	"path/filepath"
-	"sort"
-)
-
-// getClangHeaderPath returns the path to the built-in Clang headers. It tries
-// multiple locations, which should make it find the directory when installed in
-// various ways.
-func getClangHeaderPath(TINYGOROOT string) string {
-	// Check whether we're running from the source directory.
-	path := filepath.Join(TINYGOROOT, "llvm-project", "clang", "lib", "Headers")
-	if _, err := os.Stat(path); !os.IsNotExist(err) {
-		return path
-	}
-
-	// Check whether we're running from the installation directory.
-	path = filepath.Join(TINYGOROOT, "lib", "clang", "include")
-	if _, err := os.Stat(path); !os.IsNotExist(err) {
-		return path
-	}
-
-	// It looks like we are built with a system-installed LLVM. Do a last
-	// attempt: try to use Clang headers relative to the clang binary.
-	for _, cmdName := range commands["clang"] {
-		binpath, err := exec.LookPath(cmdName)
-		if err == nil {
-			// This should be the command that will also be used by
-			// execCommand. To avoid inconsistencies, make sure we use the
-			// headers relative to this command.
-			binpath, err = filepath.EvalSymlinks(binpath)
-			if err != nil {
-				// Unexpected.
-				return ""
-			}
-			// Example executable:
-			//     /usr/lib/llvm-9/bin/clang
-			// Example include path:
-			//     /usr/lib/llvm-9/lib/clang/9.0.1/include/
-			llvmRoot := filepath.Dir(filepath.Dir(binpath))
-			clangVersionRoot := filepath.Join(llvmRoot, "lib", "clang")
-			dirs, err := ioutil.ReadDir(clangVersionRoot)
-			if err != nil {
-				// Unexpected.
-				continue
-			}
-			dirnames := make([]string, len(dirs))
-			for i, d := range dirs {
-				dirnames[i] = d.Name()
-			}
-			sort.Strings(dirnames)
-			// Check for the highest version first.
-			for i := len(dirnames) - 1; i >= 0; i-- {
-				path := filepath.Join(clangVersionRoot, dirnames[i], "include")
-				_, err := os.Stat(filepath.Join(path, "stdint.h"))
-				if err == nil {
-					return path
-				}
-			}
-		}
-	}
-
-	// Could not find it.
-	return ""
-}
@@ -1,39 +0,0 @@
-package builder
-
-// MultiError is a list of multiple errors (actually: diagnostics) returned
-// during LLVM IR generation.
-type MultiError struct {
-	Errs []error
-}
-
-func (e *MultiError) Error() string {
-	// Return the first error, to conform to the error interface. Clients should
-	// really do a type-assertion on *MultiError.
-	return e.Errs[0].Error()
-}
-
-// newMultiError returns a *MultiError if there is more than one error, or
-// returns that error directly when there is only one. Passing an empty slice
-// will lead to a panic.
-func newMultiError(errs []error) error {
-	switch len(errs) {
-	case 0:
-		panic("attempted to create empty MultiError")
-	case 1:
-		return errs[0]
-	default:
-		return &MultiError{errs}
-	}
-}
-
-// commandError is an error type to wrap os/exec.Command errors. This provides
-// some more information regarding what went wrong while running a command.
-type commandError struct {
-	Msg  string
-	File string
-	Err  error
-}
-
-func (e *commandError) Error() string {
-	return e.Msg + " " + e.File + ": " + e.Err.Error()
-}
@@ -1,102 +0,0 @@
-package builder
-
-import (
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"strings"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// Library is a container for information about a single C library, such as a
-// compiler runtime or libc.
-type Library struct {
-	// The library name, such as compiler-rt or picolibc.
-	name string
-
-	cflags func() []string
-
-	// The source directory, relative to TINYGOROOT.
-	sourceDir string
-
-	// The source files, relative to sourceDir.
-	sources func(target string) []string
-}
-
-// fullPath returns the full path to the source directory.
-func (l *Library) fullPath() string {
-	return filepath.Join(goenv.Get("TINYGOROOT"), l.sourceDir)
-}
-
-// sourcePaths returns a slice with the full paths to the source files.
-func (l *Library) sourcePaths(target string) []string {
-	sources := l.sources(target)
-	paths := make([]string, len(sources))
-	for i, name := range sources {
-		paths[i] = filepath.Join(l.fullPath(), name)
-	}
-	return paths
-}
-
-// Load the library archive, possibly generating and caching it if needed.
-func (l *Library) Load(target string) (path string, err error) {
-	// Try to load a precompiled library.
-	precompiledPath := filepath.Join(goenv.Get("TINYGOROOT"), "pkg", target, l.name+".a")
-	if _, err := os.Stat(precompiledPath); err == nil {
-		// Found a precompiled library for this OS/architecture. Return the path
-		// directly.
-		return precompiledPath, nil
-	}
-
-	outfile := l.name + "-" + target + ".a"
-
-	// Try to fetch this library from the cache.
-	if path, err := cacheLoad(outfile, commands["clang"][0], l.sourcePaths(target)); path != "" || err != nil {
-		// Cache hit.
-		return path, err
-	}
-	// Cache miss, build it now.
-
-	dirPrefix := "tinygo-" + l.name
-	remapDir := filepath.Join(os.TempDir(), dirPrefix)
-	dir, err := ioutil.TempDir(os.TempDir(), dirPrefix)
-	if err != nil {
-		return "", err
-	}
-	defer os.RemoveAll(dir)
-
-	// Precalculate the flags to the compiler invocation.
-	args := append(l.cflags(), "-c", "-Oz", "-g", "-ffunction-sections", "-fdata-sections", "-Wno-macro-redefined", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir)
-	if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
-		args = append(args, "-fshort-enums", "-fomit-frame-pointer")
-	}
-	if strings.HasPrefix(target, "riscv32-") {
-		args = append(args, "-march=rv32imac", "-mabi=ilp32", "-fforce-enable-int128")
-	}
-
-	// Compile all sources.
-	var objs []string
-	for _, srcpath := range l.sourcePaths(target) {
-		objpath := filepath.Join(dir, filepath.Base(srcpath)+".o")
-		objs = append(objs, objpath)
-		// Note: -fdebug-prefix-map is necessary to make the output archive
-		// reproducible. Otherwise the temporary directory is stored in the
-		// archive itself, which varies each run.
-		err := runCCompiler("clang", append(args, "-o", objpath, srcpath)...)
-		if err != nil {
-			return "", &commandError{"failed to build", srcpath, err}
-		}
-	}
-
-	// Put all the object files in a single archive. This archive file will be
-	// used to statically link this library.
-	arpath := filepath.Join(dir, l.name+".a")
-	err = makeArchive(arpath, objs)
-	if err != nil {
-		return "", err
-	}
-
-	// Store this archive in the cache.
-	return cacheStore(arpath, outfile, commands["clang"][0], l.sourcePaths(target))
-}
@@ -1,127 +0,0 @@
-package builder
-
-import (
-	"path/filepath"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// Picolibc is a C library for bare metal embedded devices. It was originally
-// based on newlib.
-var Picolibc = Library{
-	name: "picolibc",
-	cflags: func() []string {
-		picolibcDir := filepath.Join(goenv.Get("TINYGOROOT"), "lib/picolibc/newlib/libc")
-		return []string{"-Werror", "-Wall", "-std=gnu11", "-D_COMPILING_NEWLIB", "-nostdlibinc", "-Xclang", "-internal-isystem", "-Xclang", picolibcDir + "/include", "-I" + picolibcDir + "/tinystdio", "-I" + goenv.Get("TINYGOROOT") + "/lib/picolibc-include"}
-	},
-	sourceDir: "lib/picolibc/newlib/libc",
-	sources: func(target string) []string {
-		return picolibcSources
-	},
-}
-
-var picolibcSources = []string{
-	"string/bcmp.c",
-	"string/bcopy.c",
-	"string/bzero.c",
-	"string/explicit_bzero.c",
-	"string/ffsl.c",
-	"string/ffsll.c",
-	"string/fls.c",
-	"string/flsl.c",
-	"string/flsll.c",
-	"string/gnu_basename.c",
-	"string/index.c",
-	"string/memccpy.c",
-	"string/memchr.c",
-	"string/memcmp.c",
-	"string/memcpy.c",
-	"string/memmem.c",
-	"string/memmove.c",
-	"string/mempcpy.c",
-	"string/memrchr.c",
-	"string/memset.c",
-	"string/rawmemchr.c",
-	"string/rindex.c",
-	"string/stpcpy.c",
-	"string/stpncpy.c",
-	"string/strcasecmp.c",
-	"string/strcasecmp_l.c",
-	"string/strcasestr.c",
-	"string/strcat.c",
-	"string/strchr.c",
-	"string/strchrnul.c",
-	"string/strcmp.c",
-	"string/strcoll.c",
-	"string/strcoll_l.c",
-	"string/strcpy.c",
-	"string/strcspn.c",
-	"string/strdup.c",
-	"string/strerror.c",
-	"string/strerror_r.c",
-	"string/strlcat.c",
-	"string/strlcpy.c",
-	"string/strlen.c",
-	"string/strlwr.c",
-	"string/strncasecmp.c",
-	"string/strncasecmp_l.c",
-	"string/strncat.c",
-	"string/strncmp.c",
-	"string/strncpy.c",
-	"string/strndup.c",
-	"string/strnlen.c",
-	"string/strnstr.c",
-	"string/strpbrk.c",
-	"string/strrchr.c",
-	"string/strsep.c",
-	"string/strsignal.c",
-	"string/strspn.c",
-	"string/strstr.c",
-	"string/strtok.c",
-	"string/strtok_r.c",
-	"string/strupr.c",
-	"string/strverscmp.c",
-	"string/strxfrm.c",
-	"string/strxfrm_l.c",
-	"string/swab.c",
-	"string/timingsafe_bcmp.c",
-	"string/timingsafe_memcmp.c",
-	"string/u_strerr.c",
-	"string/wcpcpy.c",
-	"string/wcpncpy.c",
-	"string/wcscasecmp.c",
-	"string/wcscasecmp_l.c",
-	"string/wcscat.c",
-	"string/wcschr.c",
-	"string/wcscmp.c",
-	"string/wcscoll.c",
-	"string/wcscoll_l.c",
-	"string/wcscpy.c",
-	"string/wcscspn.c",
-	"string/wcsdup.c",
-	"string/wcslcat.c",
-	"string/wcslcpy.c",
-	"string/wcslen.c",
-	"string/wcsncasecmp.c",
-	"string/wcsncasecmp_l.c",
-	"string/wcsncat.c",
-	"string/wcsncmp.c",
-	"string/wcsncpy.c",
-	"string/wcsnlen.c",
-	"string/wcspbrk.c",
-	"string/wcsrchr.c",
-	"string/wcsspn.c",
-	"string/wcsstr.c",
-	"string/wcstok.c",
-	"string/wcswidth.c",
-	"string/wcsxfrm.c",
-	"string/wcsxfrm_l.c",
-	"string/wcwidth.c",
-	"string/wmemchr.c",
-	"string/wmemcmp.c",
-	"string/wmemcpy.c",
-	"string/wmemmove.c",
-	"string/wmempcpy.c",
-	"string/wmemset.c",
-	"string/xpg_strerror_r.c",
-}
@@ -1,54 +0,0 @@
-// +build byollvm
-
-package builder
-
-import (
-	"errors"
-	"unsafe"
-)
-
-/*
-#cgo CXXFLAGS: -fno-rtti
-#include <stdbool.h>
-#include <stdlib.h>
-bool tinygo_clang_driver(int argc, char **argv);
-bool tinygo_link_elf(int argc, char **argv);
-bool tinygo_link_wasm(int argc, char **argv);
-*/
-import "C"
-
-const hasBuiltinTools = true
-
-// RunTool runs the given tool (such as clang).
-//
-// This version actually runs the tools because TinyGo was compiled while
-// linking statically with LLVM (with the byollvm build tag).
-func RunTool(tool string, args ...string) error {
-	args = append([]string{"tinygo:" + tool}, args...)
-
-	var cflag *C.char
-	buf := C.calloc(C.size_t(len(args)), C.size_t(unsafe.Sizeof(cflag)))
-	defer C.free(buf)
-	cflags := (*[1 << 10]*C.char)(unsafe.Pointer(buf))[:len(args):len(args)]
-	for i, flag := range args {
-		cflag := C.CString(flag)
-		cflags[i] = cflag
-		defer C.free(unsafe.Pointer(cflag))
-	}
-
-	var ok C.bool
-	switch tool {
-	case "clang":
-		ok = C.tinygo_clang_driver(C.int(len(args)), (**C.char)(buf))
-	case "ld.lld":
-		ok = C.tinygo_link_elf(C.int(len(args)), (**C.char)(buf))
-	case "wasm-ld":
-		ok = C.tinygo_link_wasm(C.int(len(args)), (**C.char)(buf))
-	default:
-		return errors.New("unknown tool: " + tool)
-	}
-	if !ok {
-		return errors.New("failed to run tool: " + tool)
-	}
-	return nil
-}
@@ -1,15 +0,0 @@
-// +build !byollvm
-
-package builder
-
-import "errors"
-
-const hasBuiltinTools = false
-
-// RunTool runs the given tool (such as clang).
-//
-// This version doesn't actually run the tool: TinyGo has not been compiled by
-// statically linking to LLVM.
-func RunTool(tool string, args ...string) error {
-	return errors.New("cannot run tool: " + tool)
-}
@@ -1,59 +0,0 @@
-package builder
-
-import (
-	"errors"
-	"os"
-	"os/exec"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// runCCompiler invokes a C compiler with the given arguments.
-func runCCompiler(command string, flags ...string) error {
-	if hasBuiltinTools && command == "clang" {
-		// Compile this with the internal Clang compiler.
-		headerPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))
-		if headerPath == "" {
-			return errors.New("could not locate Clang headers")
-		}
-		flags = append(flags, "-I"+headerPath)
-		cmd := exec.Command(os.Args[0], append([]string{"clang"}, flags...)...)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		return cmd.Run()
-	}
-
-	// Running some other compiler. Maybe it has been defined in the
-	// commands map (unlikely).
-	if cmdNames, ok := commands[command]; ok {
-		return execCommand(cmdNames, flags...)
-	}
-
-	// Alternatively, run the compiler directly.
-	cmd := exec.Command(command, flags...)
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	return cmd.Run()
-}
-
-// link invokes a linker with the given name and flags.
-func link(linker string, flags ...string) error {
-	if hasBuiltinTools && (linker == "ld.lld" || linker == "wasm-ld") {
-		// Run command with internal linker.
-		cmd := exec.Command(os.Args[0], append([]string{linker}, flags...)...)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		return cmd.Run()
-	}
-
-	// Fall back to external command.
-	if cmdNames, ok := commands[linker]; ok {
-		return execCommand(cmdNames, flags...)
-	}
-
-	cmd := exec.Command(linker, flags...)
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	cmd.Dir = goenv.Get("TINYGOROOT")
-	return cmd.Run()
-}
@@ -0,0 +1,294 @@
+package main
+
+import (
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/blakesmith/ar"
+)
+
+// These are the GENERIC_SOURCES according to CMakeList.txt.
+var genericBuiltins = []string{
+	"absvdi2.c",
+	"absvsi2.c",
+	"absvti2.c",
+	"adddf3.c",
+	"addsf3.c",
+	"addtf3.c",
+	"addvdi3.c",
+	"addvsi3.c",
+	"addvti3.c",
+	"apple_versioning.c",
+	"ashldi3.c",
+	"ashlti3.c",
+	"ashrdi3.c",
+	"ashrti3.c",
+	"bswapdi2.c",
+	"bswapsi2.c",
+	"clzdi2.c",
+	"clzsi2.c",
+	"clzti2.c",
+	"cmpdi2.c",
+	"cmpti2.c",
+	"comparedf2.c",
+	"comparesf2.c",
+	"ctzdi2.c",
+	"ctzsi2.c",
+	"ctzti2.c",
+	"divdc3.c",
+	"divdf3.c",
+	"divdi3.c",
+	"divmoddi4.c",
+	"divmodsi4.c",
+	"divsc3.c",
+	"divsf3.c",
+	"divsi3.c",
+	"divtc3.c",
+	"divti3.c",
+	"divtf3.c",
+	"extendsfdf2.c",
+	"extendhfsf2.c",
+	"ffsdi2.c",
+	"ffssi2.c",
+	"ffsti2.c",
+	"fixdfdi.c",
+	"fixdfsi.c",
+	"fixdfti.c",
+	"fixsfdi.c",
+	"fixsfsi.c",
+	"fixsfti.c",
+	"fixunsdfdi.c",
+	"fixunsdfsi.c",
+	"fixunsdfti.c",
+	"fixunssfdi.c",
+	"fixunssfsi.c",
+	"fixunssfti.c",
+	"floatdidf.c",
+	"floatdisf.c",
+	"floatsidf.c",
+	"floatsisf.c",
+	"floattidf.c",
+	"floattisf.c",
+	"floatundidf.c",
+	"floatundisf.c",
+	"floatunsidf.c",
+	"floatunsisf.c",
+	"floatuntidf.c",
+	"floatuntisf.c",
+	//"int_util.c",
+	"lshrdi3.c",
+	"lshrti3.c",
+	"moddi3.c",
+	"modsi3.c",
+	"modti3.c",
+	"muldc3.c",
+	"muldf3.c",
+	"muldi3.c",
+	"mulodi4.c",
+	"mulosi4.c",
+	"muloti4.c",
+	"mulsc3.c",
+	"mulsf3.c",
+	"multi3.c",
+	"multf3.c",
+	"mulvdi3.c",
+	"mulvsi3.c",
+	"mulvti3.c",
+	"negdf2.c",
+	"negdi2.c",
+	"negsf2.c",
+	"negti2.c",
+	"negvdi2.c",
+	"negvsi2.c",
+	"negvti2.c",
+	"os_version_check.c",
+	"paritydi2.c",
+	"paritysi2.c",
+	"parityti2.c",
+	"popcountdi2.c",
+	"popcountsi2.c",
+	"popcountti2.c",
+	"powidf2.c",
+	"powisf2.c",
+	"powitf2.c",
+	"subdf3.c",
+	"subsf3.c",
+	"subvdi3.c",
+	"subvsi3.c",
+	"subvti3.c",
+	"subtf3.c",
+	"trampoline_setup.c",
+	"truncdfhf2.c",
+	"truncdfsf2.c",
+	"truncsfhf2.c",
+	"ucmpdi2.c",
+	"ucmpti2.c",
+	"udivdi3.c",
+	"udivmoddi4.c",
+	"udivmodsi4.c",
+	"udivmodti4.c",
+	"udivsi3.c",
+	"udivti3.c",
+	"umoddi3.c",
+	"umodsi3.c",
+	"umodti3.c",
+}
+
+var aeabiBuiltins = []string{
+	"arm/aeabi_cdcmp.S",
+	"arm/aeabi_cdcmpeq_check_nan.c",
+	"arm/aeabi_cfcmp.S",
+	"arm/aeabi_cfcmpeq_check_nan.c",
+	"arm/aeabi_dcmp.S",
+	"arm/aeabi_div0.c",
+	"arm/aeabi_drsub.c",
+	"arm/aeabi_fcmp.S",
+	"arm/aeabi_frsub.c",
+	"arm/aeabi_idivmod.S",
+	"arm/aeabi_ldivmod.S",
+	"arm/aeabi_memcmp.S",
+	"arm/aeabi_memcpy.S",
+	"arm/aeabi_memmove.S",
+	"arm/aeabi_memset.S",
+	"arm/aeabi_uidivmod.S",
+	"arm/aeabi_uldivmod.S",
+}
+
+func builtinFiles(target string) []string {
+	builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
+	if strings.HasPrefix(target, "arm") {
+		builtins = append(builtins, aeabiBuiltins...)
+	}
+	return builtins
+}
+
+// builtinsDir returns the directory where the sources for compiler-rt are kept.
+func builtinsDir() string {
+	return filepath.Join(sourceDir(), "lib", "compiler-rt", "lib", "builtins")
+}
+
+// Get the builtins archive, possibly generating it as needed.
+func loadBuiltins(target string) (path string, err error) {
+	// Try to load a precompiled compiler-rt library.
+	precompiledPath := filepath.Join(sourceDir(), "pkg", target, "compiler-rt.a")
+	if _, err := os.Stat(precompiledPath); err == nil {
+		// Found a precompiled compiler-rt for this OS/architecture. Return the
+		// path directly.
+		return precompiledPath, nil
+	}
+
+	outfile := "librt-" + target + ".a"
+	builtinsDir := builtinsDir()
+
+	builtins := builtinFiles(target)
+	srcs := make([]string, len(builtins))
+	for i, name := range builtins {
+		srcs[i] = filepath.Join(builtinsDir, name)
+	}
+
+	if path, err := cacheLoad(outfile, commands["clang"][0], srcs); path != "" || err != nil {
+		return path, err
+	}
+
+	var cachepath string
+	err = compileBuiltins(target, func(path string) error {
+		path, err := cacheStore(path, outfile, commands["clang"][0], srcs)
+		cachepath = path
+		return err
+	})
+	return cachepath, err
+}
+
+// compileBuiltins compiles builtins from compiler-rt into a static library.
+// When it succeeds, it will call the callback with the resulting path. The path
+// will be removed after callback returns. If callback returns an error, this is
+// passed through to the return value of this function.
+func compileBuiltins(target string, callback func(path string) error) error {
+	builtinsDir := builtinsDir()
+
+	builtins := builtinFiles(target)
+	srcs := make([]string, len(builtins))
+	for i, name := range builtins {
+		srcs[i] = filepath.Join(builtinsDir, name)
+	}
+
+	dirPrefix := "tinygo-builtins"
+	remapDir := filepath.Join(os.TempDir(), dirPrefix)
+	dir, err := ioutil.TempDir(os.TempDir(), dirPrefix)
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(dir)
+
+	// Compile all builtins.
+	// TODO: use builtins optimized for a given target if available.
+	objs := make([]string, 0, len(builtins))
+	for _, name := range builtins {
+		objname := name
+		if strings.LastIndexByte(objname, '/') >= 0 {
+			objname = objname[strings.LastIndexByte(objname, '/'):]
+		}
+		objpath := filepath.Join(dir, objname+".o")
+		objs = append(objs, objpath)
+		srcpath := filepath.Join(builtinsDir, name)
+		// Note: -fdebug-prefix-map is necessary to make the output archive
+		// reproducible. Otherwise the temporary directory is stored in the
+		// archive itself, which varies each run.
+		err := execCommand(commands["clang"], "-c", "-Oz", "-g", "-Werror", "-Wall", "-std=c11", "-fshort-enums", "-nostdlibinc", "-ffunction-sections", "-fdata-sections", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir, "-o", objpath, srcpath)
+		if err != nil {
+			return &commandError{"failed to build", srcpath, err}
+		}
+	}
+
+	// Put all builtins in an archive to link as a static library.
+	// Note: this does not create a symbol index, but ld.lld doesn't seem to
+	// care.
+	arpath := filepath.Join(dir, "librt.a")
+	arfile, err := os.Create(arpath)
+	if err != nil {
+		return err
+	}
+	defer arfile.Close()
+	arwriter := ar.NewWriter(arfile)
+	err = arwriter.WriteGlobalHeader()
+	if err != nil {
+		return &os.PathError{"write ar header", arpath, err}
+	}
+	for _, objpath := range objs {
+		name := filepath.Base(objpath)
+		objfile, err := os.Open(objpath)
+		if err != nil {
+			return err
+		}
+		defer objfile.Close()
+		st, err := objfile.Stat()
+		if err != nil {
+			return err
+		}
+		arwriter.WriteHeader(&ar.Header{
+			Name:    name,
+			ModTime: time.Unix(0, 0),
+			Uid:     0,
+			Gid:     0,
+			Mode:    0644,
+			Size:    st.Size(),
+		})
+		n, err := io.Copy(arwriter, objfile)
+		if err != nil {
+			return err
+		}
+		if n != st.Size() {
+			return errors.New("file modified during ar creation: " + arpath)
+		}
+	}
+
+	// Give the caller the resulting file. The callback must copy the file,
+	// because after it returns the temporary directory will be removed.
+	arfile.Close()
+	return callback(arpath)
+}
@@ -12,16 +12,12 @@ package cgo
 // source file parsing.

 import (
-	"fmt"
 	"go/ast"
-	"go/scanner"
 	"go/token"
-	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"

-	"github.com/google/shlex"
 	"golang.org/x/tools/go/ast/astutil"
 )

@@ -46,7 +42,7 @@ type cgoPackage struct {
 // constantInfo stores some information about a CGo constant found by libclang
 // and declared in the Go AST.
 type constantInfo struct {
-	expr ast.Expr
+	expr *ast.BasicLit
 	pos  token.Pos
 }

@@ -73,11 +69,9 @@ type typedefInfo struct {
 // elaboratedTypeInfo contains some information about an elaborated type
 // (struct, union) found in the C AST.
 type elaboratedTypeInfo struct {
-	typeExpr   *ast.StructType
-	pos        token.Pos
-	bitfields  []bitfieldInfo
-	unionSize  int64 // union size in bytes, nonzero when union getters/setters should be created
-	unionAlign int64 // union alignment in bytes
+	typeExpr  *ast.StructType
+	pos       token.Pos
+	bitfields []bitfieldInfo
 }

 // bitfieldInfo contains information about a single bitfield in a struct. It
@@ -137,7 +131,6 @@ var builtinAliases = map[string]struct{}{
 // somehow from C. This is done by adding some typedefs to get the size of each
 // type.
 const cgoTypes = `
-# 1 "<cgo>"
 typedef char                _Cgo_char;
 typedef signed char         _Cgo_schar;
 typedef unsigned char       _Cgo_uchar;
@@ -170,28 +163,11 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		enums:           map[string]enumInfo{},
 	}

-	// Disable _FORTIFY_SOURCE as it causes problems on macOS.
-	// Note that it is only disabled for memcpy (etc) calls made from Go, which
-	// have better alternatives anyway.
-	cflags = append(cflags, "-D_FORTIFY_SOURCE=0")
-
 	// Add a new location for the following file.
 	generatedTokenPos := p.fset.AddFile(dir+"/!cgo.go", -1, 0)
 	generatedTokenPos.SetLines([]int{0})
 	p.generatedPos = generatedTokenPos.Pos(0)

-	// Find the absolute path for this package.
-	packagePath, err := filepath.Abs(fset.File(files[0].Pos()).Name())
-	if err != nil {
-		return nil, []error{
-			scanner.Error{
-				Pos: fset.Position(files[0].Pos()),
-				Msg: "cgo: cannot find absolute path: " + err.Error(), // TODO: wrap this error
-			},
-		}
-	}
-	packagePath = filepath.Dir(packagePath)
-
 	// Construct a new in-memory AST for CGo declarations of this package.
 	unsafeImport := &ast.ImportSpec{
 		Path: &ast.BasicLit{
@@ -208,7 +184,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 			Name:    files[0].Name.Name,
 		},
 		Decls: []ast.Decl{
-			// import "unsafe"
 			&ast.GenDecl{
 				TokPos: p.generatedPos,
 				Tok:    token.IMPORT,
@@ -216,32 +191,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 					unsafeImport,
 				},
 			},
-			// var _ unsafe.Pointer
-			// This avoids type errors when the unsafe package is never used.
-			&ast.GenDecl{
-				Tok: token.VAR,
-				Specs: []ast.Spec{
-					&ast.ValueSpec{
-						Names: []*ast.Ident{
-							&ast.Ident{
-								Name: "_",
-								Obj: &ast.Object{
-									Kind: ast.Var,
-									Name: "_",
-								},
-							},
-						},
-						Type: &ast.SelectorExpr{
-							X: &ast.Ident{
-								Name: "unsafe",
-							},
-							Sel: &ast.Ident{
-								Name: "Pointer",
-							},
-						},
-					},
-				},
-			},
 		},
 		Imports: []*ast.ImportSpec{unsafeImport},
 	}
@@ -255,7 +204,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	}

 	// Find `import "C"` statements in the file.
-	var statements []*ast.GenDecl
 	for _, f := range files {
 		for i := 0; i < len(f.Decls); i++ {
 			decl := f.Decls[i]
@@ -272,16 +220,19 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 			}
 			path, err := strconv.Unquote(spec.Path.Value)
 			if err != nil {
-				// This should not happen. An import path that is not properly
-				// quoted should not exist in a correct AST.
 				panic("could not parse import path: " + err.Error())
 			}
 			if path != "C" {
 				continue
 			}
+			cgoComment := genDecl.Doc.Text()

-			// Found a CGo statement.
-			statements = append(statements, genDecl)
+			pos := genDecl.Pos()
+			if genDecl.Doc != nil {
+				pos = genDecl.Doc.Pos()
+			}
+			position := fset.PositionFor(pos, true)
+			p.parseFragment(cgoComment+cgoTypes, cflags, position.Filename, position.Line)

 			// Remove this import declaration.
 			f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
@@ -292,94 +243,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		//ast.Print(fset, f)
 	}

-	// Find all #cgo lines.
-	for _, genDecl := range statements {
-		if genDecl.Doc == nil {
-			continue
-		}
-		for _, comment := range genDecl.Doc.List {
-			for {
-				// Extract the #cgo line, and replace it with spaces.
-				// Replacing with spaces makes sure that error locations are
-				// still correct, while not interfering with parsing in any way.
-				lineStart := strings.Index(comment.Text, "#cgo ")
-				if lineStart < 0 {
-					break
-				}
-				lineLen := strings.IndexByte(comment.Text[lineStart:], '\n')
-				if lineLen < 0 {
-					lineLen = len(comment.Text) - lineStart
-				}
-				lineEnd := lineStart + lineLen
-				line := comment.Text[lineStart:lineEnd]
-				spaces := make([]byte, len(line))
-				for i := range spaces {
-					spaces[i] = ' '
-				}
-				lenBefore := len(comment.Text)
-				comment.Text = comment.Text[:lineStart] + string(spaces) + comment.Text[lineEnd:]
-				if len(comment.Text) != lenBefore {
-					println(lenBefore, len(comment.Text))
-					panic("length of preamble changed!")
-				}
-
-				// Get the text before the colon in the #cgo directive.
-				colon := strings.IndexByte(line, ':')
-				if colon < 0 {
-					p.addErrorAfter(comment.Slash, comment.Text[:lineStart], "missing colon in #cgo line")
-					continue
-				}
-
-				// Extract the fields before the colon. These fields are a list
-				// of build tags and the C environment variable.
-				fields := strings.Fields(line[4:colon])
-				if len(fields) == 0 {
-					p.addErrorAfter(comment.Slash, comment.Text[:lineStart+colon-1], "invalid #cgo line")
-					continue
-				}
-
-				if len(fields) > 1 {
-					p.addErrorAfter(comment.Slash, comment.Text[:lineStart+5], "not implemented: build constraints in #cgo line")
-					continue
-				}
-
-				name := fields[len(fields)-1]
-				value := line[colon+1:]
-				switch name {
-				case "CFLAGS":
-					flags, err := shlex.Split(value)
-					if err != nil {
-						// TODO: find the exact location where the error happened.
-						p.addErrorAfter(comment.Slash, comment.Text[:lineStart+colon+1], "failed to parse flags in #cgo line: "+err.Error())
-						continue
-					}
-					if err := checkCompilerFlags(name, flags); err != nil {
-						p.addErrorAfter(comment.Slash, comment.Text[:lineStart+colon+1], err.Error())
-						continue
-					}
-					makePathsAbsolute(flags, packagePath)
-					cflags = append(cflags, flags...)
-				default:
-					startPos := strings.LastIndex(line[4:colon], name) + 4
-					p.addErrorAfter(comment.Slash, comment.Text[:lineStart+startPos], "invalid #cgo line: "+name)
-					continue
-				}
-			}
-		}
-	}
-
-	// Process all CGo imports.
-	for _, genDecl := range statements {
-		cgoComment := genDecl.Doc.Text()
-
-		pos := genDecl.Pos()
-		if genDecl.Doc != nil {
-			pos = genDecl.Doc.Pos()
-		}
-		position := fset.PositionFor(pos, true)
-		p.parseFragment(cgoComment+cgoTypes, cflags, position.Filename, position.Line)
-	}
-
 	// Declare functions found by libclang.
 	p.addFuncDecls()

@@ -415,30 +278,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	return p.generated, p.errors
 }

-// makePathsAbsolute converts some common path compiler flags (-I, -L) from
-// relative flags into absolute flags, if they are relative. This is necessary
-// because the C compiler is usually not invoked from the package path.
-func makePathsAbsolute(args []string, packagePath string) {
-	nextIsPath := false
-	for i, arg := range args {
-		if nextIsPath {
-			if !filepath.IsAbs(arg) {
-				args[i] = filepath.Join(packagePath, arg)
-			}
-		}
-		if arg == "-I" || arg == "-L" {
-			nextIsPath = true
-			continue
-		}
-		if strings.HasPrefix(arg, "-I") || strings.HasPrefix(arg, "-L") {
-			path := arg[2:]
-			if !filepath.IsAbs(path) {
-				args[i] = arg[:2] + filepath.Join(packagePath, path)
-			}
-		}
-	}
-}
-
 // addFuncDecls adds the C function declarations found by libclang in the
 // comment above the `import "C"` statement.
 func (p *cgoPackage) addFuncDecls() {
@@ -504,18 +343,18 @@ func (p *cgoPackage) addFuncPtrDecls() {
 	if len(p.functions) == 0 {
 		return
 	}
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.VAR,
+		Lparen: token.NoPos,
+		Rparen: token.NoPos,
+	}
 	names := make([]string, 0, len(p.functions))
 	for name := range p.functions {
 		names = append(names, name)
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.VAR,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
 		fn := p.functions[name]
 		obj := &ast.Object{
 			Kind: ast.Typ,
@@ -540,32 +379,34 @@ func (p *cgoPackage) addFuncPtrDecls() {
 		}
 		obj.Decl = valueSpec
 		gen.Specs = append(gen.Specs, valueSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 // addConstDecls declares external C constants in the Go source.
 // It adds code like the following to the AST:
 //
-//     const C.CONST_INT = 5
-//     const C.CONST_FLOAT = 5.8
-//     // ...
+//     const (
+//         C.CONST_INT = 5
+//         C.CONST_FLOAT = 5.8
+//         // ...
+//     )
 func (p *cgoPackage) addConstDecls() {
 	if len(p.constants) == 0 {
 		return
 	}
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.CONST,
+		Lparen: token.NoPos,
+		Rparen: token.NoPos,
+	}
 	names := make([]string, 0, len(p.constants))
 	for name := range p.constants {
 		names = append(names, name)
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.CONST,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
 		constVal := p.constants[name]
 		obj := &ast.Object{
 			Kind: ast.Con,
@@ -581,32 +422,34 @@ func (p *cgoPackage) addConstDecls() {
 		}
 		obj.Decl = valueSpec
 		gen.Specs = append(gen.Specs, valueSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 // addVarDecls declares external C globals in the Go source.
 // It adds code like the following to the AST:
 //
-//     var C.globalInt  int
-//     var C.globalBool bool
-//     // ...
+//     var (
+//         C.globalInt  int
+//         C.globalBool bool
+//         // ...
+//     )
 func (p *cgoPackage) addVarDecls() {
 	if len(p.globals) == 0 {
 		return
 	}
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.VAR,
+		Lparen: token.NoPos,
+		Rparen: token.NoPos,
+	}
 	names := make([]string, 0, len(p.globals))
 	for name := range p.globals {
 		names = append(names, name)
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.VAR,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
 		global := p.globals[name]
 		obj := &ast.Object{
 			Kind: ast.Var,
@@ -622,29 +465,31 @@ func (p *cgoPackage) addVarDecls() {
 		}
 		obj.Decl = valueSpec
 		gen.Specs = append(gen.Specs, valueSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 // addTypeAliases aliases some built-in Go types with their equivalent C types.
 // It adds code like the following to the AST:
 //
-//     type C.int8_t  = int8
-//     type C.int16_t = int16
-//     // ...
+//     type (
+//         C.int8_t  = int8
+//         C.int16_t = int16
+//         // ...
+//     )
 func (p *cgoPackage) addTypeAliases() {
 	aliasKeys := make([]string, 0, len(cgoAliases))
 	for key := range cgoAliases {
 		aliasKeys = append(aliasKeys, key)
 	}
 	sort.Strings(aliasKeys)
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.TYPE,
+		Lparen: token.NoPos,
+		Rparen: token.NoPos,
+	}
 	for _, typeName := range aliasKeys {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
 		goTypeName := cgoAliases[typeName]
 		obj := &ast.Object{
 			Kind: ast.Typ,
@@ -664,24 +509,24 @@ func (p *cgoPackage) addTypeAliases() {
 		}
 		obj.Decl = typeSpec
 		gen.Specs = append(gen.Specs, typeSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 func (p *cgoPackage) addTypedefs() {
 	if len(p.typedefs) == 0 {
 		return
 	}
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.TYPE,
+	}
 	names := make([]string, 0, len(p.typedefs))
 	for name := range p.typedefs {
 		names = append(names, name)
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-		}
 		typedef := p.typedefs[name]
 		typeName := "C." + name
 		isAlias := true
@@ -710,8 +555,8 @@ func (p *cgoPackage) addTypedefs() {
 		}
 		obj.Decl = typeSpec
 		gen.Specs = append(gen.Specs, typeSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 // addElaboratedTypes adds C elaborated types as aliases. These are the "struct
@@ -723,47 +568,29 @@ func (p *cgoPackage) addElaboratedTypes() {
 	if len(p.elaboratedTypes) == 0 {
 		return
 	}
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.TYPE,
+	}
 	names := make([]string, 0, len(p.elaboratedTypes))
 	for name := range p.elaboratedTypes {
 		names = append(names, name)
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-		}
 		typ := p.elaboratedTypes[name]
 		typeName := "C." + name
 		obj := &ast.Object{
 			Kind: ast.Typ,
 			Name: typeName,
 		}
-		typeExpr := typ.typeExpr
-		if typ.unionSize != 0 {
-			// Create getters/setters.
-			for _, field := range typ.typeExpr.Fields.List {
-				if len(field.Names) != 1 {
-					p.addError(typ.pos, fmt.Sprintf("union must have field with a single name, it has %d names", len(field.Names)))
-					continue
-				}
-				p.createUnionAccessor(field, typeName)
-			}
-			// Convert to a single-field struct type.
-			typeExpr = p.makeUnionField(typ)
-			if typeExpr == nil {
-				// There was an error, that was already added to the list of
-				// errors.
-				continue
-			}
-		}
 		typeSpec := &ast.TypeSpec{
 			Name: &ast.Ident{
 				NamePos: typ.pos,
 				Name:    typeName,
 				Obj:     obj,
 			},
-			Type: typeExpr,
+			Type: typ.typeExpr,
 		}
 		obj.Decl = typeSpec
 		gen.Specs = append(gen.Specs, typeSpec)
@@ -772,185 +599,8 @@ func (p *cgoPackage) addElaboratedTypes() {
 			p.createBitfieldGetter(bitfield, typeName)
 			p.createBitfieldSetter(bitfield, typeName)
 		}
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
-}
-
-// makeUnionField creates a new struct from an existing *elaboratedTypeInfo,
-// that has just a single field that must be accessed through special accessors.
-// It returns nil when there is an error. In case of an error, that error has
-// already been added to the list of errors using p.addError.
-func (p *cgoPackage) makeUnionField(typ *elaboratedTypeInfo) *ast.StructType {
-	unionFieldTypeName, ok := map[int64]string{
-		1: "uint8",
-		2: "uint16",
-		4: "uint32",
-		8: "uint64",
-	}[typ.unionAlign]
-	if !ok {
-		p.addError(typ.typeExpr.Struct, fmt.Sprintf("expected union alignment to be one of 1, 2, 4, or 8, but got %d", typ.unionAlign))
-		return nil
-	}
-	var unionFieldType ast.Expr = &ast.Ident{
-		NamePos: token.NoPos,
-		Name:    unionFieldTypeName,
-	}
-	if typ.unionSize != typ.unionAlign {
-		// A plain struct{uintX} isn't enough, we have to make a
-		// struct{[N]uintX} to make the union big enough.
-		if typ.unionSize/typ.unionAlign*typ.unionAlign != typ.unionSize {
-			p.addError(typ.typeExpr.Struct, fmt.Sprintf("union alignment (%d) must be a multiple of union alignment (%d)", typ.unionSize, typ.unionAlign))
-			return nil
-		}
-		unionFieldType = &ast.ArrayType{
-			Len: &ast.BasicLit{
-				Kind:  token.INT,
-				Value: strconv.FormatInt(typ.unionSize/typ.unionAlign, 10),
-			},
-			Elt: unionFieldType,
-		}
-	}
-	return &ast.StructType{
-		Struct: typ.typeExpr.Struct,
-		Fields: &ast.FieldList{
-			Opening: typ.typeExpr.Fields.Opening,
-			List: []*ast.Field{&ast.Field{
-				Names: []*ast.Ident{
-					&ast.Ident{
-						NamePos: typ.typeExpr.Fields.Opening,
-						Name:    "$union",
-					},
-				},
-				Type: unionFieldType,
-			}},
-			Closing: typ.typeExpr.Fields.Closing,
-		},
-	}
-}
-
-// createUnionAccessor creates a function that returns a typed pointer to a
-// union field for each field in a union. For example:
-//
-//     func (union *C.union_1) unionfield_d() *float64 {
-//         return (*float64)(unsafe.Pointer(&union.$union))
-//     }
-//
-// Where C.union_1 is defined as:
-//
-//     type C.union_1 struct{
-//         $union uint64
-//     }
-//
-// The returned pointer can be used to get or set the field, or get the pointer
-// to a subfield.
-func (p *cgoPackage) createUnionAccessor(field *ast.Field, typeName string) {
-	if len(field.Names) != 1 {
-		panic("number of names in union field must be exactly 1")
-	}
-	fieldName := field.Names[0]
-	pos := fieldName.NamePos
-
-	// The method receiver.
-	receiver := &ast.SelectorExpr{
-		X: &ast.Ident{
-			NamePos: pos,
-			Name:    "union",
-			Obj:     nil,
-		},
-		Sel: &ast.Ident{
-			NamePos: pos,
-			Name:    "$union",
-		},
-	}
-
-	// Get the address of the $union field.
-	receiverPtr := &ast.UnaryExpr{
-		Op: token.AND,
-		X:  receiver,
-	}
-
-	// Cast to unsafe.Pointer.
-	sourcePointer := &ast.CallExpr{
-		Fun: &ast.SelectorExpr{
-			X:   &ast.Ident{Name: "unsafe"},
-			Sel: &ast.Ident{Name: "Pointer"},
-		},
-		Args: []ast.Expr{receiverPtr},
-	}
-
-	// Cast to the target pointer type.
-	targetPointer := &ast.CallExpr{
-		Lparen: pos,
-		Fun: &ast.ParenExpr{
-			Lparen: pos,
-			X: &ast.StarExpr{
-				X: field.Type,
-			},
-			Rparen: pos,
-		},
-		Args:   []ast.Expr{sourcePointer},
-		Rparen: pos,
-	}
-
-	// Create the accessor function.
-	accessor := &ast.FuncDecl{
-		Recv: &ast.FieldList{
-			Opening: pos,
-			List: []*ast.Field{
-				&ast.Field{
-					Names: []*ast.Ident{
-						&ast.Ident{
-							NamePos: pos,
-							Name:    "union",
-						},
-					},
-					Type: &ast.StarExpr{
-						Star: pos,
-						X: &ast.Ident{
-							NamePos: pos,
-							Name:    typeName,
-							Obj:     nil,
-						},
-					},
-				},
-			},
-			Closing: pos,
-		},
-		Name: &ast.Ident{
-			NamePos: pos,
-			Name:    "unionfield_" + fieldName.Name,
-		},
-		Type: &ast.FuncType{
-			Func: pos,
-			Params: &ast.FieldList{
-				Opening: pos,
-				Closing: pos,
-			},
-			Results: &ast.FieldList{
-				List: []*ast.Field{
-					&ast.Field{
-						Type: &ast.StarExpr{
-							Star: pos,
-							X:    field.Type,
-						},
-					},
-				},
-			},
-		},
-		Body: &ast.BlockStmt{
-			Lbrace: pos,
-			List: []ast.Stmt{
-				&ast.ReturnStmt{
-					Return: pos,
-					Results: []ast.Expr{
-						targetPointer,
-					},
-				},
-			},
-			Rbrace: pos,
-		},
-	}
-	p.generated.Decls = append(p.generated.Decls, accessor)
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 // createBitfieldGetter creates a bitfield getter function like the following:
@@ -1255,16 +905,16 @@ func (p *cgoPackage) addEnumTypes() {
 	if len(p.enums) == 0 {
 		return
 	}
+	gen := &ast.GenDecl{
+		TokPos: token.NoPos,
+		Tok:    token.TYPE,
+	}
 	names := make([]string, 0, len(p.enums))
 	for name := range p.enums {
 		names = append(names, name)
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-		}
 		typ := p.enums[name]
 		typeName := "C.enum_" + name
 		obj := &ast.Object{
@@ -1281,8 +931,8 @@ func (p *cgoPackage) addEnumTypes() {
 		}
 		obj.Decl = typeSpec
 		gen.Specs = append(gen.Specs, typeSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
 	}
+	p.generated.Decls = append(p.generated.Decls, gen)
 }

 // findMissingCGoNames traverses the AST and finds all C.something names. Only
@@ -1345,29 +995,3 @@ func (p *cgoPackage) walker(cursor *astutil.Cursor) bool {
 	}
 	return true
 }
-
-// renameFieldKeywords renames all reserved words in Go to some other field name
-// with a "_" prefix. For example, it renames `type` to `_type`.
-//
-// See: https://golang.org/cmd/cgo/#hdr-Go_references_to_C
-func renameFieldKeywords(fieldList *ast.FieldList) {
-	renameFieldName(fieldList, "type")
-}
-
-// renameFieldName renames a given field name to a name with a "_" prepended. It
-// makes sure to do the same thing for any field sharing the same name.
-func renameFieldName(fieldList *ast.FieldList, name string) {
-	var ident *ast.Ident
-	for _, f := range fieldList.List {
-		for _, n := range f.Names {
-			if n.Name == name {
-				ident = n
-			}
-		}
-	}
-	if ident == nil {
-		return
-	}
-	renameFieldName(fieldList, "_"+name)
-	ident.Name = "_" + ident.Name
-}
@@ -1,145 +0,0 @@
-package cgo
-
-import (
-	"bytes"
-	"flag"
-	"fmt"
-	"go/ast"
-	"go/format"
-	"go/parser"
-	"go/token"
-	"go/types"
-	"io/ioutil"
-	"path/filepath"
-	"regexp"
-	"runtime"
-	"strings"
-	"testing"
-)
-
-// Pass -update to go test to update the output of the test files.
-var flagUpdate = flag.Bool("update", false, "Update images based on test output.")
-
-// normalizeResult normalizes Go source code that comes out of tests across
-// platforms and Go versions.
-func normalizeResult(result string) string {
-	actual := strings.Replace(result, "\r\n", "\n", -1)
-
-	// Make sure all functions are wrapped, even those that would otherwise be
-	// single-line functions. This is necessary because Go 1.14 changed the way
-	// such functions are wrapped and it's important to have consistent test
-	// results.
-	re := regexp.MustCompile(`func \((.+)\)( .*?) +{ (.+) }`)
-	actual = re.ReplaceAllString(actual, "func ($1)$2 {\n\t$3\n}")
-
-	return actual
-}
-
-func TestCGo(t *testing.T) {
-	var cflags = []string{"--target=armv6m-none-eabi"}
-
-	for _, name := range []string{"basic", "errors", "types", "flags", "const"} {
-		name := name // avoid a race condition
-		t.Run(name, func(t *testing.T) {
-			// Read the AST in memory.
-			path := filepath.Join("testdata", name+".go")
-			fset := token.NewFileSet()
-			f, err := parser.ParseFile(fset, path, nil, parser.ParseComments)
-			if err != nil {
-				t.Fatal("could not parse Go source file:", err)
-			}
-
-			// Process the AST with CGo.
-			cgoAST, cgoErrors := Process([]*ast.File{f}, "testdata", fset, cflags)
-
-			// Check the AST for type errors.
-			var typecheckErrors []error
-			config := types.Config{
-				Error: func(err error) {
-					typecheckErrors = append(typecheckErrors, err)
-				},
-				Importer: simpleImporter{},
-				Sizes:    types.SizesFor("gccgo", "arm"),
-			}
-			_, err = config.Check("", fset, []*ast.File{f, cgoAST}, nil)
-			if err != nil && len(typecheckErrors) == 0 {
-				// Only report errors when no type errors are found (an
-				// unexpected condition).
-				t.Error(err)
-			}
-
-			// Store the (formatted) output in a buffer. Format it, so it
-			// becomes easier to read (and will hopefully change less with CGo
-			// changes).
-			buf := &bytes.Buffer{}
-			if len(cgoErrors) != 0 {
-				buf.WriteString("// CGo errors:\n")
-				for _, err := range cgoErrors {
-					buf.WriteString(formatDiagnostic(err))
-				}
-				buf.WriteString("\n")
-			}
-			if len(typecheckErrors) != 0 {
-				buf.WriteString("// Type checking errors after CGo processing:\n")
-				for _, err := range typecheckErrors {
-					buf.WriteString(formatDiagnostic(err))
-				}
-				buf.WriteString("\n")
-			}
-			err = format.Node(buf, fset, cgoAST)
-			if err != nil {
-				t.Errorf("could not write out CGo AST: %v", err)
-			}
-			actual := normalizeResult(string(buf.Bytes()))
-
-			// Read the file with the expected output, to compare against.
-			outfile := filepath.Join("testdata", name+".out.go")
-			expectedBytes, err := ioutil.ReadFile(outfile)
-			if err != nil {
-				t.Fatalf("could not read expected output: %v", err)
-			}
-			expected := strings.Replace(string(expectedBytes), "\r\n", "\n", -1)
-
-			// Check whether the output is as expected.
-			if expected != actual {
-				// It is not. Test failed.
-				if *flagUpdate {
-					// Update the file with the expected data.
-					err := ioutil.WriteFile(outfile, []byte(actual), 0666)
-					if err != nil {
-						t.Error("could not write updated output file:", err)
-					}
-					return
-				}
-				t.Errorf("output did not match:\n%s", string(actual))
-			}
-		})
-	}
-}
-
-// simpleImporter implements the types.Importer interface, but only allows
-// importing the unsafe package.
-type simpleImporter struct {
-}
-
-// Import implements the Importer interface. For testing usage only: it only
-// supports importing the unsafe package.
-func (i simpleImporter) Import(path string) (*types.Package, error) {
-	switch path {
-	case "unsafe":
-		return types.Unsafe, nil
-	default:
-		return nil, fmt.Errorf("importer not implemented for package %s", path)
-	}
-}
-
-// formatDiagnostics formats the error message to be an indented comment. It
-// also fixes Windows path name issues (backward slashes).
-func formatDiagnostic(err error) string {
-	msg := err.Error()
-	if runtime.GOOS == "windows" {
-		// Fix Windows path slashes.
-		msg = strings.Replace(msg, "testdata\\", "testdata/", -1)
-	}
-	return "//     " + msg + "\n"
-}
@@ -1,218 +0,0 @@
-package cgo
-
-// This file implements a parser of a subset of the C language, just enough to
-// parse common #define statements to Go constant expressions.
-
-import (
-	"fmt"
-	"go/ast"
-	"go/scanner"
-	"go/token"
-	"strings"
-)
-
-// parseConst parses the given string as a C constant.
-func parseConst(pos token.Pos, fset *token.FileSet, value string) (ast.Expr, *scanner.Error) {
-	t := newTokenizer(pos, fset, value)
-	expr, err := parseConstExpr(t)
-	if t.token != token.EOF {
-		return nil, &scanner.Error{
-			Pos: t.fset.Position(t.pos),
-			Msg: "unexpected token " + t.token.String(),
-		}
-	}
-	return expr, err
-}
-
-// parseConstExpr parses a stream of C tokens to a Go expression.
-func parseConstExpr(t *tokenizer) (ast.Expr, *scanner.Error) {
-	switch t.token {
-	case token.LPAREN:
-		lparen := t.pos
-		t.Next()
-		x, err := parseConstExpr(t)
-		if err != nil {
-			return nil, err
-		}
-		if t.token != token.RPAREN {
-			return nil, unexpectedToken(t, token.RPAREN)
-		}
-		expr := &ast.ParenExpr{
-			Lparen: lparen,
-			X:      x,
-			Rparen: t.pos,
-		}
-		t.Next()
-		return expr, nil
-	case token.INT, token.FLOAT, token.STRING, token.CHAR:
-		expr := &ast.BasicLit{
-			ValuePos: t.pos,
-			Kind:     t.token,
-			Value:    t.value,
-		}
-		t.Next()
-		return expr, nil
-	case token.IDENT:
-		expr := &ast.Ident{
-			NamePos: t.pos,
-			Name:    "C." + t.value,
-		}
-		t.Next()
-		return expr, nil
-	case token.EOF:
-		return nil, &scanner.Error{
-			Pos: t.fset.Position(t.pos),
-			Msg: "empty constant",
-		}
-	default:
-		return nil, &scanner.Error{
-			Pos: t.fset.Position(t.pos),
-			Msg: fmt.Sprintf("unexpected token %s", t.token),
-		}
-	}
-}
-
-// unexpectedToken returns an error of the form "unexpected token FOO, expected
-// BAR".
-func unexpectedToken(t *tokenizer, expected token.Token) *scanner.Error {
-	return &scanner.Error{
-		Pos: t.fset.Position(t.pos),
-		Msg: fmt.Sprintf("unexpected token %s, expected %s", t.token, expected),
-	}
-}
-
-// tokenizer reads C source code and converts it to Go tokens.
-type tokenizer struct {
-	pos   token.Pos
-	fset  *token.FileSet
-	token token.Token
-	value string
-	buf   string
-}
-
-// newTokenizer initializes a new tokenizer, positioned at the first token in
-// the string.
-func newTokenizer(start token.Pos, fset *token.FileSet, buf string) *tokenizer {
-	t := &tokenizer{
-		pos:   start,
-		fset:  fset,
-		buf:   buf,
-		token: token.ILLEGAL,
-	}
-	t.Next() // Parse the first token.
-	return t
-}
-
-// Next consumes the next token in the stream. There is no return value, read
-// the next token from the pos, token and value properties.
-func (t *tokenizer) Next() {
-	t.pos += token.Pos(len(t.value))
-	for {
-		if len(t.buf) == 0 {
-			t.token = token.EOF
-			return
-		}
-		c := t.buf[0]
-		switch {
-		case c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v':
-			// Skip whitespace.
-			// Based on this source, not sure whether it represents C whitespace:
-			// https://en.cppreference.com/w/cpp/string/byte/isspace
-			t.pos++
-			t.buf = t.buf[1:]
-		case c == '(' || c == ')':
-			// Single-character tokens.
-			switch c {
-			case '(':
-				t.token = token.LPAREN
-			case ')':
-				t.token = token.RPAREN
-			}
-			t.value = t.buf[:1]
-			t.buf = t.buf[1:]
-			return
-		case c >= '0' && c <= '9':
-			// Numeric constant (int, float, etc.).
-			// Find the last non-numeric character.
-			tokenLen := len(t.buf)
-			hasDot := false
-			for i, c := range t.buf {
-				if c == '.' {
-					hasDot = true
-				}
-				if c >= '0' && c <= '9' || c == '.' || c == '_' || c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' {
-					tokenLen = i + 1
-				} else {
-					break
-				}
-			}
-			t.value = t.buf[:tokenLen]
-			t.buf = t.buf[tokenLen:]
-			if hasDot {
-				// Integer constants are more complicated than this but this is
-				// a close approximation.
-				// https://en.cppreference.com/w/cpp/language/integer_literal
-				t.token = token.FLOAT
-				t.value = strings.TrimRight(t.value, "f")
-			} else {
-				t.token = token.INT
-				t.value = strings.TrimRight(t.value, "uUlL")
-			}
-			return
-		case c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c == '_':
-			// Identifier. Find all remaining tokens that are part of this
-			// identifier.
-			tokenLen := len(t.buf)
-			for i, c := range t.buf {
-				if c >= '0' && c <= '9' || c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c == '_' {
-					tokenLen = i + 1
-				} else {
-					break
-				}
-			}
-			t.value = t.buf[:tokenLen]
-			t.buf = t.buf[tokenLen:]
-			t.token = token.IDENT
-			return
-		case c == '"':
-			// String constant. Find the first '"' character that is not
-			// preceded by a backslash.
-			escape := false
-			tokenLen := len(t.buf)
-			for i, c := range t.buf {
-				if i != 0 && c == '"' && !escape {
-					tokenLen = i + 1
-					break
-				}
-				if !escape {
-					escape = c == '\\'
-				}
-			}
-			t.token = token.STRING
-			t.value = t.buf[:tokenLen]
-			t.buf = t.buf[tokenLen:]
-			return
-		case c == '\'':
-			// Char (rune) constant. Find the first '\'' character that is not
-			// preceded by a backslash.
-			escape := false
-			tokenLen := len(t.buf)
-			for i, c := range t.buf {
-				if i != 0 && c == '\'' && !escape {
-					tokenLen = i + 1
-					break
-				}
-				if !escape {
-					escape = c == '\\'
-				}
-			}
-			t.token = token.CHAR
-			t.value = t.buf[:tokenLen]
-			t.buf = t.buf[tokenLen:]
-			return
-		default:
-			t.token = token.ILLEGAL
-			return
-		}
-	}
-}
@@ -1,60 +0,0 @@
-package cgo
-
-import (
-	"bytes"
-	"go/format"
-	"go/token"
-	"strings"
-	"testing"
-)
-
-func TestParseConst(t *testing.T) {
-	// Test converting a C constant to a Go constant.
-	for _, tc := range []struct {
-		C  string
-		Go string
-	}{
-		{`5`, `5`},
-		{`(5)`, `(5)`},
-		{`(((5)))`, `(5)`},
-		{`)`, `error: 1:1: unexpected token )`},
-		{`5)`, `error: 1:2: unexpected token )`},
-		{"  \t)", `error: 1:4: unexpected token )`},
-		{`5.8f`, `5.8`},
-		{`foo`, `C.foo`},
-		{``, `error: 1:1: empty constant`}, // empty constants not allowed in Go
-		{`"foo"`, `"foo"`},
-		{`"a\\n"`, `"a\\n"`},
-		{`"a\n"`, `"a\n"`},
-		{`"a\""`, `"a\""`},
-		{`'a'`, `'a'`},
-		{`0b10`, `0b10`},
-		{`0x1234_5678`, `0x1234_5678`},
-		{`5 5`, `error: 1:3: unexpected token INT`}, // test for a bugfix
-	} {
-		fset := token.NewFileSet()
-		startPos := fset.AddFile("", -1, 1000).Pos(0)
-		expr, err := parseConst(startPos, fset, tc.C)
-		s := "<invalid>"
-		if err != nil {
-			if !strings.HasPrefix(tc.Go, "error: ") {
-				t.Errorf("expected value %#v for C constant %#v but got error %#v", tc.Go, tc.C, err.Error())
-				continue
-			}
-			s = "error: " + err.Error()
-		} else if expr != nil {
-			// Serialize the Go constant to a string, for more readable test
-			// cases.
-			buf := &bytes.Buffer{}
-			err := format.Node(buf, fset, expr)
-			if err != nil {
-				t.Errorf("could not format expr from C constant %#v: %v", tc.C, err)
-				continue
-			}
-			s = buf.String()
-		}
-		if s != tc.Go {
-			t.Errorf("C constant %#v was parsed to %#v while expecting %#v", tc.C, s, tc.Go)
-		}
-	}
-}
@@ -15,7 +15,7 @@ import (
 )

 /*
-#include <clang-c/Index.h> // if this fails, install libclang-10-dev
+#include <clang-c/Index.h> // if this fails, install libclang-8-dev
 #include <stdlib.h>
 #include <stdint.h>

@@ -109,8 +109,7 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, posFilename
 		C.CXTranslationUnit_DetailedPreprocessingRecord,
 		&unit)
 	if errCode != 0 {
-		// This is probably a bug in the usage of libclang.
-		panic("cgo: failed to parse source with libclang")
+		panic("loader: failed to parse source with libclang")
 	}
 	defer C.clang_disposeTranslationUnit(unit)

@@ -119,8 +118,27 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, posFilename
 			spelling := getString(C.clang_getDiagnosticSpelling(diagnostic))
 			severity := diagnosticSeverity[C.clang_getDiagnosticSeverity(diagnostic)]
 			location := C.clang_getDiagnosticLocation(diagnostic)
-			pos := p.getClangLocationPosition(location, unit)
-			p.addError(pos, severity+": "+spelling)
+			var libclangFilename C.CXString
+			var line C.unsigned
+			var column C.unsigned
+			C.clang_getPresumedLocation(location, &libclangFilename, &line, &column)
+			filename := getString(libclangFilename)
+			if filepath.IsAbs(filename) {
+				// Relative paths for readability, like other Go parser errors.
+				relpath, err := filepath.Rel(p.dir, filename)
+				if err == nil {
+					filename = relpath
+				}
+			}
+			p.errors = append(p.errors, &scanner.Error{
+				Pos: token.Position{
+					Filename: filename,
+					Offset:   0, // not provided by clang_getPresumedLocation
+					Line:     int(line),
+					Column:   int(column),
+				},
+				Msg: severity + ": " + spelling,
+			})
 		}
 		for i := 0; i < numDiagnostics; i++ {
 			diagnostic := C.clang_getDiagnostic(unit, C.uint(i))
@@ -132,6 +150,7 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, posFilename
 				addDiagnostic(C.clang_getDiagnosticInSet(diagnostics, C.uint(j)))
 			}
 		}
+		return
 	}

 	ref := storedRefs.Put(p)
@@ -218,17 +237,14 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 		var startOffset, endOffset C.unsigned
 		C.clang_getExpansionLocation(start, &file, nil, nil, &startOffset)
 		if file == nil {
-			p.addError(pos, "internal error: could not find file where macro is defined")
-			break
+			panic("could not find file where macro is defined")
 		}
 		C.clang_getExpansionLocation(end, &endFile, nil, nil, &endOffset)
 		if file != endFile {
-			p.addError(pos, "internal error: expected start and end location of a macro to be in the same file")
-			break
+			panic("expected start and end location of a #define to be in the same file")
 		}
 		if startOffset > endOffset {
-			p.addError(pos, "internal error: start offset of macro is after end offset")
-			break
+			panic("startOffset > endOffset")
 		}

 		// read file contents and extract the relevant byte range
@@ -236,29 +252,59 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 		var size C.size_t
 		sourcePtr := C.clang_getFileContents(tu, file, &size)
 		if endOffset >= C.uint(size) {
-			p.addError(pos, "internal error: end offset of macro lies after end of file")
-			break
+			panic("endOffset lies after end of file")
 		}
 		source := string(((*[1 << 28]byte)(unsafe.Pointer(sourcePtr)))[startOffset:endOffset:endOffset])
 		if !strings.HasPrefix(source, name) {
-			p.addError(pos, fmt.Sprintf("internal error: expected macro value to start with %#v, got %#v", name, source))
-			break
+			panic(fmt.Sprintf("expected #define value to start with %#v, got %#v", name, source))
 		}
-		value := source[len(name):]
-		// Try to convert this #define into a Go constant expression.
-		expr, err := parseConst(pos+token.Pos(len(name)), p.fset, value)
-		if err != nil {
-			p.errors = append(p.errors, err)
+		value := strings.TrimSpace(source[len(name):])
+		for len(value) != 0 && value[0] == '(' && value[len(value)-1] == ')' {
+			value = strings.TrimSpace(value[1 : len(value)-1])
 		}
-		if expr != nil {
-			// Parsing was successful.
-			p.constants[name] = constantInfo{expr, pos}
+		if len(value) == 0 {
+			// Pretend it doesn't exist at all.
+			return C.CXChildVisit_Continue
+		}
+		// For information about integer literals:
+		// https://en.cppreference.com/w/cpp/language/integer_literal
+		if value[0] == '"' {
+			// string constant
+			p.constants[name] = constantInfo{&ast.BasicLit{pos, token.STRING, value}, pos}
+			return C.CXChildVisit_Continue
+		}
+		if value[0] == '\'' {
+			// char constant
+			p.constants[name] = constantInfo{&ast.BasicLit{pos, token.CHAR, value}, pos}
+			return C.CXChildVisit_Continue
+		}
+		// assume it's a number (int or float)
+		value = strings.Replace(value, "'", "", -1) // remove ' chars
+		value = strings.TrimRight(value, "lu")      // remove llu suffixes etc.
+		// find the first non-number
+		nonnum := byte(0)
+		for i := 0; i < len(value); i++ {
+			if value[i] < '0' || value[i] > '9' {
+				nonnum = value[i]
+				break
+			}
+		}
+		// determine number type based on the first non-number
+		switch nonnum {
+		case 0:
+			// no non-number found, must be an integer
+			p.constants[name] = constantInfo{&ast.BasicLit{pos, token.INT, value}, pos}
+		case 'x', 'X':
+			// hex integer constant
+			// TODO: may also be a floating point number per C++17.
+			p.constants[name] = constantInfo{&ast.BasicLit{pos, token.INT, value}, pos}
+		case '.', 'e':
+			// float constant
+			value = strings.TrimRight(value, "fFlL")
+			p.constants[name] = constantInfo{&ast.BasicLit{pos, token.FLOAT, value}, pos}
+		default:
+			// unknown type, ignore
 		}
-	case C.CXCursor_EnumDecl:
-		// Visit all enums, because the fields may be used even when the enum
-		// type itself is not.
-		typ := C.tinygo_clang_getCursorType(c)
-		p.makeASTType(typ, pos)
 	}
 	return C.CXChildVisit_Continue
 }
@@ -270,16 +316,11 @@ func getString(clangString C.CXString) (s string) {
 	return
 }

-// getCursorPosition returns a usable token.Pos from a libclang cursor.
+// getCursorPosition returns a usable token.Pos from a libclang cursor. If the
+// file for this cursor has not been seen before, it is read from libclang
+// (which already has the file in memory) and added to the token.FileSet.
 func (p *cgoPackage) getCursorPosition(cursor C.GoCXCursor) token.Pos {
-	return p.getClangLocationPosition(C.tinygo_clang_getCursorLocation(cursor), C.tinygo_clang_Cursor_getTranslationUnit(cursor))
-}
-
-// getClangLocationPosition returns a usable token.Pos based on a libclang
-// location and translation unit. If the file for this cursor has not been seen
-// before, it is read from libclang (which already has the file in memory) and
-// added to the token.FileSet.
-func (p *cgoPackage) getClangLocationPosition(location C.CXSourceLocation, tu C.CXTranslationUnit) token.Pos {
+	location := C.tinygo_clang_getCursorLocation(cursor)
 	var file C.CXFile
 	var line C.unsigned
 	var column C.unsigned
@@ -293,6 +334,7 @@ func (p *cgoPackage) getClangLocationPosition(location C.CXSourceLocation, tu C.
 	if _, ok := p.tokenFiles[filename]; !ok {
 		// File has not been seen before in this package, add line information
 		// now by reading the file from libclang.
+		tu := C.tinygo_clang_Cursor_getTranslationUnit(cursor)
 		var size C.size_t
 		sourcePtr := C.clang_getFileContents(tu, file, &size)
 		source := ((*[1 << 28]byte)(unsafe.Pointer(sourcePtr)))[:size:size]
@@ -306,62 +348,7 @@ func (p *cgoPackage) getClangLocationPosition(location C.CXSourceLocation, tu C.
 		f.SetLines(lines)
 		p.tokenFiles[filename] = f
 	}
-	positionFile := p.tokenFiles[filename]
-
-	// Check for alternative line/column information (set with a line directive).
-	var filename2String C.CXString
-	var line2 C.unsigned
-	var column2 C.unsigned
-	C.clang_getPresumedLocation(location, &filename2String, &line2, &column2)
-	filename2 := getString(filename2String)
-	if filename2 != filename || line2 != line || column2 != column {
-		// The location was changed with a preprocessor directive.
-		// TODO: this only works for locations that are added in order. Adding
-		// line/column info to a file that already has line/column info after
-		// the given offset is ignored.
-		positionFile.AddLineColumnInfo(int(offset), filename2, int(line2), int(column2))
-	}
-
-	return positionFile.Pos(int(offset))
-}
-
-// addError is a utility function to add an error to the list of errors. It will
-// convert the token position to a line/column position first, and call
-// addErrorAt.
-func (p *cgoPackage) addError(pos token.Pos, msg string) {
-	p.addErrorAt(p.fset.PositionFor(pos, true), msg)
-}
-
-// addErrorAfter is like addError, but adds the text `after` to the source
-// location.
-func (p *cgoPackage) addErrorAfter(pos token.Pos, after, msg string) {
-	position := p.fset.PositionFor(pos, true)
-	lines := strings.Split(after, "\n")
-	if len(lines) != 1 {
-		// Adjust lines.
-		// For why we can't just do pos+token.Pos(len(after)), see:
-		// https://github.com/golang/go/issues/35803
-		position.Line += len(lines) - 1
-		position.Column = len(lines[len(lines)-1]) + 1
-	} else {
-		position.Column += len(after)
-	}
-	p.addErrorAt(position, msg)
-}
-
-// addErrorAt is a utility function to add an error to the list of errors.
-func (p *cgoPackage) addErrorAt(position token.Position, msg string) {
-	if filepath.IsAbs(position.Filename) {
-		// Relative paths for readability, like other Go parser errors.
-		relpath, err := filepath.Rel(p.dir, position.Filename)
-		if err == nil {
-			position.Filename = relpath
-		}
-	}
-	p.errors = append(p.errors, scanner.Error{
-		Pos: position,
-		Msg: msg,
-	})
+	return p.tokenFiles[filename].Pos(int(offset))
 }

 // makeASTType return the ast.Expr for the given libclang type. In other words,
@@ -472,7 +459,7 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 						// This happens for some very special purpose architectures
 						// (DSPs etc.) that are not currently targeted.
 						// https://www.embecosm.com/2017/04/18/non-8-bit-char-support-in-clang-and-llvm/
-						p.addError(pos, fmt.Sprintf("unknown char width: %d", typeSize))
+						panic("unknown char width")
 					}
 					switch underlyingType.kind {
 					case C.CXType_Char_S:
@@ -521,44 +508,48 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 		case C.CXType_Enum:
 			return p.makeASTType(underlying, pos)
 		default:
-			typeKindSpelling := getString(C.clang_getTypeKindSpelling(underlying.kind))
-			p.addError(pos, fmt.Sprintf("unknown elaborated type (libclang type kind %s)", typeKindSpelling))
-			typeName = "<unknown>"
+			panic("unknown elaborated type")
 		}
 	case C.CXType_Record:
 		cursor := C.tinygo_clang_getTypeDeclaration(typ)
 		name := getString(C.tinygo_clang_getCursorSpelling(cursor))
-		var cgoRecordPrefix string
-		switch C.tinygo_clang_getCursorKind(cursor) {
-		case C.CXCursor_StructDecl:
-			cgoRecordPrefix = "struct_"
-		case C.CXCursor_UnionDecl:
-			cgoRecordPrefix = "union_"
-		default:
-			// makeASTRecordType will create an appropriate error.
-			cgoRecordPrefix = "record_"
-		}
 		if name == "" {
 			// Anonymous record, probably inside a typedef.
-			typeInfo := p.makeASTRecordType(cursor, pos)
-			if typeInfo.bitfields != nil || typeInfo.unionSize != 0 {
-				// This record is a union or is a struct with bitfields, so we
-				// have to declare it as a named type (for getters/setters to
-				// work).
+			typeExpr, bitfieldList := p.makeASTRecordType(cursor, pos)
+			if bitfieldList != nil {
+				// This struct has bitfields, so we have to declare it as a
+				// named type (for bitfield getters/setters to work).
 				p.anonStructNum++
-				cgoName := cgoRecordPrefix + strconv.Itoa(p.anonStructNum)
-				p.elaboratedTypes[cgoName] = typeInfo
+				cgoName := "struct_" + strconv.Itoa(p.anonStructNum)
+				p.elaboratedTypes[cgoName] = &elaboratedTypeInfo{
+					typeExpr:  typeExpr,
+					pos:       pos,
+					bitfields: bitfieldList,
+				}
 				return &ast.Ident{
 					NamePos: pos,
 					Name:    "C." + cgoName,
 				}
 			}
-			return typeInfo.typeExpr
+			return typeExpr
 		} else {
-			cgoName := cgoRecordPrefix + name
+			var cgoName string
+			switch C.tinygo_clang_getCursorKind(cursor) {
+			case C.CXCursor_StructDecl:
+				cgoName = "struct_" + name
+			case C.CXCursor_UnionDecl:
+				cgoName = "union_" + name
+			default:
+				panic("unknown record declaration")
+			}
 			if _, ok := p.elaboratedTypes[cgoName]; !ok {
 				p.elaboratedTypes[cgoName] = nil // predeclare (to avoid endless recursion)
-				p.elaboratedTypes[cgoName] = p.makeASTRecordType(cursor, pos)
+				typeExpr, bitfieldList := p.makeASTRecordType(cursor, pos)
+				p.elaboratedTypes[cgoName] = &elaboratedTypeInfo{
+					typeExpr:  typeExpr,
+					pos:       pos,
+					bitfields: bitfieldList,
+				}
 			}
 			return &ast.Ident{
 				NamePos: pos,
@@ -594,10 +585,14 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 	}
 	if typeName == "" {
 		// Report this as an error.
-		typeSpelling := getString(C.clang_getTypeSpelling(typ))
-		typeKindSpelling := getString(C.clang_getTypeKindSpelling(typ.kind))
-		p.addError(pos, fmt.Sprintf("unknown C type: %v (libclang type kind %s)", typeSpelling, typeKindSpelling))
-		typeName = "C.<unknown>"
+		spelling := getString(C.clang_getTypeSpelling(typ))
+		p.errors = append(p.errors, scanner.Error{
+			Pos: p.fset.PositionFor(pos, true),
+			Msg: fmt.Sprintf("unknown C type: %v (libclang type kind %d)", spelling, typ.kind),
+		})
+		// Fallback, probably incorrect but at least the error points to an odd
+		// type name.
+		typeName = "C." + spelling
 	}
 	return &ast.Ident{
 		NamePos: pos,
@@ -606,8 +601,9 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 }

 // makeASTRecordType parses a C record (struct or union) and translates it into
-// a Go struct type.
-func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elaboratedTypeInfo {
+// a Go struct type. Unions are implemented by setting the first field to a
+// zero-lengt "C union" field, which cannot be written in Go directly.
+func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) (*ast.StructType, []bitfieldInfo) {
 	fieldList := &ast.FieldList{
 		Opening: pos,
 		Closing: pos,
@@ -624,53 +620,53 @@ func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elab
 	}{fieldList, p, &inBitfield, &bitfieldNum, &bitfieldList})
 	defer storedRefs.Remove(ref)
 	C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_struct_visitor), C.CXClientData(ref))
-	renameFieldKeywords(fieldList)
 	switch C.tinygo_clang_getCursorKind(cursor) {
 	case C.CXCursor_StructDecl:
-		return &elaboratedTypeInfo{
-			typeExpr: &ast.StructType{
-				Struct: pos,
-				Fields: fieldList,
-			},
-			pos:       pos,
-			bitfields: bitfieldList,
-		}
+		return &ast.StructType{
+			Struct: pos,
+			Fields: fieldList,
+		}, bitfieldList
 	case C.CXCursor_UnionDecl:
-		typeInfo := &elaboratedTypeInfo{
-			typeExpr: &ast.StructType{
-				Struct: pos,
-				Fields: fieldList,
-			},
-			pos:       pos,
-			bitfields: bitfieldList,
-		}
-		if len(fieldList.List) <= 1 {
-			// Useless union, treat it as a regular struct.
-			return typeInfo
-		}
 		if bitfieldList != nil {
 			// This is valid C... but please don't do this.
-			p.addError(pos, "bitfield in a union is not supported")
+			p.errors = append(p.errors, scanner.Error{
+				Pos: p.fset.PositionFor(pos, true),
+				Msg: fmt.Sprintf("bitfield in a union is not supported"),
+			})
 		}
-		typ := C.tinygo_clang_getCursorType(cursor)
-		alignInBytes := int64(C.clang_Type_getAlignOf(typ))
-		sizeInBytes := int64(C.clang_Type_getSizeOf(typ))
-		if sizeInBytes == 0 {
-			p.addError(pos, "zero-length union is not supported")
+		if len(fieldList.List) > 1 {
+			// Insert a special field at the front (of zero width) as a
+			// marker that this is struct is actually a union. This is done
+			// by giving the field a name that cannot be expressed directly
+			// in Go.
+			// Other parts of the compiler look at the first element in a
+			// struct (of size > 2) to know whether this is a union.
+			// Note that we don't have to insert it for single-element
+			// unions as they're basically equivalent to a struct.
+			unionMarker := &ast.Field{
+				Type: &ast.StructType{
+					Struct: pos,
+				},
+			}
+			unionMarker.Names = []*ast.Ident{
+				&ast.Ident{
+					NamePos: pos,
+					Name:    "C union",
+					Obj: &ast.Object{
+						Kind: ast.Var,
+						Name: "C union",
+						Decl: unionMarker,
+					},
+				},
+			}
+			fieldList.List = append([]*ast.Field{unionMarker}, fieldList.List...)
 		}
-		typeInfo.unionSize = sizeInBytes
-		typeInfo.unionAlign = alignInBytes
-		return typeInfo
+		return &ast.StructType{
+			Struct: pos,
+			Fields: fieldList,
+		}, bitfieldList
 	default:
-		cursorKind := C.tinygo_clang_getCursorKind(cursor)
-		cursorKindSpelling := getString(C.clang_getCursorKindSpelling(cursorKind))
-		p.addError(pos, fmt.Sprintf("expected StructDecl or UnionDecl, not %s", cursorKindSpelling))
-		return &elaboratedTypeInfo{
-			typeExpr: &ast.StructType{
-				Struct: pos,
-			},
-			pos: pos,
-		}
+		panic("unknown record declaration")
 	}
 }

@@ -688,17 +684,8 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 	inBitfield := passed.inBitfield
 	bitfieldNum := passed.bitfieldNum
 	bitfieldList := passed.bitfieldList
-	pos := p.getCursorPosition(c)
-	switch cursorKind := C.tinygo_clang_getCursorKind(c); cursorKind {
-	case C.CXCursor_FieldDecl:
-		// Expected. This is a regular field.
-	case C.CXCursor_StructDecl, C.CXCursor_UnionDecl:
-		// Ignore. The next field will be the struct/union itself.
-		return C.CXChildVisit_Continue
-	default:
-		cursorKindSpelling := getString(C.clang_getCursorKindSpelling(cursorKind))
-		p.addError(pos, fmt.Sprintf("expected FieldDecl in struct or union, not %s", cursorKindSpelling))
-		return C.CXChildVisit_Continue
+	if C.tinygo_clang_getCursorKind(c) != C.CXCursor_FieldDecl {
+		panic("expected field inside cursor")
 	}
 	name := getString(C.tinygo_clang_getCursorSpelling(c))
 	if name == "" {
@@ -707,6 +694,7 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 		return C.CXChildVisit_Continue
 	}
 	typ := C.tinygo_clang_getCursorType(c)
+	pos := p.getCursorPosition(c)
 	field := &ast.Field{
 		Type: p.makeASTType(typ, p.getCursorPosition(c)),
 	}
@@ -715,8 +703,7 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 	bitfieldOffset := offsetof % alignOf
 	if bitfieldOffset != 0 {
 		if C.tinygo_clang_Cursor_isBitField(c) != 1 {
-			p.addError(pos, "expected a bitfield")
-			return C.CXChildVisit_Continue
+			panic("expected a bitfield")
 		}
 		if !*inBitfield {
 			*bitfieldNum++
@@ -1,14 +1,11 @@
 // +build !byollvm
-// +build !llvm9

 package cgo

 /*
-#cgo linux  CFLAGS: -I/usr/lib/llvm-10/include
-#cgo darwin CFLAGS: -I/usr/local/opt/llvm@10/include
-#cgo freebsd CFLAGS: -I/usr/local/llvm10/include
-#cgo linux  LDFLAGS: -L/usr/lib/llvm-10/lib -lclang
-#cgo darwin LDFLAGS: -L/usr/local/opt/llvm@10/lib -lclang -lffi
-#cgo freebsd LDFLAGS: -L/usr/local/llvm10/lib -lclang
+#cgo linux  CFLAGS: -I/usr/lib/llvm-8/include
+#cgo darwin CFLAGS: -I/usr/local/opt/llvm/include
+#cgo linux  LDFLAGS: -L/usr/lib/llvm-8/lib -lclang
+#cgo darwin LDFLAGS: -L/usr/local/opt/llvm/lib -lclang -lffi
 */
 import "C"
@@ -1,14 +0,0 @@
-// +build !byollvm
-// +build llvm9
-
-package cgo
-
-/*
-#cgo linux  CFLAGS: -I/usr/lib/llvm-9/include
-#cgo darwin CFLAGS: -I/usr/local/opt/llvm@9/include
-#cgo freebsd CFLAGS: -I/usr/local/llvm9/include
-#cgo linux  LDFLAGS: -L/usr/lib/llvm-9/lib -lclang
-#cgo darwin LDFLAGS: -L/usr/local/opt/llvm@9/lib -lclang -lffi
-#cgo freebsd LDFLAGS: -L/usr/local/llvm9/lib -lclang
-*/
-import "C"
@@ -3,7 +3,7 @@
 // are slightly different from the ones defined in libclang.go, but they
 // should be ABI compatible.

-#include <clang-c/Index.h> // if this fails, install libclang-10-dev
+#include <clang-c/Index.h> // if this fails, install libclang-8-dev

 CXCursor tinygo_clang_getTranslationUnitCursor(CXTranslationUnit tu) {
 	return clang_getTranslationUnitCursor(tu);
@@ -1,301 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// This file has been copied from the Go 1.13 release tree.
-
-// Checking of compiler and linker flags.
-// We must avoid flags like -fplugin=, which can allow
-// arbitrary code execution during the build.
-// Do not make changes here without carefully
-// considering the implications.
-// (That's why the code is isolated in a file named security.go.)
-//
-// Note that -Wl,foo means split foo on commas and pass to
-// the linker, so that -Wl,-foo,bar means pass -foo bar to
-// the linker. Similarly -Wa,foo for the assembler and so on.
-// If any of these are permitted, the wildcard portion must
-// disallow commas.
-//
-// Note also that GNU binutils accept any argument @foo
-// as meaning "read more flags from the file foo", so we must
-// guard against any command-line argument beginning with @,
-// even things like "-I @foo".
-// We use safeArg (which is even more conservative)
-// to reject these.
-//
-// Even worse, gcc -I@foo (one arg) turns into cc1 -I @foo (two args),
-// so although gcc doesn't expand the @foo, cc1 will.
-// So out of paranoia, we reject @ at the beginning of every
-// flag argument that might be split into its own argument.
-
-package cgo
-
-import (
-	"fmt"
-	"os"
-	"regexp"
-	"strings"
-	"unicode/utf8"
-)
-
-var re = regexp.MustCompile
-
-var validCompilerFlags = []*regexp.Regexp{
-	re(`-D([A-Za-z_].*)`),
-	re(`-F([^@\-].*)`),
-	re(`-I([^@\-].*)`),
-	re(`-O`),
-	re(`-O([^@\-].*)`),
-	re(`-W`),
-	re(`-W([^@,]+)`), // -Wall but not -Wa,-foo.
-	re(`-Wa,-mbig-obj`),
-	re(`-Wp,-D([A-Za-z_].*)`),
-	re(`-ansi`),
-	re(`-f(no-)?asynchronous-unwind-tables`),
-	re(`-f(no-)?blocks`),
-	re(`-f(no-)builtin-[a-zA-Z0-9_]*`),
-	re(`-f(no-)?common`),
-	re(`-f(no-)?constant-cfstrings`),
-	re(`-fdiagnostics-show-note-include-stack`),
-	re(`-f(no-)?eliminate-unused-debug-types`),
-	re(`-f(no-)?exceptions`),
-	re(`-f(no-)?fast-math`),
-	re(`-f(no-)?inline-functions`),
-	re(`-finput-charset=([^@\-].*)`),
-	re(`-f(no-)?fat-lto-objects`),
-	re(`-f(no-)?keep-inline-dllexport`),
-	re(`-f(no-)?lto`),
-	re(`-fmacro-backtrace-limit=(.+)`),
-	re(`-fmessage-length=(.+)`),
-	re(`-f(no-)?modules`),
-	re(`-f(no-)?objc-arc`),
-	re(`-f(no-)?objc-nonfragile-abi`),
-	re(`-f(no-)?objc-legacy-dispatch`),
-	re(`-f(no-)?omit-frame-pointer`),
-	re(`-f(no-)?openmp(-simd)?`),
-	re(`-f(no-)?permissive`),
-	re(`-f(no-)?(pic|PIC|pie|PIE)`),
-	re(`-f(no-)?plt`),
-	re(`-f(no-)?rtti`),
-	re(`-f(no-)?split-stack`),
-	re(`-f(no-)?stack-(.+)`),
-	re(`-f(no-)?strict-aliasing`),
-	re(`-f(un)signed-char`),
-	re(`-f(no-)?use-linker-plugin`), // safe if -B is not used; we don't permit -B
-	re(`-f(no-)?visibility-inlines-hidden`),
-	re(`-fsanitize=(.+)`),
-	re(`-ftemplate-depth-(.+)`),
-	re(`-fvisibility=(.+)`),
-	re(`-g([^@\-].*)?`),
-	re(`-m32`),
-	re(`-m64`),
-	re(`-m(abi|arch|cpu|fpu|tune)=([^@\-].*)`),
-	re(`-m(no-)?v?aes`),
-	re(`-marm`),
-	re(`-m(no-)?avx[0-9a-z]*`),
-	re(`-mfloat-abi=([^@\-].*)`),
-	re(`-mfpmath=[0-9a-z,+]*`),
-	re(`-m(no-)?avx[0-9a-z.]*`),
-	re(`-m(no-)?ms-bitfields`),
-	re(`-m(no-)?stack-(.+)`),
-	re(`-mmacosx-(.+)`),
-	re(`-mios-simulator-version-min=(.+)`),
-	re(`-miphoneos-version-min=(.+)`),
-	re(`-mtvos-simulator-version-min=(.+)`),
-	re(`-mtvos-version-min=(.+)`),
-	re(`-mwatchos-simulator-version-min=(.+)`),
-	re(`-mwatchos-version-min=(.+)`),
-	re(`-mnop-fun-dllimport`),
-	re(`-m(no-)?sse[0-9.]*`),
-	re(`-m(no-)?ssse3`),
-	re(`-mthumb(-interwork)?`),
-	re(`-mthreads`),
-	re(`-mwindows`),
-	re(`--param=ssp-buffer-size=[0-9]*`),
-	re(`-pedantic(-errors)?`),
-	re(`-pipe`),
-	re(`-pthread`),
-	re(`-?-std=([^@\-].*)`),
-	re(`-?-stdlib=([^@\-].*)`),
-	re(`--sysroot=([^@\-].*)`),
-	re(`-w`),
-	re(`-x([^@\-].*)`),
-	re(`-v`),
-}
-
-var validCompilerFlagsWithNextArg = []string{
-	"-arch",
-	"-D",
-	"-I",
-	"-framework",
-	"-isysroot",
-	"-isystem",
-	"--sysroot",
-	"-target",
-	"-x",
-}
-
-var validLinkerFlags = []*regexp.Regexp{
-	re(`-F([^@\-].*)`),
-	re(`-l([^@\-].*)`),
-	re(`-L([^@\-].*)`),
-	re(`-O`),
-	re(`-O([^@\-].*)`),
-	re(`-f(no-)?(pic|PIC|pie|PIE)`),
-	re(`-f(no-)?openmp(-simd)?`),
-	re(`-fsanitize=([^@\-].*)`),
-	re(`-flat_namespace`),
-	re(`-g([^@\-].*)?`),
-	re(`-headerpad_max_install_names`),
-	re(`-m(abi|arch|cpu|fpu|tune)=([^@\-].*)`),
-	re(`-mfloat-abi=([^@\-].*)`),
-	re(`-mmacosx-(.+)`),
-	re(`-mios-simulator-version-min=(.+)`),
-	re(`-miphoneos-version-min=(.+)`),
-	re(`-mthreads`),
-	re(`-mwindows`),
-	re(`-(pic|PIC|pie|PIE)`),
-	re(`-pthread`),
-	re(`-rdynamic`),
-	re(`-shared`),
-	re(`-?-static([-a-z0-9+]*)`),
-	re(`-?-stdlib=([^@\-].*)`),
-	re(`-v`),
-
-	// Note that any wildcards in -Wl need to exclude comma,
-	// since -Wl splits its argument at commas and passes
-	// them all to the linker uninterpreted. Allowing comma
-	// in a wildcard would allow tunnelling arbitrary additional
-	// linker arguments through one of these.
-	re(`-Wl,--(no-)?allow-multiple-definition`),
-	re(`-Wl,--(no-)?allow-shlib-undefined`),
-	re(`-Wl,--(no-)?as-needed`),
-	re(`-Wl,-Bdynamic`),
-	re(`-Wl,-berok`),
-	re(`-Wl,-Bstatic`),
-	re(`-WL,-O([^@,\-][^,]*)?`),
-	re(`-Wl,-d[ny]`),
-	re(`-Wl,--disable-new-dtags`),
-	re(`-Wl,-e[=,][a-zA-Z0-9]*`),
-	re(`-Wl,--enable-new-dtags`),
-	re(`-Wl,--end-group`),
-	re(`-Wl,--(no-)?export-dynamic`),
-	re(`-Wl,-framework,[^,@\-][^,]+`),
-	re(`-Wl,-headerpad_max_install_names`),
-	re(`-Wl,--no-undefined`),
-	re(`-Wl,-R([^@\-][^,@]*$)`),
-	re(`-Wl,--just-symbols[=,]([^,@\-][^,@]+)`),
-	re(`-Wl,-rpath(-link)?[=,]([^,@\-][^,]+)`),
-	re(`-Wl,-s`),
-	re(`-Wl,-search_paths_first`),
-	re(`-Wl,-sectcreate,([^,@\-][^,]+),([^,@\-][^,]+),([^,@\-][^,]+)`),
-	re(`-Wl,--start-group`),
-	re(`-Wl,-?-static`),
-	re(`-Wl,-?-subsystem,(native|windows|console|posix|xbox)`),
-	re(`-Wl,-syslibroot[=,]([^,@\-][^,]+)`),
-	re(`-Wl,-undefined[=,]([^,@\-][^,]+)`),
-	re(`-Wl,-?-unresolved-symbols=[^,]+`),
-	re(`-Wl,--(no-)?warn-([^,]+)`),
-	re(`-Wl,-z,(no)?execstack`),
-	re(`-Wl,-z,relro`),
-
-	re(`[a-zA-Z0-9_/].*\.(a|o|obj|dll|dylib|so)`), // direct linker inputs: x.o or libfoo.so (but not -foo.o or @foo.o)
-	re(`\./.*\.(a|o|obj|dll|dylib|so)`),
-}
-
-var validLinkerFlagsWithNextArg = []string{
-	"-arch",
-	"-F",
-	"-l",
-	"-L",
-	"-framework",
-	"-isysroot",
-	"--sysroot",
-	"-target",
-	"-Wl,-framework",
-	"-Wl,-rpath",
-	"-Wl,-R",
-	"-Wl,--just-symbols",
-	"-Wl,-undefined",
-}
-
-func checkCompilerFlags(name string, list []string) error {
-	return checkFlags(name, list, validCompilerFlags, validCompilerFlagsWithNextArg)
-}
-
-func checkLinkerFlags(name string, list []string) error {
-	return checkFlags(name, list, validLinkerFlags, validLinkerFlagsWithNextArg)
-}
-
-func checkFlags(name string, list []string, valid []*regexp.Regexp, validNext []string) error {
-	// Let users override rules with $CGO_CFLAGS_ALLOW, $CGO_CFLAGS_DISALLOW, etc.
-	var (
-		allow    *regexp.Regexp
-		disallow *regexp.Regexp
-	)
-	if env := os.Getenv("CGO_" + name + "_ALLOW"); env != "" {
-		r, err := regexp.Compile(env)
-		if err != nil {
-			return fmt.Errorf("parsing $CGO_%s_ALLOW: %v", name, err)
-		}
-		allow = r
-	}
-	if env := os.Getenv("CGO_" + name + "_DISALLOW"); env != "" {
-		r, err := regexp.Compile(env)
-		if err != nil {
-			return fmt.Errorf("parsing $CGO_%s_DISALLOW: %v", name, err)
-		}
-		disallow = r
-	}
-
-Args:
-	for i := 0; i < len(list); i++ {
-		arg := list[i]
-		if disallow != nil && disallow.FindString(arg) == arg {
-			goto Bad
-		}
-		if allow != nil && allow.FindString(arg) == arg {
-			continue Args
-		}
-		for _, re := range valid {
-			if re.FindString(arg) == arg { // must be complete match
-				continue Args
-			}
-		}
-		for _, x := range validNext {
-			if arg == x {
-				if i+1 < len(list) && safeArg(list[i+1]) {
-					i++
-					continue Args
-				}
-
-				// Permit -Wl,-framework -Wl,name.
-				if i+1 < len(list) &&
-					strings.HasPrefix(arg, "-Wl,") &&
-					strings.HasPrefix(list[i+1], "-Wl,") &&
-					safeArg(list[i+1][4:]) &&
-					!strings.Contains(list[i+1][4:], ",") {
-					i++
-					continue Args
-				}
-
-				if i+1 < len(list) {
-					return fmt.Errorf("invalid flag: %s %s (see https://golang.org/s/invalidflag)", arg, list[i+1])
-				}
-				return fmt.Errorf("invalid flag: %s without argument (see https://golang.org/s/invalidflag)", arg)
-			}
-		}
-	Bad:
-		return fmt.Errorf("invalid flag: %s", arg)
-	}
-	return nil
-}
-
-func safeArg(name string) bool {
-	if name == "" {
-		return false
-	}
-	c := name[0]
-	return '0' <= c && c <= '9' || 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || c == '.' || c == '_' || c == '/' || c >= utf8.RuneSelf
-}
@@ -1,260 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// This file has been copied from the Go 1.13 release tree.
-
-package cgo
-
-import (
-	"os"
-	"testing"
-)
-
-var goodCompilerFlags = [][]string{
-	{"-DFOO"},
-	{"-Dfoo=bar"},
-	{"-F/Qt"},
-	{"-I/"},
-	{"-I/etc/passwd"},
-	{"-I."},
-	{"-O"},
-	{"-O2"},
-	{"-Osmall"},
-	{"-W"},
-	{"-Wall"},
-	{"-fobjc-arc"},
-	{"-fno-objc-arc"},
-	{"-fomit-frame-pointer"},
-	{"-fno-omit-frame-pointer"},
-	{"-fpic"},
-	{"-fno-pic"},
-	{"-fPIC"},
-	{"-fno-PIC"},
-	{"-fpie"},
-	{"-fno-pie"},
-	{"-fPIE"},
-	{"-fno-PIE"},
-	{"-fsplit-stack"},
-	{"-fno-split-stack"},
-	{"-fstack-xxx"},
-	{"-fno-stack-xxx"},
-	{"-fsanitize=hands"},
-	{"-g"},
-	{"-ggdb"},
-	{"-march=souza"},
-	{"-mcpu=123"},
-	{"-mfpu=123"},
-	{"-mtune=happybirthday"},
-	{"-mstack-overflow"},
-	{"-mno-stack-overflow"},
-	{"-mmacosx-version"},
-	{"-mnop-fun-dllimport"},
-	{"-pthread"},
-	{"-std=c99"},
-	{"-xc"},
-	{"-D", "FOO"},
-	{"-D", "foo=bar"},
-	{"-I", "."},
-	{"-I", "/etc/passwd"},
-	{"-I", "世界"},
-	{"-framework", "Chocolate"},
-	{"-x", "c"},
-	{"-v"},
-}
-
-var badCompilerFlags = [][]string{
-	{"-D@X"},
-	{"-D-X"},
-	{"-F@dir"},
-	{"-F-dir"},
-	{"-I@dir"},
-	{"-I-dir"},
-	{"-O@1"},
-	{"-Wa,-foo"},
-	{"-W@foo"},
-	{"-g@gdb"},
-	{"-g-gdb"},
-	{"-march=@dawn"},
-	{"-march=-dawn"},
-	{"-std=@c99"},
-	{"-std=-c99"},
-	{"-x@c"},
-	{"-x-c"},
-	{"-D", "@foo"},
-	{"-D", "-foo"},
-	{"-I", "@foo"},
-	{"-I", "-foo"},
-	{"-framework", "-Caffeine"},
-	{"-framework", "@Home"},
-	{"-x", "--c"},
-	{"-x", "@obj"},
-}
-
-func TestCheckCompilerFlags(t *testing.T) {
-	for _, f := range goodCompilerFlags {
-		if err := checkCompilerFlags("test", f); err != nil {
-			t.Errorf("unexpected error for %q: %v", f, err)
-		}
-	}
-	for _, f := range badCompilerFlags {
-		if err := checkCompilerFlags("test", f); err == nil {
-			t.Errorf("missing error for %q", f)
-		}
-	}
-}
-
-var goodLinkerFlags = [][]string{
-	{"-Fbar"},
-	{"-lbar"},
-	{"-Lbar"},
-	{"-fpic"},
-	{"-fno-pic"},
-	{"-fPIC"},
-	{"-fno-PIC"},
-	{"-fpie"},
-	{"-fno-pie"},
-	{"-fPIE"},
-	{"-fno-PIE"},
-	{"-fsanitize=hands"},
-	{"-g"},
-	{"-ggdb"},
-	{"-march=souza"},
-	{"-mcpu=123"},
-	{"-mfpu=123"},
-	{"-mtune=happybirthday"},
-	{"-pic"},
-	{"-pthread"},
-	{"-Wl,-rpath,foo"},
-	{"-Wl,-rpath,$ORIGIN/foo"},
-	{"-Wl,-R", "/foo"},
-	{"-Wl,-R", "foo"},
-	{"-Wl,-R,foo"},
-	{"-Wl,--just-symbols=foo"},
-	{"-Wl,--just-symbols,foo"},
-	{"-Wl,--warn-error"},
-	{"-Wl,--no-warn-error"},
-	{"foo.so"},
-	{"_世界.dll"},
-	{"./x.o"},
-	{"libcgosotest.dylib"},
-	{"-F", "framework"},
-	{"-l", "."},
-	{"-l", "/etc/passwd"},
-	{"-l", "世界"},
-	{"-L", "framework"},
-	{"-framework", "Chocolate"},
-	{"-v"},
-	{"-Wl,-framework", "-Wl,Chocolate"},
-	{"-Wl,-framework,Chocolate"},
-	{"-Wl,-unresolved-symbols=ignore-all"},
-}
-
-var badLinkerFlags = [][]string{
-	{"-DFOO"},
-	{"-Dfoo=bar"},
-	{"-W"},
-	{"-Wall"},
-	{"-fobjc-arc"},
-	{"-fno-objc-arc"},
-	{"-fomit-frame-pointer"},
-	{"-fno-omit-frame-pointer"},
-	{"-fsplit-stack"},
-	{"-fno-split-stack"},
-	{"-fstack-xxx"},
-	{"-fno-stack-xxx"},
-	{"-mstack-overflow"},
-	{"-mno-stack-overflow"},
-	{"-mnop-fun-dllimport"},
-	{"-std=c99"},
-	{"-xc"},
-	{"-D", "FOO"},
-	{"-D", "foo=bar"},
-	{"-I", "FOO"},
-	{"-L", "@foo"},
-	{"-L", "-foo"},
-	{"-x", "c"},
-	{"-D@X"},
-	{"-D-X"},
-	{"-I@dir"},
-	{"-I-dir"},
-	{"-O@1"},
-	{"-Wa,-foo"},
-	{"-W@foo"},
-	{"-g@gdb"},
-	{"-g-gdb"},
-	{"-march=@dawn"},
-	{"-march=-dawn"},
-	{"-std=@c99"},
-	{"-std=-c99"},
-	{"-x@c"},
-	{"-x-c"},
-	{"-D", "@foo"},
-	{"-D", "-foo"},
-	{"-I", "@foo"},
-	{"-I", "-foo"},
-	{"-l", "@foo"},
-	{"-l", "-foo"},
-	{"-framework", "-Caffeine"},
-	{"-framework", "@Home"},
-	{"-Wl,-framework,-Caffeine"},
-	{"-Wl,-framework", "-Wl,@Home"},
-	{"-Wl,-framework", "@Home"},
-	{"-Wl,-framework,Chocolate,@Home"},
-	{"-x", "--c"},
-	{"-x", "@obj"},
-	{"-Wl,-rpath,@foo"},
-	{"-Wl,-R,foo,bar"},
-	{"-Wl,-R,@foo"},
-	{"-Wl,--just-symbols,@foo"},
-	{"../x.o"},
-}
-
-func TestCheckLinkerFlags(t *testing.T) {
-	for _, f := range goodLinkerFlags {
-		if err := checkLinkerFlags("test", f); err != nil {
-			t.Errorf("unexpected error for %q: %v", f, err)
-		}
-	}
-	for _, f := range badLinkerFlags {
-		if err := checkLinkerFlags("test", f); err == nil {
-			t.Errorf("missing error for %q", f)
-		}
-	}
-}
-
-func TestCheckFlagAllowDisallow(t *testing.T) {
-	if err := checkCompilerFlags("TEST", []string{"-disallow"}); err == nil {
-		t.Fatalf("missing error for -disallow")
-	}
-	os.Setenv("CGO_TEST_ALLOW", "-disallo")
-	if err := checkCompilerFlags("TEST", []string{"-disallow"}); err == nil {
-		t.Fatalf("missing error for -disallow with CGO_TEST_ALLOW=-disallo")
-	}
-	os.Setenv("CGO_TEST_ALLOW", "-disallow")
-	if err := checkCompilerFlags("TEST", []string{"-disallow"}); err != nil {
-		t.Fatalf("unexpected error for -disallow with CGO_TEST_ALLOW=-disallow: %v", err)
-	}
-	os.Unsetenv("CGO_TEST_ALLOW")
-
-	if err := checkCompilerFlags("TEST", []string{"-Wall"}); err != nil {
-		t.Fatalf("unexpected error for -Wall: %v", err)
-	}
-	os.Setenv("CGO_TEST_DISALLOW", "-Wall")
-	if err := checkCompilerFlags("TEST", []string{"-Wall"}); err == nil {
-		t.Fatalf("missing error for -Wall with CGO_TEST_DISALLOW=-Wall")
-	}
-	os.Setenv("CGO_TEST_ALLOW", "-Wall") // disallow wins
-	if err := checkCompilerFlags("TEST", []string{"-Wall"}); err == nil {
-		t.Fatalf("missing error for -Wall with CGO_TEST_DISALLOW=-Wall and CGO_TEST_ALLOW=-Wall")
-	}
-
-	os.Setenv("CGO_TEST_ALLOW", "-fplugin.*")
-	os.Setenv("CGO_TEST_DISALLOW", "-fplugin=lint.so")
-	if err := checkCompilerFlags("TEST", []string{"-fplugin=faster.so"}); err != nil {
-		t.Fatalf("unexpected error for -fplugin=faster.so: %v", err)
-	}
-	if err := checkCompilerFlags("TEST", []string{"-fplugin=lint.so"}); err == nil {
-		t.Fatalf("missing error for -fplugin=lint.so: %v", err)
-	}
-}
@@ -1,3 +0,0 @@
-package main
-
-import "C"
@@ -1,26 +0,0 @@
-package main
-
-import "unsafe"
-
-var _ unsafe.Pointer
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
@@ -1,12 +0,0 @@
-package main
-
-/*
-#define foo 3
-#define bar foo
-*/
-import "C"
-
-const (
-	Foo = C.foo
-	Bar = C.bar
-)
@@ -1,29 +0,0 @@
-package main
-
-import "unsafe"
-
-var _ unsafe.Pointer
-
-const C.bar = C.foo
-const C.foo = 3
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
@@ -1,33 +0,0 @@
-package main
-
-/*
-#warning some warning
-
-typedef struct {
-	int x;
-	int y;
-} point_t;
-
-typedef someType noType; // undefined type
-
-#define SOME_CONST_1 5) // invalid const syntax
-#define SOME_CONST_2 6) // const not used (so no error)
-#define SOME_CONST_3 1234 // const too large for byte
-*/
-import "C"
-
-// Make sure that errors for the following lines won't change with future
-// additions to the CGo preamble.
-//line errors.go:100
-var (
-	// constant too large
-	_ C.uint8_t = 2 << 10
-
-	// z member does not exist
-	_ C.point_t = C.point_t{z: 3}
-
-	// constant has syntax error
-	_ = C.SOME_CONST_1
-
-	_ byte = C.SOME_CONST_3
-)
@@ -1,43 +0,0 @@
-// CGo errors:
-//     testdata/errors.go:4:2: warning: some warning
-//     testdata/errors.go:11:9: error: unknown type name 'someType'
-//     testdata/errors.go:13:23: unexpected token )
-
-// Type checking errors after CGo processing:
-//     testdata/errors.go:102: 2 << 10 (untyped int constant 2048) overflows uint8
-//     testdata/errors.go:105: unknown field z in struct literal
-//     testdata/errors.go:108: undeclared name: C.SOME_CONST_1
-//     testdata/errors.go:110: C.SOME_CONST_3 (untyped int constant 1234) overflows byte
-
-package main
-
-import "unsafe"
-
-var _ unsafe.Pointer
-
-const C.SOME_CONST_3 = 1234
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
-type C.point_t = struct {
-	x C.int
-	y C.int
-}
@@ -1,30 +0,0 @@
-package main
-
-/*
-// this name doesn't exist
-#cgo  NOFLAGS: -foo
-
-// unknown flag
-#cgo CFLAGS: -fdoes-not-exist -DNOTDEFINED
-
-#cgo CFLAGS: -DFOO
-
-#cgo CFLAGS: -Iinclude
-#include "foo.h"
-
-#if defined(FOO)
-#define BAR 3
-#else
-#define BAR 5
-#endif
-
-#if defined(NOTDEFINED)
-#warning flag must not be defined
-#endif
-*/
-import "C"
-
-var (
-	_ = C.BAR
-	_ = C.FOO_H
-)
@@ -1,33 +0,0 @@
-// CGo errors:
-//     testdata/flags.go:5:7: invalid #cgo line: NOFLAGS
-//     testdata/flags.go:8:13: invalid flag: -fdoes-not-exist
-
-package main
-
-import "unsafe"
-
-var _ unsafe.Pointer
-
-const C.BAR = 3
-const C.FOO_H = 1
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
@@ -1 +0,0 @@
-#define FOO_H 1
@@ -1,165 +0,0 @@
-package main
-
-/*
-// Simple typedef.
-typedef int myint;
-
-// Structs, with or without name.
-typedef struct {
-	int x;
-	int y;
-} point2d_t;
-typedef struct point3d {
-	int x;
-	int y;
-	int z;
-} point3d_t;
-
-// Structs with reserved field names.
-struct type1 {
-	// All these fields should be renamed.
-	int type;
-	int _type;
-	int __type;
-};
-struct type2 {
-	// This field should not be renamed.
-	int _type;
-};
-
-// Unions.
-typedef union {
-	// Union should be treated as a struct.
-	int i;
-} union1_t;
-typedef union {
-	// Union must contain a single field and have special getters/setters.
-	int    i;
-	double d;
-	short  s;
-} union3_t;
-typedef union union2d {
-	int i;
-	double d[2];
-} union2d_t;
-typedef union {
-	unsigned char arr[10];
-} unionarray_t;
-
-// Nested structs and unions.
-typedef struct {
-	point2d_t begin;
-	point2d_t end;
-	int       tag;
-	union {
-		point2d_t area;
-		point3d_t solid;
-	} coord;
-} struct_nested_t;
-typedef union {
-	point3d_t    point;
-	unionarray_t array;
-	union3_t     thing;
-} union_nested_t;
-
-// Enums. These define constant numbers. All these constants must be given the
-// correct number.
-typedef enum option {
-	optionA,
-	optionB,
-	optionC = -5,
-	optionD,
-	optionE = 10,
-	optionF,
-	optionG,
-} option_t;
-enum unused {
-	unused1 = 5,
-};
-
-// Anonymous enum.
-typedef enum {
-	option2A = 20,
-} option2_t;
-
-// Various types that are usually translated directly to Go types, but storing
-// them in a struct reveals them.
-typedef struct {
-	float  f;
-	double d;
-	int    *ptr;
-} types_t;
-
-// Arrays.
-typedef int myIntArray[10];
-
-// Bitfields.
-typedef struct {
-	unsigned char start;
-	unsigned char a : 5;
-	unsigned char b : 1;
-	unsigned char c : 2;
-	unsigned char :0; // new field
-	unsigned char d : 6;
-	unsigned char e : 3;
-	// Note that C++ allows bitfields bigger than the underlying type.
-} bitfield_t;
-*/
-import "C"
-
-var (
-	// Simple typedefs.
-	_ C.myint
-
-	// Structs.
-	_ C.point2d_t
-	_ C.point3d_t
-	_ C.struct_point3d
-
-	// Structs with reserved field names.
-	_ C.struct_type1
-	_ C.struct_type2
-
-	// Unions.
-	_ C.union1_t
-	_ C.union3_t
-	_ C.union2d_t
-	_ C.unionarray_t
-
-	// Nested structs and unions.
-	_ C.struct_nested_t
-	_ C.union_nested_t
-
-	// Enums (anonymous and named).
-	_ C.option_t
-	_ C.enum_option
-	_ C.option2_t
-
-	// Various types.
-	_ C.types_t
-
-	// Arrays.
-	_ C.myIntArray
-)
-
-// Test bitfield accesses.
-func accessBitfields() {
-	var x C.bitfield_t
-	x.start = 3
-	x.set_bitfield_a(4)
-	x.set_bitfield_b(1)
-	x.set_bitfield_c(2)
-	x.d = 10
-	x.e = 5
-	var _ C.uchar = x.bitfield_a()
-}
-
-// Test union accesses.
-func accessUnion() {
-	var union1 C.union1_t
-	union1.i = 5
-
-	var union2d C.union2d_t
-	var _ *C.int = union2d.unionfield_i()
-	var _ *[2]float64 = union2d.unionfield_d()
-}
@@ -1,145 +0,0 @@
-package main
-
-import "unsafe"
-
-var _ unsafe.Pointer
-
-const C.option2A = 20
-const C.optionA = 0
-const C.optionB = 1
-const C.optionC = -5
-const C.optionD = -4
-const C.optionE = 10
-const C.optionF = 11
-const C.optionG = 12
-const C.unused1 = 5
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
-type C.bitfield_t = C.struct_4
-type C.myIntArray = [10]C.int
-type C.myint = C.int
-type C.option2_t = C.uint
-type C.option_t = C.enum_option
-type C.point2d_t = struct {
-	x C.int
-	y C.int
-}
-type C.point3d_t = C.struct_point3d
-type C.struct_nested_t = struct {
-	begin C.point2d_t
-	end   C.point2d_t
-	tag   C.int
-
-	coord C.union_2
-}
-type C.types_t = struct {
-	f   float32
-	d   float64
-	ptr *C.int
-}
-type C.union1_t = struct{ i C.int }
-type C.union2d_t = C.union_union2d
-type C.union3_t = C.union_1
-type C.union_nested_t = C.union_3
-type C.unionarray_t = struct{ arr [10]C.uchar }
-
-func (s *C.struct_4) bitfield_a() C.uchar {
-	return s.__bitfield_1 & 0x1f
-}
-func (s *C.struct_4) set_bitfield_a(value C.uchar) {
-	s.__bitfield_1 = s.__bitfield_1&^0x1f | value&0x1f<<0
-}
-func (s *C.struct_4) bitfield_b() C.uchar {
-	return s.__bitfield_1 >> 5 & 0x1
-}
-func (s *C.struct_4) set_bitfield_b(value C.uchar) {
-	s.__bitfield_1 = s.__bitfield_1&^0x20 | value&0x1<<5
-}
-func (s *C.struct_4) bitfield_c() C.uchar {
-	return s.__bitfield_1 >> 6
-}
-func (s *C.struct_4) set_bitfield_c(value C.uchar,
-
-) { s.__bitfield_1 = s.__bitfield_1&0x3f | value<<6 }
-
-type C.struct_4 struct {
-	start        C.uchar
-	__bitfield_1 C.uchar
-
-	d C.uchar
-	e C.uchar
-}
-type C.struct_point3d struct {
-	x C.int
-	y C.int
-	z C.int
-}
-type C.struct_type1 struct {
-	_type   C.int
-	__type  C.int
-	___type C.int
-}
-type C.struct_type2 struct{ _type C.int }
-
-func (union *C.union_1) unionfield_i() *C.int {
-	return (*C.int)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_1) unionfield_d() *float64 {
-	return (*float64)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_1) unionfield_s() *C.short {
-	return (*C.short)(unsafe.Pointer(&union.$union))
-}
-
-type C.union_1 struct{ $union uint64 }
-
-func (union *C.union_2) unionfield_area() *C.point2d_t {
-	return (*C.point2d_t)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_2) unionfield_solid() *C.point3d_t {
-	return (*C.point3d_t)(unsafe.Pointer(&union.$union))
-}
-
-type C.union_2 struct{ $union [3]uint32 }
-
-func (union *C.union_3) unionfield_point() *C.point3d_t {
-	return (*C.point3d_t)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_3) unionfield_array() *C.unionarray_t {
-	return (*C.unionarray_t)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_3) unionfield_thing() *C.union3_t {
-	return (*C.union3_t)(unsafe.Pointer(&union.$union))
-}
-
-type C.union_3 struct{ $union [2]uint64 }
-
-func (union *C.union_union2d) unionfield_i() *C.int {
-	return (*C.int)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_union2d) unionfield_d() *[2]float64 {
-	return (*[2]float64)(unsafe.Pointer(&union.$union))
-}
-
-type C.union_union2d struct{ $union [2]uint64 }
-type C.enum_option C.int
-type C.enum_unused C.uint
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+)
+
+// Commands used by the compilation process might have different file names
+// across operating systems and distributions.
+var commands = map[string][]string{
+	"clang":   {"clang-8"},
+	"ld.lld":  {"ld.lld-8", "ld.lld"},
+	"wasm-ld": {"wasm-ld-8", "wasm-ld"},
+}
+
+func init() {
+	// Add the path to a Homebrew-installed LLVM 8 for ease of use (no need to
+	// manually set $PATH).
+	if runtime.GOOS == "darwin" {
+		commands["clang"] = append(commands["clang"], "/usr/local/opt/llvm/bin/clang-8")
+		commands["ld.lld"] = append(commands["ld.lld"], "/usr/local/opt/llvm/bin/ld.lld")
+		commands["wasm-ld"] = append(commands["wasm-ld"], "/usr/local/opt/llvm/bin/wasm-ld")
+	}
+}
+
+func execCommand(cmdNames []string, args ...string) error {
+	for _, cmdName := range cmdNames {
+		cmd := exec.Command(cmdName, args...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		err := cmd.Run()
+		if err != nil {
+			if err, ok := err.(*exec.Error); ok && err.Err == exec.ErrNotFound {
+				// this command was not found, try the next
+				continue
+			}
+			return err
+		}
+		return nil
+	}
+	return errors.New("none of these commands were found in your $PATH: " + strings.Join(cmdNames, " "))
+}
@@ -1,278 +0,0 @@
-// Package compileopts contains the configuration for a single to-be-built
-// binary.
-package compileopts
-
-import (
-	"errors"
-	"fmt"
-	"path/filepath"
-	"regexp"
-	"strconv"
-	"strings"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// Config keeps all configuration affecting the build in a single struct.
-type Config struct {
-	Options        *Options
-	Target         *TargetSpec
-	GoMinorVersion int
-	ClangHeaders   string // Clang built-in header include path
-	TestConfig     TestConfig
-}
-
-// FuncValueImplementation is an enum for the particular implementations of Go
-// func values.
-type FuncValueImplementation int
-
-// These constants describe the various possible implementations of Go func
-// values.
-const (
-	FuncValueNone FuncValueImplementation = iota
-
-	// A func value is implemented as a pair of pointers:
-	//     {context, function pointer}
-	// where the context may be a pointer to a heap-allocated struct containing
-	// the free variables, or it may be undef if the function being pointed to
-	// doesn't need a context. The function pointer is a regular function
-	// pointer.
-	FuncValueDoubleword
-
-	// As funcValueDoubleword, but with the function pointer replaced by a
-	// unique ID per function signature. Function values are called by using a
-	// switch statement and choosing which function to call.
-	FuncValueSwitch
-)
-
-// Triple returns the LLVM target triple, like armv6m-none-eabi.
-func (c *Config) Triple() string {
-	return c.Target.Triple
-}
-
-// CPU returns the LLVM CPU name, like atmega328p or arm7tdmi. It may return an
-// empty string if the CPU name is not known.
-func (c *Config) CPU() string {
-	return c.Target.CPU
-}
-
-// Features returns a list of features this CPU supports. For example, for a
-// RISC-V processor, that could be ["+a", "+c", "+m"]. For many targets, an
-// empty list will be returned.
-func (c *Config) Features() []string {
-	return c.Target.Features
-}
-
-// GOOS returns the GOOS of the target. This might not always be the actual OS:
-// for example, bare-metal targets will usually pretend to be linux to get the
-// standard library to compile.
-func (c *Config) GOOS() string {
-	return c.Target.GOOS
-}
-
-// GOARCH returns the GOARCH of the target. This might not always be the actual
-// archtecture: for example, the AVR target is not supported by the Go standard
-// library so such targets will usually pretend to be linux/arm.
-func (c *Config) GOARCH() string {
-	return c.Target.GOARCH
-}
-
-// BuildTags returns the complete list of build tags used during this build.
-func (c *Config) BuildTags() []string {
-	tags := append(c.Target.BuildTags, []string{"tinygo", "gc." + c.GC(), "scheduler." + c.Scheduler()}...)
-	for i := 1; i <= c.GoMinorVersion; i++ {
-		tags = append(tags, fmt.Sprintf("go1.%d", i))
-	}
-	if extraTags := strings.Fields(c.Options.Tags); len(extraTags) != 0 {
-		tags = append(tags, extraTags...)
-	}
-	return tags
-}
-
-// CgoEnabled returns true if (and only if) CGo is enabled. It is true by
-// default and false if CGO_ENABLED is set to "0".
-func (c *Config) CgoEnabled() bool {
-	return goenv.Get("CGO_ENABLED") == "1"
-}
-
-// GC returns the garbage collection strategy in use on this platform. Valid
-// values are "none", "leaking", "extalloc", and "conservative".
-func (c *Config) GC() string {
-	if c.Options.GC != "" {
-		return c.Options.GC
-	}
-	if c.Target.GC != "" {
-		return c.Target.GC
-	}
-	for _, tag := range c.Target.BuildTags {
-		if tag == "baremetal" || tag == "wasm" {
-			return "conservative"
-		}
-	}
-	return "extalloc"
-}
-
-// NeedsStackObjects returns true if the compiler should insert stack objects
-// that can be traced by the garbage collector.
-func (c *Config) NeedsStackObjects() bool {
-	switch c.GC() {
-	case "conservative", "extalloc":
-		for _, tag := range c.BuildTags() {
-			if tag == "baremetal" {
-				return false
-			}
-		}
-
-		return true
-	default:
-		return false
-	}
-}
-
-// Scheduler returns the scheduler implementation. Valid values are "coroutines"
-// and "tasks".
-func (c *Config) Scheduler() string {
-	if c.Options.Scheduler != "" {
-		return c.Options.Scheduler
-	}
-	if c.Target.Scheduler != "" {
-		return c.Target.Scheduler
-	}
-	// Fall back to coroutines, which are supported everywhere.
-	return "coroutines"
-}
-
-// FuncImplementation picks an appropriate func value implementation for the
-// target.
-func (c *Config) FuncImplementation() FuncValueImplementation {
-	// Always pick the switch implementation, as it allows the use of blocking
-	// inside a function that is used as a func value.
-	switch c.Scheduler() {
-	case "none", "coroutines":
-		return FuncValueSwitch
-	case "tasks":
-		return FuncValueDoubleword
-	default:
-		panic("unknown scheduler type")
-	}
-}
-
-// PanicStrategy returns the panic strategy selected for this target. Valid
-// values are "print" (print the panic value, then exit) or "trap" (issue a trap
-// instruction).
-func (c *Config) PanicStrategy() string {
-	return c.Options.PanicStrategy
-}
-
-// CFlags returns the flags to pass to the C compiler. This is necessary for CGo
-// preprocessing.
-func (c *Config) CFlags() []string {
-	cflags := append([]string{}, c.Options.CFlags...)
-	for _, flag := range c.Target.CFlags {
-		cflags = append(cflags, strings.Replace(flag, "{root}", goenv.Get("TINYGOROOT"), -1))
-	}
-	if c.Target.Libc == "picolibc" {
-		root := goenv.Get("TINYGOROOT")
-		cflags = append(cflags, "-nostdlibinc", "-Xclang", "-internal-isystem", "-Xclang", filepath.Join(root, "lib", "picolibc", "newlib", "libc", "include"))
-		cflags = append(cflags, "-I"+filepath.Join(root, "lib/picolibc-include"))
-	}
-	return cflags
-}
-
-// LDFlags returns the flags to pass to the linker. A few more flags are needed
-// (like the one for the compiler runtime), but this represents the majority of
-// the flags.
-func (c *Config) LDFlags() []string {
-	root := goenv.Get("TINYGOROOT")
-	// Merge and adjust LDFlags.
-	ldflags := append([]string{}, c.Options.LDFlags...)
-	for _, flag := range c.Target.LDFlags {
-		ldflags = append(ldflags, strings.Replace(flag, "{root}", root, -1))
-	}
-	ldflags = append(ldflags, "-L", root)
-	if c.Target.GOARCH == "wasm" {
-		// Round heap size to next multiple of 65536 (the WebAssembly page
-		// size).
-		heapSize := (c.Options.HeapSize + (65536 - 1)) &^ (65536 - 1)
-		ldflags = append(ldflags, "--initial-memory="+strconv.FormatInt(heapSize, 10))
-	}
-	if c.Target.LinkerScript != "" {
-		ldflags = append(ldflags, "-T", c.Target.LinkerScript)
-	}
-	return ldflags
-}
-
-// ExtraFiles returns the list of extra files to be built and linked with the
-// executable. This can include extra C and assembly files.
-func (c *Config) ExtraFiles() []string {
-	return c.Target.ExtraFiles
-}
-
-// DumpSSA returns whether to dump Go SSA while compiling (-dumpssa flag). Only
-// enable this for debugging.
-func (c *Config) DumpSSA() bool {
-	return c.Options.DumpSSA
-}
-
-// VerifyIR returns whether to run extra checks on the IR. This is normally
-// disabled but enabled during testing.
-func (c *Config) VerifyIR() bool {
-	return c.Options.VerifyIR
-}
-
-// Debug returns whether to add debug symbols to the IR, for debugging with GDB
-// and similar.
-func (c *Config) Debug() bool {
-	return c.Options.Debug
-}
-
-// Programmer returns the flash method and OpenOCD interface name given a
-// particular configuration. It may either be all configured in the target JSON
-// file or be modified using the -programmmer command-line option.
-func (c *Config) Programmer() (method, openocdInterface string) {
-	switch c.Options.Programmer {
-	case "":
-		// No configuration supplied.
-		return c.Target.FlashMethod, c.Target.OpenOCDInterface
-	case "openocd", "msd", "command":
-		// The -programmer flag only specifies the flash method.
-		return c.Options.Programmer, c.Target.OpenOCDInterface
-	default:
-		// The -programmer flag specifies something else, assume it specifies
-		// the OpenOCD interface name.
-		return "openocd", c.Options.Programmer
-	}
-}
-
-// OpenOCDConfiguration returns a list of command line arguments to OpenOCD.
-// This list of command-line arguments is based on the various OpenOCD-related
-// flags in the target specification.
-func (c *Config) OpenOCDConfiguration() (args []string, err error) {
-	_, openocdInterface := c.Programmer()
-	if openocdInterface == "" {
-		return nil, errors.New("OpenOCD programmer not set")
-	}
-	if !regexp.MustCompile("^[\\p{L}0-9_-]+$").MatchString(openocdInterface) {
-		return nil, fmt.Errorf("OpenOCD programmer has an invalid name: %#v", openocdInterface)
-	}
-	if c.Target.OpenOCDTarget == "" {
-		return nil, errors.New("OpenOCD chip not set")
-	}
-	if !regexp.MustCompile("^[\\p{L}0-9_-]+$").MatchString(c.Target.OpenOCDTarget) {
-		return nil, fmt.Errorf("OpenOCD target has an invalid name: %#v", c.Target.OpenOCDTarget)
-	}
-	if c.Target.OpenOCDTransport != "" && c.Target.OpenOCDTransport != "swd" {
-		return nil, fmt.Errorf("unknown OpenOCD transport: %#v", c.Target.OpenOCDTransport)
-	}
-	args = []string{"-f", "interface/" + openocdInterface + ".cfg"}
-	if c.Target.OpenOCDTransport != "" {
-		args = append(args, "-c", "transport select "+c.Target.OpenOCDTransport)
-	}
-	args = append(args, "-f", "target/"+c.Target.OpenOCDTarget+".cfg")
-	return args, nil
-}
-
-type TestConfig struct {
-	CompileTestBinary bool
-	// TODO: Filter the test functions to run, include verbose flag, etc
-}
@@ -1,23 +0,0 @@
-package compileopts
-
-// Options contains extra options to give to the compiler. These options are
-// usually passed from the command line.
-type Options struct {
-	Target        string
-	Opt           string
-	GC            string
-	PanicStrategy string
-	Scheduler     string
-	PrintIR       bool
-	DumpSSA       bool
-	VerifyIR      bool
-	Debug         bool
-	PrintSizes    string
-	CFlags        []string
-	LDFlags       []string
-	Tags          string
-	WasmAbi       string
-	HeapSize      int64
-	TestConfig    TestConfig
-	Programmer    string
-}
@@ -1,301 +0,0 @@
-package compileopts
-
-// This file loads a target specification from a JSON file.
-
-import (
-	"encoding/json"
-	"errors"
-	"io"
-	"os"
-	"path/filepath"
-	"runtime"
-	"strings"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// Target specification for a given target. Used for bare metal targets.
-//
-// The target specification is mostly inspired by Rust:
-// https://doc.rust-lang.org/nightly/nightly-rustc/rustc_target/spec/struct.TargetOptions.html
-// https://github.com/shepmaster/rust-arduino-blink-led-no-core-with-cargo/blob/master/blink/arduino.json
-type TargetSpec struct {
-	Inherits         []string `json:"inherits"`
-	Triple           string   `json:"llvm-target"`
-	CPU              string   `json:"cpu"`
-	Features         []string `json:"features"`
-	GOOS             string   `json:"goos"`
-	GOARCH           string   `json:"goarch"`
-	BuildTags        []string `json:"build-tags"`
-	GC               string   `json:"gc"`
-	Scheduler        string   `json:"scheduler"`
-	Compiler         string   `json:"compiler"`
-	Linker           string   `json:"linker"`
-	RTLib            string   `json:"rtlib"` // compiler runtime library (libgcc, compiler-rt)
-	Libc             string   `json:"libc"`
-	CFlags           []string `json:"cflags"`
-	LDFlags          []string `json:"ldflags"`
-	LinkerScript     string   `json:"linkerscript"`
-	ExtraFiles       []string `json:"extra-files"`
-	Emulator         []string `json:"emulator"`
-	FlashCommand     string   `json:"flash-command"`
-	GDB              string   `json:"gdb"`
-	PortReset        string   `json:"flash-1200-bps-reset"`
-	FlashMethod      string   `json:"flash-method"`
-	FlashVolume      string   `json:"msd-volume-name"`
-	FlashFilename    string   `json:"msd-firmware-name"`
-	UF2FamilyID      string   `json:"uf2-family-id"`
-	OpenOCDInterface string   `json:"openocd-interface"`
-	OpenOCDTarget    string   `json:"openocd-target"`
-	OpenOCDTransport string   `json:"openocd-transport"`
-	JLinkDevice      string   `json:"jlink-device"`
-}
-
-// copyProperties copies all properties that are set in spec2 into itself.
-func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
-	// TODO: simplify this using reflection? Inherits and BuildTags are special
-	// cases, but the rest can simply be copied if set.
-	spec.Inherits = append(spec.Inherits, spec2.Inherits...)
-	if spec2.Triple != "" {
-		spec.Triple = spec2.Triple
-	}
-	if spec2.CPU != "" {
-		spec.CPU = spec2.CPU
-	}
-	spec.Features = append(spec.Features, spec2.Features...)
-	if spec2.GOOS != "" {
-		spec.GOOS = spec2.GOOS
-	}
-	if spec2.GOARCH != "" {
-		spec.GOARCH = spec2.GOARCH
-	}
-	spec.BuildTags = append(spec.BuildTags, spec2.BuildTags...)
-	if spec2.GC != "" {
-		spec.GC = spec2.GC
-	}
-	if spec2.Scheduler != "" {
-		spec.Scheduler = spec2.Scheduler
-	}
-	if spec2.Compiler != "" {
-		spec.Compiler = spec2.Compiler
-	}
-	if spec2.Linker != "" {
-		spec.Linker = spec2.Linker
-	}
-	if spec2.RTLib != "" {
-		spec.RTLib = spec2.RTLib
-	}
-	if spec2.Libc != "" {
-		spec.Libc = spec2.Libc
-	}
-	spec.CFlags = append(spec.CFlags, spec2.CFlags...)
-	spec.LDFlags = append(spec.LDFlags, spec2.LDFlags...)
-	if spec2.LinkerScript != "" {
-		spec.LinkerScript = spec2.LinkerScript
-	}
-	spec.ExtraFiles = append(spec.ExtraFiles, spec2.ExtraFiles...)
-	if len(spec2.Emulator) != 0 {
-		spec.Emulator = spec2.Emulator
-	}
-	if spec2.FlashCommand != "" {
-		spec.FlashCommand = spec2.FlashCommand
-	}
-	if spec2.GDB != "" {
-		spec.GDB = spec2.GDB
-	}
-	if spec2.PortReset != "" {
-		spec.PortReset = spec2.PortReset
-	}
-	if spec2.FlashMethod != "" {
-		spec.FlashMethod = spec2.FlashMethod
-	}
-	if spec2.FlashVolume != "" {
-		spec.FlashVolume = spec2.FlashVolume
-	}
-	if spec2.FlashFilename != "" {
-		spec.FlashFilename = spec2.FlashFilename
-	}
-	if spec2.UF2FamilyID != "" {
-		spec.UF2FamilyID = spec2.UF2FamilyID
-	}
-	if spec2.OpenOCDInterface != "" {
-		spec.OpenOCDInterface = spec2.OpenOCDInterface
-	}
-	if spec2.OpenOCDTarget != "" {
-		spec.OpenOCDTarget = spec2.OpenOCDTarget
-	}
-	if spec2.OpenOCDTransport != "" {
-		spec.OpenOCDTransport = spec2.OpenOCDTransport
-	}
-	if spec2.JLinkDevice != "" {
-		spec.JLinkDevice = spec2.JLinkDevice
-	}
-}
-
-// load reads a target specification from the JSON in the given io.Reader. It
-// may load more targets specified using the "inherits" property.
-func (spec *TargetSpec) load(r io.Reader) error {
-	err := json.NewDecoder(r).Decode(spec)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// loadFromGivenStr loads the TargetSpec from the given string that could be:
-// - targets/ directory inside the compiler sources
-// - a relative or absolute path to custom (project specific) target specification .json file;
-//   the Inherits[] could contain the files from target folder (ex. stm32f4disco)
-//   as well as path to custom files (ex. myAwesomeProject.json)
-func (spec *TargetSpec) loadFromGivenStr(str string) error {
-	path := ""
-	if strings.HasSuffix(str, ".json") {
-		path, _ = filepath.Abs(str)
-	} else {
-		path = filepath.Join(goenv.Get("TINYGOROOT"), "targets", strings.ToLower(str)+".json")
-	}
-	fp, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	defer fp.Close()
-	return spec.load(fp)
-}
-
-// resolveInherits loads inherited targets, recursively.
-func (spec *TargetSpec) resolveInherits() error {
-	// First create a new spec with all the inherited properties.
-	newSpec := &TargetSpec{}
-	for _, name := range spec.Inherits {
-		subtarget := &TargetSpec{}
-		err := subtarget.loadFromGivenStr(name)
-		if err != nil {
-			return err
-		}
-		err = subtarget.resolveInherits()
-		if err != nil {
-			return err
-		}
-		newSpec.copyProperties(subtarget)
-	}
-
-	// When all properties are loaded, make sure they are properly inherited.
-	newSpec.copyProperties(spec)
-	*spec = *newSpec
-
-	return nil
-}
-
-// Load a target specification.
-func LoadTarget(target string) (*TargetSpec, error) {
-	if target == "" {
-		// Configure based on GOOS/GOARCH environment variables (falling back to
-		// runtime.GOOS/runtime.GOARCH), and generate a LLVM target based on it.
-		goos := goenv.Get("GOOS")
-		goarch := goenv.Get("GOARCH")
-		llvmos := goos
-		llvmarch := map[string]string{
-			"386":   "i386",
-			"amd64": "x86_64",
-			"arm64": "aarch64",
-		}[goarch]
-		if llvmarch == "" {
-			llvmarch = goarch
-		}
-		target = llvmarch + "--" + llvmos
-		if goarch == "arm" {
-			target += "-gnueabihf"
-		}
-		return defaultTarget(goos, goarch, target)
-	}
-
-	// See whether there is a target specification for this target (e.g.
-	// Arduino).
-	spec := &TargetSpec{}
-	err := spec.loadFromGivenStr(target)
-	if err == nil {
-		// Successfully loaded this target from a built-in .json file. Make sure
-		// it includes all parents as specified in the "inherits" key.
-		err = spec.resolveInherits()
-		if err != nil {
-			return nil, err
-		}
-		return spec, nil
-	} else if !os.IsNotExist(err) {
-		// Expected a 'file not found' error, got something else. Report it as
-		// an error.
-		return nil, err
-	} else {
-		// Load target from given triple, ignore GOOS/GOARCH environment
-		// variables.
-		tripleSplit := strings.Split(target, "-")
-		if len(tripleSplit) < 3 {
-			return nil, errors.New("expected a full LLVM target or a custom target in -target flag")
-		}
-		if tripleSplit[0] == "arm" {
-			// LLVM and Clang have a different idea of what "arm" means, so
-			// upgrade to a slightly more modern ARM. In fact, when you pass
-			// --target=arm--linux-gnueabihf to Clang, it will convert that
-			// internally to armv7-unknown-linux-gnueabihf. Changing the
-			// architecture to armv7 will keep things consistent.
-			tripleSplit[0] = "armv7"
-		}
-		goos := tripleSplit[2]
-		if strings.HasPrefix(goos, "darwin") {
-			goos = "darwin"
-		}
-		goarch := map[string]string{ // map from LLVM arch to Go arch
-			"i386":    "386",
-			"x86_64":  "amd64",
-			"aarch64": "arm64",
-			"armv7":   "arm",
-		}[tripleSplit[0]]
-		if goarch == "" {
-			goarch = tripleSplit[0]
-		}
-		return defaultTarget(goos, goarch, strings.Join(tripleSplit, "-"))
-	}
-}
-
-func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
-	// No target spec available. Use the default one, useful on most systems
-	// with a regular OS.
-	spec := TargetSpec{
-		Triple:      triple,
-		GOOS:        goos,
-		GOARCH:      goarch,
-		BuildTags:   []string{goos, goarch},
-		Compiler:    "clang",
-		Linker:      "cc",
-		CFlags:      []string{"--target=" + triple},
-		GDB:         "gdb",
-		PortReset:   "false",
-		FlashMethod: "native",
-	}
-	if goos == "darwin" {
-		spec.LDFlags = append(spec.LDFlags, "-Wl,-dead_strip")
-	} else {
-		spec.LDFlags = append(spec.LDFlags, "-no-pie", "-Wl,--gc-sections") // WARNING: clang < 5.0 requires -nopie
-	}
-	if goarch != runtime.GOARCH {
-		// Some educated guesses as to how to invoke helper programs.
-		if goarch == "arm" && goos == "linux" {
-			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/arm-linux-gnueabihf")
-			spec.Linker = "arm-linux-gnueabihf-gcc"
-			spec.GDB = "arm-linux-gnueabihf-gdb"
-			spec.Emulator = []string{"qemu-arm", "-L", "/usr/arm-linux-gnueabihf"}
-		}
-		if goarch == "arm64" && goos == "linux" {
-			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/aarch64-linux-gnu")
-			spec.Linker = "aarch64-linux-gnu-gcc"
-			spec.GDB = "aarch64-linux-gnu-gdb"
-			spec.Emulator = []string{"qemu-aarch64", "-L", "/usr/aarch64-linux-gnu"}
-		}
-		if goarch == "386" {
-			spec.CFlags = []string{"-m32"}
-			spec.LDFlags = []string{"-m32"}
-		}
-	}
-	return &spec, nil
-}
@@ -1,19 +0,0 @@
-package compileopts
-
-import "testing"
-
-func TestLoadTarget(t *testing.T) {
-	_, err := LoadTarget("arduino")
-	if err != nil {
-		t.Error("LoadTarget test failed:", err)
-	}
-
-	_, err = LoadTarget("notexist")
-	if err == nil {
-		t.Error("LoadTarget should have failed with non existing target")
-	}
-
-	if err.Error() != "expected a full LLVM target or a custom target in -target flag" {
-		t.Error("LoadTarget failed for wrong reason:", err)
-	}
-}
@@ -4,19 +4,16 @@ package compiler
 // required by the Go programming language.

 import (
-	"fmt"
-	"go/token"
 	"go/types"

-	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )

-// createLookupBoundsCheck emits a bounds check before doing a lookup into a
+// emitLookupBoundsCheck emits a bounds check before doing a lookup into a
 // slice. This is required by the Go language spec: an index out of bounds must
 // cause a panic.
-func (b *builder) createLookupBoundsCheck(arrayLen, index llvm.Value, indexType types.Type) {
-	if b.fn.IsNoBounds() {
+func (c *Compiler) emitLookupBoundsCheck(frame *Frame, arrayLen, index llvm.Value, indexType types.Type) {
+	if frame.fn.IsNoBounds() {
 		// The //go:nobounds pragma was added to the function to avoid bounds
 		// checking.
 		return
@@ -25,30 +22,42 @@ func (b *builder) createLookupBoundsCheck(arrayLen, index llvm.Value, indexType
 	if index.Type().IntTypeWidth() < arrayLen.Type().IntTypeWidth() {
 		// Sometimes, the index can be e.g. an uint8 or int8, and we have to
 		// correctly extend that type.
-		if indexType.Underlying().(*types.Basic).Info()&types.IsUnsigned == 0 {
-			index = b.CreateZExt(index, arrayLen.Type(), "")
+		if indexType.(*types.Basic).Info()&types.IsUnsigned == 0 {
+			index = c.builder.CreateZExt(index, arrayLen.Type(), "")
 		} else {
-			index = b.CreateSExt(index, arrayLen.Type(), "")
+			index = c.builder.CreateSExt(index, arrayLen.Type(), "")
 		}
 	} else if index.Type().IntTypeWidth() > arrayLen.Type().IntTypeWidth() {
 		// The index is bigger than the array length type, so extend it.
-		arrayLen = b.CreateZExt(arrayLen, index.Type(), "")
+		arrayLen = c.builder.CreateZExt(arrayLen, index.Type(), "")
 	}

+	faultBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "lookup.outofbounds")
+	nextBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "lookup.next")
+	frame.blockExits[frame.currentBlock] = nextBlock // adjust outgoing block for phi nodes
+
 	// Now do the bounds check: index >= arrayLen
-	outOfBounds := b.CreateICmp(llvm.IntUGE, index, arrayLen, "")
-	b.createRuntimeAssert(outOfBounds, "lookup", "lookupPanic")
+	outOfBounds := c.builder.CreateICmp(llvm.IntUGE, index, arrayLen, "")
+	c.builder.CreateCondBr(outOfBounds, faultBlock, nextBlock)
+
+	// Fail: this is a nil pointer, exit with a panic.
+	c.builder.SetInsertPointAtEnd(faultBlock)
+	c.createRuntimeCall("lookupPanic", nil, "")
+	c.builder.CreateUnreachable()
+
+	// Ok: this is a valid pointer.
+	c.builder.SetInsertPointAtEnd(nextBlock)
 }

-// createSliceBoundsCheck emits a bounds check before a slicing operation to make
+// emitSliceBoundsCheck emits a bounds check before a slicing operation to make
 // sure it is within bounds.
 //
 // This function is both used for slicing a slice (low and high have their
 // normal meaning) and for creating a new slice, where 'capacity' means the
 // biggest possible slice capacity, 'low' means len and 'high' means cap. The
 // logic is the same in both cases.
-func (b *builder) createSliceBoundsCheck(capacity, low, high, max llvm.Value, lowType, highType, maxType *types.Basic) {
-	if b.fn.IsNoBounds() {
+func (c *Compiler) emitSliceBoundsCheck(frame *Frame, capacity, low, high, max llvm.Value, lowType, highType, maxType *types.Basic) {
+	if frame.fn.IsNoBounds() {
 		// The //go:nobounds pragma was added to the function to avoid bounds
 		// checking.
 		return
@@ -66,164 +75,92 @@ func (b *builder) createSliceBoundsCheck(capacity, low, high, max llvm.Value, lo
 		capacityType = max.Type()
 	}
 	if capacityType != capacity.Type() {
-		capacity = b.CreateZExt(capacity, capacityType, "")
+		capacity = c.builder.CreateZExt(capacity, capacityType, "")
 	}

 	// Extend low and high to be the same size as capacity.
 	if low.Type().IntTypeWidth() < capacityType.IntTypeWidth() {
 		if lowType.Info()&types.IsUnsigned != 0 {
-			low = b.CreateZExt(low, capacityType, "")
+			low = c.builder.CreateZExt(low, capacityType, "")
 		} else {
-			low = b.CreateSExt(low, capacityType, "")
+			low = c.builder.CreateSExt(low, capacityType, "")
 		}
 	}
 	if high.Type().IntTypeWidth() < capacityType.IntTypeWidth() {
 		if highType.Info()&types.IsUnsigned != 0 {
-			high = b.CreateZExt(high, capacityType, "")
+			high = c.builder.CreateZExt(high, capacityType, "")
 		} else {
-			high = b.CreateSExt(high, capacityType, "")
+			high = c.builder.CreateSExt(high, capacityType, "")
 		}
 	}
 	if max.Type().IntTypeWidth() < capacityType.IntTypeWidth() {
 		if maxType.Info()&types.IsUnsigned != 0 {
-			max = b.CreateZExt(max, capacityType, "")
+			max = c.builder.CreateZExt(max, capacityType, "")
 		} else {
-			max = b.CreateSExt(max, capacityType, "")
+			max = c.builder.CreateSExt(max, capacityType, "")
 		}
 	}

+	faultBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "slice.outofbounds")
+	nextBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "slice.next")
+	frame.blockExits[frame.currentBlock] = nextBlock // adjust outgoing block for phi nodes
+
 	// Now do the bounds check: low > high || high > capacity
-	outOfBounds1 := b.CreateICmp(llvm.IntUGT, low, high, "slice.lowhigh")
-	outOfBounds2 := b.CreateICmp(llvm.IntUGT, high, max, "slice.highmax")
-	outOfBounds3 := b.CreateICmp(llvm.IntUGT, max, capacity, "slice.maxcap")
-	outOfBounds := b.CreateOr(outOfBounds1, outOfBounds2, "slice.lowmax")
-	outOfBounds = b.CreateOr(outOfBounds, outOfBounds3, "slice.lowcap")
-	b.createRuntimeAssert(outOfBounds, "slice", "slicePanic")
+	outOfBounds1 := c.builder.CreateICmp(llvm.IntUGT, low, high, "slice.lowhigh")
+	outOfBounds2 := c.builder.CreateICmp(llvm.IntUGT, high, max, "slice.highmax")
+	outOfBounds3 := c.builder.CreateICmp(llvm.IntUGT, max, capacity, "slice.maxcap")
+	outOfBounds := c.builder.CreateOr(outOfBounds1, outOfBounds2, "slice.lowmax")
+	outOfBounds = c.builder.CreateOr(outOfBounds, outOfBounds3, "slice.lowcap")
+	c.builder.CreateCondBr(outOfBounds, faultBlock, nextBlock)
+
+	// Fail: this is a nil pointer, exit with a panic.
+	c.builder.SetInsertPointAtEnd(faultBlock)
+	c.createRuntimeCall("slicePanic", nil, "")
+	c.builder.CreateUnreachable()
+
+	// Ok: this is a valid pointer.
+	c.builder.SetInsertPointAtEnd(nextBlock)
 }

-// createChanBoundsCheck creates a bounds check before creating a new channel to
-// check that the value is not too big for runtime.chanMake.
-func (b *builder) createChanBoundsCheck(elementSize uint64, bufSize llvm.Value, bufSizeType *types.Basic, pos token.Pos) {
-	if b.fn.IsNoBounds() {
-		// The //go:nobounds pragma was added to the function to avoid bounds
-		// checking.
-		return
-	}
-
-	// Check whether the bufSize parameter must be cast to a wider integer for
-	// comparison.
-	if bufSize.Type().IntTypeWidth() < b.uintptrType.IntTypeWidth() {
-		if bufSizeType.Info()&types.IsUnsigned != 0 {
-			// Unsigned, so zero-extend to uint type.
-			bufSizeType = types.Typ[types.Uint]
-			bufSize = b.CreateZExt(bufSize, b.intType, "")
-		} else {
-			// Signed, so sign-extend to int type.
-			bufSizeType = types.Typ[types.Int]
-			bufSize = b.CreateSExt(bufSize, b.intType, "")
-		}
-	}
-
-	// Calculate (^uintptr(0)) >> 1, which is the max value that fits in an
-	// uintptr if uintptrs were signed.
-	maxBufSize := llvm.ConstLShr(llvm.ConstNot(llvm.ConstInt(b.uintptrType, 0, false)), llvm.ConstInt(b.uintptrType, 1, false))
-	if elementSize > maxBufSize.ZExtValue() {
-		b.addError(pos, fmt.Sprintf("channel element type is too big (%v bytes)", elementSize))
-		return
-	}
-	// Avoid divide-by-zero.
-	if elementSize == 0 {
-		elementSize = 1
-	}
-	// Make the maxBufSize actually the maximum allowed value (in number of
-	// elements in the channel buffer).
-	maxBufSize = llvm.ConstUDiv(maxBufSize, llvm.ConstInt(b.uintptrType, elementSize, false))
-
-	// Make sure maxBufSize has the same type as bufSize.
-	if maxBufSize.Type() != bufSize.Type() {
-		maxBufSize = llvm.ConstZExt(maxBufSize, bufSize.Type())
-	}
-
-	// Do the check for a too large (or negative) buffer size.
-	bufSizeTooBig := b.CreateICmp(llvm.IntUGE, bufSize, maxBufSize, "")
-	b.createRuntimeAssert(bufSizeTooBig, "chan", "chanMakePanic")
-}
-
-// createNilCheck checks whether the given pointer is nil, and panics if it is.
-// It has no effect in well-behaved programs, but makes sure no uncaught nil
+// emitNilCheck checks whether the given pointer is nil, and panics if it is. It
+// has no effect in well-behaved programs, but makes sure no uncaught nil
 // pointer dereferences exist in valid Go code.
-func (b *builder) createNilCheck(inst ssa.Value, ptr llvm.Value, blockPrefix string) {
+func (c *Compiler) emitNilCheck(frame *Frame, ptr llvm.Value, blockPrefix string) {
 	// Check whether we need to emit this check at all.
 	if !ptr.IsAGlobalValue().IsNil() {
 		return
 	}

-	switch inst := inst.(type) {
-	case *ssa.IndexAddr:
-		// This pointer is the result of an index operation into a slice or
-		// array. Such slices/arrays are already bounds checked so the pointer
-		// must be a valid (non-nil) pointer. No nil checking is necessary.
-		return
-	case *ssa.Convert:
-		// This is a pointer that comes from a conversion from unsafe.Pointer.
-		// Don't do nil checking because this is unsafe code and the code should
-		// know what it is doing.
-		// Note: all *ssa.Convert instructions that result in a pointer must
-		// come from unsafe.Pointer. Testing here for unsafe.Pointer to be sure.
-		if inst.X.Type() == types.Typ[types.UnsafePointer] {
-			return
-		}
-	}
+	// Check whether this is a nil pointer.
+	faultBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, blockPrefix+".nil")
+	nextBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, blockPrefix+".next")
+	frame.blockExits[frame.currentBlock] = nextBlock // adjust outgoing block for phi nodes

 	// Compare against nil.
-	// We previously used a hack to make sure this wouldn't break escape
-	// analysis, but this is not necessary anymore since
-	// https://reviews.llvm.org/D60047 has been merged.
-	nilptr := llvm.ConstPointerNull(ptr.Type())
-	isnil := b.CreateICmp(llvm.IntEQ, ptr, nilptr, "")
-
-	// Emit the nil check in IR.
-	b.createRuntimeAssert(isnil, blockPrefix, "nilPanic")
-}
-
-// createNegativeShiftCheck creates an assertion that panics if the given shift value is negative.
-// This function assumes that the shift value is signed.
-func (b *builder) createNegativeShiftCheck(shift llvm.Value) {
-	if b.fn.IsNoBounds() {
-		// Function disabled bounds checking - skip shift check.
-		return
+	var isnil llvm.Value
+	if ptr.Type().PointerAddressSpace() == 0 {
+		// Do the nil check using the isnil builtin, which marks the parameter
+		// as nocapture.
+		// The reason it has to go through a builtin, is that a regular icmp
+		// instruction may capture the pointer in LLVM semantics, see
+		// https://reviews.llvm.org/D60047 for details. Pointer capturing
+		// unfortunately breaks escape analysis, so we use this trick to let the
+		// functionattr pass know that this pointer doesn't really escape.
+		ptr = c.builder.CreateBitCast(ptr, c.i8ptrType, "")
+		isnil = c.createRuntimeCall("isnil", []llvm.Value{ptr}, "")
+	} else {
+		// Do the nil check using a regular icmp. This can happen with function
+		// pointers on AVR, which don't benefit from escape analysis anyway.
+		nilptr := llvm.ConstPointerNull(ptr.Type())
+		isnil = c.builder.CreateICmp(llvm.IntEQ, ptr, nilptr, "")
 	}
+	c.builder.CreateCondBr(isnil, faultBlock, nextBlock)

-	// isNegative = shift < 0
-	isNegative := b.CreateICmp(llvm.IntSLT, shift, llvm.ConstInt(shift.Type(), 0, false), "")
-	b.createRuntimeAssert(isNegative, "shift", "negativeShiftPanic")
-}
-
-// createRuntimeAssert is a common function to create a new branch on an assert
-// bool, calling an assert func if the assert value is true (1).
-func (b *builder) createRuntimeAssert(assert llvm.Value, blockPrefix, assertFunc string) {
-	// Check whether we can resolve this check at compile time.
-	if !assert.IsAConstantInt().IsNil() {
-		val := assert.ZExtValue()
-		if val == 0 {
-			// Everything is constant so the check does not have to be emitted
-			// in IR. This avoids emitting some redundant IR.
-			return
-		}
-	}
-
-	faultBlock := b.ctx.AddBasicBlock(b.fn.LLVMFn, blockPrefix+".throw")
-	nextBlock := b.ctx.AddBasicBlock(b.fn.LLVMFn, blockPrefix+".next")
-	b.blockExits[b.currentBlock] = nextBlock // adjust outgoing block for phi nodes
-
-	// Now branch to the out-of-bounds or the regular block.
-	b.CreateCondBr(assert, faultBlock, nextBlock)
-
-	// Fail: the assert triggered so panic.
-	b.SetInsertPointAtEnd(faultBlock)
-	b.createRuntimeCall(assertFunc, nil, "")
-	b.CreateUnreachable()
-
-	// Ok: assert didn't trigger so continue normally.
-	b.SetInsertPointAtEnd(nextBlock)
+	// Fail: this is a nil pointer, exit with a panic.
+	c.builder.SetInsertPointAtEnd(faultBlock)
+	c.createRuntimeCall("nilPanic", nil, "")
+	c.builder.CreateUnreachable()
+
+	// Ok: this is a valid pointer.
+	c.builder.SetInsertPointAtEnd(nextBlock)
 }
@@ -1,9 +1,7 @@
 package compiler

 import (
-	"go/types"
-	"strconv"
-
+	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )

@@ -12,80 +10,59 @@ import (

 // The maximum number of arguments that can be expanded from a single struct. If
 // a struct contains more fields, it is passed as a struct without expanding.
-const maxFieldsPerParam = 3
+const MaxFieldsPerParam = 3

-// paramInfo contains some information collected about a function parameter,
-// useful while declaring or defining a function.
-type paramInfo struct {
-	llvmType llvm.Type
-	name     string // name, possibly with suffixes for e.g. struct fields
-	flags    paramFlags
-}
-
-// paramFlags identifies parameter attributes for flags. Most importantly, it
-// determines which parameters are dereferenceable_or_null and which aren't.
-type paramFlags uint8
-
-const (
-	// Parameter may have the deferenceable_or_null attribute. This attribute
-	// cannot be applied to unsafe.Pointer and to the data pointer of slices.
-	paramIsDeferenceableOrNull = 1 << iota
-)
-
-// createCall creates a new call to runtime.<fnName> with the given arguments.
-func (b *builder) createRuntimeCall(fnName string, args []llvm.Value, name string) llvm.Value {
-	fullName := "runtime." + fnName
-	fn := b.mod.NamedFunction(fullName)
-	if fn.IsNil() {
-		panic("trying to call non-existent function: " + fullName)
+// Shortcut: create a call to runtime.<fnName> with the given arguments.
+func (c *Compiler) createRuntimeCall(fnName string, args []llvm.Value, name string) llvm.Value {
+	runtimePkg := c.ir.Program.ImportedPackage("runtime")
+	member := runtimePkg.Members[fnName]
+	if member == nil {
+		panic("trying to call runtime." + fnName)
 	}
-	args = append(args, llvm.Undef(b.i8ptrType))            // unused context parameter
-	args = append(args, llvm.ConstPointerNull(b.i8ptrType)) // coroutine handle
-	return b.createCall(fn, args, name)
+	fn := c.ir.GetFunction(member.(*ssa.Function))
+	if !fn.IsExported() {
+		args = append(args, llvm.Undef(c.i8ptrType))            // unused context parameter
+		args = append(args, llvm.ConstPointerNull(c.i8ptrType)) // coroutine handle
+	}
+	return c.createCall(fn.LLVMFn, args, name)
 }

-// createCall creates a call to the given function with the arguments possibly
-// expanded.
-func (b *builder) createCall(fn llvm.Value, args []llvm.Value, name string) llvm.Value {
+// Create a call to the given function with the arguments possibly expanded.
+func (c *Compiler) createCall(fn llvm.Value, args []llvm.Value, name string) llvm.Value {
 	expanded := make([]llvm.Value, 0, len(args))
 	for _, arg := range args {
-		fragments := b.expandFormalParam(arg)
+		fragments := c.expandFormalParam(arg)
 		expanded = append(expanded, fragments...)
 	}
-	return b.CreateCall(fn, expanded, name)
+	return c.builder.CreateCall(fn, expanded, name)
 }

 // Expand an argument type to a list that can be used in a function call
 // parameter list.
-func expandFormalParamType(t llvm.Type, name string, goType types.Type) []paramInfo {
+func (c *Compiler) expandFormalParamType(t llvm.Type) []llvm.Type {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
-		fieldInfos := flattenAggregateType(t, name, goType)
-		if len(fieldInfos) <= maxFieldsPerParam {
-			return fieldInfos
+		fields := c.flattenAggregateType(t)
+		if len(fields) <= MaxFieldsPerParam {
+			return fields
 		} else {
 			// failed to lower
+			return []llvm.Type{t}
 		}
-	}
-	// TODO: split small arrays
-	return []paramInfo{
-		{
-			llvmType: t,
-			name:     name,
-			flags:    getTypeFlags(goType),
-		},
+	default:
+		// TODO: split small arrays
+		return []llvm.Type{t}
 	}
 }

-// expandFormalParamOffsets returns a list of offsets from the start of an
-// object of type t after it would have been split up by expandFormalParam. This
-// is useful for debug information, where it is necessary to know the offset
-// from the start of the combined object.
-func (b *builder) expandFormalParamOffsets(t llvm.Type) []uint64 {
+// Expand an argument type to a list of offsets from the start of the object.
+// Used together with expandFormalParam to get the offset of each value from the
+// start of the non-expanded value.
+func (c *Compiler) expandFormalParamOffsets(t llvm.Type) []uint64 {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
-		fields := b.flattenAggregateTypeOffsets(t)
-		if len(fields) <= maxFieldsPerParam {
+		fields := c.flattenAggregateTypeOffsets(t)
+		if len(fields) <= MaxFieldsPerParam {
 			return fields
 		} else {
 			// failed to lower
@@ -97,17 +74,14 @@ func (b *builder) expandFormalParamOffsets(t llvm.Type) []uint64 {
 	}
 }

-// expandFormalParam splits a formal param value into pieces, so it can be
-// passed directly as part of a function call. For example, it splits up small
-// structs into individual fields. It is the equivalent of expandFormalParamType
-// for parameter values.
-func (b *builder) expandFormalParam(v llvm.Value) []llvm.Value {
+// Equivalent of expandFormalParamType for parameter values.
+func (c *Compiler) expandFormalParam(v llvm.Value) []llvm.Value {
 	switch v.Type().TypeKind() {
 	case llvm.StructTypeKind:
-		fieldInfos := flattenAggregateType(v.Type(), "", nil)
-		if len(fieldInfos) <= maxFieldsPerParam {
-			fields := b.flattenAggregate(v)
-			if len(fields) != len(fieldInfos) {
+		fieldTypes := c.flattenAggregateType(v.Type())
+		if len(fieldTypes) <= MaxFieldsPerParam {
+			fields := c.flattenAggregate(v)
+			if len(fields) != len(fieldTypes) {
 				panic("type and value param lowering don't match")
 			}
 			return fields
@@ -123,98 +97,24 @@ func (b *builder) expandFormalParam(v llvm.Value) []llvm.Value {

 // Try to flatten a struct type to a list of types. Returns a 1-element slice
 // with the passed in type if this is not possible.
-func flattenAggregateType(t llvm.Type, name string, goType types.Type) []paramInfo {
-	typeFlags := getTypeFlags(goType)
+func (c *Compiler) flattenAggregateType(t llvm.Type) []llvm.Type {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
-		paramInfos := make([]paramInfo, 0, t.StructElementTypesCount())
-		for i, subfield := range t.StructElementTypes() {
-			suffix := strconv.Itoa(i)
-			if goType != nil {
-				// Try to come up with a good suffix for this struct field,
-				// depending on which Go type it's based on.
-				switch goType := goType.Underlying().(type) {
-				case *types.Interface:
-					suffix = []string{"typecode", "value"}[i]
-				case *types.Slice:
-					suffix = []string{"data", "len", "cap"}[i]
-				case *types.Struct:
-					suffix = goType.Field(i).Name()
-				case *types.Basic:
-					switch goType.Kind() {
-					case types.Complex64, types.Complex128:
-						suffix = []string{"r", "i"}[i]
-					case types.String:
-						suffix = []string{"data", "len"}[i]
-					}
-				case *types.Signature:
-					suffix = []string{"context", "funcptr"}[i]
-				}
-			}
-			subInfos := flattenAggregateType(subfield, name+"."+suffix, extractSubfield(goType, i))
-			for i := range subInfos {
-				subInfos[i].flags |= typeFlags
-			}
-			paramInfos = append(paramInfos, subInfos...)
+		fields := make([]llvm.Type, 0, t.StructElementTypesCount())
+		for _, subfield := range t.StructElementTypes() {
+			subfields := c.flattenAggregateType(subfield)
+			fields = append(fields, subfields...)
 		}
-		return paramInfos
+		return fields
 	default:
-		return []paramInfo{
-			{
-				llvmType: t,
-				name:     name,
-				flags:    typeFlags,
-			},
-		}
+		return []llvm.Type{t}
 	}
 }

-// getTypeFlags returns the type flags for a given type. It will not recurse
-// into sub-types (such as in structs).
-func getTypeFlags(t types.Type) paramFlags {
-	if t == nil {
-		return 0
-	}
-	switch t.Underlying().(type) {
-	case *types.Pointer:
-		// Pointers in Go must either point to an object or be nil.
-		return paramIsDeferenceableOrNull
-	case *types.Chan, *types.Map:
-		// Channels and maps are implemented as pointers pointing to some
-		// object, and follow the same rules as *types.Pointer.
-		return paramIsDeferenceableOrNull
-	default:
-		return 0
-	}
-}
-
-// extractSubfield extracts a field from a struct, or returns null if this is
-// not a struct and thus no subfield can be obtained.
-func extractSubfield(t types.Type, field int) types.Type {
-	if t == nil {
-		return nil
-	}
-	switch t := t.Underlying().(type) {
-	case *types.Struct:
-		return t.Field(field).Type()
-	case *types.Interface, *types.Slice, *types.Basic, *types.Signature:
-		// These Go types are (sometimes) implemented as LLVM structs but can't
-		// really be split further up in Go (with the possible exception of
-		// complex numbers).
-		return nil
-	default:
-		// This should be unreachable.
-		panic("cannot split subfield: " + t.String())
-	}
-}
-
-// flattenAggregateTypeOffset returns the offsets from the start of an object of
-// type t if this object were flattened like in flattenAggregate. Used together
-// with flattenAggregate to know the start indices of each value in the
-// non-flattened object.
-//
-// Note: this is an implementation detail, use expandFormalParamOffsets instead.
-func (c *compilerContext) flattenAggregateTypeOffsets(t llvm.Type) []uint64 {
+// Return the offsets from the start of the object if this object type were
+// flattened like in flattenAggregate. Used together with flattenAggregate to
+// know the start indices of each value in the non-flattened object.
+func (c *Compiler) flattenAggregateTypeOffsets(t llvm.Type) []uint64 {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
 		fields := make([]uint64, 0, t.StructElementTypesCount())
@@ -232,15 +132,15 @@ func (c *compilerContext) flattenAggregateTypeOffsets(t llvm.Type) []uint64 {
 	}
 }

-// flattenAggregate breaks down a struct into its elementary values for argument
-// passing. It is the value equivalent of flattenAggregateType
-func (b *builder) flattenAggregate(v llvm.Value) []llvm.Value {
+// Break down a struct into its elementary types for argument passing. The value
+// equivalent of flattenAggregateType
+func (c *Compiler) flattenAggregate(v llvm.Value) []llvm.Value {
 	switch v.Type().TypeKind() {
 	case llvm.StructTypeKind:
 		fields := make([]llvm.Value, 0, v.Type().StructElementTypesCount())
 		for i := range v.Type().StructElementTypes() {
-			subfield := b.CreateExtractValue(v, i, "")
-			subfields := b.flattenAggregate(subfield)
+			subfield := c.builder.CreateExtractValue(v, i, "")
+			subfields := c.flattenAggregate(subfield)
 			fields = append(fields, subfields...)
 		}
 		return fields
@@ -249,29 +149,25 @@ func (b *builder) flattenAggregate(v llvm.Value) []llvm.Value {
 	}
 }

-// collapseFormalParam combines an aggregate object back into the original
-// value. This is used to join multiple LLVM parameters into a single Go value
-// in the function entry block.
-func (b *builder) collapseFormalParam(t llvm.Type, fields []llvm.Value) llvm.Value {
-	param, remaining := b.collapseFormalParamInternal(t, fields)
+// Collapse a list of fields into its original value.
+func (c *Compiler) collapseFormalParam(t llvm.Type, fields []llvm.Value) llvm.Value {
+	param, remaining := c.collapseFormalParamInternal(t, fields)
 	if len(remaining) != 0 {
 		panic("failed to expand back all fields")
 	}
 	return param
 }

-// collapseFormalParamInternal is an implementation detail of
-// collapseFormalParam: it works by recursing until there are no fields left.
-func (b *builder) collapseFormalParamInternal(t llvm.Type, fields []llvm.Value) (llvm.Value, []llvm.Value) {
+// Returns (value, remainingFields). Used by collapseFormalParam.
+func (c *Compiler) collapseFormalParamInternal(t llvm.Type, fields []llvm.Value) (llvm.Value, []llvm.Value) {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
-		flattened := flattenAggregateType(t, "", nil)
-		if len(flattened) <= maxFieldsPerParam {
-			value := llvm.ConstNull(t)
+		if len(c.flattenAggregateType(t)) <= MaxFieldsPerParam {
+			value := c.getZeroValue(t)
 			for i, subtyp := range t.StructElementTypes() {
-				structField, remaining := b.collapseFormalParamInternal(subtyp, fields)
+				structField, remaining := c.collapseFormalParamInternal(subtyp, fields)
 				fields = remaining
-				value = b.CreateInsertValue(value, structField, i, "")
+				value = c.builder.CreateInsertValue(value, structField, i, "")
 			}
 			return value, fields
 		} else {
@@ -4,86 +4,98 @@ package compiler
 // or pseudo-operations that are lowered during goroutine lowering.

 import (
+	"fmt"
 	"go/types"

-	"github.com/tinygo-org/tinygo/compiler/llvmutil"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )

-func (b *builder) createMakeChan(expr *ssa.MakeChan) llvm.Value {
-	elementSize := b.targetData.TypeAllocSize(b.getLLVMType(expr.Type().(*types.Chan).Elem()))
-	elementSizeValue := llvm.ConstInt(b.uintptrType, elementSize, false)
-	bufSize := b.getValue(expr.Size)
-	b.createChanBoundsCheck(elementSize, bufSize, expr.Size.Type().Underlying().(*types.Basic), expr.Pos())
-	if bufSize.Type().IntTypeWidth() < b.uintptrType.IntTypeWidth() {
-		bufSize = b.CreateZExt(bufSize, b.uintptrType, "")
-	} else if bufSize.Type().IntTypeWidth() > b.uintptrType.IntTypeWidth() {
-		bufSize = b.CreateTrunc(bufSize, b.uintptrType, "")
+// emitMakeChan returns a new channel value for the given channel type.
+func (c *Compiler) emitMakeChan(expr *ssa.MakeChan) (llvm.Value, error) {
+	chanType := c.getLLVMType(expr.Type())
+	size := c.targetData.TypeAllocSize(chanType.ElementType())
+	sizeValue := llvm.ConstInt(c.uintptrType, size, false)
+	ptr := c.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "chan.alloc")
+	ptr = c.builder.CreateBitCast(ptr, chanType, "chan")
+	// Set the elementSize field
+	elementSizePtr := c.builder.CreateGEP(ptr, []llvm.Value{
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+	}, "")
+	elementSize := c.targetData.TypeAllocSize(c.getLLVMType(expr.Type().(*types.Chan).Elem()))
+	if elementSize > 0xffff {
+		return ptr, c.makeError(expr.Pos(), fmt.Sprintf("element size is %d bytes, which is bigger than the maximum of %d bytes", elementSize, 0xffff))
 	}
-	return b.createRuntimeCall("chanMake", []llvm.Value{elementSizeValue, bufSize}, "")
+	elementSizeValue := llvm.ConstInt(c.ctx.Int16Type(), elementSize, false)
+	c.builder.CreateStore(elementSizeValue, elementSizePtr)
+	return ptr, nil
 }

-// createChanSend emits a pseudo chan send operation. It is lowered to the
-// actual channel send operation during goroutine lowering.
-func (b *builder) createChanSend(instr *ssa.Send) {
-	ch := b.getValue(instr.Chan)
-	chanValue := b.getValue(instr.X)
+// emitChanSend emits a pseudo chan send operation. It is lowered to the actual
+// channel send operation during goroutine lowering.
+func (c *Compiler) emitChanSend(frame *Frame, instr *ssa.Send) {
+	ch := c.getValue(frame, instr.Chan)
+	chanValue := c.getValue(frame, instr.X)

 	// store value-to-send
-	valueType := b.getLLVMType(instr.X.Type())
-	valueAlloca, valueAllocaCast, valueAllocaSize := b.createTemporaryAlloca(valueType, "chan.value")
-	b.CreateStore(chanValue, valueAlloca)
+	valueType := c.getLLVMType(instr.X.Type())
+	valueAlloca, valueAllocaCast, valueAllocaSize := c.createTemporaryAlloca(valueType, "chan.value")
+	c.builder.CreateStore(chanValue, valueAlloca)

 	// Do the send.
-	b.createRuntimeCall("chanSend", []llvm.Value{ch, valueAllocaCast}, "")
+	coroutine := c.createRuntimeCall("getCoroutine", nil, "")
+	c.createRuntimeCall("chanSend", []llvm.Value{coroutine, ch, valueAllocaCast}, "")

 	// End the lifetime of the alloca.
 	// This also works around a bug in CoroSplit, at least in LLVM 8:
 	// https://bugs.llvm.org/show_bug.cgi?id=41742
-	b.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)
+	c.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)
 }

-// createChanRecv emits a pseudo chan receive operation. It is lowered to the
+// emitChanRecv emits a pseudo chan receive operation. It is lowered to the
 // actual channel receive operation during goroutine lowering.
-func (b *builder) createChanRecv(unop *ssa.UnOp) llvm.Value {
-	valueType := b.getLLVMType(unop.X.Type().(*types.Chan).Elem())
-	ch := b.getValue(unop.X)
+func (c *Compiler) emitChanRecv(frame *Frame, unop *ssa.UnOp) llvm.Value {
+	valueType := c.getLLVMType(unop.X.Type().(*types.Chan).Elem())
+	ch := c.getValue(frame, unop.X)

 	// Allocate memory to receive into.
-	valueAlloca, valueAllocaCast, valueAllocaSize := b.createTemporaryAlloca(valueType, "chan.value")
+	valueAlloca, valueAllocaCast, valueAllocaSize := c.createTemporaryAlloca(valueType, "chan.value")

 	// Do the receive.
-	commaOk := b.createRuntimeCall("chanRecv", []llvm.Value{ch, valueAllocaCast}, "")
-	received := b.CreateLoad(valueAlloca, "chan.received")
-	b.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)
+	coroutine := c.createRuntimeCall("getCoroutine", nil, "")
+	c.createRuntimeCall("chanRecv", []llvm.Value{coroutine, ch, valueAllocaCast}, "")
+	received := c.builder.CreateLoad(valueAlloca, "chan.received")
+	c.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)

 	if unop.CommaOk {
-		tuple := llvm.Undef(b.ctx.StructType([]llvm.Type{valueType, b.ctx.Int1Type()}, false))
-		tuple = b.CreateInsertValue(tuple, received, 0, "")
-		tuple = b.CreateInsertValue(tuple, commaOk, 1, "")
+		commaOk := c.createRuntimeCall("getTaskStateData", []llvm.Value{coroutine}, "chan.commaOk.wide")
+		commaOk = c.builder.CreateTrunc(commaOk, c.ctx.Int1Type(), "chan.commaOk")
+		tuple := llvm.Undef(c.ctx.StructType([]llvm.Type{valueType, c.ctx.Int1Type()}, false))
+		tuple = c.builder.CreateInsertValue(tuple, received, 0, "")
+		tuple = c.builder.CreateInsertValue(tuple, commaOk, 1, "")
 		return tuple
 	} else {
 		return received
 	}
 }

-// createChanClose closes the given channel.
-func (b *builder) createChanClose(param ssa.Value) {
-	ch := b.getValue(param)
-	b.createRuntimeCall("chanClose", []llvm.Value{ch}, "")
+// emitChanClose closes the given channel.
+func (c *Compiler) emitChanClose(frame *Frame, param ssa.Value) {
+	ch := c.getValue(frame, param)
+	c.createRuntimeCall("chanClose", []llvm.Value{ch}, "")
 }

-// createSelect emits all IR necessary for a select statements. That's a
+// emitSelect emits all IR necessary for a select statements. That's a
 // non-trivial amount of code because select is very complex to implement.
-func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
+func (c *Compiler) emitSelect(frame *Frame, expr *ssa.Select) llvm.Value {
 	if len(expr.States) == 0 {
 		// Shortcuts for some simple selects.
-		llvmType := b.getLLVMType(expr.Type())
+		llvmType := c.getLLVMType(expr.Type())
 		if expr.Blocking {
 			// Blocks forever:
 			//     select {}
-			b.createRuntimeCall("deadlock", nil, "")
+			c.createRuntimeCall("deadlock", nil, "")
 			return llvm.Undef(llvmType)
 		} else {
 			// No-op:
@@ -91,7 +103,7 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 			//     default:
 			//     }
 			retval := llvm.Undef(llvmType)
-			retval = b.CreateInsertValue(retval, llvm.ConstInt(b.intType, 0xffffffffffffffff, true), 0, "")
+			retval = c.builder.CreateInsertValue(retval, llvm.ConstInt(c.intType, 0xffffffffffffffff, true), 0, "")
 			return retval // {-1, false}
 		}
 	}
@@ -109,30 +121,30 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 	recvbufAlign := 0
 	hasReceives := false
 	var selectStates []llvm.Value
-	chanSelectStateType := b.getLLVMRuntimeType("chanSelectState")
+	chanSelectStateType := c.getLLVMRuntimeType("chanSelectState")
 	for _, state := range expr.States {
-		ch := b.getValue(state.Chan)
-		selectState := llvm.ConstNull(chanSelectStateType)
-		selectState = b.CreateInsertValue(selectState, ch, 0, "")
+		ch := c.getValue(frame, state.Chan)
+		selectState := c.getZeroValue(chanSelectStateType)
+		selectState = c.builder.CreateInsertValue(selectState, ch, 0, "")
 		switch state.Dir {
 		case types.RecvOnly:
 			// Make sure the receive buffer is big enough and has the correct alignment.
-			llvmType := b.getLLVMType(state.Chan.Type().(*types.Chan).Elem())
-			if size := b.targetData.TypeAllocSize(llvmType); size > recvbufSize {
+			llvmType := c.getLLVMType(state.Chan.Type().(*types.Chan).Elem())
+			if size := c.targetData.TypeAllocSize(llvmType); size > recvbufSize {
 				recvbufSize = size
 			}
-			if align := b.targetData.ABITypeAlignment(llvmType); align > recvbufAlign {
+			if align := c.targetData.ABITypeAlignment(llvmType); align > recvbufAlign {
 				recvbufAlign = align
 			}
 			hasReceives = true
 		case types.SendOnly:
 			// Store this value in an alloca and put a pointer to this alloca
 			// in the send state.
-			sendValue := b.getValue(state.Send)
-			alloca := llvmutil.CreateEntryBlockAlloca(b.Builder, sendValue.Type(), "select.send.value")
-			b.CreateStore(sendValue, alloca)
-			ptr := b.CreateBitCast(alloca, b.i8ptrType, "")
-			selectState = b.CreateInsertValue(selectState, ptr, 1, "")
+			sendValue := c.getValue(frame, state.Send)
+			alloca := c.createEntryBlockAlloca(sendValue.Type(), "select.send.value")
+			c.builder.CreateStore(sendValue, alloca)
+			ptr := c.builder.CreateBitCast(alloca, c.i8ptrType, "")
+			selectState = c.builder.CreateInsertValue(selectState, ptr, 1, "")
 		default:
 			panic("unreachable")
 		}
@@ -140,74 +152,57 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 	}

 	// Create a receive buffer, where the received value will be stored.
-	recvbuf := llvm.Undef(b.i8ptrType)
+	recvbuf := llvm.Undef(c.i8ptrType)
 	if hasReceives {
-		allocaType := llvm.ArrayType(b.ctx.Int8Type(), int(recvbufSize))
-		recvbufAlloca, _, _ := b.createTemporaryAlloca(allocaType, "select.recvbuf.alloca")
+		allocaType := llvm.ArrayType(c.ctx.Int8Type(), int(recvbufSize))
+		recvbufAlloca := c.builder.CreateAlloca(allocaType, "select.recvbuf.alloca")
 		recvbufAlloca.SetAlignment(recvbufAlign)
-		recvbuf = b.CreateGEP(recvbufAlloca, []llvm.Value{
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
+		recvbuf = c.builder.CreateGEP(recvbufAlloca, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
 		}, "select.recvbuf")
 	}

 	// Create the states slice (allocated on the stack).
 	statesAllocaType := llvm.ArrayType(chanSelectStateType, len(selectStates))
-	statesAlloca, statesI8, statesSize := b.createTemporaryAlloca(statesAllocaType, "select.states.alloca")
+	statesAlloca := c.builder.CreateAlloca(statesAllocaType, "select.states.alloca")
 	for i, state := range selectStates {
 		// Set each slice element to the appropriate channel.
-		gep := b.CreateGEP(statesAlloca, []llvm.Value{
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(b.ctx.Int32Type(), uint64(i), false),
+		gep := c.builder.CreateGEP(statesAlloca, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
 		}, "")
-		b.CreateStore(state, gep)
+		c.builder.CreateStore(state, gep)
 	}
-	statesPtr := b.CreateGEP(statesAlloca, []llvm.Value{
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false),
+	statesPtr := c.builder.CreateGEP(statesAlloca, []llvm.Value{
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
 	}, "select.states")
-	statesLen := llvm.ConstInt(b.uintptrType, uint64(len(selectStates)), false)
+	statesLen := llvm.ConstInt(c.uintptrType, uint64(len(selectStates)), false)
+
+	// Convert the 'blocking' flag on this select into a LLVM value.
+	blockingInt := uint64(0)
+	if expr.Blocking {
+		blockingInt = 1
+	}
+	blockingValue := llvm.ConstInt(c.ctx.Int1Type(), blockingInt, false)

 	// Do the select in the runtime.
-	var results llvm.Value
-	if expr.Blocking {
-		// Stack-allocate operation structures.
-		// If these were simply created as a slice, they would heap-allocate.
-		chBlockAllocaType := llvm.ArrayType(b.getLLVMRuntimeType("channelBlockedList"), len(selectStates))
-		chBlockAlloca, chBlockAllocaPtr, chBlockSize := b.createTemporaryAlloca(chBlockAllocaType, "select.block.alloca")
-		chBlockLen := llvm.ConstInt(b.uintptrType, uint64(len(selectStates)), false)
-		chBlockPtr := b.CreateGEP(chBlockAlloca, []llvm.Value{
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-		}, "select.block")
-
-		results = b.createRuntimeCall("chanSelect", []llvm.Value{
-			recvbuf,
-			statesPtr, statesLen, statesLen, // []chanSelectState
-			chBlockPtr, chBlockLen, chBlockLen, // []channelBlockList
-		}, "select.result")
-
-		// Terminate the lifetime of the operation structures.
-		b.emitLifetimeEnd(chBlockAllocaPtr, chBlockSize)
-	} else {
-		results = b.createRuntimeCall("tryChanSelect", []llvm.Value{
-			recvbuf,
-			statesPtr, statesLen, statesLen, // []chanSelectState
-		}, "select.result")
-	}
-
-	// Terminate the lifetime of the states alloca.
-	b.emitLifetimeEnd(statesI8, statesSize)
+	results := c.createRuntimeCall("chanSelect", []llvm.Value{
+		recvbuf,
+		statesPtr, statesLen, statesLen, // []chanSelectState
+		blockingValue,
+	}, "")

 	// The result value does not include all the possible received values,
 	// because we can't load them in advance. Instead, the *ssa.Extract
 	// instruction will treat a *ssa.Select specially and load it there inline.
 	// Store the receive alloca in a sidetable until we hit this extract
 	// instruction.
-	if b.selectRecvBuf == nil {
-		b.selectRecvBuf = make(map[*ssa.Select]llvm.Value)
+	if frame.selectRecvBuf == nil {
+		frame.selectRecvBuf = make(map[*ssa.Select]llvm.Value)
 	}
-	b.selectRecvBuf[expr] = recvbuf
+	frame.selectRecvBuf[expr] = recvbuf

 	return results
 }
@@ -216,28 +211,28 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 // when extracting a value from a select statement (*ssa.Select). Because
 // *ssa.Select cannot load all values in advance, it does this later in the
 // *ssa.Extract expression.
-func (b *builder) getChanSelectResult(expr *ssa.Extract) llvm.Value {
+func (c *Compiler) getChanSelectResult(frame *Frame, expr *ssa.Extract) llvm.Value {
 	if expr.Index == 0 {
 		// index
-		value := b.getValue(expr.Tuple)
-		index := b.CreateExtractValue(value, expr.Index, "")
-		if index.Type().IntTypeWidth() < b.intType.IntTypeWidth() {
-			index = b.CreateSExt(index, b.intType, "")
+		value := c.getValue(frame, expr.Tuple)
+		index := c.builder.CreateExtractValue(value, expr.Index, "")
+		if index.Type().IntTypeWidth() < c.intType.IntTypeWidth() {
+			index = c.builder.CreateSExt(index, c.intType, "")
 		}
 		return index
 	} else if expr.Index == 1 {
 		// comma-ok
-		value := b.getValue(expr.Tuple)
-		return b.CreateExtractValue(value, expr.Index, "")
+		value := c.getValue(frame, expr.Tuple)
+		return c.builder.CreateExtractValue(value, expr.Index, "")
 	} else {
 		// Select statements are (index, ok, ...) where ... is a number of
 		// received values, depending on how many receive statements there
 		// are. They are all combined into one alloca (because only one
 		// receive can proceed at a time) so we'll get that alloca, bitcast
 		// it to the correct type, and dereference it.
-		recvbuf := b.selectRecvBuf[expr.Tuple.(*ssa.Select)]
-		typ := llvm.PointerType(b.getLLVMType(expr.Type()), 0)
-		ptr := b.CreateBitCast(recvbuf, typ, "")
-		return b.CreateLoad(ptr, "")
+		recvbuf := frame.selectRecvBuf[expr.Tuple.(*ssa.Select)]
+		typ := llvm.PointerType(c.getLLVMType(expr.Type()), 0)
+		ptr := c.builder.CreateBitCast(recvbuf, typ, "")
+		return c.builder.CreateLoad(ptr, "")
 	}
 }
@@ -0,0 +1,121 @@
+package compiler
+
+import (
+	"errors"
+	"fmt"
+
+	"tinygo.org/x/go-llvm"
+)
+
+func (c *Compiler) checkType(t llvm.Type, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) {
+	if t.IsNil() {
+		panic(t)
+	}
+
+	// prevent infinite recursion for self-referential types
+	if _, ok := checked[t]; ok {
+		return
+	}
+	checked[t] = struct{}{}
+
+	// check for any context mismatches
+	switch {
+	case t.Context() == c.ctx:
+		// this is correct
+	case t.Context() == llvm.GlobalContext():
+		// somewhere we accidentally used the global context instead of a real context
+		panic(fmt.Errorf("type %q uses global context", t.String()))
+	default:
+		// we used some other context by accident
+		panic(fmt.Errorf("type %q uses context %v instead of the main context %v", t.Context(), c.ctx))
+	}
+
+	// if this is a composite type, check the components of the type
+	switch t.TypeKind() {
+	case llvm.VoidTypeKind, llvm.LabelTypeKind, llvm.TokenTypeKind, llvm.MetadataTypeKind:
+		// there should only be one of any of these
+		if s, ok := specials[t.TypeKind()]; !ok {
+			specials[t.TypeKind()] = t
+		} else if s != t {
+			panic(fmt.Errorf("duplicate special type %q: %v and %v", t.TypeKind().String(), t, s))
+		}
+	case llvm.FloatTypeKind, llvm.DoubleTypeKind, llvm.X86_FP80TypeKind, llvm.FP128TypeKind, llvm.PPC_FP128TypeKind:
+		// floating point numbers are primitives - nothing to recurse
+	case llvm.IntegerTypeKind:
+		// integers are primitives - nothing to recurse
+	case llvm.FunctionTypeKind:
+		// check arguments and return(s)
+		for _, v := range t.ParamTypes() {
+			c.checkType(v, checked, specials)
+		}
+		c.checkType(t.ReturnType(), checked, specials)
+	case llvm.StructTypeKind:
+		// check all elements
+		for _, v := range t.StructElementTypes() {
+			c.checkType(v, checked, specials)
+		}
+	case llvm.ArrayTypeKind:
+		// check element type
+		c.checkType(t.ElementType(), checked, specials)
+	case llvm.PointerTypeKind:
+		// check underlying type
+		c.checkType(t.ElementType(), checked, specials)
+	case llvm.VectorTypeKind:
+		// check element type
+		c.checkType(t.ElementType(), checked, specials)
+	}
+}
+
+func (c *Compiler) checkValue(v llvm.Value, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) {
+	// check type
+	c.checkType(v.Type(), checked, specials)
+}
+
+func (c *Compiler) checkInstruction(inst llvm.Value, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) {
+	// check value properties
+	c.checkValue(inst, checked, specials)
+}
+
+func (c *Compiler) checkBasicBlock(bb llvm.BasicBlock, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) {
+	// check basic block value and type
+	c.checkValue(bb.AsValue(), checked, specials)
+
+	// check instructions
+	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
+		c.checkInstruction(inst, checked, specials)
+	}
+}
+
+func (c *Compiler) checkFunction(fn llvm.Value, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) {
+	// check function value and type
+	c.checkValue(fn, checked, specials)
+
+	// check basic blocks
+	for bb := fn.FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
+		c.checkBasicBlock(bb, checked, specials)
+	}
+}
+
+func (c *Compiler) check() {
+	// check for any context mismatches
+	switch {
+	case c.mod.Context() == c.ctx:
+		// this is correct
+	case c.mod.Context() == llvm.GlobalContext():
+		// somewhere we accidentally used the global context instead of a real context
+		panic(errors.New("module uses global context"))
+	default:
+		// we used some other context by accident
+		panic(fmt.Errorf("module uses context %v instead of the main context %v", c.mod.Context(), c.ctx))
+	}
+
+	// base of type-check stack
+	checked := map[llvm.Type]struct{}{}
+	specials := map[llvm.TypeKind]llvm.Type{}
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+		c.checkFunction(fn, checked, specials)
+	}
+	for g := c.mod.FirstGlobal(); !g.IsNil(); g = llvm.NextGlobal(g) {
+		c.checkValue(g, checked, specials)
+	}
+}
@@ -14,7 +14,6 @@ package compiler
 //     frames.

 import (
-	"github.com/tinygo-org/tinygo/compiler/llvmutil"
 	"github.com/tinygo-org/tinygo/ir"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
@@ -23,100 +22,65 @@ import (
 // deferInitFunc sets up this function for future deferred calls. It must be
 // called from within the entry block when this function contains deferred
 // calls.
-func (b *builder) deferInitFunc() {
+func (c *Compiler) deferInitFunc(frame *Frame) {
 	// Some setup.
-	b.deferFuncs = make(map[*ir.Function]int)
-	b.deferInvokeFuncs = make(map[string]int)
-	b.deferClosureFuncs = make(map[*ir.Function]int)
+	frame.deferFuncs = make(map[*ir.Function]int)
+	frame.deferInvokeFuncs = make(map[string]int)
+	frame.deferClosureFuncs = make(map[*ir.Function]int)

 	// Create defer list pointer.
-	deferType := llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)
-	b.deferPtr = b.CreateAlloca(deferType, "deferPtr")
-	b.CreateStore(llvm.ConstPointerNull(deferType), b.deferPtr)
+	deferType := llvm.PointerType(c.getLLVMRuntimeType("_defer"), 0)
+	frame.deferPtr = c.builder.CreateAlloca(deferType, "deferPtr")
+	c.builder.CreateStore(llvm.ConstPointerNull(deferType), frame.deferPtr)
 }

-// isInLoop checks if there is a path from a basic block to itself.
-func isInLoop(start *ssa.BasicBlock) bool {
-	// Use a breadth-first search to scan backwards through the block graph.
-	queue := []*ssa.BasicBlock{start}
-	checked := map[*ssa.BasicBlock]struct{}{}
-
-	for len(queue) > 0 {
-		// pop a block off of the queue
-		block := queue[len(queue)-1]
-		queue = queue[:len(queue)-1]
-
-		// Search through predecessors.
-		// Searching backwards means that this is pretty fast when the block is close to the start of the function.
-		// Defers are often placed near the start of the function.
-		for _, pred := range block.Preds {
-			if pred == start {
-				// cycle found
-				return true
-			}
-
-			if _, ok := checked[pred]; ok {
-				// block already checked
-				continue
-			}
-
-			// add to queue and checked map
-			queue = append(queue, pred)
-			checked[pred] = struct{}{}
-		}
-	}
-
-	return false
-}
-
-// createDefer emits a single defer instruction, to be run when this function
+// emitDefer emits a single defer instruction, to be run when this function
 // returns.
-func (b *builder) createDefer(instr *ssa.Defer) {
+func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) {
 	// The pointer to the previous defer struct, which we will replace to
 	// make a linked list.
-	next := b.CreateLoad(b.deferPtr, "defer.next")
+	next := c.builder.CreateLoad(frame.deferPtr, "defer.next")

 	var values []llvm.Value
-	valueTypes := []llvm.Type{b.uintptrType, next.Type()}
+	valueTypes := []llvm.Type{c.uintptrType, next.Type()}
 	if instr.Call.IsInvoke() {
 		// Method call on an interface.

 		// Get callback type number.
 		methodName := instr.Call.Method.FullName()
-		if _, ok := b.deferInvokeFuncs[methodName]; !ok {
-			b.deferInvokeFuncs[methodName] = len(b.allDeferFuncs)
-			b.allDeferFuncs = append(b.allDeferFuncs, &instr.Call)
+		if _, ok := frame.deferInvokeFuncs[methodName]; !ok {
+			frame.deferInvokeFuncs[methodName] = len(frame.allDeferFuncs)
+			frame.allDeferFuncs = append(frame.allDeferFuncs, &instr.Call)
 		}
-		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferInvokeFuncs[methodName]), false)
+		callback := llvm.ConstInt(c.uintptrType, uint64(frame.deferInvokeFuncs[methodName]), false)

 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields, followed by the call parameters).
-		itf := b.getValue(instr.Call.Value) // interface
-		typecode := b.CreateExtractValue(itf, 0, "invoke.func.typecode")
-		receiverValue := b.CreateExtractValue(itf, 1, "invoke.func.receiver")
-		values = []llvm.Value{callback, next, typecode, receiverValue}
-		valueTypes = append(valueTypes, b.uintptrType, b.i8ptrType)
+		itf := c.getValue(frame, instr.Call.Value) // interface
+		receiverValue := c.builder.CreateExtractValue(itf, 1, "invoke.func.receiver")
+		values = []llvm.Value{callback, next, receiverValue}
+		valueTypes = append(valueTypes, c.i8ptrType)
 		for _, arg := range instr.Call.Args {
-			val := b.getValue(arg)
+			val := c.getValue(frame, arg)
 			values = append(values, val)
 			valueTypes = append(valueTypes, val.Type())
 		}

 	} else if callee, ok := instr.Call.Value.(*ssa.Function); ok {
 		// Regular function call.
-		fn := b.ir.GetFunction(callee)
+		fn := c.ir.GetFunction(callee)

-		if _, ok := b.deferFuncs[fn]; !ok {
-			b.deferFuncs[fn] = len(b.allDeferFuncs)
-			b.allDeferFuncs = append(b.allDeferFuncs, fn)
+		if _, ok := frame.deferFuncs[fn]; !ok {
+			frame.deferFuncs[fn] = len(frame.allDeferFuncs)
+			frame.allDeferFuncs = append(frame.allDeferFuncs, fn)
 		}
-		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferFuncs[fn]), false)
+		callback := llvm.ConstInt(c.uintptrType, uint64(frame.deferFuncs[fn]), false)

 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields).
 		values = []llvm.Value{callback, next}
 		for _, param := range instr.Call.Args {
-			llvmParam := b.getValue(param)
+			llvmParam := c.getValue(frame, param)
 			values = append(values, llvmParam)
 			valueTypes = append(valueTypes, llvmParam.Type())
 		}
@@ -128,23 +92,23 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		// pointer.
 		// TODO: ignore this closure entirely and put pointers to the free
 		// variables directly in the defer struct, avoiding a memory allocation.
-		closure := b.getValue(instr.Call.Value)
-		context := b.CreateExtractValue(closure, 0, "")
+		closure := c.getValue(frame, instr.Call.Value)
+		context := c.builder.CreateExtractValue(closure, 0, "")

 		// Get the callback number.
-		fn := b.ir.GetFunction(makeClosure.Fn.(*ssa.Function))
-		if _, ok := b.deferClosureFuncs[fn]; !ok {
-			b.deferClosureFuncs[fn] = len(b.allDeferFuncs)
-			b.allDeferFuncs = append(b.allDeferFuncs, makeClosure)
+		fn := c.ir.GetFunction(makeClosure.Fn.(*ssa.Function))
+		if _, ok := frame.deferClosureFuncs[fn]; !ok {
+			frame.deferClosureFuncs[fn] = len(frame.allDeferFuncs)
+			frame.allDeferFuncs = append(frame.allDeferFuncs, makeClosure)
 		}
-		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferClosureFuncs[fn]), false)
+		callback := llvm.ConstInt(c.uintptrType, uint64(frame.deferClosureFuncs[fn]), false)

 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields, followed by all parameters including the
 		// context pointer).
 		values = []llvm.Value{callback, next}
 		for _, param := range instr.Call.Args {
-			llvmParam := b.getValue(param)
+			llvmParam := c.getValue(frame, param)
 			values = append(values, llvmParam)
 			valueTypes = append(valueTypes, llvmParam.Type())
 		}
@@ -152,41 +116,31 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		valueTypes = append(valueTypes, context.Type())

 	} else {
-		b.addError(instr.Pos(), "todo: defer on uncommon function call type")
+		c.addError(instr.Pos(), "todo: defer on uncommon function call type")
 		return
 	}

 	// Make a struct out of the collected values to put in the defer frame.
-	deferFrameType := b.ctx.StructType(valueTypes, false)
-	deferFrame := llvm.ConstNull(deferFrameType)
+	deferFrameType := c.ctx.StructType(valueTypes, false)
+	deferFrame := c.getZeroValue(deferFrameType)
 	for i, value := range values {
-		deferFrame = b.CreateInsertValue(deferFrame, value, i, "")
+		deferFrame = c.builder.CreateInsertValue(deferFrame, value, i, "")
 	}

-	// Put this struct in an allocation.
-	var alloca llvm.Value
-	if !isInLoop(instr.Block()) {
-		// This can safely use a stack allocation.
-		alloca = llvmutil.CreateEntryBlockAlloca(b.Builder, deferFrameType, "defer.alloca")
-	} else {
-		// This may be hit a variable number of times, so use a heap allocation.
-		size := b.targetData.TypeAllocSize(deferFrameType)
-		sizeValue := llvm.ConstInt(b.uintptrType, size, false)
-		allocCall := b.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "defer.alloc.call")
-		alloca = b.CreateBitCast(allocCall, llvm.PointerType(deferFrameType, 0), "defer.alloc")
+	// Put this struct in an alloca.
+	alloca := c.builder.CreateAlloca(deferFrameType, "defer.alloca")
+	c.builder.CreateStore(deferFrame, alloca)
+	if c.needsStackObjects() {
+		c.trackPointer(alloca)
 	}
-	if b.NeedsStackObjects() {
-		b.trackPointer(alloca)
-	}
-	b.CreateStore(deferFrame, alloca)

 	// Push it on top of the linked list by replacing deferPtr.
-	allocaCast := b.CreateBitCast(alloca, next.Type(), "defer.alloca.cast")
-	b.CreateStore(allocaCast, b.deferPtr)
+	allocaCast := c.builder.CreateBitCast(alloca, next.Type(), "defer.alloca.cast")
+	c.builder.CreateStore(allocaCast, frame.deferPtr)
 }

-// createRunDefers emits code to run all deferred functions.
-func (b *builder) createRunDefers() {
+// emitRunDefers emits code to run all deferred functions.
+func (c *Compiler) emitRunDefers(frame *Frame) {
 	// Add a loop like the following:
 	//     for stack != nil {
 	//         _stack := stack
@@ -203,44 +157,44 @@ func (b *builder) createRunDefers() {
 	//     }

 	// Create loop.
-	loophead := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.loophead")
-	loop := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.loop")
-	unreachable := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.default")
-	end := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.end")
-	b.CreateBr(loophead)
+	loophead := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "rundefers.loophead")
+	loop := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "rundefers.loop")
+	unreachable := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "rundefers.default")
+	end := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "rundefers.end")
+	c.builder.CreateBr(loophead)

 	// Create loop head:
 	//     for stack != nil {
-	b.SetInsertPointAtEnd(loophead)
-	deferData := b.CreateLoad(b.deferPtr, "")
-	stackIsNil := b.CreateICmp(llvm.IntEQ, deferData, llvm.ConstPointerNull(deferData.Type()), "stackIsNil")
-	b.CreateCondBr(stackIsNil, end, loop)
+	c.builder.SetInsertPointAtEnd(loophead)
+	deferData := c.builder.CreateLoad(frame.deferPtr, "")
+	stackIsNil := c.builder.CreateICmp(llvm.IntEQ, deferData, llvm.ConstPointerNull(deferData.Type()), "stackIsNil")
+	c.builder.CreateCondBr(stackIsNil, end, loop)

 	// Create loop body:
 	//     _stack := stack
 	//     stack = stack.next
 	//     switch stack.callback {
-	b.SetInsertPointAtEnd(loop)
-	nextStackGEP := b.CreateInBoundsGEP(deferData, []llvm.Value{
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-		llvm.ConstInt(b.ctx.Int32Type(), 1, false), // .next field
+	c.builder.SetInsertPointAtEnd(loop)
+	nextStackGEP := c.builder.CreateInBoundsGEP(deferData, []llvm.Value{
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		llvm.ConstInt(c.ctx.Int32Type(), 1, false), // .next field
 	}, "stack.next.gep")
-	nextStack := b.CreateLoad(nextStackGEP, "stack.next")
-	b.CreateStore(nextStack, b.deferPtr)
-	gep := b.CreateInBoundsGEP(deferData, []llvm.Value{
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false), // .callback field
+	nextStack := c.builder.CreateLoad(nextStackGEP, "stack.next")
+	c.builder.CreateStore(nextStack, frame.deferPtr)
+	gep := c.builder.CreateInBoundsGEP(deferData, []llvm.Value{
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false), // .callback field
 	}, "callback.gep")
-	callback := b.CreateLoad(gep, "callback")
-	sw := b.CreateSwitch(callback, unreachable, len(b.allDeferFuncs))
+	callback := c.builder.CreateLoad(gep, "callback")
+	sw := c.builder.CreateSwitch(callback, unreachable, len(frame.allDeferFuncs))

-	for i, callback := range b.allDeferFuncs {
+	for i, callback := range frame.allDeferFuncs {
 		// Create switch case, for example:
 		//     case 0:
 		//         // run first deferred call
-		block := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.callback")
-		sw.AddCase(llvm.ConstInt(b.uintptrType, uint64(i), false), block)
-		b.SetInsertPointAtEnd(block)
+		block := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "rundefers.callback")
+		sw.AddCase(llvm.ConstInt(c.uintptrType, uint64(i), false), block)
+		c.builder.SetInsertPointAtEnd(block)
 		switch callback := callback.(type) {
 		case *ssa.CallCommon:
 			// Call on an interface value.
@@ -249,112 +203,105 @@ func (b *builder) createRunDefers() {
 			}

 			// Get the real defer struct type and cast to it.
-			valueTypes := []llvm.Type{b.uintptrType, llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0), b.uintptrType, b.i8ptrType}
+			valueTypes := []llvm.Type{c.uintptrType, llvm.PointerType(c.getLLVMRuntimeType("_defer"), 0), c.i8ptrType}
 			for _, arg := range callback.Args {
-				valueTypes = append(valueTypes, b.getLLVMType(arg.Type()))
+				valueTypes = append(valueTypes, c.getLLVMType(arg.Type()))
 			}
-			deferFrameType := b.ctx.StructType(valueTypes, false)
-			deferFramePtr := b.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")
+			deferFrameType := c.ctx.StructType(valueTypes, false)
+			deferFramePtr := c.builder.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")

 			// Extract the params from the struct (including receiver).
 			forwardParams := []llvm.Value{}
-			zero := llvm.ConstInt(b.ctx.Int32Type(), 0, false)
+			zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 			for i := 2; i < len(valueTypes); i++ {
-				gep := b.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(b.ctx.Int32Type(), uint64(i), false)}, "gep")
-				forwardParam := b.CreateLoad(gep, "param")
+				gep := c.builder.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false)}, "gep")
+				forwardParam := c.builder.CreateLoad(gep, "param")
 				forwardParams = append(forwardParams, forwardParam)
 			}

-			// Isolate the typecode.
-			typecode, forwardParams := forwardParams[0], forwardParams[1:]
-
 			// Add the context parameter. An interface call cannot also be a
 			// closure but we have to supply the parameter anyway for platforms
 			// with a strict calling convention.
-			forwardParams = append(forwardParams, llvm.Undef(b.i8ptrType))
+			forwardParams = append(forwardParams, llvm.Undef(c.i8ptrType))

 			// Parent coroutine handle.
-			forwardParams = append(forwardParams, llvm.Undef(b.i8ptrType))
+			forwardParams = append(forwardParams, llvm.Undef(c.i8ptrType))

-			fnPtr := b.getInvokePtr(callback, typecode)
-			b.createCall(fnPtr, forwardParams, "")
+			fnPtr, _ := c.getInvokeCall(frame, callback)
+			c.createCall(fnPtr, forwardParams, "")

 		case *ir.Function:
 			// Direct call.

 			// Get the real defer struct type and cast to it.
-			valueTypes := []llvm.Type{b.uintptrType, llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)}
+			valueTypes := []llvm.Type{c.uintptrType, llvm.PointerType(c.getLLVMRuntimeType("_defer"), 0)}
 			for _, param := range callback.Params {
-				valueTypes = append(valueTypes, b.getLLVMType(param.Type()))
+				valueTypes = append(valueTypes, c.getLLVMType(param.Type()))
 			}
-			deferFrameType := b.ctx.StructType(valueTypes, false)
-			deferFramePtr := b.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")
+			deferFrameType := c.ctx.StructType(valueTypes, false)
+			deferFramePtr := c.builder.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")

 			// Extract the params from the struct.
 			forwardParams := []llvm.Value{}
-			zero := llvm.ConstInt(b.ctx.Int32Type(), 0, false)
+			zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 			for i := range callback.Params {
-				gep := b.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(b.ctx.Int32Type(), uint64(i+2), false)}, "gep")
-				forwardParam := b.CreateLoad(gep, "param")
+				gep := c.builder.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i+2), false)}, "gep")
+				forwardParam := c.builder.CreateLoad(gep, "param")
 				forwardParams = append(forwardParams, forwardParam)
 			}

-			// Plain TinyGo functions add some extra parameters to implement async functionality and function recievers.
-			// These parameters should not be supplied when calling into an external C/ASM function.
-			if !callback.IsExported() {
-				// Add the context parameter. We know it is ignored by the receiving
-				// function, but we have to pass one anyway.
-				forwardParams = append(forwardParams, llvm.Undef(b.i8ptrType))
+			// Add the context parameter. We know it is ignored by the receiving
+			// function, but we have to pass one anyway.
+			forwardParams = append(forwardParams, llvm.Undef(c.i8ptrType))

-				// Parent coroutine handle.
-				forwardParams = append(forwardParams, llvm.Undef(b.i8ptrType))
-			}
+			// Parent coroutine handle.
+			forwardParams = append(forwardParams, llvm.Undef(c.i8ptrType))

 			// Call real function.
-			b.createCall(callback.LLVMFn, forwardParams, "")
+			c.createCall(callback.LLVMFn, forwardParams, "")

 		case *ssa.MakeClosure:
 			// Get the real defer struct type and cast to it.
-			fn := b.ir.GetFunction(callback.Fn.(*ssa.Function))
-			valueTypes := []llvm.Type{b.uintptrType, llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)}
+			fn := c.ir.GetFunction(callback.Fn.(*ssa.Function))
+			valueTypes := []llvm.Type{c.uintptrType, llvm.PointerType(c.getLLVMRuntimeType("_defer"), 0)}
 			params := fn.Signature.Params()
 			for i := 0; i < params.Len(); i++ {
-				valueTypes = append(valueTypes, b.getLLVMType(params.At(i).Type()))
+				valueTypes = append(valueTypes, c.getLLVMType(params.At(i).Type()))
 			}
-			valueTypes = append(valueTypes, b.i8ptrType) // closure
-			deferFrameType := b.ctx.StructType(valueTypes, false)
-			deferFramePtr := b.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")
+			valueTypes = append(valueTypes, c.i8ptrType) // closure
+			deferFrameType := c.ctx.StructType(valueTypes, false)
+			deferFramePtr := c.builder.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")

 			// Extract the params from the struct.
 			forwardParams := []llvm.Value{}
-			zero := llvm.ConstInt(b.ctx.Int32Type(), 0, false)
+			zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 			for i := 2; i < len(valueTypes); i++ {
-				gep := b.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(b.ctx.Int32Type(), uint64(i), false)}, "")
-				forwardParam := b.CreateLoad(gep, "param")
+				gep := c.builder.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false)}, "")
+				forwardParam := c.builder.CreateLoad(gep, "param")
 				forwardParams = append(forwardParams, forwardParam)
 			}

 			// Parent coroutine handle.
-			forwardParams = append(forwardParams, llvm.Undef(b.i8ptrType))
+			forwardParams = append(forwardParams, llvm.Undef(c.i8ptrType))

 			// Call deferred function.
-			b.createCall(fn.LLVMFn, forwardParams, "")
+			c.createCall(fn.LLVMFn, forwardParams, "")

 		default:
 			panic("unknown deferred function type")
 		}

 		// Branch back to the start of the loop.
-		b.CreateBr(loophead)
+		c.builder.CreateBr(loophead)
 	}

 	// Create default unreachable block:
 	//     default:
 	//         unreachable
 	//     }
-	b.SetInsertPointAtEnd(unreachable)
-	b.CreateUnreachable()
+	c.builder.SetInsertPointAtEnd(unreachable)
+	c.builder.CreateUnreachable()

 	// End of loop.
-	b.SetInsertPointAtEnd(end)
+	c.builder.SetInsertPointAtEnd(end)
 }
@@ -1,18 +1,11 @@
 package compiler

-// This file contains some utility functions related to error handling.
-
 import (
-	"go/scanner"
 	"go/token"
 	"go/types"
-	"path/filepath"
-
-	"tinygo.org/x/go-llvm"
 )

-// makeError makes it easy to create an error from a token.Pos with a message.
-func (c *compilerContext) makeError(pos token.Pos, msg string) types.Error {
+func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
 	return types.Error{
 		Fset: c.ir.Program.Fset,
 		Pos:  pos,
@@ -20,45 +13,6 @@ func (c *compilerContext) makeError(pos token.Pos, msg string) types.Error {
 	}
 }

-func (c *compilerContext) addError(pos token.Pos, msg string) {
+func (c *Compiler) addError(pos token.Pos, msg string) {
 	c.diagnostics = append(c.diagnostics, c.makeError(pos, msg))
 }
-
-// errorAt returns an error value at the location of the instruction.
-// The location information may not be complete as it depends on debug
-// information in the IR.
-func errorAt(inst llvm.Value, msg string) scanner.Error {
-	return scanner.Error{
-		Pos: getPosition(inst),
-		Msg: msg,
-	}
-}
-
-// getPosition returns the position information for the given value, as far as
-// it is available.
-func getPosition(val llvm.Value) token.Position {
-	if !val.IsAInstruction().IsNil() {
-		loc := val.InstructionDebugLoc()
-		if loc.IsNil() {
-			return token.Position{}
-		}
-		file := loc.LocationScope().ScopeFile()
-		return token.Position{
-			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-			Line:     int(loc.LocationLine()),
-			Column:   int(loc.LocationColumn()),
-		}
-	} else if !val.IsAFunction().IsNil() {
-		loc := val.Subprogram()
-		if loc.IsNil() {
-			return token.Position{}
-		}
-		file := loc.ScopeFile()
-		return token.Position{
-			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-			Line:     int(loc.SubprogramLine()),
-		}
-	} else {
-		return token.Position{}
-	}
-}
@@ -0,0 +1,285 @@
+package compiler
+
+// This file lowers func values into their final form. This is necessary for
+// funcValueSwitch, which needs full program analysis.
+
+import (
+	"sort"
+	"strconv"
+
+	"tinygo.org/x/go-llvm"
+)
+
+// funcSignatureInfo keeps information about a single signature and its uses.
+type funcSignatureInfo struct {
+	sig                     llvm.Value   // *uint8 to identify the signature
+	funcValueWithSignatures []llvm.Value // slice of runtime.funcValueWithSignature
+}
+
+// funcWithUses keeps information about a single function used as func value and
+// the assigned function ID. More commonly used functions are assigned a lower
+// ID.
+type funcWithUses struct {
+	funcPtr  llvm.Value
+	useCount int // how often this function is used in a func value
+	id       int // assigned ID
+}
+
+// Slice to sort functions by their use counts, or else their name if they're
+// used equally often.
+type funcWithUsesList []*funcWithUses
+
+func (l funcWithUsesList) Len() int { return len(l) }
+func (l funcWithUsesList) Less(i, j int) bool {
+	if l[i].useCount != l[j].useCount {
+		// return the reverse: we want the highest use counts sorted first
+		return l[i].useCount > l[j].useCount
+	}
+	iName := l[i].funcPtr.Name()
+	jName := l[j].funcPtr.Name()
+	return iName < jName
+}
+func (l funcWithUsesList) Swap(i, j int) {
+	l[i], l[j] = l[j], l[i]
+}
+
+// LowerFuncValue lowers the runtime.funcValueWithSignature type and
+// runtime.getFuncPtr function to their final form.
+func (c *Compiler) LowerFuncValues() {
+	if c.funcImplementation() != funcValueSwitch {
+		return
+	}
+
+	// Find all func values used in the program with their signatures.
+	funcValueWithSignaturePtr := llvm.PointerType(c.getLLVMRuntimeType("funcValueWithSignature"), 0)
+	signatures := map[string]*funcSignatureInfo{}
+	for global := c.mod.FirstGlobal(); !global.IsNil(); global = llvm.NextGlobal(global) {
+		if global.Type() != funcValueWithSignaturePtr {
+			continue
+		}
+		sig := llvm.ConstExtractValue(global.Initializer(), []uint32{1})
+		name := sig.Name()
+		if info, ok := signatures[name]; ok {
+			info.funcValueWithSignatures = append(info.funcValueWithSignatures, global)
+		} else {
+			signatures[name] = &funcSignatureInfo{
+				sig:                     sig,
+				funcValueWithSignatures: []llvm.Value{global},
+			}
+		}
+	}
+
+	// Sort the signatures, for deterministic execution.
+	names := make([]string, 0, len(signatures))
+	for name := range signatures {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+
+	for _, name := range names {
+		info := signatures[name]
+		functions := make(funcWithUsesList, len(info.funcValueWithSignatures))
+		for i, use := range info.funcValueWithSignatures {
+			var useCount int
+			for _, use2 := range getUses(use) {
+				useCount += len(getUses(use2))
+			}
+			functions[i] = &funcWithUses{
+				funcPtr:  llvm.ConstExtractValue(use.Initializer(), []uint32{0}).Operand(0),
+				useCount: useCount,
+			}
+		}
+		sort.Sort(functions)
+
+		for i, fn := range functions {
+			fn.id = i + 1
+			for _, ptrtoint := range getUses(fn.funcPtr) {
+				if ptrtoint.IsAConstantExpr().IsNil() || ptrtoint.Opcode() != llvm.PtrToInt {
+					continue
+				}
+				for _, funcValueWithSignatureConstant := range getUses(ptrtoint) {
+					for _, funcValueWithSignatureGlobal := range getUses(funcValueWithSignatureConstant) {
+						for _, use := range getUses(funcValueWithSignatureGlobal) {
+							if ptrtoint.IsAConstantExpr().IsNil() || ptrtoint.Opcode() != llvm.PtrToInt {
+								panic("expected const ptrtoint")
+							}
+							use.ReplaceAllUsesWith(llvm.ConstInt(c.uintptrType, uint64(fn.id), false))
+						}
+					}
+				}
+			}
+		}
+
+		for _, getFuncPtrCall := range getUses(info.sig) {
+			if getFuncPtrCall.IsACallInst().IsNil() {
+				continue
+			}
+			if getFuncPtrCall.CalledValue().Name() != "runtime.getFuncPtr" {
+				panic("expected all call uses to be runtime.getFuncPtr")
+			}
+			funcID := getFuncPtrCall.Operand(1)
+			switch len(functions) {
+			case 0:
+				// There are no functions used in a func value that implement
+				// this signature. The only possible value is a nil value.
+				for _, inttoptr := range getUses(getFuncPtrCall) {
+					if inttoptr.IsAIntToPtrInst().IsNil() {
+						panic("expected inttoptr")
+					}
+					nilptr := llvm.ConstPointerNull(inttoptr.Type())
+					inttoptr.ReplaceAllUsesWith(nilptr)
+					inttoptr.EraseFromParentAsInstruction()
+				}
+				getFuncPtrCall.EraseFromParentAsInstruction()
+			case 1:
+				// There is exactly one function with this signature that is
+				// used in a func value. The func value itself can be either nil
+				// or this one function.
+				c.builder.SetInsertPointBefore(getFuncPtrCall)
+				zero := llvm.ConstInt(c.uintptrType, 0, false)
+				isnil := c.builder.CreateICmp(llvm.IntEQ, funcID, zero, "")
+				funcPtrNil := llvm.ConstPointerNull(functions[0].funcPtr.Type())
+				funcPtr := c.builder.CreateSelect(isnil, funcPtrNil, functions[0].funcPtr, "")
+				for _, inttoptr := range getUses(getFuncPtrCall) {
+					if inttoptr.IsAIntToPtrInst().IsNil() {
+						panic("expected inttoptr")
+					}
+					inttoptr.ReplaceAllUsesWith(funcPtr)
+					inttoptr.EraseFromParentAsInstruction()
+				}
+				getFuncPtrCall.EraseFromParentAsInstruction()
+			default:
+				// There are multiple functions used in a func value that
+				// implement this signature.
+				// What we'll do is transform the following:
+				//     rawPtr := runtime.getFuncPtr(func.ptr)
+				//     if rawPtr == nil {
+				//         runtime.nilPanic()
+				//     }
+				//     result := rawPtr(...args, func.context)
+				// into this:
+				//     if false {
+				//         runtime.nilPanic()
+				//     }
+				//     var result // Phi
+				//     switch fn.id {
+				//     case 0:
+				//         runtime.nilPanic()
+				//     case 1:
+				//         result = call first implementation...
+				//     case 2:
+				//         result = call second implementation...
+				//     default:
+				//         unreachable
+				//     }
+
+				// Remove some casts, checks, and the old call which we're going
+				// to replace.
+				for _, callIntPtr := range getUses(getFuncPtrCall) {
+					if !callIntPtr.IsACallInst().IsNil() && callIntPtr.CalledValue().Name() == "runtime.makeGoroutine" {
+						for _, inttoptr := range getUses(callIntPtr) {
+							if inttoptr.IsAIntToPtrInst().IsNil() {
+								panic("expected a inttoptr")
+							}
+							for _, use := range getUses(inttoptr) {
+								c.addFuncLoweringSwitch(funcID, use, c.emitStartGoroutine, functions)
+								use.EraseFromParentAsInstruction()
+							}
+							inttoptr.EraseFromParentAsInstruction()
+						}
+						callIntPtr.EraseFromParentAsInstruction()
+						continue
+					}
+					if callIntPtr.IsAIntToPtrInst().IsNil() {
+						panic("expected inttoptr")
+					}
+					for _, ptrUse := range getUses(callIntPtr) {
+						if !ptrUse.IsABitCastInst().IsNil() {
+							for _, bitcastUse := range getUses(ptrUse) {
+								if bitcastUse.IsACallInst().IsNil() || bitcastUse.CalledValue().IsAFunction().IsNil() {
+									panic("expected a call instruction")
+								}
+								switch bitcastUse.CalledValue().Name() {
+								case "runtime.isnil":
+									bitcastUse.ReplaceAllUsesWith(llvm.ConstInt(c.ctx.Int1Type(), 0, false))
+									bitcastUse.EraseFromParentAsInstruction()
+								default:
+									panic("expected a call to runtime.isnil")
+								}
+							}
+						} else if !ptrUse.IsACallInst().IsNil() && ptrUse.CalledValue() == callIntPtr {
+							c.addFuncLoweringSwitch(funcID, ptrUse, func(funcPtr llvm.Value, params []llvm.Value) llvm.Value {
+								return c.builder.CreateCall(funcPtr, params, "")
+							}, functions)
+						} else {
+							panic("unexpected getFuncPtrCall")
+						}
+						ptrUse.EraseFromParentAsInstruction()
+					}
+					callIntPtr.EraseFromParentAsInstruction()
+				}
+				getFuncPtrCall.EraseFromParentAsInstruction()
+			}
+		}
+	}
+}
+
+// addFuncLoweringSwitch creates a new switch on a function ID and inserts calls
+// to the newly created direct calls. The funcID is the number to switch on,
+// call is the call instruction to replace, and createCall is the callback that
+// actually creates the new call. By changing createCall to something other than
+// c.builder.CreateCall, instead of calling a function it can start a new
+// goroutine for example.
+func (c *Compiler) addFuncLoweringSwitch(funcID, call llvm.Value, createCall func(funcPtr llvm.Value, params []llvm.Value) llvm.Value, functions funcWithUsesList) {
+	// The block that cannot be reached with correct funcValues (to help the
+	// optimizer).
+	c.builder.SetInsertPointBefore(call)
+	defaultBlock := c.ctx.AddBasicBlock(call.InstructionParent().Parent(), "func.default")
+	c.builder.SetInsertPointAtEnd(defaultBlock)
+	c.builder.CreateUnreachable()
+
+	// Create the switch.
+	c.builder.SetInsertPointBefore(call)
+	sw := c.builder.CreateSwitch(funcID, defaultBlock, len(functions)+1)
+
+	// Split right after the switch. We will need to insert a few basic blocks
+	// in this gap.
+	nextBlock := c.splitBasicBlock(sw, llvm.NextBasicBlock(sw.InstructionParent()), "func.next")
+
+	// The 0 case, which is actually a nil check.
+	nilBlock := c.ctx.InsertBasicBlock(nextBlock, "func.nil")
+	c.builder.SetInsertPointAtEnd(nilBlock)
+	c.createRuntimeCall("nilPanic", nil, "")
+	c.builder.CreateUnreachable()
+	sw.AddCase(llvm.ConstInt(c.uintptrType, 0, false), nilBlock)
+
+	// Gather the list of parameters for every call we're going to make.
+	callParams := make([]llvm.Value, call.OperandsCount()-1)
+	for i := range callParams {
+		callParams[i] = call.Operand(i)
+	}
+
+	// If the call produces a value, we need to get it using a PHI
+	// node.
+	phiBlocks := make([]llvm.BasicBlock, len(functions))
+	phiValues := make([]llvm.Value, len(functions))
+	for i, fn := range functions {
+		// Insert a switch case.
+		bb := c.ctx.InsertBasicBlock(nextBlock, "func.call"+strconv.Itoa(fn.id))
+		c.builder.SetInsertPointAtEnd(bb)
+		result := createCall(fn.funcPtr, callParams)
+		c.builder.CreateBr(nextBlock)
+		sw.AddCase(llvm.ConstInt(c.uintptrType, uint64(fn.id), false), bb)
+		phiBlocks[i] = bb
+		phiValues[i] = result
+	}
+	// Create the PHI node so that the call result flows into the
+	// next block (after the split). This is only necessary when the
+	// call produced a value.
+	if call.Type().TypeKind() != llvm.VoidTypeKind {
+		c.builder.SetInsertPointBefore(nextBlock.FirstInstruction())
+		phi := c.builder.CreatePHI(call.Type(), "")
+		phi.AddIncoming(phiValues, phiBlocks)
+		call.ReplaceAllUsesWith(phi)
+	}
+}
@@ -6,26 +6,53 @@ package compiler
 import (
 	"go/types"

-	"github.com/tinygo-org/tinygo/compileopts"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )

-// createFuncValue creates a function value from a raw function pointer with no
-// context.
-func (b *builder) createFuncValue(funcPtr, context llvm.Value, sig *types.Signature) llvm.Value {
-	return b.compilerContext.createFuncValue(b.Builder, funcPtr, context, sig)
+type funcValueImplementation int
+
+const (
+	funcValueNone funcValueImplementation = iota
+
+	// A func value is implemented as a pair of pointers:
+	//     {context, function pointer}
+	// where the context may be a pointer to a heap-allocated struct containing
+	// the free variables, or it may be undef if the function being pointed to
+	// doesn't need a context. The function pointer is a regular function
+	// pointer.
+	funcValueDoubleword
+
+	// As funcValueDoubleword, but with the function pointer replaced by a
+	// unique ID per function signature. Function values are called by using a
+	// switch statement and choosing which function to call.
+	funcValueSwitch
+)
+
+// funcImplementation picks an appropriate func value implementation for the
+// target.
+func (c *Compiler) funcImplementation() funcValueImplementation {
+	// Always pick the switch implementation, as it allows the use of blocking
+	// inside a function that is used as a func value.
+	switch c.selectScheduler() {
+	case "coroutines":
+		return funcValueSwitch
+	case "tasks":
+		return funcValueDoubleword
+	default:
+		panic("unknown scheduler type")
+	}
 }

 // createFuncValue creates a function value from a raw function pointer with no
 // context.
-func (c *compilerContext) createFuncValue(builder llvm.Builder, funcPtr, context llvm.Value, sig *types.Signature) llvm.Value {
+func (c *Compiler) createFuncValue(funcPtr, context llvm.Value, sig *types.Signature) llvm.Value {
 	var funcValueScalar llvm.Value
-	switch c.FuncImplementation() {
-	case compileopts.FuncValueDoubleword:
+	switch c.funcImplementation() {
+	case funcValueDoubleword:
 		// Closure is: {context, function pointer}
 		funcValueScalar = funcPtr
-	case compileopts.FuncValueSwitch:
+	case funcValueSwitch:
 		sigGlobal := c.getTypeCode(sig)
 		funcValueWithSignatureGlobalName := funcPtr.Name() + "$withSignature"
 		funcValueWithSignatureGlobal := c.mod.NamedGlobal(funcValueWithSignatureGlobalName)
@@ -46,35 +73,35 @@ func (c *compilerContext) createFuncValue(builder llvm.Builder, funcPtr, context
 	}
 	funcValueType := c.getFuncType(sig)
 	funcValue := llvm.Undef(funcValueType)
-	funcValue = builder.CreateInsertValue(funcValue, context, 0, "")
-	funcValue = builder.CreateInsertValue(funcValue, funcValueScalar, 1, "")
+	funcValue = c.builder.CreateInsertValue(funcValue, context, 0, "")
+	funcValue = c.builder.CreateInsertValue(funcValue, funcValueScalar, 1, "")
 	return funcValue
 }

 // extractFuncScalar returns some scalar that can be used in comparisons. It is
 // a cheap operation.
-func (b *builder) extractFuncScalar(funcValue llvm.Value) llvm.Value {
-	return b.CreateExtractValue(funcValue, 1, "")
+func (c *Compiler) extractFuncScalar(funcValue llvm.Value) llvm.Value {
+	return c.builder.CreateExtractValue(funcValue, 1, "")
 }

 // extractFuncContext extracts the context pointer from this function value. It
 // is a cheap operation.
-func (b *builder) extractFuncContext(funcValue llvm.Value) llvm.Value {
-	return b.CreateExtractValue(funcValue, 0, "")
+func (c *Compiler) extractFuncContext(funcValue llvm.Value) llvm.Value {
+	return c.builder.CreateExtractValue(funcValue, 0, "")
 }

 // decodeFuncValue extracts the context and the function pointer from this func
 // value. This may be an expensive operation.
-func (b *builder) decodeFuncValue(funcValue llvm.Value, sig *types.Signature) (funcPtr, context llvm.Value) {
-	context = b.CreateExtractValue(funcValue, 0, "")
-	switch b.FuncImplementation() {
-	case compileopts.FuncValueDoubleword:
-		funcPtr = b.CreateExtractValue(funcValue, 1, "")
-	case compileopts.FuncValueSwitch:
-		llvmSig := b.getRawFuncType(sig)
-		sigGlobal := b.getTypeCode(sig)
-		funcPtr = b.createRuntimeCall("getFuncPtr", []llvm.Value{funcValue, sigGlobal}, "")
-		funcPtr = b.CreateIntToPtr(funcPtr, llvmSig, "")
+func (c *Compiler) decodeFuncValue(funcValue llvm.Value, sig *types.Signature) (funcPtr, context llvm.Value) {
+	context = c.builder.CreateExtractValue(funcValue, 0, "")
+	switch c.funcImplementation() {
+	case funcValueDoubleword:
+		funcPtr = c.builder.CreateExtractValue(funcValue, 1, "")
+	case funcValueSwitch:
+		llvmSig := c.getRawFuncType(sig)
+		sigGlobal := c.getTypeCode(sig)
+		funcPtr = c.createRuntimeCall("getFuncPtr", []llvm.Value{funcValue, sigGlobal}, "")
+		funcPtr = c.builder.CreateIntToPtr(funcPtr, llvmSig, "")
 	default:
 		panic("unimplemented func value variant")
 	}
@@ -82,12 +109,12 @@ func (b *builder) decodeFuncValue(funcValue llvm.Value, sig *types.Signature) (f
 }

 // getFuncType returns the type of a func value given a signature.
-func (c *compilerContext) getFuncType(typ *types.Signature) llvm.Type {
-	switch c.FuncImplementation() {
-	case compileopts.FuncValueDoubleword:
+func (c *Compiler) getFuncType(typ *types.Signature) llvm.Type {
+	switch c.funcImplementation() {
+	case funcValueDoubleword:
 		rawPtr := c.getRawFuncType(typ)
 		return c.ctx.StructType([]llvm.Type{c.i8ptrType, rawPtr}, false)
-	case compileopts.FuncValueSwitch:
+	case funcValueSwitch:
 		return c.getLLVMRuntimeType("funcValue")
 	default:
 		panic("unimplemented func value variant")
@@ -95,7 +122,7 @@ func (c *compilerContext) getFuncType(typ *types.Signature) llvm.Type {
 }

 // getRawFuncType returns a LLVM function pointer type for a given signature.
-func (c *compilerContext) getRawFuncType(typ *types.Signature) llvm.Type {
+func (c *Compiler) getRawFuncType(typ *types.Signature) llvm.Type {
 	// Get the return type.
 	var returnType llvm.Type
 	switch typ.Results().Len() {
@@ -125,15 +152,11 @@ func (c *compilerContext) getRawFuncType(typ *types.Signature) llvm.Type {
 			// The receiver is not an interface, but a i8* type.
 			recv = c.i8ptrType
 		}
-		for _, info := range expandFormalParamType(recv, "", nil) {
-			paramTypes = append(paramTypes, info.llvmType)
-		}
+		paramTypes = append(paramTypes, c.expandFormalParamType(recv)...)
 	}
 	for i := 0; i < typ.Params().Len(); i++ {
 		subType := c.getLLVMType(typ.Params().At(i).Type())
-		for _, info := range expandFormalParamType(subType, "", nil) {
-			paramTypes = append(paramTypes, info.llvmType)
-		}
+		paramTypes = append(paramTypes, c.expandFormalParamType(subType)...)
 	}
 	// All functions take these parameters at the end.
 	paramTypes = append(paramTypes, c.i8ptrType) // context
@@ -145,24 +168,24 @@ func (c *compilerContext) getRawFuncType(typ *types.Signature) llvm.Type {

 // parseMakeClosure makes a function value (with context) from the given
 // closure expression.
-func (b *builder) parseMakeClosure(expr *ssa.MakeClosure) (llvm.Value, error) {
+func (c *Compiler) parseMakeClosure(frame *Frame, expr *ssa.MakeClosure) (llvm.Value, error) {
 	if len(expr.Bindings) == 0 {
 		panic("unexpected: MakeClosure without bound variables")
 	}
-	f := b.ir.GetFunction(expr.Fn.(*ssa.Function))
+	f := c.ir.GetFunction(expr.Fn.(*ssa.Function))

 	// Collect all bound variables.
 	boundVars := make([]llvm.Value, len(expr.Bindings))
 	for i, binding := range expr.Bindings {
 		// The context stores the bound variables.
-		llvmBoundVar := b.getValue(binding)
+		llvmBoundVar := c.getValue(frame, binding)
 		boundVars[i] = llvmBoundVar
 	}

 	// Store the bound variables in a single object, allocating it on the heap
 	// if necessary.
-	context := b.emitPointerPack(boundVars)
+	context := c.emitPointerPack(boundVars)

 	// Create the closure.
-	return b.createFuncValue(f.LLVMFn, context, f.Signature), nil
+	return c.createFuncValue(f.LLVMFn, context, f.Signature), nil
 }
@@ -5,66 +5,76 @@ package compiler

 import (
 	"go/token"
+	"math/big"

 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )

+// needsStackObjects returns true if the compiler should insert stack objects
+// that can be traced by the garbage collector.
+func (c *Compiler) needsStackObjects() bool {
+	if c.selectGC() != "conservative" {
+		return false
+	}
+	for _, tag := range c.BuildTags {
+		if tag == "baremetal" {
+			return false
+		}
+	}
+
+	return true
+}
+
 // trackExpr inserts pointer tracking intrinsics for the GC if the expression is
 // one of the expressions that need this.
-func (b *builder) trackExpr(expr ssa.Value, value llvm.Value) {
+func (c *Compiler) trackExpr(frame *Frame, expr ssa.Value, value llvm.Value) {
 	// There are uses of this expression, Make sure the pointers
 	// are tracked during GC.
 	switch expr := expr.(type) {
 	case *ssa.Alloc, *ssa.MakeChan, *ssa.MakeMap:
 		// These values are always of pointer type in IR.
-		b.trackPointer(value)
+		c.trackPointer(value)
 	case *ssa.Call, *ssa.Convert, *ssa.MakeClosure, *ssa.MakeInterface, *ssa.MakeSlice, *ssa.Next:
 		if !value.IsNil() {
-			b.trackValue(value)
+			c.trackValue(value)
 		}
 	case *ssa.Select:
-		if alloca, ok := b.selectRecvBuf[expr]; ok {
+		if alloca, ok := frame.selectRecvBuf[expr]; ok {
 			if alloca.IsAUndefValue().IsNil() {
-				b.trackPointer(alloca)
+				c.trackPointer(alloca)
 			}
 		}
 	case *ssa.UnOp:
 		switch expr.Op {
 		case token.MUL:
 			// Pointer dereference.
-			b.trackValue(value)
+			c.trackValue(value)
 		case token.ARROW:
 			// Channel receive operator.
 			// It's not necessary to look at commaOk here, because in that
 			// case it's just an aggregate and trackValue will extract the
 			// pointer in there (if there is one).
-			b.trackValue(value)
-		}
-	case *ssa.BinOp:
-		switch expr.Op {
-		case token.ADD:
-			// String concatenation.
-			b.trackValue(value)
+			c.trackValue(value)
 		}
 	}
 }

 // trackValue locates pointers in a value (possibly an aggregate) and tracks the
 // individual pointers
-func (b *builder) trackValue(value llvm.Value) {
+func (c *Compiler) trackValue(value llvm.Value) {
 	typ := value.Type()
 	switch typ.TypeKind() {
 	case llvm.PointerTypeKind:
-		b.trackPointer(value)
+		c.trackPointer(value)
 	case llvm.StructTypeKind:
 		if !typeHasPointers(typ) {
 			return
 		}
 		numElements := typ.StructElementTypesCount()
 		for i := 0; i < numElements; i++ {
-			subValue := b.CreateExtractValue(value, i, "")
-			b.trackValue(subValue)
+			subValue := c.builder.CreateExtractValue(value, i, "")
+			c.trackValue(subValue)
 		}
 	case llvm.ArrayTypeKind:
 		if !typeHasPointers(typ) {
@@ -72,19 +82,19 @@ func (b *builder) trackValue(value llvm.Value) {
 		}
 		numElements := typ.ArrayLength()
 		for i := 0; i < numElements; i++ {
-			subValue := b.CreateExtractValue(value, i, "")
-			b.trackValue(subValue)
+			subValue := c.builder.CreateExtractValue(value, i, "")
+			c.trackValue(subValue)
 		}
 	}
 }

 // trackPointer creates a call to runtime.trackPointer, bitcasting the poitner
 // first if needed. The input value must be of LLVM pointer type.
-func (b *builder) trackPointer(value llvm.Value) {
-	if value.Type() != b.i8ptrType {
-		value = b.CreateBitCast(value, b.i8ptrType, "")
+func (c *Compiler) trackPointer(value llvm.Value) {
+	if value.Type() != c.i8ptrType {
+		value = c.builder.CreateBitCast(value, c.i8ptrType, "")
 	}
-	b.createRuntimeCall("trackPointer", []llvm.Value{value}, "")
+	c.createRuntimeCall("trackPointer", []llvm.Value{value}, "")
 }

 // typeHasPointers returns whether this type is a pointer or contains pointers.
@@ -110,3 +120,363 @@ func typeHasPointers(t llvm.Type) bool {
 		return false
 	}
 }
+
+// makeGCStackSlots converts all calls to runtime.trackPointer to explicit
+// stores to stack slots that are scannable by the GC.
+func (c *Compiler) makeGCStackSlots() bool {
+	// Check whether there are allocations at all.
+	alloc := c.mod.NamedFunction("runtime.alloc")
+	if alloc.IsNil() {
+		// Nothing to. Make sure all remaining bits and pieces for stack
+		// chains are neutralized.
+		for _, call := range getUses(c.mod.NamedFunction("runtime.trackPointer")) {
+			call.EraseFromParentAsInstruction()
+		}
+		stackChainStart := c.mod.NamedGlobal("runtime.stackChainStart")
+		if !stackChainStart.IsNil() {
+			stackChainStart.SetInitializer(c.getZeroValue(stackChainStart.Type().ElementType()))
+			stackChainStart.SetGlobalConstant(true)
+		}
+	}
+
+	trackPointer := c.mod.NamedFunction("runtime.trackPointer")
+	if trackPointer.IsNil() || trackPointer.FirstUse().IsNil() {
+		return false // nothing to do
+	}
+
+	// Look at *all* functions to see whether they are free of function pointer
+	// calls.
+	// This takes less than 5ms for ~100kB of WebAssembly but would perhaps be
+	// faster when written in C++ (to avoid the CGo overhead).
+	funcsWithFPCall := map[llvm.Value]struct{}{}
+	n := 0
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+		n++
+		if _, ok := funcsWithFPCall[fn]; ok {
+			continue // already found
+		}
+		done := false
+		for bb := fn.FirstBasicBlock(); !bb.IsNil() && !done; bb = llvm.NextBasicBlock(bb) {
+			for call := bb.FirstInstruction(); !call.IsNil() && !done; call = llvm.NextInstruction(call) {
+				if call.IsACallInst().IsNil() {
+					continue // only looking at calls
+				}
+				called := call.CalledValue()
+				if !called.IsAFunction().IsNil() {
+					continue // only looking for function pointers
+				}
+				funcsWithFPCall[fn] = struct{}{}
+				markParentFunctions(funcsWithFPCall, fn)
+				done = true
+			}
+		}
+	}
+
+	// Determine which functions need stack objects. Many leaf functions don't
+	// need it: it only causes overhead for them.
+	// Actually, in one test it was only able to eliminate stack object from 12%
+	// of functions that had a call to runtime.trackPointer (8 out of 68
+	// functions), so this optimization is not as big as it may seem.
+	allocatingFunctions := map[llvm.Value]struct{}{} // set of allocating functions
+
+	// Work from runtime.alloc and trace all parents to check which functions do
+	// a heap allocation (and thus which functions do not).
+	markParentFunctions(allocatingFunctions, alloc)
+
+	// Also trace all functions that call a function pointer.
+	for fn := range funcsWithFPCall {
+		// Assume that functions that call a function pointer do a heap
+		// allocation as a conservative guess because the called function might
+		// do a heap allocation.
+		allocatingFunctions[fn] = struct{}{}
+		markParentFunctions(allocatingFunctions, fn)
+	}
+
+	// Collect some variables used below in the loop.
+	stackChainStart := c.mod.NamedGlobal("runtime.stackChainStart")
+	if stackChainStart.IsNil() {
+		panic("stack chain start not found!")
+	}
+	stackChainStartType := stackChainStart.Type().ElementType()
+	stackChainStart.SetInitializer(c.getZeroValue(stackChainStartType))
+
+	// Iterate until runtime.trackPointer has no uses left.
+	for use := trackPointer.FirstUse(); !use.IsNil(); use = trackPointer.FirstUse() {
+		// Pick the first use of runtime.trackPointer.
+		call := use.User()
+		if call.IsACallInst().IsNil() {
+			panic("expected runtime.trackPointer use to be a call")
+		}
+
+		// Pick the parent function.
+		fn := call.InstructionParent().Parent()
+
+		if _, ok := allocatingFunctions[fn]; !ok {
+			// This function nor any of the functions it calls (recursively)
+			// allocate anything from the heap, so it will not trigger a garbage
+			// collection cycle. Thus, it does not need to track local pointer
+			// values.
+			// This is a useful optimization but not as big as you might guess,
+			// as described above (it avoids stack objects for ~12% of
+			// functions).
+			call.EraseFromParentAsInstruction()
+			continue
+		}
+
+		// Find all calls to runtime.trackPointer in this function.
+		var calls []llvm.Value
+		var returns []llvm.Value
+		for bb := fn.FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
+			for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
+				switch inst.InstructionOpcode() {
+				case llvm.Call:
+					if inst.CalledValue() == trackPointer {
+						calls = append(calls, inst)
+					}
+				case llvm.Ret:
+					returns = append(returns, inst)
+				}
+			}
+		}
+
+		// Determine what to do with each call.
+		var allocas, pointers []llvm.Value
+		for _, call := range calls {
+			ptr := call.Operand(0)
+			call.EraseFromParentAsInstruction()
+			if ptr.IsAInstruction().IsNil() {
+				continue
+			}
+
+			// Some trivial optimizations.
+			if ptr.IsAInstruction().IsNil() {
+				continue
+			}
+			switch ptr.InstructionOpcode() {
+			case llvm.PHI, llvm.GetElementPtr:
+				// These values do not create new values: the values already
+				// existed locally in this function so must have been tracked
+				// already.
+				continue
+			case llvm.ExtractValue, llvm.BitCast:
+				// These instructions do not create new values, but their
+				// original value may not be tracked. So keep tracking them for
+				// now.
+				// With more analysis, it should be possible to optimize a
+				// significant chunk of these away.
+			case llvm.Call, llvm.Load, llvm.IntToPtr:
+				// These create new values so must be stored locally. But
+				// perhaps some of these can be fused when they actually refer
+				// to the same value.
+			default:
+				// Ambiguous. These instructions are uncommon, but perhaps could
+				// be optimized if needed.
+			}
+
+			if !ptr.IsAAllocaInst().IsNil() {
+				if typeHasPointers(ptr.Type().ElementType()) {
+					allocas = append(allocas, ptr)
+				}
+			} else {
+				pointers = append(pointers, ptr)
+			}
+		}
+
+		if len(allocas) == 0 && len(pointers) == 0 {
+			// This function does not need to keep track of stack pointers.
+			continue
+		}
+
+		// Determine the type of the required stack slot.
+		fields := []llvm.Type{
+			stackChainStartType, // Pointer to parent frame.
+			c.uintptrType,       // Number of elements in this frame.
+		}
+		for _, alloca := range allocas {
+			fields = append(fields, alloca.Type().ElementType())
+		}
+		for _, ptr := range pointers {
+			fields = append(fields, ptr.Type())
+		}
+		stackObjectType := c.ctx.StructType(fields, false)
+
+		// Create the stack object at the function entry.
+		c.builder.SetInsertPointBefore(fn.EntryBasicBlock().FirstInstruction())
+		stackObject := c.builder.CreateAlloca(stackObjectType, "gc.stackobject")
+		initialStackObject := c.getZeroValue(stackObjectType)
+		numSlots := (c.targetData.TypeAllocSize(stackObjectType) - c.targetData.TypeAllocSize(c.i8ptrType)*2) / uint64(c.targetData.ABITypeAlignment(c.uintptrType))
+		numSlotsValue := llvm.ConstInt(c.uintptrType, numSlots, false)
+		initialStackObject = llvm.ConstInsertValue(initialStackObject, numSlotsValue, []uint32{1})
+		c.builder.CreateStore(initialStackObject, stackObject)
+
+		// Update stack start.
+		parent := c.builder.CreateLoad(stackChainStart, "")
+		gep := c.builder.CreateGEP(stackObject, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		}, "")
+		c.builder.CreateStore(parent, gep)
+		stackObjectCast := c.builder.CreateBitCast(stackObject, stackChainStartType, "")
+		c.builder.CreateStore(stackObjectCast, stackChainStart)
+
+		// Replace all independent allocas with GEPs in the stack object.
+		for i, alloca := range allocas {
+			gep := c.builder.CreateGEP(stackObject, []llvm.Value{
+				llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+				llvm.ConstInt(c.ctx.Int32Type(), uint64(2+i), false),
+			}, "")
+			alloca.ReplaceAllUsesWith(gep)
+			alloca.EraseFromParentAsInstruction()
+		}
+
+		// Do a store to the stack object after each new pointer that is created.
+		for i, ptr := range pointers {
+			c.builder.SetInsertPointBefore(llvm.NextInstruction(ptr))
+			gep := c.builder.CreateGEP(stackObject, []llvm.Value{
+				llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+				llvm.ConstInt(c.ctx.Int32Type(), uint64(2+len(allocas)+i), false),
+			}, "")
+			c.builder.CreateStore(ptr, gep)
+		}
+
+		// Make sure this stack object is popped from the linked list of stack
+		// objects at return.
+		for _, ret := range returns {
+			c.builder.SetInsertPointBefore(ret)
+			c.builder.CreateStore(parent, stackChainStart)
+		}
+	}
+
+	return true
+}
+
+func (c *Compiler) addGlobalsBitmap() bool {
+	if c.mod.NamedGlobal("runtime.trackedGlobalsStart").IsNil() {
+		return false // nothing to do: no GC in use
+	}
+
+	var trackedGlobals []llvm.Value
+	var trackedGlobalTypes []llvm.Type
+	for global := c.mod.FirstGlobal(); !global.IsNil(); global = llvm.NextGlobal(global) {
+		if global.IsDeclaration() {
+			continue
+		}
+		typ := global.Type().ElementType()
+		ptrs := c.getPointerBitmap(typ, global.Name())
+		if ptrs.BitLen() == 0 {
+			continue
+		}
+		trackedGlobals = append(trackedGlobals, global)
+		trackedGlobalTypes = append(trackedGlobalTypes, typ)
+	}
+
+	globalsBundleType := c.ctx.StructType(trackedGlobalTypes, false)
+	globalsBundle := llvm.AddGlobal(c.mod, globalsBundleType, "tinygo.trackedGlobals")
+	globalsBundle.SetLinkage(llvm.InternalLinkage)
+	globalsBundle.SetUnnamedAddr(true)
+	initializer := llvm.Undef(globalsBundleType)
+	for i, global := range trackedGlobals {
+		initializer = llvm.ConstInsertValue(initializer, global.Initializer(), []uint32{uint32(i)})
+		gep := llvm.ConstGEP(globalsBundle, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
+		})
+		global.ReplaceAllUsesWith(gep)
+		global.EraseFromParentAsGlobal()
+	}
+	globalsBundle.SetInitializer(initializer)
+
+	trackedGlobalsStart := llvm.ConstPtrToInt(globalsBundle, c.uintptrType)
+	c.mod.NamedGlobal("runtime.trackedGlobalsStart").SetInitializer(trackedGlobalsStart)
+
+	alignment := c.targetData.PrefTypeAlignment(c.i8ptrType)
+	trackedGlobalsLength := llvm.ConstInt(c.uintptrType, c.targetData.TypeAllocSize(globalsBundleType)/uint64(alignment), false)
+	c.mod.NamedGlobal("runtime.trackedGlobalsLength").SetInitializer(trackedGlobalsLength)
+
+	bitmapBytes := c.getPointerBitmap(globalsBundleType, "globals bundle").Bytes()
+	bitmapValues := make([]llvm.Value, len(bitmapBytes))
+	for i, b := range bitmapBytes {
+		bitmapValues[len(bitmapBytes)-i-1] = llvm.ConstInt(c.ctx.Int8Type(), uint64(b), false)
+	}
+	bitmapArray := llvm.ConstArray(c.ctx.Int8Type(), bitmapValues)
+	bitmapNew := llvm.AddGlobal(c.mod, bitmapArray.Type(), "runtime.trackedGlobalsBitmap.tmp")
+	bitmapOld := c.mod.NamedGlobal("runtime.trackedGlobalsBitmap")
+	for _, inst := range getUses(bitmapOld) {
+		c.builder.SetInsertPointBefore(inst)
+		bc := c.builder.CreateBitCast(bitmapNew, bitmapOld.Type(), "runtime.trackedGlobalsBitmap.cast")
+		for i := 0; i < inst.OperandsCount(); i++ {
+			if inst.Operand(i) == bitmapOld {
+				inst.SetOperand(i, bc)
+			}
+		}
+	}
+	if len(getUses(bitmapOld)) > 0 {
+		panic("failed to eliminate tracked globals bitmap representation")
+	}
+	bitmapNew.SetInitializer(bitmapArray)
+	bitmapNew.SetName("runtime.trackedGlobalsBitmap")
+
+	return true // the IR was changed
+}
+
+func (c *Compiler) getPointerBitmap(typ llvm.Type, name string) *big.Int {
+	alignment := c.targetData.PrefTypeAlignment(c.i8ptrType)
+	switch typ.TypeKind() {
+	case llvm.IntegerTypeKind, llvm.FloatTypeKind, llvm.DoubleTypeKind:
+		return big.NewInt(0)
+	case llvm.PointerTypeKind:
+		return big.NewInt(1)
+	case llvm.StructTypeKind:
+		ptrs := big.NewInt(0)
+		for i, subtyp := range typ.StructElementTypes() {
+			subptrs := c.getPointerBitmap(subtyp, name)
+			if subptrs.BitLen() == 0 {
+				continue
+			}
+			offset := c.targetData.ElementOffset(typ, i)
+			if offset%uint64(alignment) != 0 {
+				panic("precise GC: global contains unaligned pointer: " + name)
+			}
+			subptrs.Lsh(subptrs, uint(offset)/uint(alignment))
+			ptrs.Or(ptrs, subptrs)
+		}
+		return ptrs
+	case llvm.ArrayTypeKind:
+		subtyp := typ.ElementType()
+		subptrs := c.getPointerBitmap(subtyp, name)
+		ptrs := big.NewInt(0)
+		if subptrs.BitLen() == 0 {
+			return ptrs
+		}
+		elementSize := c.targetData.TypeAllocSize(subtyp)
+		for i := 0; i < typ.ArrayLength(); i++ {
+			ptrs.Lsh(ptrs, uint(elementSize)/uint(alignment))
+			ptrs.Or(ptrs, subptrs)
+		}
+		return ptrs
+	default:
+		panic("unknown type kind of global: " + name)
+	}
+}
+
+// markParentFunctions traverses all parent function calls (recursively) and
+// adds them to the set of marked functions. It only considers function calls:
+// any other uses of such a function is ignored.
+func markParentFunctions(marked map[llvm.Value]struct{}, fn llvm.Value) {
+	worklist := []llvm.Value{fn}
+	for len(worklist) != 0 {
+		fn := worklist[len(worklist)-1]
+		worklist = worklist[:len(worklist)-1]
+		for _, use := range getUses(fn) {
+			if use.IsACallInst().IsNil() || use.CalledValue() != fn {
+				// Not the parent function.
+				continue
+			}
+			parent := use.InstructionParent().Parent()
+			if _, ok := marked[parent]; !ok {
+				marked[parent] = struct{}{}
+				worklist = append(worklist, parent)
+			}
+		}
+	}
+}
@@ -0,0 +1,673 @@
+package compiler
+
+// This file implements lowering for the goroutine scheduler. There are two
+// scheduler implementations, one based on tasks (like RTOSes and the main Go
+// runtime) and one based on a coroutine compiler transformation. The task based
+// implementation requires very little work from the compiler but is not very
+// portable (in particular, it is very hard if not impossible to support on
+// WebAssembly). The coroutine based one requires a lot of work by the compiler
+// to implement, but can run virtually anywhere with a single scheduler
+// implementation.
+//
+// The below description is for the coroutine based scheduler.
+//
+// This file lowers goroutine pseudo-functions into coroutines scheduled by a
+// scheduler at runtime. It uses coroutine support in LLVM for this
+// transformation: https://llvm.org/docs/Coroutines.html
+//
+// For example, take the following code:
+//
+//     func main() {
+//         go foo()
+//         time.Sleep(2 * time.Second)
+//         println("some other operation")
+//         i := bar()
+//         println("done", *i)
+//     }
+//
+//     func foo() {
+//         for {
+//             println("foo!")
+//             time.Sleep(time.Second)
+//         }
+//     }
+//
+//     func bar() *int {
+//         time.Sleep(time.Second)
+//         println("blocking operation completed)
+//         return new(int)
+//     }
+//
+// It is transformed by the IR generator in compiler.go into the following
+// pseudo-Go code:
+//
+//     func main() {
+//         fn := runtime.makeGoroutine(foo)
+//         fn()
+//         time.Sleep(2 * time.Second)
+//         println("some other operation")
+//         i := bar() // imagine an 'await' keyword in front of this call
+//         println("done", *i)
+//     }
+//
+//     func foo() {
+//         for {
+//             println("foo!")
+//             time.Sleep(time.Second)
+//         }
+//     }
+//
+//     func bar() *int {
+//         time.Sleep(time.Second)
+//         println("blocking operation completed)
+//         return new(int)
+//     }
+//
+// The pass in this file transforms this code even further, to the following
+// async/await style pseudocode:
+//
+//     func main(parent) {
+//         hdl := llvm.makeCoroutine()
+//         foo(nil)                                // do not pass the parent coroutine: this is an independent goroutine
+//         runtime.sleepTask(hdl, 2 * time.Second) // ask the scheduler to re-activate this coroutine at the right time
+//         llvm.suspend(hdl)                       // suspend point
+//         println("some other operation")
+//         var i *int                              // allocate space on the stack for the return value
+//         runtime.setTaskStatePtr(hdl, &i)        // store return value alloca in our coroutine promise
+//         bar(hdl)                                // await, pass a continuation (hdl) to bar
+//         llvm.suspend(hdl)                       // suspend point, wait for the callee to re-activate
+//         println("done", *i)
+//         runtime.activateTask(parent)            // re-activate the parent (nop, there is no parent)
+//     }
+//
+//     func foo(parent) {
+//         hdl := llvm.makeCoroutine()
+//         for {
+//             println("foo!")
+//             runtime.sleepTask(hdl, time.Second) // ask the scheduler to re-activate this coroutine at the right time
+//             llvm.suspend(hdl)                   // suspend point
+//         }
+//     }
+//
+//     func bar(parent) {
+//         hdl := llvm.makeCoroutine()
+//         runtime.sleepTask(hdl, time.Second) // ask the scheduler to re-activate this coroutine at the right time
+//         llvm.suspend(hdl)                   // suspend point
+//         println("blocking operation completed)
+//         runtime.activateTask(parent)        // re-activate the parent coroutine before returning
+//     }
+//
+// The real LLVM code is more complicated, but this is the general idea.
+//
+// The LLVM coroutine passes will then process this file further transforming
+// these three functions into coroutines. Most of the actual work is done by the
+// scheduler, which runs in the background scheduling all coroutines.
+
+import (
+	"errors"
+	"strings"
+
+	"tinygo.org/x/go-llvm"
+)
+
+type asyncFunc struct {
+	taskHandle       llvm.Value
+	cleanupBlock     llvm.BasicBlock
+	suspendBlock     llvm.BasicBlock
+	unreachableBlock llvm.BasicBlock
+}
+
+// LowerGoroutines performs some IR transformations necessary to support
+// goroutines. It does something different based on whether it uses the
+// coroutine or the tasks implementation of goroutines, and whether goroutines
+// are necessary at all.
+func (c *Compiler) LowerGoroutines() error {
+	switch c.selectScheduler() {
+	case "coroutines":
+		return c.lowerCoroutines()
+	case "tasks":
+		return c.lowerTasks()
+	default:
+		panic("unknown scheduler type")
+	}
+}
+
+// lowerTasks starts the main goroutine and then runs the scheduler.
+// This is enough compiler-level transformation for the task-based scheduler.
+func (c *Compiler) lowerTasks() error {
+	uses := getUses(c.mod.NamedFunction("runtime.callMain"))
+	if len(uses) != 1 || uses[0].IsACallInst().IsNil() {
+		panic("expected exactly 1 call of runtime.callMain, check the entry point")
+	}
+	mainCall := uses[0]
+
+	realMain := c.mod.NamedFunction(c.ir.MainPkg().Pkg.Path() + ".main")
+	if len(getUses(c.mod.NamedFunction("runtime.startGoroutine"))) != 0 {
+		// Program needs a scheduler. Start main.main as a goroutine and start
+		// the scheduler.
+		realMainWrapper := c.createGoroutineStartWrapper(realMain)
+		c.builder.SetInsertPointBefore(mainCall)
+		zero := llvm.ConstInt(c.uintptrType, 0, false)
+		c.createRuntimeCall("startGoroutine", []llvm.Value{realMainWrapper, zero}, "")
+		c.createRuntimeCall("scheduler", nil, "")
+		sleep := c.mod.NamedFunction("time.Sleep")
+		if !sleep.IsNil() {
+			sleep.ReplaceAllUsesWith(c.mod.NamedFunction("runtime.sleepCurrentTask"))
+		}
+	} else {
+		// Program doesn't need a scheduler. Call main.main directly.
+		c.builder.SetInsertPointBefore(mainCall)
+		params := []llvm.Value{
+			llvm.Undef(c.i8ptrType), // unused context parameter
+			llvm.Undef(c.i8ptrType), // unused coroutine handle
+		}
+		c.createCall(realMain, params, "")
+		// runtime.Goexit isn't needed so let it be optimized away by
+		// globalopt.
+		c.mod.NamedFunction("runtime.Goexit").SetLinkage(llvm.InternalLinkage)
+	}
+	mainCall.EraseFromParentAsInstruction()
+
+	// main.main was set to external linkage during IR construction. Set it to
+	// internal linkage to enable interprocedural optimizations.
+	realMain.SetLinkage(llvm.InternalLinkage)
+
+	return nil
+}
+
+// lowerCoroutines transforms the IR into one where all blocking functions are
+// turned into goroutines and blocking calls into await calls. It also makes
+// sure that the first coroutine is started and the coroutine scheduler will be
+// run.
+func (c *Compiler) lowerCoroutines() error {
+	needsScheduler, err := c.markAsyncFunctions()
+	if err != nil {
+		return err
+	}
+
+	uses := getUses(c.mod.NamedFunction("runtime.callMain"))
+	if len(uses) != 1 || uses[0].IsACallInst().IsNil() {
+		panic("expected exactly 1 call of runtime.callMain, check the entry point")
+	}
+	mainCall := uses[0]
+
+	// Replace call of runtime.callMain() with a real call to main.main(),
+	// optionally followed by a call to runtime.scheduler().
+	c.builder.SetInsertPointBefore(mainCall)
+	realMain := c.mod.NamedFunction(c.ir.MainPkg().Pkg.Path() + ".main")
+	c.builder.CreateCall(realMain, []llvm.Value{llvm.Undef(c.i8ptrType), llvm.ConstPointerNull(c.i8ptrType)}, "")
+	if needsScheduler {
+		c.createRuntimeCall("scheduler", nil, "")
+	}
+	mainCall.EraseFromParentAsInstruction()
+
+	if !needsScheduler {
+		go_scheduler := c.mod.NamedFunction("go_scheduler")
+		if !go_scheduler.IsNil() {
+			// This is the WebAssembly backend.
+			// There is no need to export the go_scheduler function, but it is
+			// still exported. Make sure it is optimized away.
+			go_scheduler.SetLinkage(llvm.InternalLinkage)
+		}
+	}
+
+	// main.main was set to external linkage during IR construction. Set it to
+	// internal linkage to enable interprocedural optimizations.
+	realMain.SetLinkage(llvm.InternalLinkage)
+
+	return nil
+}
+
+// markAsyncFunctions does the bulk of the work of lowering goroutines. It
+// determines whether a scheduler is needed, and if it is, it transforms
+// blocking operations into goroutines and blocking calls into await calls.
+//
+// It does the following operations:
+//    * Find all blocking functions.
+//    * Determine whether a scheduler is necessary. If not, it skips the
+//      following operations.
+//    * Transform call instructions into await calls.
+//    * Transform return instructions into final suspends.
+//    * Set up the coroutine frames for async functions.
+//    * Transform blocking calls into their async equivalents.
+func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
+	var worklist []llvm.Value
+
+	sleep := c.mod.NamedFunction("time.Sleep")
+	if !sleep.IsNil() {
+		worklist = append(worklist, sleep)
+	}
+	deadlock := c.mod.NamedFunction("runtime.deadlock")
+	if !deadlock.IsNil() {
+		worklist = append(worklist, deadlock)
+	}
+	chanSend := c.mod.NamedFunction("runtime.chanSend")
+	if !chanSend.IsNil() {
+		worklist = append(worklist, chanSend)
+	}
+	chanRecv := c.mod.NamedFunction("runtime.chanRecv")
+	if !chanRecv.IsNil() {
+		worklist = append(worklist, chanRecv)
+	}
+
+	if len(worklist) == 0 {
+		// There are no blocking operations, so no need to transform anything.
+		return false, c.lowerMakeGoroutineCalls()
+	}
+
+	// Find all async functions.
+	// Keep reducing this worklist by marking a function as recursively async
+	// from the worklist and pushing all its parents that are non-async.
+	// This is somewhat similar to a worklist in a mark-sweep garbage collector:
+	// the work items are then grey objects.
+	asyncFuncs := make(map[llvm.Value]*asyncFunc)
+	asyncList := make([]llvm.Value, 0, 4)
+	for len(worklist) != 0 {
+		// Pick the topmost.
+		f := worklist[len(worklist)-1]
+		worklist = worklist[:len(worklist)-1]
+		if _, ok := asyncFuncs[f]; ok {
+			continue // already processed
+		}
+		// Add to set of async functions.
+		asyncFuncs[f] = &asyncFunc{}
+		asyncList = append(asyncList, f)
+
+		// Add all callees to the worklist.
+		for _, use := range getUses(f) {
+			if use.IsConstant() && use.Opcode() == llvm.PtrToInt {
+				for _, call := range getUses(use) {
+					if call.IsACallInst().IsNil() || call.CalledValue().Name() != "runtime.makeGoroutine" {
+						return false, errors.New("async function " + f.Name() + " incorrectly used in ptrtoint, expected runtime.makeGoroutine")
+					}
+				}
+				// This is a go statement. Do not mark the parent as async, as
+				// starting a goroutine is not a blocking operation.
+				continue
+			}
+			if use.IsConstant() && use.Opcode() == llvm.BitCast {
+				// Not sure why this const bitcast is here but as long as it
+				// has no uses it can be ignored, I guess?
+				// I think it was created for the runtime.isnil check but
+				// somehow wasn't removed when all these checks are removed.
+				if len(getUses(use)) == 0 {
+					continue
+				}
+			}
+			if use.IsACallInst().IsNil() {
+				// Not a call instruction. Maybe a store to a global? In any
+				// case, this requires support for async calls across function
+				// pointers which is not yet supported.
+				return false, errors.New("async function " + f.Name() + " used as function pointer")
+			}
+			parent := use.InstructionParent().Parent()
+			for i := 0; i < use.OperandsCount()-1; i++ {
+				if use.Operand(i) == f {
+					return false, errors.New("async function " + f.Name() + " used as function pointer in " + parent.Name())
+				}
+			}
+			worklist = append(worklist, parent)
+		}
+	}
+
+	// Check whether a scheduler is needed.
+	makeGoroutine := c.mod.NamedFunction("runtime.makeGoroutine")
+	if c.GOOS == "js" && strings.HasPrefix(c.Triple, "wasm") {
+		// JavaScript always needs a scheduler, as in general no blocking
+		// operations are possible. Blocking operations block the browser UI,
+		// which is very bad.
+		needsScheduler = true
+	} else {
+		// Only use a scheduler when an async goroutine is started. When the
+		// goroutine is not async (does not do any blocking operation), no
+		// scheduler is necessary as it can be called directly.
+		for _, use := range getUses(makeGoroutine) {
+			// Input param must be const ptrtoint of function.
+			ptrtoint := use.Operand(0)
+			if !ptrtoint.IsConstant() || ptrtoint.Opcode() != llvm.PtrToInt {
+				panic("expected const ptrtoint operand of runtime.makeGoroutine")
+			}
+			goroutine := ptrtoint.Operand(0)
+			if _, ok := asyncFuncs[goroutine]; ok {
+				needsScheduler = true
+				break
+			}
+		}
+	}
+
+	if !needsScheduler {
+		// No scheduler is needed. Do not transform all functions here.
+		// However, make sure that all go calls (which are all non-async) are
+		// transformed into regular calls.
+		return false, c.lowerMakeGoroutineCalls()
+	}
+
+	// Create a few LLVM intrinsics for coroutine support.
+
+	coroIdType := llvm.FunctionType(c.ctx.TokenType(), []llvm.Type{c.ctx.Int32Type(), c.i8ptrType, c.i8ptrType, c.i8ptrType}, false)
+	coroIdFunc := llvm.AddFunction(c.mod, "llvm.coro.id", coroIdType)
+
+	coroSizeType := llvm.FunctionType(c.ctx.Int32Type(), nil, false)
+	coroSizeFunc := llvm.AddFunction(c.mod, "llvm.coro.size.i32", coroSizeType)
+
+	coroBeginType := llvm.FunctionType(c.i8ptrType, []llvm.Type{c.ctx.TokenType(), c.i8ptrType}, false)
+	coroBeginFunc := llvm.AddFunction(c.mod, "llvm.coro.begin", coroBeginType)
+
+	coroSuspendType := llvm.FunctionType(c.ctx.Int8Type(), []llvm.Type{c.ctx.TokenType(), c.ctx.Int1Type()}, false)
+	coroSuspendFunc := llvm.AddFunction(c.mod, "llvm.coro.suspend", coroSuspendType)
+
+	coroEndType := llvm.FunctionType(c.ctx.Int1Type(), []llvm.Type{c.i8ptrType, c.ctx.Int1Type()}, false)
+	coroEndFunc := llvm.AddFunction(c.mod, "llvm.coro.end", coroEndType)
+
+	coroFreeType := llvm.FunctionType(c.i8ptrType, []llvm.Type{c.ctx.TokenType(), c.i8ptrType}, false)
+	coroFreeFunc := llvm.AddFunction(c.mod, "llvm.coro.free", coroFreeType)
+
+	// Transform all async functions into coroutines.
+	for _, f := range asyncList {
+		if f == sleep || f == deadlock || f == chanSend || f == chanRecv {
+			continue
+		}
+
+		frame := asyncFuncs[f]
+		frame.cleanupBlock = c.ctx.AddBasicBlock(f, "task.cleanup")
+		frame.suspendBlock = c.ctx.AddBasicBlock(f, "task.suspend")
+		frame.unreachableBlock = c.ctx.AddBasicBlock(f, "task.unreachable")
+
+		// Scan for async calls and return instructions that need to have
+		// suspend points inserted.
+		var asyncCalls []llvm.Value
+		var returns []llvm.Value
+		for bb := f.EntryBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
+			for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
+				if !inst.IsACallInst().IsNil() {
+					callee := inst.CalledValue()
+					if _, ok := asyncFuncs[callee]; !ok || callee == sleep || callee == deadlock || callee == chanSend || callee == chanRecv {
+						continue
+					}
+					asyncCalls = append(asyncCalls, inst)
+				} else if !inst.IsAReturnInst().IsNil() {
+					returns = append(returns, inst)
+				}
+			}
+		}
+
+		// Coroutine setup.
+		c.builder.SetInsertPointBefore(f.EntryBasicBlock().FirstInstruction())
+		taskState := c.builder.CreateAlloca(c.getLLVMRuntimeType("taskState"), "task.state")
+		stateI8 := c.builder.CreateBitCast(taskState, c.i8ptrType, "task.state.i8")
+		id := c.builder.CreateCall(coroIdFunc, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			stateI8,
+			llvm.ConstNull(c.i8ptrType),
+			llvm.ConstNull(c.i8ptrType),
+		}, "task.token")
+		size := c.builder.CreateCall(coroSizeFunc, nil, "task.size")
+		if c.targetData.TypeAllocSize(size.Type()) > c.targetData.TypeAllocSize(c.uintptrType) {
+			size = c.builder.CreateTrunc(size, c.uintptrType, "task.size.uintptr")
+		} else if c.targetData.TypeAllocSize(size.Type()) < c.targetData.TypeAllocSize(c.uintptrType) {
+			size = c.builder.CreateZExt(size, c.uintptrType, "task.size.uintptr")
+		}
+		data := c.createRuntimeCall("alloc", []llvm.Value{size}, "task.data")
+		if c.needsStackObjects() {
+			c.trackPointer(data)
+		}
+		frame.taskHandle = c.builder.CreateCall(coroBeginFunc, []llvm.Value{id, data}, "task.handle")
+
+		// Modify async calls so this function suspends right after the child
+		// returns, because the child is probably not finished yet. Wait until
+		// the child reactivates the parent.
+		for _, inst := range asyncCalls {
+			inst.SetOperand(inst.OperandsCount()-2, frame.taskHandle)
+
+			// Split this basic block.
+			await := c.splitBasicBlock(inst, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.await")
+
+			// Allocate space for the return value.
+			var retvalAlloca llvm.Value
+			if inst.Type().TypeKind() != llvm.VoidTypeKind {
+				c.builder.SetInsertPointBefore(inst.InstructionParent().Parent().EntryBasicBlock().FirstInstruction())
+				retvalAlloca = c.builder.CreateAlloca(inst.Type(), "coro.retvalAlloca")
+				c.builder.SetInsertPointBefore(inst)
+				data := c.builder.CreateBitCast(retvalAlloca, c.i8ptrType, "")
+				c.createRuntimeCall("setTaskStatePtr", []llvm.Value{frame.taskHandle, data}, "")
+			}
+
+			// Suspend.
+			c.builder.SetInsertPointAtEnd(inst.InstructionParent())
+			continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+				llvm.ConstNull(c.ctx.TokenType()),
+				llvm.ConstInt(c.ctx.Int1Type(), 0, false),
+			}, "")
+			sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), await)
+			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+
+			if inst.Type().TypeKind() != llvm.VoidTypeKind {
+				// Load the return value from the alloca. The callee has
+				// written the return value to it.
+				c.builder.SetInsertPointBefore(await.FirstInstruction())
+				retval := c.builder.CreateLoad(retvalAlloca, "coro.retval")
+				inst.ReplaceAllUsesWith(retval)
+			}
+		}
+
+		// Replace return instructions with suspend points that should
+		// reactivate the parent coroutine.
+		for _, inst := range returns {
+			// These properties were added by the functionattrs pass. Remove
+			// them, because now we start using the parameter.
+			// https://llvm.org/docs/Passes.html#functionattrs-deduce-function-attributes
+			for _, kind := range []string{"nocapture", "readnone"} {
+				kindID := llvm.AttributeKindID(kind)
+				f.RemoveEnumAttributeAtIndex(f.ParamsCount(), kindID)
+			}
+
+			c.builder.SetInsertPointBefore(inst)
+
+			var parentHandle llvm.Value
+			if f.Linkage() == llvm.ExternalLinkage {
+				// Exported function.
+				// Note that getTaskStatePtr will panic if it is called with
+				// a nil pointer, so blocking exported functions that try to
+				// return anything will not work.
+				parentHandle = llvm.ConstPointerNull(c.i8ptrType)
+			} else {
+				parentHandle = f.LastParam()
+				if parentHandle.IsNil() || parentHandle.Name() != "parentHandle" {
+					// sanity check
+					panic("trying to make exported function async: " + f.Name())
+				}
+			}
+
+			// Store return values.
+			switch inst.OperandsCount() {
+			case 0:
+				// Nothing to return.
+			case 1:
+				// Return this value by writing to the pointer stored in the
+				// parent handle. The parent coroutine has made an alloca that
+				// we can write to to store our return value.
+				returnValuePtr := c.createRuntimeCall("getTaskStatePtr", []llvm.Value{parentHandle}, "coro.parentData")
+				alloca := c.builder.CreateBitCast(returnValuePtr, llvm.PointerType(inst.Operand(0).Type(), 0), "coro.parentAlloca")
+				c.builder.CreateStore(inst.Operand(0), alloca)
+			default:
+				panic("unreachable")
+			}
+
+			// Reactivate the parent coroutine. This adds it back to the run
+			// queue, so it is started again by the scheduler when possible
+			// (possibly right after the following suspend).
+			c.createRuntimeCall("activateTask", []llvm.Value{parentHandle}, "")
+
+			// Suspend this coroutine.
+			// It would look like this is unnecessary, but if this
+			// suspend point is left out, it leads to undefined
+			// behavior somehow (with the unreachable instruction).
+			continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+				llvm.ConstNull(c.ctx.TokenType()),
+				llvm.ConstInt(c.ctx.Int1Type(), 0, false),
+			}, "ret")
+			sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), frame.unreachableBlock)
+			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+			inst.EraseFromParentAsInstruction()
+		}
+
+		// Coroutine cleanup. Free resources associated with this coroutine.
+		c.builder.SetInsertPointAtEnd(frame.cleanupBlock)
+		mem := c.builder.CreateCall(coroFreeFunc, []llvm.Value{id, frame.taskHandle}, "task.data.free")
+		c.createRuntimeCall("free", []llvm.Value{mem}, "")
+		c.builder.CreateBr(frame.suspendBlock)
+
+		// Coroutine suspend. A call to llvm.coro.suspend() will branch here.
+		c.builder.SetInsertPointAtEnd(frame.suspendBlock)
+		c.builder.CreateCall(coroEndFunc, []llvm.Value{frame.taskHandle, llvm.ConstInt(c.ctx.Int1Type(), 0, false)}, "unused")
+		returnType := f.Type().ElementType().ReturnType()
+		if returnType.TypeKind() == llvm.VoidTypeKind {
+			c.builder.CreateRetVoid()
+		} else {
+			c.builder.CreateRet(llvm.Undef(returnType))
+		}
+
+		// Coroutine exit. All final suspends (return instructions) will branch
+		// here.
+		c.builder.SetInsertPointAtEnd(frame.unreachableBlock)
+		c.builder.CreateUnreachable()
+	}
+
+	// Replace calls to runtime.getCoroutineCall with the coroutine of this
+	// frame.
+	for _, getCoroutineCall := range getUses(c.mod.NamedFunction("runtime.getCoroutine")) {
+		frame := asyncFuncs[getCoroutineCall.InstructionParent().Parent()]
+		getCoroutineCall.ReplaceAllUsesWith(frame.taskHandle)
+		getCoroutineCall.EraseFromParentAsInstruction()
+	}
+
+	// Transform calls to time.Sleep() into coroutine suspend points.
+	for _, sleepCall := range getUses(sleep) {
+		// sleepCall must be a call instruction.
+		frame := asyncFuncs[sleepCall.InstructionParent().Parent()]
+		duration := sleepCall.Operand(0)
+
+		// Set task state to TASK_STATE_SLEEP and set the duration.
+		c.builder.SetInsertPointBefore(sleepCall)
+		c.createRuntimeCall("sleepTask", []llvm.Value{frame.taskHandle, duration}, "")
+
+		// Yield to scheduler.
+		continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+			llvm.ConstNull(c.ctx.TokenType()),
+			llvm.ConstInt(c.ctx.Int1Type(), 0, false),
+		}, "")
+		wakeup := c.splitBasicBlock(sleepCall, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.wakeup")
+		c.builder.SetInsertPointBefore(sleepCall)
+		sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), wakeup)
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+		sleepCall.EraseFromParentAsInstruction()
+	}
+
+	// Transform calls to runtime.deadlock into coroutine suspends (without
+	// resume).
+	for _, deadlockCall := range getUses(deadlock) {
+		// deadlockCall must be a call instruction.
+		frame := asyncFuncs[deadlockCall.InstructionParent().Parent()]
+
+		// Exit coroutine.
+		c.builder.SetInsertPointBefore(deadlockCall)
+		continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+			llvm.ConstNull(c.ctx.TokenType()),
+			llvm.ConstInt(c.ctx.Int1Type(), 0, false),
+		}, "")
+		c.splitBasicBlock(deadlockCall, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.wakeup.dead")
+		c.builder.SetInsertPointBefore(deadlockCall)
+		sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), frame.unreachableBlock)
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+		deadlockCall.EraseFromParentAsInstruction()
+	}
+
+	// Transform calls to runtime.chanSend into channel send operations.
+	for _, sendOp := range getUses(chanSend) {
+		// sendOp must be a call instruction.
+		frame := asyncFuncs[sendOp.InstructionParent().Parent()]
+
+		// Yield to scheduler.
+		c.builder.SetInsertPointBefore(llvm.NextInstruction(sendOp))
+		continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+			llvm.ConstNull(c.ctx.TokenType()),
+			llvm.ConstInt(c.ctx.Int1Type(), 0, false),
+		}, "")
+		sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+		wakeup := c.splitBasicBlock(sw, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.sent")
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), wakeup)
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+	}
+
+	// Transform calls to runtime.chanRecv into channel receive operations.
+	for _, recvOp := range getUses(chanRecv) {
+		// recvOp must be a call instruction.
+		frame := asyncFuncs[recvOp.InstructionParent().Parent()]
+
+		// Yield to scheduler.
+		c.builder.SetInsertPointBefore(llvm.NextInstruction(recvOp))
+		continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+			llvm.ConstNull(c.ctx.TokenType()),
+			llvm.ConstInt(c.ctx.Int1Type(), 0, false),
+		}, "")
+		sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+		wakeup := c.splitBasicBlock(sw, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.received")
+		c.builder.SetInsertPointAtEnd(recvOp.InstructionParent())
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), wakeup)
+		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+	}
+
+	return true, c.lowerMakeGoroutineCalls()
+}
+
+// Lower runtime.makeGoroutine calls to regular call instructions. This is done
+// after the regular goroutine transformations. The started goroutines are
+// either non-blocking (in which case they can be called directly) or blocking,
+// in which case they will ask the scheduler themselves to be rescheduled.
+func (c *Compiler) lowerMakeGoroutineCalls() error {
+	// The following Go code:
+	//   go startedGoroutine()
+	//
+	// Is translated to the following during IR construction, to preserve the
+	// fact that this function should be called as a new goroutine.
+	//   %0 = call i8* @runtime.makeGoroutine(i8* bitcast (void (i8*, i8*)* @main.startedGoroutine to i8*), i8* undef, i8* null)
+	//   %1 = bitcast i8* %0 to void (i8*, i8*)*
+	//   call void %1(i8* undef, i8* undef)
+	//
+	// This function rewrites it to a direct call:
+	//   call void @main.startedGoroutine(i8* undef, i8* null)
+
+	makeGoroutine := c.mod.NamedFunction("runtime.makeGoroutine")
+	for _, goroutine := range getUses(makeGoroutine) {
+		ptrtointIn := goroutine.Operand(0)
+		origFunc := ptrtointIn.Operand(0)
+		uses := getUses(goroutine)
+		if len(uses) != 1 || uses[0].IsAIntToPtrInst().IsNil() {
+			return errors.New("expected exactly 1 inttoptr use of runtime.makeGoroutine")
+		}
+		inttoptrOut := uses[0]
+		uses = getUses(inttoptrOut)
+		if len(uses) != 1 || uses[0].IsACallInst().IsNil() {
+			return errors.New("expected exactly 1 call use of runtime.makeGoroutine bitcast")
+		}
+		realCall := uses[0]
+
+		// Create call instruction.
+		var params []llvm.Value
+		for i := 0; i < realCall.OperandsCount()-1; i++ {
+			params = append(params, realCall.Operand(i))
+		}
+		params[len(params)-1] = llvm.ConstPointerNull(c.i8ptrType) // parent coroutine handle (must be nil)
+		c.builder.SetInsertPointBefore(realCall)
+		c.builder.CreateCall(origFunc, params, "")
+		realCall.EraseFromParentAsInstruction()
+		inttoptrOut.EraseFromParentAsInstruction()
+		goroutine.EraseFromParentAsInstruction()
+	}
+
+	return nil
+}
@@ -3,32 +3,31 @@ package compiler
 // This file implements the 'go' keyword to start a new goroutine. See
 // goroutine-lowering.go for more details.

-import (
-	"go/token"
+import "tinygo.org/x/go-llvm"

-	"github.com/tinygo-org/tinygo/compiler/llvmutil"
-	"tinygo.org/x/go-llvm"
-)
-
-// createGoInstruction starts a new goroutine with the provided function pointer
+// emitStartGoroutine starts a new goroutine with the provided function pointer
 // and parameters.
-// In general, you should pass all regular parameters plus the context parameter.
-// There is one exception: the task-based scheduler needs to have the function
-// pointer passed in as a parameter too in addition to the context.
 //
 // Because a go statement doesn't return anything, return undef.
-func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, prefix string, pos token.Pos) llvm.Value {
-	paramBundle := b.emitPointerPack(params)
-	var callee llvm.Value
-	switch b.Scheduler() {
-	case "none", "tasks":
-		callee = b.createGoroutineStartWrapper(funcPtr, prefix, pos)
+func (c *Compiler) emitStartGoroutine(funcPtr llvm.Value, params []llvm.Value) llvm.Value {
+	switch c.selectScheduler() {
+	case "tasks":
+		paramBundle := c.emitPointerPack(params)
+		paramBundle = c.builder.CreatePtrToInt(paramBundle, c.uintptrType, "")
+
+		calleeValue := c.createGoroutineStartWrapper(funcPtr)
+		c.createRuntimeCall("startGoroutine", []llvm.Value{calleeValue, paramBundle}, "")
 	case "coroutines":
-		callee = b.CreatePtrToInt(funcPtr, b.uintptrType, "")
+		// We roundtrip through runtime.makeGoroutine as a signal (to find these
+		// calls) and to break any optimizations LLVM will try to do: they are
+		// invalid if we called this as a regular function to be updated later.
+		calleeValue := c.builder.CreatePtrToInt(funcPtr, c.uintptrType, "")
+		calleeValue = c.createRuntimeCall("makeGoroutine", []llvm.Value{calleeValue}, "")
+		calleeValue = c.builder.CreateIntToPtr(calleeValue, funcPtr.Type(), "")
+		c.createCall(calleeValue, params, "")
 	default:
 		panic("unreachable")
 	}
-	b.createCall(b.mod.NamedFunction("internal/task.start"), []llvm.Value{callee, paramBundle, llvm.Undef(b.i8ptrType), llvm.ConstPointerNull(b.i8ptrType)}, "")
 	return llvm.Undef(funcPtr.Type().ElementType().ReturnType())
 }

@@ -50,57 +49,36 @@ func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, p
 // allows a single (pointer) argument to the newly started goroutine. Also, it
 // ignores the return value because newly started goroutines do not have a
 // return value.
-func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix string, pos token.Pos) llvm.Value {
+func (c *Compiler) createGoroutineStartWrapper(fn llvm.Value) llvm.Value {
 	var wrapper llvm.Value

-	builder := c.ctx.NewBuilder()
-	defer builder.Dispose()
-
 	if !fn.IsAFunction().IsNil() {
 		// See whether this wrapper has already been created. If so, return it.
 		name := fn.Name()
 		wrapper = c.mod.NamedFunction(name + "$gowrapper")
 		if !wrapper.IsNil() {
-			return llvm.ConstPtrToInt(wrapper, c.uintptrType)
+			return c.builder.CreatePtrToInt(wrapper, c.uintptrType, "")
 		}

+		// Save the current position in the IR builder.
+		currentBlock := c.builder.GetInsertBlock()
+		defer c.builder.SetInsertPointAtEnd(currentBlock)
+
 		// Create the wrapper.
 		wrapperType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.i8ptrType}, false)
 		wrapper = llvm.AddFunction(c.mod, name+"$gowrapper", wrapperType)
 		wrapper.SetLinkage(llvm.PrivateLinkage)
 		wrapper.SetUnnamedAddr(true)
 		entry := c.ctx.AddBasicBlock(wrapper, "entry")
-		builder.SetInsertPointAtEnd(entry)
-
-		if c.Debug() {
-			pos := c.ir.Program.Fset.Position(pos)
-			diFuncType := c.dibuilder.CreateSubroutineType(llvm.DISubroutineType{
-				File:       c.getDIFile(pos.Filename),
-				Parameters: nil, // do not show parameters in debugger
-				Flags:      0,   // ?
-			})
-			difunc := c.dibuilder.CreateFunction(c.getDIFile(pos.Filename), llvm.DIFunction{
-				Name:         "<goroutine wrapper>",
-				File:         c.getDIFile(pos.Filename),
-				Line:         pos.Line,
-				Type:         diFuncType,
-				LocalToUnit:  true,
-				IsDefinition: true,
-				ScopeLine:    0,
-				Flags:        llvm.FlagPrototyped,
-				Optimized:    true,
-			})
-			wrapper.SetSubprogram(difunc)
-			builder.SetCurrentDebugLocation(uint(pos.Line), uint(pos.Column), difunc, llvm.Metadata{})
-		}
+		c.builder.SetInsertPointAtEnd(entry)

 		// Create the list of params for the call.
 		paramTypes := fn.Type().ElementType().ParamTypes()
-		params := llvmutil.EmitPointerUnpack(builder, c.mod, wrapper.Param(0), paramTypes[:len(paramTypes)-1])
-		params = append(params, llvm.Undef(c.i8ptrType))
+		params := c.emitPointerUnpack(wrapper.Param(0), paramTypes[:len(paramTypes)-2])
+		params = append(params, llvm.Undef(c.i8ptrType), llvm.ConstPointerNull(c.i8ptrType))

 		// Create the call.
-		builder.CreateCall(fn, params, "")
+		c.builder.CreateCall(fn, params, "")

 	} else {
 		// For a function pointer like this:
@@ -120,40 +98,22 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		// With a bit of luck, identical wrapper functions like these can be
 		// merged into one.

+		// Save the current position in the IR builder.
+		currentBlock := c.builder.GetInsertBlock()
+		defer c.builder.SetInsertPointAtEnd(currentBlock)
+
 		// Create the wrapper.
 		wrapperType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.i8ptrType}, false)
-		wrapper = llvm.AddFunction(c.mod, prefix+".gowrapper", wrapperType)
+		wrapper = llvm.AddFunction(c.mod, ".gowrapper", wrapperType)
 		wrapper.SetLinkage(llvm.InternalLinkage)
 		wrapper.SetUnnamedAddr(true)
 		entry := c.ctx.AddBasicBlock(wrapper, "entry")
-		builder.SetInsertPointAtEnd(entry)
-
-		if c.Debug() {
-			pos := c.ir.Program.Fset.Position(pos)
-			diFuncType := c.dibuilder.CreateSubroutineType(llvm.DISubroutineType{
-				File:       c.getDIFile(pos.Filename),
-				Parameters: nil, // do not show parameters in debugger
-				Flags:      0,   // ?
-			})
-			difunc := c.dibuilder.CreateFunction(c.getDIFile(pos.Filename), llvm.DIFunction{
-				Name:         "<goroutine wrapper>",
-				File:         c.getDIFile(pos.Filename),
-				Line:         pos.Line,
-				Type:         diFuncType,
-				LocalToUnit:  true,
-				IsDefinition: true,
-				ScopeLine:    0,
-				Flags:        llvm.FlagPrototyped,
-				Optimized:    true,
-			})
-			wrapper.SetSubprogram(difunc)
-			builder.SetCurrentDebugLocation(uint(pos.Line), uint(pos.Column), difunc, llvm.Metadata{})
-		}
+		c.builder.SetInsertPointAtEnd(entry)

 		// Get the list of parameters, with the extra parameters at the end.
 		paramTypes := fn.Type().ElementType().ParamTypes()
 		paramTypes[len(paramTypes)-1] = fn.Type() // the last element is the function pointer
-		params := llvmutil.EmitPointerUnpack(builder, c.mod, wrapper.Param(0), paramTypes)
+		params := c.emitPointerUnpack(wrapper.Param(0), paramTypes)

 		// Get the function pointer.
 		fnPtr := params[len(params)-1]
@@ -163,13 +123,13 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		params[len(params)-1] = llvm.Undef(c.i8ptrType)

 		// Create the call.
-		builder.CreateCall(fnPtr, params, "")
+		c.builder.CreateCall(fnPtr, params, "")
 	}

 	// Finish the function. Every basic block must end in a terminator, and
 	// because goroutines never return a value we can simply return void.
-	builder.CreateRetVoid()
+	c.builder.CreateRetVoid()

 	// Return a ptrtoint of the wrapper, not the function itself.
-	return builder.CreatePtrToInt(wrapper, c.uintptrType, "")
+	return c.builder.CreatePtrToInt(wrapper, c.uintptrType, "")
 }
@@ -13,6 +13,27 @@ import (
 	"tinygo.org/x/go-llvm"
 )

+// This is a compiler builtin, which reads the given register by name:
+//
+//     func ReadRegister(name string) uintptr
+//
+// The register name must be a constant, for example "sp".
+func (c *Compiler) emitReadRegister(name string, args []ssa.Value) (llvm.Value, error) {
+	fnType := llvm.FunctionType(c.uintptrType, []llvm.Type{}, false)
+	regname := constant.StringVal(args[0].(*ssa.Const).Value)
+	var asm string
+	switch name {
+	case "device/arm.ReadRegister":
+		asm = "mov $0, " + regname
+	case "device/riscv.ReadRegister":
+		asm = "mv $0, " + regname
+	default:
+		panic("unknown architecture")
+	}
+	target := llvm.InlineAsm(fnType, asm, "=r", false, false, 0)
+	return c.builder.CreateCall(target, nil, ""), nil
+}
+
 // This is a compiler builtin, which emits a piece of inline assembly with no
 // operands or return values. It is useful for trivial instructions, like wfi in
 // ARM or sleep in AVR.
@@ -20,18 +41,18 @@ import (
 //     func Asm(asm string)
 //
 // The provided assembly must be a constant.
-func (b *builder) createInlineAsm(args []ssa.Value) (llvm.Value, error) {
+func (c *Compiler) emitAsm(args []ssa.Value) (llvm.Value, error) {
 	// Magic function: insert inline assembly instead of calling it.
-	fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{}, false)
+	fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{}, false)
 	asm := constant.StringVal(args[0].(*ssa.Const).Value)
 	target := llvm.InlineAsm(fnType, asm, "", true, false, 0)
-	return b.CreateCall(target, nil, ""), nil
+	return c.builder.CreateCall(target, nil, ""), nil
 }

 // This is a compiler builtin, which allows assembly to be called in a flexible
 // way.
 //
-//     func AsmFull(asm string, regs map[string]interface{}) uintptr
+//     func AsmFull(asm string, regs map[string]interface{})
 //
 // The asm parameter must be a constant string. The regs parameter must be
 // provided immediately. For example:
@@ -42,27 +63,27 @@ func (b *builder) createInlineAsm(args []ssa.Value) (llvm.Value, error) {
 //             "value":  1
 //             "result": &dest,
 //         })
-func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error) {
+func (c *Compiler) emitAsmFull(frame *Frame, instr *ssa.CallCommon) (llvm.Value, error) {
 	asmString := constant.StringVal(instr.Args[0].(*ssa.Const).Value)
 	registers := map[string]llvm.Value{}
-	if registerMap, ok := instr.Args[1].(*ssa.MakeMap); ok {
-		for _, r := range *registerMap.Referrers() {
-			switch r := r.(type) {
-			case *ssa.DebugRef:
-				// ignore
-			case *ssa.MapUpdate:
-				if r.Block() != registerMap.Block() {
-					return llvm.Value{}, b.makeError(instr.Pos(), "register value map must be created in the same basic block")
-				}
-				key := constant.StringVal(r.Key.(*ssa.Const).Value)
-				registers[key] = b.getValue(r.Value.(*ssa.MakeInterface).X)
-			case *ssa.Call:
-				if r.Common() == instr {
-					break
-				}
-			default:
-				return llvm.Value{}, b.makeError(instr.Pos(), "don't know how to handle argument to inline assembly: "+r.String())
+	registerMap := instr.Args[1].(*ssa.MakeMap)
+	for _, r := range *registerMap.Referrers() {
+		switch r := r.(type) {
+		case *ssa.DebugRef:
+			// ignore
+		case *ssa.MapUpdate:
+			if r.Block() != registerMap.Block() {
+				return llvm.Value{}, c.makeError(instr.Pos(), "register value map must be created in the same basic block")
 			}
+			key := constant.StringVal(r.Key.(*ssa.Const).Value)
+			//println("value:", r.Value.(*ssa.MakeInterface).X.String())
+			registers[key] = c.getValue(frame, r.Value.(*ssa.MakeInterface).X)
+		case *ssa.Call:
+			if r.Common() == instr {
+				break
+			}
+		default:
+			return llvm.Value{}, c.makeError(instr.Pos(), "don't know how to handle argument to inline assembly: "+r.String())
 		}
 	}
 	// TODO: handle dollar signs in asm string
@@ -71,22 +92,13 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 	argTypes := []llvm.Type{}
 	args := []llvm.Value{}
 	constraints := []string{}
-	hasOutput := false
-	asmString = regexp.MustCompile("\\{\\}").ReplaceAllStringFunc(asmString, func(s string) string {
-		hasOutput = true
-		return "$0"
-	})
-	if hasOutput {
-		constraints = append(constraints, "=&r")
-		registerNumbers[""] = 0
-	}
 	asmString = regexp.MustCompile("\\{[a-zA-Z]+\\}").ReplaceAllStringFunc(asmString, func(s string) string {
 		// TODO: skip strings like {r4} etc. that look like ARM push/pop
 		// instructions.
 		name := s[1 : len(s)-1]
 		if _, ok := registers[name]; !ok {
 			if err == nil {
-				err = b.makeError(instr.Pos(), "unknown register name: "+name)
+				err = c.makeError(instr.Pos(), "unknown register name: "+name)
 			}
 			return s
 		}
@@ -100,7 +112,7 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 			case llvm.PointerTypeKind:
 				constraints = append(constraints, "*m")
 			default:
-				err = b.makeError(instr.Pos(), "unknown type in inline assembly for value: "+name)
+				err = c.makeError(instr.Pos(), "unknown type in inline assembly for value: "+name)
 				return s
 			}
 		}
@@ -109,21 +121,9 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 	if err != nil {
 		return llvm.Value{}, err
 	}
-	var outputType llvm.Type
-	if hasOutput {
-		outputType = b.uintptrType
-	} else {
-		outputType = b.ctx.VoidType()
-	}
-	fnType := llvm.FunctionType(outputType, argTypes, false)
+	fnType := llvm.FunctionType(c.ctx.VoidType(), argTypes, false)
 	target := llvm.InlineAsm(fnType, asmString, strings.Join(constraints, ","), true, false, 0)
-	result := b.CreateCall(target, args, "")
-	if hasOutput {
-		return result, nil
-	} else {
-		// Make sure we return something valid.
-		return llvm.ConstInt(b.uintptrType, 0, false), nil
-	}
+	return c.builder.CreateCall(target, args, ""), nil
 }

 // This is a compiler builtin which emits an inline SVCall instruction. It can
@@ -137,7 +137,7 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 //
 // The num parameter must be a constant. All other parameters may be any scalar
 // value supported by LLVM inline assembly.
-func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
+func (c *Compiler) emitSVCall(frame *Frame, args []ssa.Value) (llvm.Value, error) {
 	num, _ := constant.Uint64Val(args[0].(*ssa.Const).Value)
 	llvmArgs := []llvm.Value{}
 	argTypes := []llvm.Type{}
@@ -150,7 +150,7 @@ func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
 		} else {
 			constraints += ",{r" + strconv.Itoa(i) + "}"
 		}
-		llvmValue := b.getValue(arg)
+		llvmValue := c.getValue(frame, arg)
 		llvmArgs = append(llvmArgs, llvmValue)
 		argTypes = append(argTypes, llvmValue.Type())
 	}
@@ -158,52 +158,7 @@ func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
 	// clobbered. r0 is used as an output register so doesn't have to be
 	// marked as clobbered.
 	constraints += ",~{r1},~{r2},~{r3}"
-	fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
+	fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 	target := llvm.InlineAsm(fnType, asm, constraints, true, false, 0)
-	return b.CreateCall(target, llvmArgs, ""), nil
-}
-
-// This is a compiler builtin which emits CSR instructions. It can be one of:
-//
-//     func (csr CSR) Get() uintptr
-//     func (csr CSR) Set(uintptr)
-//     func (csr CSR) SetBits(uintptr) uintptr
-//     func (csr CSR) ClearBits(uintptr) uintptr
-//
-// The csr parameter (method receiver) must be a constant. Other parameter can
-// be any value.
-func (b *builder) emitCSROperation(call *ssa.CallCommon) (llvm.Value, error) {
-	csrConst, ok := call.Args[0].(*ssa.Const)
-	if !ok {
-		return llvm.Value{}, b.makeError(call.Pos(), "CSR must be constant")
-	}
-	csr := csrConst.Uint64()
-	switch name := call.StaticCallee().Name(); name {
-	case "Get":
-		// Note that this instruction may have side effects, and thus must be
-		// marked as such.
-		fnType := llvm.FunctionType(b.uintptrType, nil, false)
-		asm := fmt.Sprintf("csrr $0, %d", csr)
-		target := llvm.InlineAsm(fnType, asm, "=r", true, false, 0)
-		return b.CreateCall(target, nil, ""), nil
-	case "Set":
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.uintptrType}, false)
-		asm := fmt.Sprintf("csrw %d, $0", csr)
-		target := llvm.InlineAsm(fnType, asm, "r", true, false, 0)
-		return b.CreateCall(target, []llvm.Value{b.getValue(call.Args[1])}, ""), nil
-	case "SetBits":
-		// Note: it may be possible to optimize this to csrrsi in many cases.
-		fnType := llvm.FunctionType(b.uintptrType, []llvm.Type{b.uintptrType}, false)
-		asm := fmt.Sprintf("csrrs $0, %d, $1", csr)
-		target := llvm.InlineAsm(fnType, asm, "=r,r", true, false, 0)
-		return b.CreateCall(target, []llvm.Value{b.getValue(call.Args[1])}, ""), nil
-	case "ClearBits":
-		// Note: it may be possible to optimize this to csrrci in many cases.
-		fnType := llvm.FunctionType(b.uintptrType, []llvm.Type{b.uintptrType}, false)
-		asm := fmt.Sprintf("csrrc $0, %d, $1", csr)
-		target := llvm.InlineAsm(fnType, asm, "=r,r", true, false, 0)
-		return b.CreateCall(target, []llvm.Value{b.getValue(call.Args[1])}, ""), nil
-	default:
-		return llvm.Value{}, b.makeError(call.Pos(), "unknown CSR operation: "+name)
-	}
+	return c.builder.CreateCall(target, llvmArgs, ""), nil
 }
@@ -1,4 +1,4 @@
-package transform
+package compiler

 // This file provides function to lower interface intrinsics to their final LLVM
 // form, optimizing them in the process.
@@ -17,10 +17,17 @@ package transform
 //     Replaced with an icmp instruction so it can be directly used in a type
 //     switch. This is very easy to optimize for LLVM: it will often translate a
 //     type switch into a regular switch statement.
+//     When this type assert is not possible (the type is never used in an
+//     interface), this call is replaced with a constant false to optimize the
+//     type assert away completely.
 //
 // interfaceImplements:
 //     This call is translated into a call that checks whether the underlying
 //     type is one of the types implementing this interface.
+//     When there is only one type implementing this interface, the check is
+//     replaced with a simple icmp instruction, just like a type assert.
+//     When there is no type at all that implements this interface, it is
+//     replaced with a constant false to optimize it completely.
 //
 // interfaceMethod:
 //     This call is replaced with a call to a function that calls the
@@ -38,7 +45,6 @@ import (
 	"sort"
 	"strings"

-	"github.com/tinygo-org/tinygo/compiler/llvmutil"
 	"tinygo.org/x/go-llvm"
 )

@@ -134,37 +140,31 @@ func (itf *interfaceInfo) id() string {
 // pass has been implemented as an object type because of its complexity, but
 // should be seen as a regular function call (see LowerInterfaces).
 type lowerInterfacesPass struct {
-	mod         llvm.Module
-	builder     llvm.Builder
-	ctx         llvm.Context
-	uintptrType llvm.Type
-	types       map[string]*typeInfo
-	signatures  map[string]*signatureInfo
-	interfaces  map[string]*interfaceInfo
+	*Compiler
+	types      map[string]*typeInfo
+	signatures map[string]*signatureInfo
+	interfaces map[string]*interfaceInfo
 }

-// LowerInterfaces lowers all intermediate interface calls and globals that are
-// emitted by the compiler as higher-level intrinsics. They need some lowering
-// before LLVM can work on them. This is done so that a few cleanup passes can
-// run before assigning the final type codes.
-func LowerInterfaces(mod llvm.Module) error {
+// Lower all interface functions. They are emitted by the compiler as
+// higher-level intrinsics that need some lowering before LLVM can work on them.
+// This is done so that a few cleanup passes can run before assigning the final
+// type codes.
+func (c *Compiler) LowerInterfaces() {
 	p := &lowerInterfacesPass{
-		mod:         mod,
-		builder:     mod.Context().NewBuilder(),
-		ctx:         mod.Context(),
-		uintptrType: mod.Context().IntType(llvm.NewTargetData(mod.DataLayout()).PointerSize() * 8),
-		types:       make(map[string]*typeInfo),
-		signatures:  make(map[string]*signatureInfo),
-		interfaces:  make(map[string]*interfaceInfo),
+		Compiler:   c,
+		types:      make(map[string]*typeInfo),
+		signatures: make(map[string]*signatureInfo),
+		interfaces: make(map[string]*interfaceInfo),
 	}
-	return p.run()
+	p.run()
 }

 // run runs the pass itself.
-func (p *lowerInterfacesPass) run() error {
+func (p *lowerInterfacesPass) run() {
 	// Collect all type codes.
-	typecodeIDPtr := llvm.PointerType(p.mod.GetTypeByName("runtime.typecodeID"), 0)
-	typeInInterfacePtr := llvm.PointerType(p.mod.GetTypeByName("runtime.typeInInterface"), 0)
+	typecodeIDPtr := llvm.PointerType(p.getLLVMRuntimeType("typecodeID"), 0)
+	typeInInterfacePtr := llvm.PointerType(p.getLLVMRuntimeType("typeInInterface"), 0)
 	var typesInInterfaces []llvm.Value
 	for global := p.mod.FirstGlobal(); !global.IsNil(); global = llvm.NextGlobal(global) {
 		switch global.Type() {
@@ -303,44 +303,44 @@ func (p *lowerInterfacesPass) run() error {
 		} else if len(itf.types) == 1 {
 			// There is only one implementation of the given type.
 			// Call that function directly.
-			err := p.replaceInvokeWithCall(use, itf.types[0], signature)
-			if err != nil {
-				return err
-			}
+			p.replaceInvokeWithCall(use, itf.types[0], signature)
 		} else {
 			// There are multiple types implementing this interface, thus there
 			// are multiple possible functions to call. Delegate calling the
 			// right function to a special wrapper function.
 			inttoptrs := getUses(use)
 			if len(inttoptrs) != 1 || inttoptrs[0].IsAIntToPtrInst().IsNil() {
-				return errorAt(use, "internal error: expected exactly one inttoptr use of runtime.interfaceMethod")
+				panic("expected exactly one inttoptr use of runtime.interfaceMethod")
 			}
 			inttoptr := inttoptrs[0]
 			calls := getUses(inttoptr)
-			for _, call := range calls {
-				// Set up parameters for the call. First copy the regular params...
-				params := make([]llvm.Value, call.OperandsCount())
-				paramTypes := make([]llvm.Type, len(params))
-				for i := 0; i < len(params)-1; i++ {
-					params[i] = call.Operand(i)
-					paramTypes[i] = params[i].Type()
-				}
-				// then add the typecode to the end of the list.
-				params[len(params)-1] = typecode
-				paramTypes[len(params)-1] = p.uintptrType
-
-				// Create a function that redirects the call to the destination
-				// call, after selecting the right concrete type.
-				redirector := p.getInterfaceMethodFunc(itf, signature, call.Type(), paramTypes)
-
-				// Replace the old lookup/inttoptr/call with the new call.
-				p.builder.SetInsertPointBefore(call)
-				retval := p.builder.CreateCall(redirector, append(params, llvm.ConstNull(llvm.PointerType(p.ctx.Int8Type(), 0))), "")
-				if retval.Type().TypeKind() != llvm.VoidTypeKind {
-					call.ReplaceAllUsesWith(retval)
-				}
-				call.EraseFromParentAsInstruction()
+			if len(calls) != 1 || calls[0].IsACallInst().IsNil() {
+				panic("expected exactly one call use of runtime.interfaceMethod")
 			}
+			call := calls[0]
+
+			// Set up parameters for the call. First copy the regular params...
+			params := make([]llvm.Value, call.OperandsCount())
+			paramTypes := make([]llvm.Type, len(params))
+			for i := 0; i < len(params)-1; i++ {
+				params[i] = call.Operand(i)
+				paramTypes[i] = params[i].Type()
+			}
+			// then add the typecode to the end of the list.
+			params[len(params)-1] = typecode
+			paramTypes[len(params)-1] = p.uintptrType
+
+			// Create a function that redirects the call to the destination
+			// call, after selecting the right concrete type.
+			redirector := p.getInterfaceMethodFunc(itf, signature, call.Type(), paramTypes)
+
+			// Replace the old lookup/inttoptr/call with the new call.
+			p.builder.SetInsertPointBefore(call)
+			retval := p.builder.CreateCall(redirector, params, "")
+			if retval.Type().TypeKind() != llvm.VoidTypeKind {
+				call.ReplaceAllUsesWith(retval)
+			}
+			call.EraseFromParentAsInstruction()
 			inttoptr.EraseFromParentAsInstruction()
 			use.EraseFromParentAsInstruction()
 		}
@@ -353,13 +353,32 @@ func (p *lowerInterfacesPass) run() error {

 		methodSet := use.Operand(1).Operand(0) // global variable
 		itf := p.interfaces[methodSet.Name()]
-		// Create a function that does a type switch on all available types
-		// that implement this interface.
-		fn := p.getInterfaceImplementsFunc(itf)
-		p.builder.SetInsertPointBefore(use)
-		commaOk := p.builder.CreateCall(fn, []llvm.Value{actualType}, "typeassert.ok")
-		use.ReplaceAllUsesWith(commaOk)
-		use.EraseFromParentAsInstruction()
+		if len(itf.types) == 0 {
+			// There are no types implementing this interface, so this assert
+			// can never succeed.
+			// Signal this to the optimizer by branching on constant false. It
+			// should remove the "then" block.
+			use.ReplaceAllUsesWith(llvm.ConstInt(p.ctx.Int1Type(), 0, false))
+			use.EraseFromParentAsInstruction()
+		} else if len(itf.types) == 1 {
+			// There is only one type implementing this interface.
+			// Transform this interface assert into comparison against a
+			// constant.
+			p.builder.SetInsertPointBefore(use)
+			assertedType := p.builder.CreatePtrToInt(itf.types[0].typecode, p.uintptrType, "typeassert.typecode")
+			commaOk := p.builder.CreateICmp(llvm.IntEQ, assertedType, actualType, "typeassert.ok")
+			use.ReplaceAllUsesWith(commaOk)
+			use.EraseFromParentAsInstruction()
+		} else {
+			// There are multiple possible types implementing this interface.
+			// Create a function that does a type switch on all available types
+			// that implement this interface.
+			fn := p.getInterfaceImplementsFunc(itf)
+			p.builder.SetInsertPointBefore(use)
+			commaOk := p.builder.CreateCall(fn, []llvm.Value{actualType}, "typeassert.ok")
+			use.ReplaceAllUsesWith(commaOk)
+			use.EraseFromParentAsInstruction()
+		}
 	}

 	// Make a slice of types sorted by frequency of use.
@@ -369,8 +388,13 @@ func (p *lowerInterfacesPass) run() error {
 	}
 	sort.Sort(sort.Reverse(typeSlice))

+	// A type code must fit in 16 bits.
+	if len(typeSlice) >= 1<<16 {
+		panic("typecode does not fit in a uint16: too many types in this program")
+	}
+
 	// Assign a type code for each type.
-	assignTypeCodes(p.mod, typeSlice)
+	p.assignTypeCodes(typeSlice)

 	// Replace each use of a runtime.typeInInterface with the constant type
 	// code.
@@ -387,8 +411,16 @@ func (p *lowerInterfacesPass) run() error {
 	for _, use := range typeAssertUses {
 		actualType := use.Operand(0)
 		assertedTypeGlobal := use.Operand(1)
-		p.builder.SetInsertPointBefore(use)
-		commaOk := p.builder.CreateICmp(llvm.IntEQ, llvm.ConstPtrToInt(assertedTypeGlobal, p.uintptrType), actualType, "typeassert.ok")
+		t := p.types[assertedTypeGlobal.Name()]
+		var commaOk llvm.Value
+		if t.countMakeInterfaces == 0 {
+			// impossible type assert: optimize accordingly
+			commaOk = llvm.ConstInt(p.ctx.Int1Type(), 0, false)
+		} else {
+			// regular type assert
+			p.builder.SetInsertPointBefore(use)
+			commaOk = p.builder.CreateICmp(llvm.IntEQ, llvm.ConstPtrToInt(assertedTypeGlobal, p.uintptrType), actualType, "typeassert.ok")
+		}
 		use.ReplaceAllUsesWith(commaOk)
 		use.EraseFromParentAsInstruction()
 	}
@@ -428,7 +460,6 @@ func (p *lowerInterfacesPass) run() error {
 			typ.methodSet = llvm.Value{}
 		}
 	}
-	return nil
 }

 // addTypeMethods reads the method set of the given type info struct. It
@@ -489,10 +520,10 @@ func (p *lowerInterfacesPass) getSignature(name string) *signatureInfo {
 // replaceInvokeWithCall replaces a runtime.interfaceMethod + inttoptr with a
 // concrete method. This can be done when only one type implements the
 // interface.
-func (p *lowerInterfacesPass) replaceInvokeWithCall(use llvm.Value, typ *typeInfo, signature *signatureInfo) error {
+func (p *lowerInterfacesPass) replaceInvokeWithCall(use llvm.Value, typ *typeInfo, signature *signatureInfo) {
 	inttoptrs := getUses(use)
 	if len(inttoptrs) != 1 || inttoptrs[0].IsAIntToPtrInst().IsNil() {
-		return errorAt(use, "internal error: expected exactly one inttoptr use of runtime.interfaceMethod")
+		panic("expected exactly one inttoptr use of runtime.interfaceMethod")
 	}
 	inttoptr := inttoptrs[0]
 	function := typ.getMethod(signature).function
@@ -507,7 +538,7 @@ func (p *lowerInterfacesPass) replaceInvokeWithCall(use llvm.Value, typ *typeInf
 		// function.
 		for _, call := range getUses(inttoptr) {
 			if call.IsACallInst().IsNil() || call.CalledValue() != inttoptr {
-				return errorAt(call, "internal error: expected the inttoptr to be called as a method, this is not a method call")
+				panic("expected the inttoptr to be called as a method, this is not a method call")
 			}
 			operands := make([]llvm.Value, call.OperandsCount()-1)
 			for i := range operands {
@@ -518,11 +549,11 @@ func (p *lowerInterfacesPass) replaceInvokeWithCall(use llvm.Value, typ *typeInf
 			methodParamTypes := paramTypes[len(paramTypes)-(len(operands)-1):]
 			for i, methodParamType := range methodParamTypes {
 				if methodParamType != operands[i+1].Type() {
-					return errorAt(call, "internal error: expected method call param type and function param type to be the same")
+					panic("expected method call param type and function param type to be the same")
 				}
 			}
 			p.builder.SetInsertPointBefore(call)
-			receiverParams := llvmutil.EmitPointerUnpack(p.builder, p.mod, operands[0], receiverParamTypes)
+			receiverParams := p.emitPointerUnpack(operands[0], receiverParamTypes)
 			result := p.builder.CreateCall(function, append(receiverParams, operands[1:]...), "")
 			if result.Type().TypeKind() != llvm.VoidTypeKind {
 				call.ReplaceAllUsesWith(result)
@@ -532,7 +563,6 @@ func (p *lowerInterfacesPass) replaceInvokeWithCall(use llvm.Value, typ *typeInf
 	}
 	inttoptr.EraseFromParentAsInstruction()
 	use.EraseFromParentAsInstruction()
-	return nil
 }

 // getInterfaceImplementsFunc returns a function that checks whether a given
@@ -610,10 +640,9 @@ func (p *lowerInterfacesPass) getInterfaceMethodFunc(itf *interfaceInfo, signatu
 	// Construct the function name, which is of the form:
 	//     (main.Stringer).String
 	fnName := "(" + itf.id() + ")." + signature.methodName()
-	fnType := llvm.FunctionType(returnType, append(params, llvm.PointerType(p.ctx.Int8Type(), 0)), false)
+	fnType := llvm.FunctionType(returnType, params, false)
 	fn := llvm.AddFunction(p.mod, fnName, fnType)
-	llvm.PrevParam(fn.LastParam()).SetName("actualType")
-	fn.LastParam().SetName("parentHandle")
+	fn.LastParam().SetName("actualType")
 	itf.methodFuncs[signature] = fn
 	return fn
 }
@@ -642,13 +671,13 @@ func (p *lowerInterfacesPass) createInterfaceMethodFunc(itf *interfaceInfo, sign

 	// Create type switch in entry block.
 	p.builder.SetInsertPointAtEnd(entry)
-	actualType := llvm.PrevParam(fn.LastParam())
+	actualType := fn.LastParam()
 	sw := p.builder.CreateSwitch(actualType, defaultBlock, len(itf.types))

 	// Collect the params that will be passed to the functions to call.
 	// These params exclude the receiver (which may actually consist of multiple
 	// parts).
-	params := make([]llvm.Value, fn.ParamsCount()-3)
+	params := make([]llvm.Value, fn.ParamsCount()-2)
 	for i := range params {
 		params[i] = fn.Param(i + 1)
 	}
@@ -16,35 +16,35 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// createMakeInterface emits the LLVM IR for the *ssa.MakeInterface instruction.
+// parseMakeInterface emits the LLVM IR for the *ssa.MakeInterface instruction.
 // It tries to put the type in the interface value, but if that's not possible,
 // it will do an allocation of the right size and put that in the interface
 // value field.
 //
-// An interface value is a {typecode, value} tuple named runtime._interface.
-func (b *builder) createMakeInterface(val llvm.Value, typ types.Type, pos token.Pos) llvm.Value {
-	itfValue := b.emitPointerPack([]llvm.Value{val})
-	itfTypeCodeGlobal := b.getTypeCode(typ)
-	itfMethodSetGlobal := b.getTypeMethodSet(typ)
-	itfConcreteTypeGlobal := b.mod.NamedGlobal("typeInInterface:" + itfTypeCodeGlobal.Name())
+// An interface value is a {typecode, value} tuple, or {i16, i8*} to be exact.
+func (c *Compiler) parseMakeInterface(val llvm.Value, typ types.Type, pos token.Pos) llvm.Value {
+	itfValue := c.emitPointerPack([]llvm.Value{val})
+	itfTypeCodeGlobal := c.getTypeCode(typ)
+	itfMethodSetGlobal := c.getTypeMethodSet(typ)
+	itfConcreteTypeGlobal := c.mod.NamedGlobal("typeInInterface:" + itfTypeCodeGlobal.Name())
 	if itfConcreteTypeGlobal.IsNil() {
-		typeInInterface := b.getLLVMRuntimeType("typeInInterface")
-		itfConcreteTypeGlobal = llvm.AddGlobal(b.mod, typeInInterface, "typeInInterface:"+itfTypeCodeGlobal.Name())
+		typeInInterface := c.getLLVMRuntimeType("typeInInterface")
+		itfConcreteTypeGlobal = llvm.AddGlobal(c.mod, typeInInterface, "typeInInterface:"+itfTypeCodeGlobal.Name())
 		itfConcreteTypeGlobal.SetInitializer(llvm.ConstNamedStruct(typeInInterface, []llvm.Value{itfTypeCodeGlobal, itfMethodSetGlobal}))
 		itfConcreteTypeGlobal.SetGlobalConstant(true)
 		itfConcreteTypeGlobal.SetLinkage(llvm.PrivateLinkage)
 	}
-	itfTypeCode := b.CreatePtrToInt(itfConcreteTypeGlobal, b.uintptrType, "")
-	itf := llvm.Undef(b.getLLVMRuntimeType("_interface"))
-	itf = b.CreateInsertValue(itf, itfTypeCode, 0, "")
-	itf = b.CreateInsertValue(itf, itfValue, 1, "")
+	itfTypeCode := c.builder.CreatePtrToInt(itfConcreteTypeGlobal, c.uintptrType, "")
+	itf := llvm.Undef(c.getLLVMRuntimeType("_interface"))
+	itf = c.builder.CreateInsertValue(itf, itfTypeCode, 0, "")
+	itf = c.builder.CreateInsertValue(itf, itfValue, 1, "")
 	return itf
 }

 // getTypeCode returns a reference to a type code.
 // It returns a pointer to an external global which should be replaced with the
 // real type in the interface lowering pass.
-func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
+func (c *Compiler) getTypeCode(typ types.Type) llvm.Value {
 	globalName := "reflect/types.type:" + getTypeCodeName(typ)
 	global := c.mod.NamedGlobal(globalName)
 	if global.IsNil() {
@@ -74,7 +74,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 		}
 		if !references.IsNil() {
 			// Set the 'references' field of the runtime.typecodeID struct.
-			globalValue := llvm.ConstNull(global.Type().ElementType())
+			globalValue := c.getZeroValue(global.Type().ElementType())
 			globalValue = llvm.ConstInsertValue(globalValue, references, []uint32{0})
 			if length != 0 {
 				lengthValue := llvm.ConstInt(c.uintptrType, uint64(length), false)
@@ -91,14 +91,14 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 // makeStructTypeFields creates a new global that stores all type information
 // related to this struct type, and returns the resulting global. This global is
 // actually an array of all the fields in the structs.
-func (c *compilerContext) makeStructTypeFields(typ *types.Struct) llvm.Value {
+func (c *Compiler) makeStructTypeFields(typ *types.Struct) llvm.Value {
 	// The global is an array of runtime.structField structs.
 	runtimeStructField := c.getLLVMRuntimeType("structField")
 	structGlobalType := llvm.ArrayType(runtimeStructField, typ.NumFields())
 	structGlobal := llvm.AddGlobal(c.mod, structGlobalType, "reflect/types.structFields")
-	structGlobalValue := llvm.ConstNull(structGlobalType)
+	structGlobalValue := c.getZeroValue(structGlobalType)
 	for i := 0; i < typ.NumFields(); i++ {
-		fieldGlobalValue := llvm.ConstNull(runtimeStructField)
+		fieldGlobalValue := c.getZeroValue(runtimeStructField)
 		fieldGlobalValue = llvm.ConstInsertValue(fieldGlobalValue, c.getTypeCode(typ.Field(i).Type()), []uint32{0})
 		fieldName := c.makeGlobalArray([]byte(typ.Field(i).Name()), "reflect/types.structFieldName", c.ctx.Int8Type())
 		fieldName.SetLinkage(llvm.PrivateLinkage)
@@ -210,6 +210,10 @@ func getTypeCodeName(t types.Type) string {
 		return "slice:" + getTypeCodeName(t.Elem())
 	case *types.Struct:
 		elems := make([]string, t.NumFields())
+		if t.NumFields() > 2 && t.Field(0).Name() == "C union" {
+			// TODO: report this as a normal error instead of panicking.
+			panic("cgo unions are not allowed in interfaces")
+		}
 		for i := 0; i < t.NumFields(); i++ {
 			embedded := ""
 			if t.Field(i).Embedded() {
@@ -228,7 +232,7 @@ func getTypeCodeName(t types.Type) string {

 // getTypeMethodSet returns a reference (GEP) to a global method set. This
 // method set should be unreferenced after the interface lowering pass.
-func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
+func (c *Compiler) getTypeMethodSet(typ types.Type) llvm.Value {
 	global := c.mod.NamedGlobal(typ.String() + "$methodset")
 	zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 	if !global.IsNil() {
@@ -271,28 +275,23 @@ func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
 // getInterfaceMethodSet returns a global variable with the method set of the
 // given named interface type. This method set is used by the interface lowering
 // pass.
-func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
-	name := typ.String()
-	if _, ok := typ.(*types.Named); !ok {
-		// Anonymous interface.
-		name = "reflect/types.interface:" + name
-	}
-	global := c.mod.NamedGlobal(name + "$interface")
+func (c *Compiler) getInterfaceMethodSet(typ *types.Named) llvm.Value {
+	global := c.mod.NamedGlobal(typ.String() + "$interface")
 	zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 	if !global.IsNil() {
 		// method set already exist, return it
 		return llvm.ConstGEP(global, []llvm.Value{zero, zero})
 	}

-	// Every method is a *i8 reference indicating the signature of this method.
+	// Every method is a *i16 reference indicating the signature of this method.
 	methods := make([]llvm.Value, typ.Underlying().(*types.Interface).NumMethods())
 	for i := range methods {
 		method := typ.Underlying().(*types.Interface).Method(i)
 		methods[i] = c.getMethodSignature(method)
 	}

-	value := llvm.ConstArray(c.i8ptrType, methods)
-	global = llvm.AddGlobal(c.mod, value.Type(), name+"$interface")
+	value := llvm.ConstArray(methods[0].Type(), methods)
+	global = llvm.AddGlobal(c.mod, value.Type(), typ.String()+"$interface")
 	global.SetInitializer(value)
 	global.SetGlobalConstant(true)
 	global.SetLinkage(llvm.PrivateLinkage)
@@ -300,9 +299,9 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 }

 // getMethodSignature returns a global variable which is a reference to an
-// external *i8 indicating the indicating the signature of this method. It is
+// external *i16 indicating the indicating the signature of this method. It is
 // used during the interface lowering pass.
-func (c *compilerContext) getMethodSignature(method *types.Func) llvm.Value {
+func (c *Compiler) getMethodSignature(method *types.Func) llvm.Value {
 	signature := ir.MethodSignature(method)
 	signatureGlobal := c.mod.NamedGlobal("func " + signature)
 	if signatureGlobal.IsNil() {
@@ -312,18 +311,18 @@ func (c *compilerContext) getMethodSignature(method *types.Func) llvm.Value {
 	return signatureGlobal
 }

-// createTypeAssert will emit the code for a typeassert, used in if statements
+// parseTypeAssert will emit the code for a typeassert, used in if statements
 // and in type switches (Go SSA does not have type switches, only if/else
 // chains). Note that even though the Go SSA does not contain type switches,
 // LLVM will recognize the pattern and make it a real switch in many cases.
 //
 // Type asserts on concrete types are trivial: just compare type numbers. Type
 // asserts on interfaces are more difficult, see the comments in the function.
-func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
-	itf := b.getValue(expr.X)
-	assertedType := b.getLLVMType(expr.AssertedType)
+func (c *Compiler) parseTypeAssert(frame *Frame, expr *ssa.TypeAssert) llvm.Value {
+	itf := c.getValue(frame, expr.X)
+	assertedType := c.getLLVMType(expr.AssertedType)

-	actualTypeNum := b.CreateExtractValue(itf, 0, "interface.type")
+	actualTypeNum := c.builder.CreateExtractValue(itf, 0, "interface.type")
 	commaOk := llvm.Value{}
 	if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
 		// Type assert on interface type.
@@ -334,15 +333,15 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 		// the main Go compiler, where the runtime checks whether the type
 		// implements each method of the interface. See:
 		// https://research.swtch.com/interfaces
-		methodSet := b.getInterfaceMethodSet(expr.AssertedType)
-		commaOk = b.createRuntimeCall("interfaceImplements", []llvm.Value{actualTypeNum, methodSet}, "")
+		methodSet := c.getInterfaceMethodSet(expr.AssertedType.(*types.Named))
+		commaOk = c.createRuntimeCall("interfaceImplements", []llvm.Value{actualTypeNum, methodSet}, "")

 	} else {
 		// Type assert on concrete type.
 		// Call runtime.typeAssert, which will be lowered to a simple icmp or
 		// const false in the interface lowering pass.
-		assertedTypeCodeGlobal := b.getTypeCode(expr.AssertedType)
-		commaOk = b.createRuntimeCall("typeAssert", []llvm.Value{actualTypeNum, assertedTypeCodeGlobal}, "typecode")
+		assertedTypeCodeGlobal := c.getTypeCode(expr.AssertedType)
+		commaOk = c.createRuntimeCall("typeAssert", []llvm.Value{actualTypeNum, assertedTypeCodeGlobal}, "typecode")
 	}

 	// Add 2 new basic blocks (that should get optimized away): one for the
@@ -356,15 +355,15 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 	// typeassert should return a zero value, not an incorrectly casted
 	// value.

-	prevBlock := b.GetInsertBlock()
-	okBlock := b.ctx.AddBasicBlock(b.fn.LLVMFn, "typeassert.ok")
-	nextBlock := b.ctx.AddBasicBlock(b.fn.LLVMFn, "typeassert.next")
-	b.blockExits[b.currentBlock] = nextBlock // adjust outgoing block for phi nodes
-	b.CreateCondBr(commaOk, okBlock, nextBlock)
+	prevBlock := c.builder.GetInsertBlock()
+	okBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "typeassert.ok")
+	nextBlock := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "typeassert.next")
+	frame.blockExits[frame.currentBlock] = nextBlock // adjust outgoing block for phi nodes
+	c.builder.CreateCondBr(commaOk, okBlock, nextBlock)

 	// Retrieve the value from the interface if the type assert was
 	// successful.
-	b.SetInsertPointAtEnd(okBlock)
+	c.builder.SetInsertPointAtEnd(okBlock)
 	var valueOk llvm.Value
 	if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
 		// Type assert on interface type. Easy: just return the same
@@ -373,70 +372,74 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 	} else {
 		// Type assert on concrete type. Extract the underlying type from
 		// the interface (but only after checking it matches).
-		valuePtr := b.CreateExtractValue(itf, 1, "typeassert.value.ptr")
-		valueOk = b.emitPointerUnpack(valuePtr, []llvm.Type{assertedType})[0]
+		valuePtr := c.builder.CreateExtractValue(itf, 1, "typeassert.value.ptr")
+		valueOk = c.emitPointerUnpack(valuePtr, []llvm.Type{assertedType})[0]
 	}
-	b.CreateBr(nextBlock)
+	c.builder.CreateBr(nextBlock)

 	// Continue after the if statement.
-	b.SetInsertPointAtEnd(nextBlock)
-	phi := b.CreatePHI(assertedType, "typeassert.value")
-	phi.AddIncoming([]llvm.Value{llvm.ConstNull(assertedType), valueOk}, []llvm.BasicBlock{prevBlock, okBlock})
+	c.builder.SetInsertPointAtEnd(nextBlock)
+	phi := c.builder.CreatePHI(assertedType, "typeassert.value")
+	phi.AddIncoming([]llvm.Value{c.getZeroValue(assertedType), valueOk}, []llvm.BasicBlock{prevBlock, okBlock})

 	if expr.CommaOk {
-		tuple := b.ctx.ConstStruct([]llvm.Value{llvm.Undef(assertedType), llvm.Undef(b.ctx.Int1Type())}, false) // create empty tuple
-		tuple = b.CreateInsertValue(tuple, phi, 0, "")                                                          // insert value
-		tuple = b.CreateInsertValue(tuple, commaOk, 1, "")                                                      // insert 'comma ok' boolean
+		tuple := c.ctx.ConstStruct([]llvm.Value{llvm.Undef(assertedType), llvm.Undef(c.ctx.Int1Type())}, false) // create empty tuple
+		tuple = c.builder.CreateInsertValue(tuple, phi, 0, "")                                                  // insert value
+		tuple = c.builder.CreateInsertValue(tuple, commaOk, 1, "")                                              // insert 'comma ok' boolean
 		return tuple
 	} else {
 		// This is kind of dirty as the branch above becomes mostly useless,
 		// but hopefully this gets optimized away.
-		b.createRuntimeCall("interfaceTypeAssert", []llvm.Value{commaOk}, "")
+		c.createRuntimeCall("interfaceTypeAssert", []llvm.Value{commaOk}, "")
 		return phi
 	}
 }

-// getInvokePtr creates an interface function pointer lookup for the specified invoke instruction, using a specified typecode.
-func (b *builder) getInvokePtr(instr *ssa.CallCommon, typecode llvm.Value) llvm.Value {
-	llvmFnType := b.getRawFuncType(instr.Method.Type().(*types.Signature))
+// getInvokeCall creates and returns the function pointer and parameters of an
+// interface call. It can be used in a call or defer instruction.
+func (c *Compiler) getInvokeCall(frame *Frame, instr *ssa.CallCommon) (llvm.Value, []llvm.Value) {
+	// Call an interface method with dynamic dispatch.
+	itf := c.getValue(frame, instr.Value) // interface
+
+	llvmFnType := c.getRawFuncType(instr.Method.Type().(*types.Signature))
+
+	typecode := c.builder.CreateExtractValue(itf, 0, "invoke.typecode")
 	values := []llvm.Value{
 		typecode,
-		b.getInterfaceMethodSet(instr.Value.Type()),
-		b.getMethodSignature(instr.Method),
+		c.getInterfaceMethodSet(instr.Value.Type().(*types.Named)),
+		c.getMethodSignature(instr.Method),
 	}
-	fn := b.createRuntimeCall("interfaceMethod", values, "invoke.func")
-	return b.CreateIntToPtr(fn, llvmFnType, "invoke.func.cast")
-}
-
-// getInvokeCall creates and returns the function pointer and parameters of an
-// interface call.
-func (b *builder) getInvokeCall(instr *ssa.CallCommon) (llvm.Value, []llvm.Value) {
-	// Call an interface method with dynamic dispatch.
-	itf := b.getValue(instr.Value) // interface
-
-	typecode := b.CreateExtractValue(itf, 0, "invoke.typecode")
-	fnCast := b.getInvokePtr(instr, typecode)
-	receiverValue := b.CreateExtractValue(itf, 1, "invoke.func.receiver")
+	fn := c.createRuntimeCall("interfaceMethod", values, "invoke.func")
+	fnCast := c.builder.CreateIntToPtr(fn, llvmFnType, "invoke.func.cast")
+	receiverValue := c.builder.CreateExtractValue(itf, 1, "invoke.func.receiver")

 	args := []llvm.Value{receiverValue}
 	for _, arg := range instr.Args {
-		args = append(args, b.getValue(arg))
+		args = append(args, c.getValue(frame, arg))
 	}
 	// Add the context parameter. An interface call never takes a context but we
 	// have to supply the parameter anyway.
-	args = append(args, llvm.Undef(b.i8ptrType))
+	args = append(args, llvm.Undef(c.i8ptrType))
 	// Add the parent goroutine handle.
-	args = append(args, llvm.Undef(b.i8ptrType))
+	args = append(args, llvm.Undef(c.i8ptrType))

 	return fnCast, args
 }

-// getInterfaceInvokeWrapper returns a wrapper for the given method so it can be
-// invoked from an interface. The wrapper takes in a pointer to the underlying
-// value, dereferences or unpacks it if necessary, and calls the real method.
-// If the method to wrap has a pointer receiver, no wrapping is necessary and
-// the function is returned directly.
-func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
+// interfaceInvokeWrapper keeps some state between getInterfaceInvokeWrapper and
+// createInterfaceInvokeWrapper. The former is called during IR construction
+// itself and the latter is called when finishing up the IR.
+type interfaceInvokeWrapper struct {
+	fn           *ir.Function
+	wrapper      llvm.Value
+	receiverType llvm.Type
+}
+
+// Wrap an interface method function pointer. The wrapper takes in a pointer to
+// the underlying value, dereferences it, and calls the real method. This
+// wrapper is only needed when the interface value actually doesn't fit in a
+// pointer and a pointer to the value must be created.
+func (c *Compiler) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
 	wrapperName := f.LinkName() + "$invoke"
 	wrapper := c.mod.NamedFunction(wrapperName)
 	if !wrapper.IsNil() {
@@ -446,10 +449,7 @@ func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {

 	// Get the expanded receiver type.
 	receiverType := c.getLLVMType(f.Params[0].Type())
-	var expandedReceiverType []llvm.Type
-	for _, info := range expandFormalParamType(receiverType, "", nil) {
-		expandedReceiverType = append(expandedReceiverType, info.llvmType)
-	}
+	expandedReceiverType := c.expandFormalParamType(receiverType)

 	// Does this method even need any wrapping?
 	if len(expandedReceiverType) == 1 && receiverType.TypeKind() == llvm.PointerTypeKind {
@@ -465,40 +465,41 @@ func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
 	paramTypes := append([]llvm.Type{c.i8ptrType}, fnType.ParamTypes()[len(expandedReceiverType):]...)
 	wrapFnType := llvm.FunctionType(fnType.ReturnType(), paramTypes, false)
 	wrapper = llvm.AddFunction(c.mod, wrapperName, wrapFnType)
-	if f.LLVMFn.LastParam().Name() == "parentHandle" {
-		wrapper.LastParam().SetName("parentHandle")
-	}
+	c.interfaceInvokeWrappers = append(c.interfaceInvokeWrappers, interfaceInvokeWrapper{
+		fn:           f,
+		wrapper:      wrapper,
+		receiverType: receiverType,
+	})
+	return wrapper
+}

+// createInterfaceInvokeWrapper finishes the work of getInterfaceInvokeWrapper,
+// see that function for details.
+func (c *Compiler) createInterfaceInvokeWrapper(state interfaceInvokeWrapper) {
+	wrapper := state.wrapper
+	fn := state.fn
+	receiverType := state.receiverType
 	wrapper.SetLinkage(llvm.InternalLinkage)
 	wrapper.SetUnnamedAddr(true)

-	// Create a new builder just to create this wrapper.
-	b := builder{
-		compilerContext: c,
-		Builder:         c.ctx.NewBuilder(),
-	}
-	defer b.Builder.Dispose()
-
 	// add debug info if needed
-	if c.Debug() {
-		pos := c.ir.Program.Fset.Position(f.Pos())
-		difunc := c.attachDebugInfoRaw(f, wrapper, "$invoke", pos.Filename, pos.Line)
-		b.SetCurrentDebugLocation(uint(pos.Line), uint(pos.Column), difunc, llvm.Metadata{})
+	if c.Debug {
+		pos := c.ir.Program.Fset.Position(fn.Pos())
+		difunc := c.attachDebugInfoRaw(fn, wrapper, "$invoke", pos.Filename, pos.Line)
+		c.builder.SetCurrentDebugLocation(uint(pos.Line), uint(pos.Column), difunc, llvm.Metadata{})
 	}

 	// set up IR builder
-	block := b.ctx.AddBasicBlock(wrapper, "entry")
-	b.SetInsertPointAtEnd(block)
+	block := c.ctx.AddBasicBlock(wrapper, "entry")
+	c.builder.SetInsertPointAtEnd(block)

-	receiverValue := b.emitPointerUnpack(wrapper.Param(0), []llvm.Type{receiverType})[0]
-	params := append(b.expandFormalParam(receiverValue), wrapper.Params()[1:]...)
-	if f.LLVMFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
-		b.CreateCall(f.LLVMFn, params, "")
-		b.CreateRetVoid()
+	receiverValue := c.emitPointerUnpack(wrapper.Param(0), []llvm.Type{receiverType})[0]
+	params := append(c.expandFormalParam(receiverValue), wrapper.Params()[1:]...)
+	if fn.LLVMFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
+		c.builder.CreateCall(fn.LLVMFn, params, "")
+		c.builder.CreateRetVoid()
 	} else {
-		ret := b.CreateCall(f.LLVMFn, params, "ret")
-		b.CreateRet(ret)
+		ret := c.builder.CreateCall(fn.LLVMFn, params, "ret")
+		c.builder.CreateRet(ret)
 	}
-
-	return wrapper
 }
@@ -1,92 +0,0 @@
-package compiler
-
-import (
-	"strconv"
-	"strings"
-
-	"golang.org/x/tools/go/ssa"
-	"tinygo.org/x/go-llvm"
-)
-
-// createInterruptGlobal creates a new runtime/interrupt.Interrupt struct that
-// will be lowered to a real interrupt during interrupt lowering.
-//
-// This two-stage approach allows unused interrupts to be optimized away if
-// necessary.
-func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, error) {
-	// Get the interrupt number, which must be a compile-time constant.
-	id, ok := instr.Args[0].(*ssa.Const)
-	if !ok {
-		return llvm.Value{}, b.makeError(instr.Pos(), "interrupt ID is not a constant")
-	}
-
-	// Get the func value, which also must be a compile time constant.
-	// Note that bound functions are allowed if the function has a pointer
-	// receiver and is a global. This is rather strict but still allows for
-	// idiomatic Go code.
-	funcValue := b.getValue(instr.Args[1])
-	if funcValue.IsAConstant().IsNil() {
-		// Try to determine the cause of the non-constantness for a nice error
-		// message.
-		switch instr.Args[1].(type) {
-		case *ssa.MakeClosure:
-			// This may also be a bound method.
-			return llvm.Value{}, b.makeError(instr.Pos(), "closures are not supported in interrupt.New")
-		}
-		// Fall back to a generic error.
-		return llvm.Value{}, b.makeError(instr.Pos(), "interrupt function must be constant")
-	}
-
-	// Create a new global of type runtime/interrupt.handle. Globals of this
-	// type are lowered in the interrupt lowering pass.
-	globalType := b.ir.Program.ImportedPackage("runtime/interrupt").Type("handle").Type()
-	globalLLVMType := b.getLLVMType(globalType)
-	globalName := "runtime/interrupt.$interrupt" + strconv.FormatInt(id.Int64(), 10)
-	if global := b.mod.NamedGlobal(globalName); !global.IsNil() {
-		return llvm.Value{}, b.makeError(instr.Pos(), "interrupt redeclared in this program")
-	}
-	global := llvm.AddGlobal(b.mod, globalLLVMType, globalName)
-	global.SetLinkage(llvm.PrivateLinkage)
-	global.SetGlobalConstant(true)
-	global.SetUnnamedAddr(true)
-	initializer := llvm.ConstNull(globalLLVMType)
-	initializer = llvm.ConstInsertValue(initializer, funcValue, []uint32{0})
-	initializer = llvm.ConstInsertValue(initializer, llvm.ConstInt(b.intType, uint64(id.Int64()), true), []uint32{1, 0})
-	global.SetInitializer(initializer)
-
-	// Add debug info to the interrupt global.
-	if b.Debug() {
-		pos := b.ir.Program.Fset.Position(instr.Pos())
-		diglobal := b.dibuilder.CreateGlobalVariableExpression(b.getDIFile(pos.Filename), llvm.DIGlobalVariableExpression{
-			Name:        "interrupt" + strconv.FormatInt(id.Int64(), 10),
-			LinkageName: globalName,
-			File:        b.getDIFile(pos.Filename),
-			Line:        pos.Line,
-			Type:        b.getDIType(globalType),
-			Expr:        b.dibuilder.CreateExpression(nil),
-			LocalToUnit: false,
-		})
-		global.AddMetadata(0, diglobal)
-	}
-
-	// Create the runtime/interrupt.Interrupt type. It is a struct with a single
-	// member of type int.
-	num := llvm.ConstPtrToInt(global, b.intType)
-	interrupt := llvm.ConstNamedStruct(b.mod.GetTypeByName("runtime/interrupt.Interrupt"), []llvm.Value{num})
-
-	// Add dummy "use" call for AVR, because interrupts may be used even though
-	// they are never referenced again. This is unlike Cortex-M or the RISC-V
-	// PLIC where each interrupt must be enabled using the interrupt number, and
-	// thus keeps the Interrupt object alive.
-	// This call is removed during interrupt lowering.
-	if strings.HasPrefix(b.Triple(), "avr") {
-		useFn := b.mod.NamedFunction("runtime/interrupt.use")
-		if useFn.IsNil() {
-			useFnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{interrupt.Type()}, false)
-			useFn = llvm.AddFunction(b.mod, "runtime/interrupt.use", useFnType)
-		}
-		b.CreateCall(useFn, []llvm.Value{interrupt}, "")
-	}
-
-	return interrupt, nil
-}
@@ -1,50 +0,0 @@
-package compiler
-
-// This file contains helper functions to create calls to LLVM intrinsics.
-
-import (
-	"strconv"
-
-	"golang.org/x/tools/go/ssa"
-	"tinygo.org/x/go-llvm"
-)
-
-// createMemoryCopyCall creates a call to a builtin LLVM memcpy or memmove
-// function, declaring this function if needed. These calls are treated
-// specially by optimization passes possibly resulting in better generated code,
-// and will otherwise be lowered to regular libc memcpy/memmove calls.
-func (b *builder) createMemoryCopyCall(fn *ssa.Function, args []ssa.Value) (llvm.Value, error) {
-	fnName := "llvm." + fn.Name() + ".p0i8.p0i8.i" + strconv.Itoa(b.uintptrType.IntTypeWidth())
-	llvmFn := b.mod.NamedFunction(fnName)
-	if llvmFn.IsNil() {
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.i8ptrType, b.i8ptrType, b.uintptrType, b.ctx.Int1Type()}, false)
-		llvmFn = llvm.AddFunction(b.mod, fnName, fnType)
-	}
-	var params []llvm.Value
-	for _, param := range args {
-		params = append(params, b.getValue(param))
-	}
-	params = append(params, llvm.ConstInt(b.ctx.Int1Type(), 0, false))
-	b.CreateCall(llvmFn, params, "")
-	return llvm.Value{}, nil
-}
-
-// createMemoryZeroCall creates calls to llvm.memset.* to zero a block of
-// memory, declaring the function if needed. These calls will be lowered to
-// regular libc memset calls if they aren't optimized out in a different way.
-func (b *builder) createMemoryZeroCall(args []ssa.Value) (llvm.Value, error) {
-	fnName := "llvm.memset.p0i8.i" + strconv.Itoa(b.uintptrType.IntTypeWidth())
-	llvmFn := b.mod.NamedFunction(fnName)
-	if llvmFn.IsNil() {
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.i8ptrType, b.ctx.Int8Type(), b.uintptrType, b.ctx.Int1Type()}, false)
-		llvmFn = llvm.AddFunction(b.mod, fnName, fnType)
-	}
-	params := []llvm.Value{
-		b.getValue(args[0]),
-		llvm.ConstInt(b.ctx.Int8Type(), 0, false),
-		b.getValue(args[1]),
-		llvm.ConstInt(b.ctx.Int1Type(), 0, false),
-	}
-	b.CreateCall(llvmFn, params, "")
-	return llvm.Value{}, nil
-}
@@ -1,194 +0,0 @@
-// Package ircheck implements a checker for LLVM IR, that goes a bit further
-// than the regular LLVM IR verifier. Note that it checks different things, so
-// this is not a replacement for the LLVM verifier but does catch things that
-// the LLVM verifier doesn't catch.
-package ircheck
-
-import (
-	"errors"
-	"fmt"
-
-	"tinygo.org/x/go-llvm"
-)
-
-type checker struct {
-	ctx llvm.Context
-}
-
-func (c *checker) checkType(t llvm.Type, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
-	// prevent infinite recursion for self-referential types
-	if _, ok := checked[t]; ok {
-		return nil
-	}
-	checked[t] = struct{}{}
-
-	// check for any context mismatches
-	switch {
-	case t.Context() == c.ctx:
-		// this is correct
-	case t.Context() == llvm.GlobalContext():
-		// somewhere we accidentally used the global context instead of a real context
-		return fmt.Errorf("type %q uses global context", t.String())
-	default:
-		// we used some other context by accident
-		return fmt.Errorf("type %q uses context %v instead of the main context %v", t.Context(), c.ctx)
-	}
-
-	// if this is a composite type, check the components of the type
-	switch t.TypeKind() {
-	case llvm.VoidTypeKind, llvm.LabelTypeKind, llvm.TokenTypeKind, llvm.MetadataTypeKind:
-		// there should only be one of any of these
-		if s, ok := specials[t.TypeKind()]; !ok {
-			specials[t.TypeKind()] = t
-		} else if s != t {
-			return fmt.Errorf("duplicate special type %q: %v and %v", t.TypeKind().String(), t, s)
-		}
-	case llvm.FloatTypeKind, llvm.DoubleTypeKind, llvm.X86_FP80TypeKind, llvm.FP128TypeKind, llvm.PPC_FP128TypeKind:
-		// floating point numbers are primitives - nothing to recurse
-	case llvm.IntegerTypeKind:
-		// integers are primitives - nothing to recurse
-	case llvm.FunctionTypeKind:
-		// check arguments and return(s)
-		for i, v := range t.ParamTypes() {
-			if err := c.checkType(v, checked, specials); err != nil {
-				return fmt.Errorf("failed to verify argument %d of type %s: %s", i, t.String(), err.Error())
-			}
-		}
-		if err := c.checkType(t.ReturnType(), checked, specials); err != nil {
-			return fmt.Errorf("failed to verify return type of type %s: %s", t.String(), err.Error())
-		}
-	case llvm.StructTypeKind:
-		// check all elements
-		for i, v := range t.StructElementTypes() {
-			if err := c.checkType(v, checked, specials); err != nil {
-				return fmt.Errorf("failed to verify type of field %d of struct type %s: %s", i, t.String(), err.Error())
-			}
-		}
-	case llvm.ArrayTypeKind:
-		// check element type
-		if err := c.checkType(t.ElementType(), checked, specials); err != nil {
-			return fmt.Errorf("failed to verify element type of array type %s: %s", t.String(), err.Error())
-		}
-	case llvm.PointerTypeKind:
-		// check underlying type
-		if err := c.checkType(t.ElementType(), checked, specials); err != nil {
-			return fmt.Errorf("failed to verify underlying type of pointer type %s: %s", t.String(), err.Error())
-		}
-	case llvm.VectorTypeKind:
-		// check element type
-		if err := c.checkType(t.ElementType(), checked, specials); err != nil {
-			return fmt.Errorf("failed to verify element type of vector type %s: %s", t.String(), err.Error())
-		}
-	default:
-		return fmt.Errorf("unrecognized kind %q of type %s", t.TypeKind(), t.String())
-	}
-
-	return nil
-}
-
-func (c *checker) checkValue(v llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
-	// check type
-	if err := c.checkType(v.Type(), types, specials); err != nil {
-		return fmt.Errorf("failed to verify type of value: %s", err.Error())
-	}
-
-	// check if this is an undefined void
-	if v.IsUndef() && v.Type().TypeKind() == llvm.VoidTypeKind {
-		return errors.New("encountered undefined void value")
-	}
-
-	return nil
-}
-
-func (c *checker) checkInstruction(inst llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
-	// check value properties
-	if err := c.checkValue(inst, types, specials); err != nil {
-		return errorAt(inst, err.Error())
-	}
-
-	// The alloca instruction can be present in every basic block. However,
-	// allocas in basic blocks other than the entry basic block have a number of
-	// problems:
-	//   * They are hard to optimize, leading to potential missed optimizations.
-	//   * They may cause stack overflows in loops that would otherwise be
-	//     innocent.
-	//   * They cause extra code to be generated, because it requires the use of
-	//     a frame pointer.
-	//   * Perhaps most importantly, the coroutine lowering pass of LLVM (as of
-	//     LLVM 9) cannot deal with these allocas:
-	//     https://llvm.org/docs/Coroutines.html
-	// Therefore, alloca instructions should be limited to the entry block.
-	if !inst.IsAAllocaInst().IsNil() {
-		if inst.InstructionParent() != inst.InstructionParent().Parent().EntryBasicBlock() {
-			return errorAt(inst, "internal error: non-static alloca")
-		}
-	}
-
-	// check operands
-	for i := 0; i < inst.OperandsCount(); i++ {
-		if err := c.checkValue(inst.Operand(i), types, specials); err != nil {
-			return errorAt(inst, fmt.Sprintf("failed to validate operand %d of instruction %q: %s", i, inst.Name(), err.Error()))
-		}
-	}
-
-	return nil
-}
-
-func (c *checker) checkBasicBlock(bb llvm.BasicBlock, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) []error {
-	// check basic block value and type
-	var errs []error
-	if err := c.checkValue(bb.AsValue(), types, specials); err != nil {
-		errs = append(errs, errorAt(bb.Parent(), fmt.Sprintf("failed to validate value of basic block %s: %v", bb.AsValue().Name(), err)))
-	}
-
-	// check instructions
-	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
-		if err := c.checkInstruction(inst, types, specials); err != nil {
-			errs = append(errs, err)
-		}
-	}
-
-	return errs
-}
-
-func (c *checker) checkFunction(fn llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) []error {
-	// check function value and type
-	var errs []error
-	if err := c.checkValue(fn, types, specials); err != nil {
-		errs = append(errs, fmt.Errorf("failed to validate value of function %s: %s", fn.Name(), err.Error()))
-	}
-
-	// check basic blocks
-	for bb := fn.FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
-		errs = append(errs, c.checkBasicBlock(bb, types, specials)...)
-	}
-
-	return errs
-}
-
-// Module checks the given module and returns a slice of error, if there are
-// any.
-func Module(mod llvm.Module) []error {
-	// check for any context mismatches
-	var errs []error
-	c := checker{
-		ctx: mod.Context(),
-	}
-	if c.ctx == llvm.GlobalContext() {
-		// somewhere we accidentally used the global context instead of a real context
-		errs = append(errs, errors.New("module uses global context"))
-	}
-
-	types := map[llvm.Type]struct{}{}
-	specials := map[llvm.TypeKind]llvm.Type{}
-	for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-		errs = append(errs, c.checkFunction(fn, types, specials)...)
-	}
-	for g := mod.FirstGlobal(); !g.IsNil(); g = llvm.NextGlobal(g) {
-		if err := c.checkValue(g, types, specials); err != nil {
-			errs = append(errs, fmt.Errorf("failed to verify global %s of module: %s", g.Name(), err.Error()))
-		}
-	}
-
-	return errs
-}
@@ -1,48 +0,0 @@
-package ircheck
-
-import (
-	"go/scanner"
-	"go/token"
-	"path/filepath"
-
-	"tinygo.org/x/go-llvm"
-)
-
-// errorAt returns an error value at the location of the instruction.
-// The location information may not be complete as it depends on debug
-// information in the IR.
-func errorAt(inst llvm.Value, msg string) scanner.Error {
-	return scanner.Error{
-		Pos: getPosition(inst),
-		Msg: msg,
-	}
-}
-
-// getPosition returns the position information for the given value, as far as
-// it is available.
-func getPosition(val llvm.Value) token.Position {
-	if !val.IsAInstruction().IsNil() {
-		loc := val.InstructionDebugLoc()
-		if loc.IsNil() {
-			return token.Position{}
-		}
-		file := loc.LocationScope().ScopeFile()
-		return token.Position{
-			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-			Line:     int(loc.LocationLine()),
-			Column:   int(loc.LocationColumn()),
-		}
-	} else if !val.IsAFunction().IsNil() {
-		loc := val.Subprogram()
-		if loc.IsNil() {
-			return token.Position{}
-		}
-		file := loc.ScopeFile()
-		return token.Position{
-			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-			Line:     int(loc.SubprogramLine()),
-		}
-	} else {
-		return token.Position{}
-	}
-}
@@ -1,7 +1,8 @@
 package compiler

 import (
-	"github.com/tinygo-org/tinygo/compiler/llvmutil"
+	"reflect"
+
 	"tinygo.org/x/go-llvm"
 )

@@ -23,47 +24,178 @@ func getUses(value llvm.Value) []llvm.Value {
 	return uses
 }

+// createEntryBlockAlloca creates a new alloca in the entry block, even though
+// the IR builder is located elsewhere. It assumes that the insert point is
+// at the end of the current block.
+func (c *Compiler) createEntryBlockAlloca(t llvm.Type, name string) llvm.Value {
+	currentBlock := c.builder.GetInsertBlock()
+	entryBlock := currentBlock.Parent().EntryBasicBlock()
+	if entryBlock.FirstInstruction().IsNil() {
+		c.builder.SetInsertPointAtEnd(entryBlock)
+	} else {
+		c.builder.SetInsertPointBefore(entryBlock.FirstInstruction())
+	}
+	alloca := c.builder.CreateAlloca(t, name)
+	c.builder.SetInsertPointAtEnd(currentBlock)
+	return alloca
+}
+
 // createTemporaryAlloca creates a new alloca in the entry block and adds
-// lifetime start information in the IR signalling that the alloca won't be used
+// lifetime start infromation in the IR signalling that the alloca won't be used
 // before this point.
 //
 // This is useful for creating temporary allocas for intrinsics. Don't forget to
 // end the lifetime using emitLifetimeEnd after you're done with it.
-func (b *builder) createTemporaryAlloca(t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
-	return llvmutil.CreateTemporaryAlloca(b.Builder, b.mod, t, name)
+func (c *Compiler) createTemporaryAlloca(t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
+	alloca = c.createEntryBlockAlloca(t, name)
+	bitcast = c.builder.CreateBitCast(alloca, c.i8ptrType, name+".bitcast")
+	size = llvm.ConstInt(c.ctx.Int64Type(), c.targetData.TypeAllocSize(t), false)
+	c.builder.CreateCall(c.getLifetimeStartFunc(), []llvm.Value{size, bitcast}, "")
+	return
 }

 // emitLifetimeEnd signals the end of an (alloca) lifetime by calling the
 // llvm.lifetime.end intrinsic. It is commonly used together with
 // createTemporaryAlloca.
-func (b *builder) emitLifetimeEnd(ptr, size llvm.Value) {
-	llvmutil.EmitLifetimeEnd(b.Builder, b.mod, ptr, size)
+func (c *Compiler) emitLifetimeEnd(ptr, size llvm.Value) {
+	c.builder.CreateCall(c.getLifetimeEndFunc(), []llvm.Value{size, ptr}, "")
 }

-// emitPointerPack packs the list of values into a single pointer value using
-// bitcasts, or else allocates a value on the heap if it cannot be packed in the
-// pointer value directly. It returns the pointer with the packed data.
-func (b *builder) emitPointerPack(values []llvm.Value) llvm.Value {
-	return llvmutil.EmitPointerPack(b.Builder, b.mod, b.Config, values)
+// getLifetimeStartFunc returns the llvm.lifetime.start intrinsic and creates it
+// first if it doesn't exist yet.
+func (c *Compiler) getLifetimeStartFunc() llvm.Value {
+	fn := c.mod.NamedFunction("llvm.lifetime.start.p0i8")
+	if fn.IsNil() {
+		fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.ctx.Int64Type(), c.i8ptrType}, false)
+		fn = llvm.AddFunction(c.mod, "llvm.lifetime.start.p0i8", fnType)
+	}
+	return fn
 }

-// emitPointerUnpack extracts a list of values packed using emitPointerPack.
-func (b *builder) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
-	return llvmutil.EmitPointerUnpack(b.Builder, b.mod, ptr, valueTypes)
+// getLifetimeEndFunc returns the llvm.lifetime.end intrinsic and creates it
+// first if it doesn't exist yet.
+func (c *Compiler) getLifetimeEndFunc() llvm.Value {
+	fn := c.mod.NamedFunction("llvm.lifetime.end.p0i8")
+	if fn.IsNil() {
+		fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.ctx.Int64Type(), c.i8ptrType}, false)
+		fn = llvm.AddFunction(c.mod, "llvm.lifetime.end.p0i8", fnType)
+	}
+	return fn
+}
+
+// splitBasicBlock splits a LLVM basic block into two parts. All instructions
+// after afterInst are moved into a new basic block (created right after the
+// current one) with the given name.
+func (c *Compiler) splitBasicBlock(afterInst llvm.Value, insertAfter llvm.BasicBlock, name string) llvm.BasicBlock {
+	oldBlock := afterInst.InstructionParent()
+	newBlock := c.ctx.InsertBasicBlock(insertAfter, name)
+	var nextInstructions []llvm.Value // values to move
+
+	// Collect to-be-moved instructions.
+	inst := afterInst
+	for {
+		inst = llvm.NextInstruction(inst)
+		if inst.IsNil() {
+			break
+		}
+		nextInstructions = append(nextInstructions, inst)
+	}
+
+	// Move instructions.
+	c.builder.SetInsertPointAtEnd(newBlock)
+	for _, inst := range nextInstructions {
+		inst.RemoveFromParentAsInstruction()
+		c.builder.Insert(inst)
+	}
+
+	// Find PHI nodes to update.
+	var phiNodes []llvm.Value // PHI nodes to update
+	for bb := insertAfter.Parent().FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
+		for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
+			if inst.IsAPHINode().IsNil() {
+				continue
+			}
+			needsUpdate := false
+			incomingCount := inst.IncomingCount()
+			for i := 0; i < incomingCount; i++ {
+				if inst.IncomingBlock(i) == oldBlock {
+					needsUpdate = true
+					break
+				}
+			}
+			if !needsUpdate {
+				// PHI node has no incoming edge from the old block.
+				continue
+			}
+			phiNodes = append(phiNodes, inst)
+		}
+	}
+
+	// Update PHI nodes.
+	for _, phi := range phiNodes {
+		c.builder.SetInsertPointBefore(phi)
+		newPhi := c.builder.CreatePHI(phi.Type(), "")
+		incomingCount := phi.IncomingCount()
+		incomingVals := make([]llvm.Value, incomingCount)
+		incomingBlocks := make([]llvm.BasicBlock, incomingCount)
+		for i := 0; i < incomingCount; i++ {
+			value := phi.IncomingValue(i)
+			block := phi.IncomingBlock(i)
+			if block == oldBlock {
+				block = newBlock
+			}
+			incomingVals[i] = value
+			incomingBlocks[i] = block
+		}
+		newPhi.AddIncoming(incomingVals, incomingBlocks)
+		phi.ReplaceAllUsesWith(newPhi)
+		phi.EraseFromParentAsInstruction()
+	}
+
+	return newBlock
 }

 // makeGlobalArray creates a new LLVM global with the given name and integers as
 // contents, and returns the global.
 // Note that it is left with the default linkage etc., you should set
 // linkage/constant/etc properties yourself.
-func (c *compilerContext) makeGlobalArray(buf []byte, name string, elementType llvm.Type) llvm.Value {
-	globalType := llvm.ArrayType(elementType, len(buf))
+func (c *Compiler) makeGlobalArray(bufItf interface{}, name string, elementType llvm.Type) llvm.Value {
+	buf := reflect.ValueOf(bufItf)
+	globalType := llvm.ArrayType(elementType, buf.Len())
 	global := llvm.AddGlobal(c.mod, globalType, name)
 	value := llvm.Undef(globalType)
-	for i := 0; i < len(buf); i++ {
-		ch := uint64(buf[i])
+	for i := 0; i < buf.Len(); i++ {
+		ch := buf.Index(i).Uint()
 		value = llvm.ConstInsertValue(value, llvm.ConstInt(elementType, ch, false), []uint32{uint32(i)})
 	}
 	global.SetInitializer(value)
 	return global
 }
+
+// getGlobalBytes returns the slice contained in the array of the provided
+// global. It can recover the bytes originally created using makeGlobalArray, if
+// makeGlobalArray was given a byte slice.
+func getGlobalBytes(global llvm.Value) []byte {
+	value := global.Initializer()
+	buf := make([]byte, value.Type().ArrayLength())
+	for i := range buf {
+		buf[i] = byte(llvm.ConstExtractValue(value, []uint32{uint32(i)}).ZExtValue())
+	}
+	return buf
+}
+
+// replaceGlobalByteWithArray replaces a global integer type in the module with
+// an integer array, using a GEP to make the types match. It is a convenience
+// function used for creating reflection sidetables, for example.
+func (c *Compiler) replaceGlobalIntWithArray(name string, buf interface{}) llvm.Value {
+	oldGlobal := c.mod.NamedGlobal(name)
+	global := c.makeGlobalArray(buf, name+".tmp", oldGlobal.Type().ElementType())
+	gep := llvm.ConstGEP(global, []llvm.Value{
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+	})
+	oldGlobal.ReplaceAllUsesWith(gep)
+	oldGlobal.EraseFromParentAsGlobal()
+	global.SetName(name)
+	return global
+}
@@ -1,168 +0,0 @@
-// Package llvmutil contains utility functions used across multiple compiler
-// packages. For example, they may be used by both the compiler pacakge and
-// transformation packages.
-//
-// Normally, utility packages are avoided. However, in this case, the utility
-// functions are non-trivial and hard to get right. Copying them to multiple
-// places would be a big risk if only one of them is updated.
-package llvmutil
-
-import "tinygo.org/x/go-llvm"
-
-// CreateEntryBlockAlloca creates a new alloca in the entry block, even though
-// the IR builder is located elsewhere. It assumes that the insert point is
-// at the end of the current block.
-func CreateEntryBlockAlloca(builder llvm.Builder, t llvm.Type, name string) llvm.Value {
-	currentBlock := builder.GetInsertBlock()
-	entryBlock := currentBlock.Parent().EntryBasicBlock()
-	if entryBlock.FirstInstruction().IsNil() {
-		builder.SetInsertPointAtEnd(entryBlock)
-	} else {
-		builder.SetInsertPointBefore(entryBlock.FirstInstruction())
-	}
-	alloca := builder.CreateAlloca(t, name)
-	builder.SetInsertPointAtEnd(currentBlock)
-	return alloca
-}
-
-// CreateTemporaryAlloca creates a new alloca in the entry block and adds
-// lifetime start infromation in the IR signalling that the alloca won't be used
-// before this point.
-//
-// This is useful for creating temporary allocas for intrinsics. Don't forget to
-// end the lifetime using emitLifetimeEnd after you're done with it.
-func CreateTemporaryAlloca(builder llvm.Builder, mod llvm.Module, t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
-	ctx := t.Context()
-	targetData := llvm.NewTargetData(mod.DataLayout())
-	i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
-	alloca = CreateEntryBlockAlloca(builder, t, name)
-	bitcast = builder.CreateBitCast(alloca, i8ptrType, name+".bitcast")
-	size = llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(t), false)
-	builder.CreateCall(getLifetimeStartFunc(mod), []llvm.Value{size, bitcast}, "")
-	return
-}
-
-// CreateInstructionAlloca creates an alloca in the entry block, and places lifetime control intrinsics around the instruction
-func CreateInstructionAlloca(builder llvm.Builder, mod llvm.Module, t llvm.Type, inst llvm.Value, name string) llvm.Value {
-	ctx := mod.Context()
-	targetData := llvm.NewTargetData(mod.DataLayout())
-	i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
-
-	alloca := CreateEntryBlockAlloca(builder, t, name)
-	builder.SetInsertPointBefore(inst)
-	bitcast := builder.CreateBitCast(alloca, i8ptrType, name+".bitcast")
-	size := llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(t), false)
-	builder.CreateCall(getLifetimeStartFunc(mod), []llvm.Value{size, bitcast}, "")
-	if next := llvm.NextInstruction(inst); !next.IsNil() {
-		builder.SetInsertPointBefore(next)
-	} else {
-		builder.SetInsertPointAtEnd(inst.InstructionParent())
-	}
-	builder.CreateCall(getLifetimeEndFunc(mod), []llvm.Value{size, bitcast}, "")
-	return alloca
-}
-
-// EmitLifetimeEnd signals the end of an (alloca) lifetime by calling the
-// llvm.lifetime.end intrinsic. It is commonly used together with
-// createTemporaryAlloca.
-func EmitLifetimeEnd(builder llvm.Builder, mod llvm.Module, ptr, size llvm.Value) {
-	builder.CreateCall(getLifetimeEndFunc(mod), []llvm.Value{size, ptr}, "")
-}
-
-// getLifetimeStartFunc returns the llvm.lifetime.start intrinsic and creates it
-// first if it doesn't exist yet.
-func getLifetimeStartFunc(mod llvm.Module) llvm.Value {
-	fn := mod.NamedFunction("llvm.lifetime.start.p0i8")
-	ctx := mod.Context()
-	i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
-	if fn.IsNil() {
-		fnType := llvm.FunctionType(ctx.VoidType(), []llvm.Type{ctx.Int64Type(), i8ptrType}, false)
-		fn = llvm.AddFunction(mod, "llvm.lifetime.start.p0i8", fnType)
-	}
-	return fn
-}
-
-// getLifetimeEndFunc returns the llvm.lifetime.end intrinsic and creates it
-// first if it doesn't exist yet.
-func getLifetimeEndFunc(mod llvm.Module) llvm.Value {
-	fn := mod.NamedFunction("llvm.lifetime.end.p0i8")
-	ctx := mod.Context()
-	i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
-	if fn.IsNil() {
-		fnType := llvm.FunctionType(ctx.VoidType(), []llvm.Type{ctx.Int64Type(), i8ptrType}, false)
-		fn = llvm.AddFunction(mod, "llvm.lifetime.end.p0i8", fnType)
-	}
-	return fn
-}
-
-// SplitBasicBlock splits a LLVM basic block into two parts. All instructions
-// after afterInst are moved into a new basic block (created right after the
-// current one) with the given name.
-func SplitBasicBlock(builder llvm.Builder, afterInst llvm.Value, insertAfter llvm.BasicBlock, name string) llvm.BasicBlock {
-	oldBlock := afterInst.InstructionParent()
-	newBlock := afterInst.Type().Context().InsertBasicBlock(insertAfter, name)
-	var nextInstructions []llvm.Value // values to move
-
-	// Collect to-be-moved instructions.
-	inst := afterInst
-	for {
-		inst = llvm.NextInstruction(inst)
-		if inst.IsNil() {
-			break
-		}
-		nextInstructions = append(nextInstructions, inst)
-	}
-
-	// Move instructions.
-	builder.SetInsertPointAtEnd(newBlock)
-	for _, inst := range nextInstructions {
-		inst.RemoveFromParentAsInstruction()
-		builder.Insert(inst)
-	}
-
-	// Find PHI nodes to update.
-	var phiNodes []llvm.Value // PHI nodes to update
-	for bb := insertAfter.Parent().FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
-		for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
-			if inst.IsAPHINode().IsNil() {
-				continue
-			}
-			needsUpdate := false
-			incomingCount := inst.IncomingCount()
-			for i := 0; i < incomingCount; i++ {
-				if inst.IncomingBlock(i) == oldBlock {
-					needsUpdate = true
-					break
-				}
-			}
-			if !needsUpdate {
-				// PHI node has no incoming edge from the old block.
-				continue
-			}
-			phiNodes = append(phiNodes, inst)
-		}
-	}
-
-	// Update PHI nodes.
-	for _, phi := range phiNodes {
-		builder.SetInsertPointBefore(phi)
-		newPhi := builder.CreatePHI(phi.Type(), "")
-		incomingCount := phi.IncomingCount()
-		incomingVals := make([]llvm.Value, incomingCount)
-		incomingBlocks := make([]llvm.BasicBlock, incomingCount)
-		for i := 0; i < incomingCount; i++ {
-			value := phi.IncomingValue(i)
-			block := phi.IncomingBlock(i)
-			if block == oldBlock {
-				block = newBlock
-			}
-			incomingVals[i] = value
-			incomingBlocks[i] = block
-		}
-		newPhi.AddIncoming(incomingVals, incomingBlocks)
-		phi.ReplaceAllUsesWith(newPhi)
-		phi.EraseFromParentAsInstruction()
-	}
-
-	return newBlock
-}
@@ -1,163 +0,0 @@
-package llvmutil
-
-// This file contains utility functions to pack and unpack sets of values. It
-// can take in a list of values and tries to store it efficiently in the pointer
-// itself if possible and legal.
-
-import (
-	"github.com/tinygo-org/tinygo/compileopts"
-	"tinygo.org/x/go-llvm"
-)
-
-// EmitPointerPack packs the list of values into a single pointer value using
-// bitcasts, or else allocates a value on the heap if it cannot be packed in the
-// pointer value directly. It returns the pointer with the packed data.
-// If the values are all constants, they are be stored in a constant global and deduplicated.
-func EmitPointerPack(builder llvm.Builder, mod llvm.Module, config *compileopts.Config, values []llvm.Value) llvm.Value {
-	ctx := mod.Context()
-	targetData := llvm.NewTargetData(mod.DataLayout())
-	i8ptrType := llvm.PointerType(mod.Context().Int8Type(), 0)
-	uintptrType := ctx.IntType(llvm.NewTargetData(mod.DataLayout()).PointerSize() * 8)
-
-	valueTypes := make([]llvm.Type, len(values))
-	for i, value := range values {
-		valueTypes[i] = value.Type()
-	}
-	packedType := ctx.StructType(valueTypes, false)
-
-	// Allocate memory for the packed data.
-	var packedAlloc, packedHeapAlloc llvm.Value
-	size := targetData.TypeAllocSize(packedType)
-	if size == 0 {
-		return llvm.ConstPointerNull(i8ptrType)
-	} else if len(values) == 1 && values[0].Type().TypeKind() == llvm.PointerTypeKind {
-		return builder.CreateBitCast(values[0], i8ptrType, "pack.ptr")
-	} else if size <= targetData.TypeAllocSize(i8ptrType) {
-		// Packed data fits in a pointer, so store it directly inside the
-		// pointer.
-		if len(values) == 1 && values[0].Type().TypeKind() == llvm.IntegerTypeKind {
-			// Try to keep this cast in SSA form.
-			return builder.CreateIntToPtr(values[0], i8ptrType, "pack.int")
-		}
-		// Because packedType is a struct and we have to cast it to a *i8, store
-		// it in an alloca first for bitcasting (store+bitcast+load).
-		packedAlloc, _, _ = CreateTemporaryAlloca(builder, mod, packedType, "")
-	} else {
-		// Check if the values are all constants.
-		constant := true
-		for _, v := range values {
-			if !v.IsConstant() {
-				constant = false
-				break
-			}
-		}
-
-		if constant {
-			// The data is known at compile time, so store it in a constant global.
-			// The global address is marked as unnamed, which allows LLVM to merge duplicates.
-			funcName := builder.GetInsertBlock().Parent().Name()
-			global := llvm.AddGlobal(mod, packedType, funcName+"$pack")
-			global.SetInitializer(ctx.ConstStruct(values, false))
-			global.SetGlobalConstant(true)
-			global.SetUnnamedAddr(true)
-			global.SetLinkage(llvm.PrivateLinkage)
-			return llvm.ConstBitCast(global, i8ptrType)
-		}
-
-		// Packed data is bigger than a pointer, so allocate it on the heap.
-		sizeValue := llvm.ConstInt(uintptrType, size, false)
-		alloc := mod.NamedFunction("runtime.alloc")
-		packedHeapAlloc = builder.CreateCall(alloc, []llvm.Value{
-			sizeValue,
-			llvm.Undef(i8ptrType),            // unused context parameter
-			llvm.ConstPointerNull(i8ptrType), // coroutine handle
-		}, "")
-		if config.NeedsStackObjects() {
-			trackPointer := mod.NamedFunction("runtime.trackPointer")
-			builder.CreateCall(trackPointer, []llvm.Value{
-				packedHeapAlloc,
-				llvm.Undef(i8ptrType),            // unused context parameter
-				llvm.ConstPointerNull(i8ptrType), // coroutine handle
-			}, "")
-		}
-		packedAlloc = builder.CreateBitCast(packedHeapAlloc, llvm.PointerType(packedType, 0), "")
-	}
-	// Store all values in the alloca or heap pointer.
-	for i, value := range values {
-		indices := []llvm.Value{
-			llvm.ConstInt(ctx.Int32Type(), 0, false),
-			llvm.ConstInt(ctx.Int32Type(), uint64(i), false),
-		}
-		gep := builder.CreateInBoundsGEP(packedAlloc, indices, "")
-		builder.CreateStore(value, gep)
-	}
-
-	if packedHeapAlloc.IsNil() {
-		// Load value (as *i8) from the alloca.
-		packedAlloc = builder.CreateBitCast(packedAlloc, llvm.PointerType(i8ptrType, 0), "")
-		result := builder.CreateLoad(packedAlloc, "")
-		packedPtr := builder.CreateBitCast(packedAlloc, i8ptrType, "")
-		packedSize := llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(packedAlloc.Type()), false)
-		EmitLifetimeEnd(builder, mod, packedPtr, packedSize)
-		return result
-	} else {
-		// Get the original heap allocation pointer, which already is an *i8.
-		return packedHeapAlloc
-	}
-}
-
-// EmitPointerUnpack extracts a list of values packed using EmitPointerPack.
-func EmitPointerUnpack(builder llvm.Builder, mod llvm.Module, ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
-	ctx := mod.Context()
-	targetData := llvm.NewTargetData(mod.DataLayout())
-	i8ptrType := llvm.PointerType(mod.Context().Int8Type(), 0)
-	uintptrType := ctx.IntType(llvm.NewTargetData(mod.DataLayout()).PointerSize() * 8)
-
-	packedType := ctx.StructType(valueTypes, false)
-
-	// Get a correctly-typed pointer to the packed data.
-	var packedAlloc, packedRawAlloc llvm.Value
-	size := targetData.TypeAllocSize(packedType)
-	if size == 0 {
-		// No data to unpack.
-	} else if len(valueTypes) == 1 && valueTypes[0].TypeKind() == llvm.PointerTypeKind {
-		// A single pointer is always stored directly.
-		return []llvm.Value{builder.CreateBitCast(ptr, valueTypes[0], "unpack.ptr")}
-	} else if size <= targetData.TypeAllocSize(i8ptrType) {
-		// Packed data stored directly in pointer.
-		if len(valueTypes) == 1 && valueTypes[0].TypeKind() == llvm.IntegerTypeKind {
-			// Keep this cast in SSA form.
-			return []llvm.Value{builder.CreatePtrToInt(ptr, valueTypes[0], "unpack.int")}
-		}
-		// Fallback: load it using an alloca.
-		packedRawAlloc, _, _ = CreateTemporaryAlloca(builder, mod, llvm.PointerType(i8ptrType, 0), "unpack.raw.alloc")
-		packedRawValue := builder.CreateBitCast(ptr, llvm.PointerType(i8ptrType, 0), "unpack.raw.value")
-		builder.CreateStore(packedRawValue, packedRawAlloc)
-		packedAlloc = builder.CreateBitCast(packedRawAlloc, llvm.PointerType(packedType, 0), "unpack.alloc")
-	} else {
-		// Packed data stored on the heap. Bitcast the passed-in pointer to the
-		// correct pointer type.
-		packedAlloc = builder.CreateBitCast(ptr, llvm.PointerType(packedType, 0), "unpack.raw.ptr")
-	}
-	// Load each value from the packed data.
-	values := make([]llvm.Value, len(valueTypes))
-	for i, valueType := range valueTypes {
-		if targetData.TypeAllocSize(valueType) == 0 {
-			// This value has length zero, so there's nothing to load.
-			values[i] = llvm.ConstNull(valueType)
-			continue
-		}
-		indices := []llvm.Value{
-			llvm.ConstInt(ctx.Int32Type(), 0, false),
-			llvm.ConstInt(ctx.Int32Type(), uint64(i), false),
-		}
-		gep := builder.CreateInBoundsGEP(packedAlloc, indices, "")
-		values[i] = builder.CreateLoad(gep, "")
-	}
-	if !packedRawAlloc.IsNil() {
-		allocPtr := builder.CreateBitCast(packedRawAlloc, i8ptrType, "")
-		allocSize := llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(uintptrType), false)
-		EmitLifetimeEnd(builder, mod, allocPtr, allocSize)
-	}
-	return values
-}
@@ -6,167 +6,115 @@ import (
 	"go/token"
 	"go/types"

-	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )

-// createMakeMap creates a new map object (runtime.hashmap) by allocating and
-// initializing an appropriately sized object.
-func (b *builder) createMakeMap(expr *ssa.MakeMap) (llvm.Value, error) {
-	mapType := expr.Type().Underlying().(*types.Map)
-	keyType := mapType.Key().Underlying()
-	llvmValueType := b.getLLVMType(mapType.Elem().Underlying())
-	var llvmKeyType llvm.Type
-	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
-		// String keys.
-		llvmKeyType = b.getLLVMType(keyType)
-	} else if hashmapIsBinaryKey(keyType) {
-		// Trivially comparable keys.
-		llvmKeyType = b.getLLVMType(keyType)
-	} else {
-		// All other keys. Implemented as map[interface{}]valueType for ease of
-		// implementation.
-		llvmKeyType = b.getLLVMRuntimeType("_interface")
-	}
-	keySize := b.targetData.TypeAllocSize(llvmKeyType)
-	valueSize := b.targetData.TypeAllocSize(llvmValueType)
-	llvmKeySize := llvm.ConstInt(b.ctx.Int8Type(), keySize, false)
-	llvmValueSize := llvm.ConstInt(b.ctx.Int8Type(), valueSize, false)
-	sizeHint := llvm.ConstInt(b.uintptrType, 8, false)
-	if expr.Reserve != nil {
-		sizeHint = b.getValue(expr.Reserve)
-		var err error
-		sizeHint, err = b.createConvert(expr.Reserve.Type(), types.Typ[types.Uintptr], sizeHint, expr.Pos())
-		if err != nil {
-			return llvm.Value{}, err
-		}
-	}
-	hashmap := b.createRuntimeCall("hashmapMake", []llvm.Value{llvmKeySize, llvmValueSize, sizeHint}, "")
-	return hashmap, nil
-}
-
-// createMapLookup returns the value in a map. It calls a runtime function
-// depending on the map key type to load the map value and its comma-ok value.
-func (b *builder) createMapLookup(keyType, valueType types.Type, m, key llvm.Value, commaOk bool, pos token.Pos) (llvm.Value, error) {
-	llvmValueType := b.getLLVMType(valueType)
+func (c *Compiler) emitMapLookup(keyType, valueType types.Type, m, key llvm.Value, commaOk bool, pos token.Pos) (llvm.Value, error) {
+	llvmValueType := c.getLLVMType(valueType)

 	// Allocate the memory for the resulting type. Do not zero this memory: it
 	// will be zeroed by the hashmap get implementation if the key is not
 	// present in the map.
-	mapValueAlloca, mapValuePtr, mapValueAllocaSize := b.createTemporaryAlloca(llvmValueType, "hashmap.value")
-
-	// We need the map size (with type uintptr) to pass to the hashmap*Get
-	// functions. This is necessary because those *Get functions are valid on
-	// nil maps, and they'll need to zero the value pointer by that number of
-	// bytes.
-	mapValueSize := mapValueAllocaSize
-	if mapValueSize.Type().IntTypeWidth() > b.uintptrType.IntTypeWidth() {
-		mapValueSize = llvm.ConstTrunc(mapValueSize, b.uintptrType)
-	}
+	mapValueAlloca, mapValuePtr, mapValueSize := c.createTemporaryAlloca(llvmValueType, "hashmap.value")

 	// Do the lookup. How it is done depends on the key type.
 	var commaOkValue llvm.Value
-	keyType = keyType.Underlying()
 	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
 		// key is a string
-		params := []llvm.Value{m, key, mapValuePtr, mapValueSize}
-		commaOkValue = b.createRuntimeCall("hashmapStringGet", params, "")
+		params := []llvm.Value{m, key, mapValuePtr}
+		commaOkValue = c.createRuntimeCall("hashmapStringGet", params, "")
 	} else if hashmapIsBinaryKey(keyType) {
 		// key can be compared with runtime.memequal
 		// Store the key in an alloca, in the entry block to avoid dynamic stack
 		// growth.
-		mapKeyAlloca, mapKeyPtr, mapKeySize := b.createTemporaryAlloca(key.Type(), "hashmap.key")
-		b.CreateStore(key, mapKeyAlloca)
+		mapKeyAlloca, mapKeyPtr, mapKeySize := c.createTemporaryAlloca(key.Type(), "hashmap.key")
+		c.builder.CreateStore(key, mapKeyAlloca)
 		// Fetch the value from the hashmap.
-		params := []llvm.Value{m, mapKeyPtr, mapValuePtr, mapValueSize}
-		commaOkValue = b.createRuntimeCall("hashmapBinaryGet", params, "")
-		b.emitLifetimeEnd(mapKeyPtr, mapKeySize)
+		params := []llvm.Value{m, mapKeyPtr, mapValuePtr}
+		commaOkValue = c.createRuntimeCall("hashmapBinaryGet", params, "")
+		c.emitLifetimeEnd(mapKeyPtr, mapKeySize)
 	} else {
-		// Not trivially comparable using memcmp. Make it an interface instead.
-		itfKey := key
-		if _, ok := keyType.(*types.Interface); !ok {
-			// Not already an interface, so convert it to an interface now.
-			itfKey = b.createMakeInterface(key, keyType, pos)
-		}
-		params := []llvm.Value{m, itfKey, mapValuePtr, mapValueSize}
-		commaOkValue = b.createRuntimeCall("hashmapInterfaceGet", params, "")
+		// Not trivially comparable using memcmp.
+		return llvm.Value{}, c.makeError(pos, "only strings, bools, ints, pointers or structs of bools/ints are supported as map keys, but got: "+keyType.String())
 	}

 	// Load the resulting value from the hashmap. The value is set to the zero
 	// value if the key doesn't exist in the hashmap.
-	mapValue := b.CreateLoad(mapValueAlloca, "")
-	b.emitLifetimeEnd(mapValuePtr, mapValueAllocaSize)
+	mapValue := c.builder.CreateLoad(mapValueAlloca, "")
+	c.emitLifetimeEnd(mapValuePtr, mapValueSize)

 	if commaOk {
-		tuple := llvm.Undef(b.ctx.StructType([]llvm.Type{llvmValueType, b.ctx.Int1Type()}, false))
-		tuple = b.CreateInsertValue(tuple, mapValue, 0, "")
-		tuple = b.CreateInsertValue(tuple, commaOkValue, 1, "")
+		tuple := llvm.Undef(c.ctx.StructType([]llvm.Type{llvmValueType, c.ctx.Int1Type()}, false))
+		tuple = c.builder.CreateInsertValue(tuple, mapValue, 0, "")
+		tuple = c.builder.CreateInsertValue(tuple, commaOkValue, 1, "")
 		return tuple, nil
 	} else {
 		return mapValue, nil
 	}
 }

-// createMapUpdate updates a map key to a given value, by creating an
-// appropriate runtime call.
-func (b *builder) createMapUpdate(keyType types.Type, m, key, value llvm.Value, pos token.Pos) {
-	valueAlloca, valuePtr, valueSize := b.createTemporaryAlloca(value.Type(), "hashmap.value")
-	b.CreateStore(value, valueAlloca)
+func (c *Compiler) emitMapUpdate(keyType types.Type, m, key, value llvm.Value, pos token.Pos) {
+	valueAlloca, valuePtr, valueSize := c.createTemporaryAlloca(value.Type(), "hashmap.value")
+	c.builder.CreateStore(value, valueAlloca)
 	keyType = keyType.Underlying()
 	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
 		// key is a string
 		params := []llvm.Value{m, key, valuePtr}
-		b.createRuntimeCall("hashmapStringSet", params, "")
+		c.createRuntimeCall("hashmapStringSet", params, "")
 	} else if hashmapIsBinaryKey(keyType) {
 		// key can be compared with runtime.memequal
-		keyAlloca, keyPtr, keySize := b.createTemporaryAlloca(key.Type(), "hashmap.key")
-		b.CreateStore(key, keyAlloca)
+		keyAlloca, keyPtr, keySize := c.createTemporaryAlloca(key.Type(), "hashmap.key")
+		c.builder.CreateStore(key, keyAlloca)
 		params := []llvm.Value{m, keyPtr, valuePtr}
-		b.createRuntimeCall("hashmapBinarySet", params, "")
-		b.emitLifetimeEnd(keyPtr, keySize)
+		c.createRuntimeCall("hashmapBinarySet", params, "")
+		c.emitLifetimeEnd(keyPtr, keySize)
 	} else {
-		// Key is not trivially comparable, so compare it as an interface instead.
-		itfKey := key
-		if _, ok := keyType.(*types.Interface); !ok {
-			// Not already an interface, so convert it to an interface first.
-			itfKey = b.createMakeInterface(key, keyType, pos)
-		}
-		params := []llvm.Value{m, itfKey, valuePtr}
-		b.createRuntimeCall("hashmapInterfaceSet", params, "")
+		c.addError(pos, "only strings, bools, ints, pointers or structs of bools/ints are supported as map keys, but got: "+keyType.String())
 	}
-	b.emitLifetimeEnd(valuePtr, valueSize)
+	c.emitLifetimeEnd(valuePtr, valueSize)
 }

-// createMapDelete deletes a key from a map by calling the appropriate runtime
-// function. It is the implementation of the Go delete() builtin.
-func (b *builder) createMapDelete(keyType types.Type, m, key llvm.Value, pos token.Pos) error {
+func (c *Compiler) emitMapDelete(keyType types.Type, m, key llvm.Value, pos token.Pos) error {
 	keyType = keyType.Underlying()
 	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
 		// key is a string
 		params := []llvm.Value{m, key}
-		b.createRuntimeCall("hashmapStringDelete", params, "")
+		c.createRuntimeCall("hashmapStringDelete", params, "")
 		return nil
 	} else if hashmapIsBinaryKey(keyType) {
-		keyAlloca, keyPtr, keySize := b.createTemporaryAlloca(key.Type(), "hashmap.key")
-		b.CreateStore(key, keyAlloca)
+		keyAlloca, keyPtr, keySize := c.createTemporaryAlloca(key.Type(), "hashmap.key")
+		c.builder.CreateStore(key, keyAlloca)
 		params := []llvm.Value{m, keyPtr}
-		b.createRuntimeCall("hashmapBinaryDelete", params, "")
-		b.emitLifetimeEnd(keyPtr, keySize)
+		c.createRuntimeCall("hashmapBinaryDelete", params, "")
+		c.emitLifetimeEnd(keyPtr, keySize)
 		return nil
 	} else {
-		// Key is not trivially comparable, so compare it as an interface
-		// instead.
-		itfKey := key
-		if _, ok := keyType.(*types.Interface); !ok {
-			// Not already an interface, so convert it to an interface first.
-			itfKey = b.createMakeInterface(key, keyType, pos)
-		}
-		params := []llvm.Value{m, itfKey}
-		b.createRuntimeCall("hashmapInterfaceDelete", params, "")
-		return nil
+		return c.makeError(pos, "only strings, bools, ints, pointers or structs of bools/ints are supported as map keys, but got: "+keyType.String())
 	}
 }

+// Get FNV-1a hash of this string.
+//
+// https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
+func hashmapHash(data []byte) uint32 {
+	var result uint32 = 2166136261 // FNV offset basis
+	for _, c := range data {
+		result ^= uint32(c)
+		result *= 16777619 // FNV prime
+	}
+	return result
+}
+
+// Get the topmost 8 bits of the hash, without using a special value (like 0).
+func hashmapTopHash(hash uint32) uint8 {
+	tophash := uint8(hash >> 24)
+	if tophash < 1 {
+		// 0 means empty slot, so make it bigger.
+		tophash += 1
+	}
+	return tophash
+}
+
 // Returns true if this key type does not contain strings, interfaces etc., so
 // can be compared with runtime.memequal.
 func hashmapIsBinaryKey(keyType types.Type) bool {
@@ -0,0 +1,397 @@
+package compiler
+
+import (
+	"errors"
+
+	"tinygo.org/x/go-llvm"
+)
+
+// Run the LLVM optimizer over the module.
+// The inliner can be disabled (if necessary) by passing 0 to the inlinerThreshold.
+func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) error {
+	builder := llvm.NewPassManagerBuilder()
+	defer builder.Dispose()
+	builder.SetOptLevel(optLevel)
+	builder.SetSizeLevel(sizeLevel)
+	if inlinerThreshold != 0 {
+		builder.UseInlinerWithThreshold(inlinerThreshold)
+	}
+	builder.AddCoroutinePassesToExtensionPoints()
+
+	if c.PanicStrategy == "trap" {
+		c.replacePanicsWithTrap() // -panic=trap
+	}
+
+	// run a check of all of our code
+	c.check()
+	if err := c.Verify(); err != nil {
+		return errors.New("verification failure before optimizations")
+	}
+
+	// Run function passes for each function.
+	funcPasses := llvm.NewFunctionPassManagerForModule(c.mod)
+	defer funcPasses.Dispose()
+	builder.PopulateFunc(funcPasses)
+	funcPasses.InitializeFunc()
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+		funcPasses.RunFunc(fn)
+	}
+	funcPasses.FinalizeFunc()
+
+	if optLevel > 0 {
+		// Run some preparatory passes for the Go optimizer.
+		goPasses := llvm.NewPassManager()
+		defer goPasses.Dispose()
+		goPasses.AddGlobalOptimizerPass()
+		goPasses.AddConstantPropagationPass()
+		goPasses.AddAggressiveDCEPass()
+		goPasses.AddFunctionAttrsPass()
+		goPasses.Run(c.mod)
+
+		// Run Go-specific optimization passes.
+		c.OptimizeMaps()
+		c.OptimizeStringToBytes()
+		c.OptimizeAllocs()
+		c.LowerInterfaces()
+		c.LowerFuncValues()
+
+		// After interfaces are lowered, there are many more opportunities for
+		// interprocedural optimizations. To get them to work, function
+		// attributes have to be updated first.
+		goPasses.Run(c.mod)
+
+		// Run TinyGo-specific interprocedural optimizations.
+		c.OptimizeAllocs()
+		c.OptimizeStringToBytes()
+
+		// Lower runtime.isnil calls to regular nil comparisons.
+		isnil := c.mod.NamedFunction("runtime.isnil")
+		if !isnil.IsNil() {
+			for _, use := range getUses(isnil) {
+				c.builder.SetInsertPointBefore(use)
+				ptr := use.Operand(0)
+				if !ptr.IsABitCastInst().IsNil() {
+					ptr = ptr.Operand(0)
+				}
+				nilptr := llvm.ConstPointerNull(ptr.Type())
+				icmp := c.builder.CreateICmp(llvm.IntEQ, ptr, nilptr, "")
+				use.ReplaceAllUsesWith(icmp)
+				use.EraseFromParentAsInstruction()
+			}
+		}
+
+		err := c.LowerGoroutines()
+		if err != nil {
+			return err
+		}
+	} else {
+		// Must be run at any optimization level.
+		c.LowerInterfaces()
+		c.LowerFuncValues()
+		err := c.LowerGoroutines()
+		if err != nil {
+			return err
+		}
+	}
+	if err := c.Verify(); err != nil {
+		return errors.New("optimizations caused a verification failure")
+	}
+
+	if sizeLevel >= 2 {
+		// Set the "optsize" attribute to make slightly smaller binaries at the
+		// cost of some performance.
+		kind := llvm.AttributeKindID("optsize")
+		attr := c.ctx.CreateEnumAttribute(kind, 0)
+		for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+			fn.AddFunctionAttr(attr)
+		}
+	}
+
+	// After TinyGo-specific transforms have finished, undo exporting these functions.
+	for _, name := range functionsUsedInTransforms {
+		fn := c.mod.NamedFunction(name)
+		if fn.IsNil() {
+			continue
+		}
+		fn.SetLinkage(llvm.InternalLinkage)
+	}
+
+	// Run function passes again, because without it, llvm.coro.size.i32()
+	// doesn't get lowered.
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+		funcPasses.RunFunc(fn)
+	}
+	funcPasses.FinalizeFunc()
+
+	// Run module passes.
+	modPasses := llvm.NewPassManager()
+	defer modPasses.Dispose()
+	builder.Populate(modPasses)
+	modPasses.Run(c.mod)
+
+	hasGCPass := c.addGlobalsBitmap()
+	hasGCPass = c.makeGCStackSlots() || hasGCPass
+	if hasGCPass {
+		if err := c.Verify(); err != nil {
+			return errors.New("GC pass caused a verification failure")
+		}
+	}
+
+	return nil
+}
+
+// Replace panic calls with calls to llvm.trap, to reduce code size. This is the
+// -panic=trap intrinsic.
+func (c *Compiler) replacePanicsWithTrap() {
+	trap := c.mod.NamedFunction("llvm.trap")
+	for _, name := range []string{"runtime._panic", "runtime.runtimePanic"} {
+		fn := c.mod.NamedFunction(name)
+		if fn.IsNil() {
+			continue
+		}
+		for _, use := range getUses(fn) {
+			if use.IsACallInst().IsNil() || use.CalledValue() != fn {
+				panic("expected use of a panic function to be a call")
+			}
+			c.builder.SetInsertPointBefore(use)
+			c.builder.CreateCall(trap, nil, "")
+		}
+	}
+}
+
+// Eliminate created but not used maps.
+//
+// In the future, this should statically allocate created but never modified
+// maps. This has not yet been implemented, however.
+func (c *Compiler) OptimizeMaps() {
+	hashmapMake := c.mod.NamedFunction("runtime.hashmapMake")
+	if hashmapMake.IsNil() {
+		// nothing to optimize
+		return
+	}
+
+	hashmapBinarySet := c.mod.NamedFunction("runtime.hashmapBinarySet")
+	hashmapStringSet := c.mod.NamedFunction("runtime.hashmapStringSet")
+
+	for _, makeInst := range getUses(hashmapMake) {
+		updateInsts := []llvm.Value{}
+		unknownUses := false // are there any uses other than setting a value?
+
+		for _, use := range getUses(makeInst) {
+			if use := use.IsACallInst(); !use.IsNil() {
+				switch use.CalledValue() {
+				case hashmapBinarySet, hashmapStringSet:
+					updateInsts = append(updateInsts, use)
+				default:
+					unknownUses = true
+				}
+			} else {
+				unknownUses = true
+			}
+		}
+
+		if !unknownUses {
+			// This map can be entirely removed, as it is only created but never
+			// used.
+			for _, inst := range updateInsts {
+				inst.EraseFromParentAsInstruction()
+			}
+			makeInst.EraseFromParentAsInstruction()
+		}
+	}
+}
+
+// Transform runtime.stringToBytes(...) calls into const []byte slices whenever
+// possible. This optimizes the following pattern:
+//     w.Write([]byte("foo"))
+// where Write does not store to the slice.
+func (c *Compiler) OptimizeStringToBytes() {
+	stringToBytes := c.mod.NamedFunction("runtime.stringToBytes")
+	if stringToBytes.IsNil() {
+		// nothing to optimize
+		return
+	}
+
+	for _, call := range getUses(stringToBytes) {
+		strptr := call.Operand(0)
+		strlen := call.Operand(1)
+
+		// strptr is always constant because strings are always constant.
+
+		convertedAllUses := true
+		for _, use := range getUses(call) {
+			nilValue := llvm.Value{}
+			if use.IsAExtractValueInst() == nilValue {
+				convertedAllUses = false
+				continue
+			}
+			switch use.Type().TypeKind() {
+			case llvm.IntegerTypeKind:
+				// A length (len or cap). Propagate the length value.
+				use.ReplaceAllUsesWith(strlen)
+				use.EraseFromParentAsInstruction()
+			case llvm.PointerTypeKind:
+				// The string pointer itself.
+				if !c.isReadOnly(use) {
+					convertedAllUses = false
+					continue
+				}
+				use.ReplaceAllUsesWith(strptr)
+				use.EraseFromParentAsInstruction()
+			default:
+				// should not happen
+				panic("unknown return type of runtime.stringToBytes: " + use.Type().String())
+			}
+		}
+		if convertedAllUses {
+			// Call to runtime.stringToBytes can be eliminated: both the input
+			// and the output is constant.
+			call.EraseFromParentAsInstruction()
+		}
+	}
+}
+
+// Basic escape analysis: translate runtime.alloc calls into alloca
+// instructions.
+func (c *Compiler) OptimizeAllocs() {
+	allocator := c.mod.NamedFunction("runtime.alloc")
+	if allocator.IsNil() {
+		// nothing to optimize
+		return
+	}
+
+	heapallocs := getUses(allocator)
+	for _, heapalloc := range heapallocs {
+		nilValue := llvm.Value{}
+		if heapalloc.Operand(0).IsAConstant() == nilValue {
+			// Do not allocate variable length arrays on the stack.
+			continue
+		}
+		size := heapalloc.Operand(0).ZExtValue()
+		if size > 256 {
+			// The maximum value for a stack allocation.
+			// TODO: tune this, this is just a random value.
+			continue
+		}
+
+		// In general the pattern is:
+		//     %0 = call i8* @runtime.alloc(i32 %size)
+		//     %1 = bitcast i8* %0 to type*
+		//     (use %1 only)
+		// But the bitcast might sometimes be dropped when allocating an *i8.
+		// The 'bitcast' variable below is thus usually a bitcast of the
+		// heapalloc but not always.
+		bitcast := heapalloc // instruction that creates the value
+		if uses := getUses(heapalloc); len(uses) == 1 && uses[0].IsABitCastInst() != nilValue {
+			// getting only bitcast use
+			bitcast = uses[0]
+		}
+		if !c.doesEscape(bitcast) {
+			// Insert alloca in the entry block. Do it here so that mem2reg can
+			// promote it to a SSA value.
+			fn := bitcast.InstructionParent().Parent()
+			c.builder.SetInsertPointBefore(fn.EntryBasicBlock().FirstInstruction())
+			alignment := c.targetData.ABITypeAlignment(c.i8ptrType)
+			sizeInWords := (size + uint64(alignment) - 1) / uint64(alignment)
+			allocaType := llvm.ArrayType(c.ctx.IntType(alignment*8), int(sizeInWords))
+			alloca := c.builder.CreateAlloca(allocaType, "stackalloc.alloca")
+			zero := c.getZeroValue(alloca.Type().ElementType())
+			c.builder.CreateStore(zero, alloca)
+			stackalloc := c.builder.CreateBitCast(alloca, bitcast.Type(), "stackalloc")
+			bitcast.ReplaceAllUsesWith(stackalloc)
+			if heapalloc != bitcast {
+				bitcast.EraseFromParentAsInstruction()
+			}
+			heapalloc.EraseFromParentAsInstruction()
+		}
+	}
+}
+
+// Very basic escape analysis.
+func (c *Compiler) doesEscape(value llvm.Value) bool {
+	uses := getUses(value)
+	for _, use := range uses {
+		nilValue := llvm.Value{}
+		if use.IsAGetElementPtrInst() != nilValue {
+			if c.doesEscape(use) {
+				return true
+			}
+		} else if use.IsABitCastInst() != nilValue {
+			// A bitcast escapes if the casted-to value escapes.
+			if c.doesEscape(use) {
+				return true
+			}
+		} else if use.IsALoadInst() != nilValue {
+			// Load does not escape.
+		} else if use.IsAStoreInst() != nilValue {
+			// Store only escapes when the value is stored to, not when the
+			// value is stored into another value.
+			if use.Operand(0) == value {
+				return true
+			}
+		} else if use.IsACallInst() != nilValue {
+			if !c.hasFlag(use, value, "nocapture") {
+				return true
+			}
+		} else if use.IsAICmpInst() != nilValue {
+			// Comparing pointers don't let the pointer escape.
+			// This is often a compiler-inserted nil check.
+		} else {
+			// Unknown instruction, might escape.
+			return true
+		}
+	}
+
+	// does not escape
+	return false
+}
+
+// Check whether the given value (which is of pointer type) is never stored to.
+func (c *Compiler) isReadOnly(value llvm.Value) bool {
+	uses := getUses(value)
+	for _, use := range uses {
+		nilValue := llvm.Value{}
+		if use.IsAGetElementPtrInst() != nilValue {
+			if !c.isReadOnly(use) {
+				return false
+			}
+		} else if use.IsACallInst() != nilValue {
+			if !c.hasFlag(use, value, "readonly") {
+				return false
+			}
+		} else {
+			// Unknown instruction, might not be readonly.
+			return false
+		}
+	}
+	return true
+}
+
+// Check whether all uses of this param as parameter to the call have the given
+// flag. In most cases, there will only be one use but a function could take the
+// same parameter twice, in which case both must have the flag.
+// A flag can be any enum flag, like "readonly".
+func (c *Compiler) hasFlag(call, param llvm.Value, kind string) bool {
+	fn := call.CalledValue()
+	nilValue := llvm.Value{}
+	if fn.IsAFunction() == nilValue {
+		// This is not a function but something else, like a function pointer.
+		return false
+	}
+	kindID := llvm.AttributeKindID(kind)
+	for i := 0; i < fn.ParamsCount(); i++ {
+		if call.Operand(i) != param {
+			// This is not the parameter we're checking.
+			continue
+		}
+		index := i + 1 // param attributes start at 1
+		attr := fn.GetEnumAttributeAtIndex(index, kindID)
+		nilAttribute := llvm.Attribute{}
+		if attr == nilAttribute {
+			// At least one parameter doesn't have the flag (there may be
+			// multiple).
+			return false
+		}
+	}
+	return true
+}
@@ -1,4 +1,4 @@
-package transform
+package compiler

 // This file has some compiler support for run-time reflection using the reflect
 // package. In particular, it encodes type information in type codes in such a
@@ -125,27 +125,34 @@ type typeCodeAssignmentState struct {
 // assignTypeCodes is used to assign a type code to each type in the program
 // that is ever stored in an interface. It tries to use the smallest possible
 // numbers to make the code that works with interfaces as small as possible.
-func assignTypeCodes(mod llvm.Module, typeSlice typeInfoSlice) {
-	// if reflect were not used, we could skip generating the sidetable
-	// this does not help in practice, and is difficult to do correctly
+func (c *Compiler) assignTypeCodes(typeSlice typeInfoSlice) {
+	fn := c.mod.NamedFunction("reflect.ValueOf")
+	if fn.IsNil() {
+		// reflect.ValueOf is never used, so we can use the most efficient
+		// encoding possible.
+		for i, t := range typeSlice {
+			t.num = uint64(i + 1)
+		}
+		return
+	}

 	// Assign typecodes the way the reflect package expects.
 	state := typeCodeAssignmentState{
 		fallbackIndex:                    1,
-		uintptrLen:                       llvm.NewTargetData(mod.DataLayout()).PointerSize() * 8,
+		uintptrLen:                       c.uintptrType.IntTypeWidth(),
 		namedBasicTypes:                  make(map[string]int),
 		namedNonBasicTypes:               make(map[string]int),
 		arrayTypes:                       make(map[string]int),
 		structTypes:                      make(map[string]int),
 		structNames:                      make(map[string]int),
-		needsNamedNonBasicTypesSidetable: len(getUses(mod.NamedGlobal("reflect.namedNonBasicTypesSidetable"))) != 0,
-		needsStructTypesSidetable:        len(getUses(mod.NamedGlobal("reflect.structTypesSidetable"))) != 0,
-		needsStructNamesSidetable:        len(getUses(mod.NamedGlobal("reflect.structNamesSidetable"))) != 0,
-		needsArrayTypesSidetable:         len(getUses(mod.NamedGlobal("reflect.arrayTypesSidetable"))) != 0,
+		needsNamedNonBasicTypesSidetable: len(getUses(c.mod.NamedGlobal("reflect.namedNonBasicTypesSidetable"))) != 0,
+		needsStructTypesSidetable:        len(getUses(c.mod.NamedGlobal("reflect.structTypesSidetable"))) != 0,
+		needsStructNamesSidetable:        len(getUses(c.mod.NamedGlobal("reflect.structNamesSidetable"))) != 0,
+		needsArrayTypesSidetable:         len(getUses(c.mod.NamedGlobal("reflect.arrayTypesSidetable"))) != 0,
 	}
 	for _, t := range typeSlice {
 		num := state.getTypeCodeNum(t.typecode)
-		if num.BitLen() > state.uintptrLen || !num.IsUint64() {
+		if num.BitLen() > c.uintptrType.IntTypeWidth() || !num.IsUint64() {
 			// TODO: support this in some way, using a side table for example.
 			// That's less efficient but better than not working at all.
 			// Particularly important on systems with 16-bit pointers (e.g.
@@ -157,28 +164,24 @@ func assignTypeCodes(mod llvm.Module, typeSlice typeInfoSlice) {

 	// Only create this sidetable when it is necessary.
 	if state.needsNamedNonBasicTypesSidetable {
-		global := replaceGlobalIntWithArray(mod, "reflect.namedNonBasicTypesSidetable", state.namedNonBasicTypesSidetable)
+		global := c.replaceGlobalIntWithArray("reflect.namedNonBasicTypesSidetable", state.namedNonBasicTypesSidetable)
 		global.SetLinkage(llvm.InternalLinkage)
 		global.SetUnnamedAddr(true)
-		global.SetGlobalConstant(true)
 	}
 	if state.needsArrayTypesSidetable {
-		global := replaceGlobalIntWithArray(mod, "reflect.arrayTypesSidetable", state.arrayTypesSidetable)
+		global := c.replaceGlobalIntWithArray("reflect.arrayTypesSidetable", state.arrayTypesSidetable)
 		global.SetLinkage(llvm.InternalLinkage)
 		global.SetUnnamedAddr(true)
-		global.SetGlobalConstant(true)
 	}
 	if state.needsStructTypesSidetable {
-		global := replaceGlobalIntWithArray(mod, "reflect.structTypesSidetable", state.structTypesSidetable)
+		global := c.replaceGlobalIntWithArray("reflect.structTypesSidetable", state.structTypesSidetable)
 		global.SetLinkage(llvm.InternalLinkage)
 		global.SetUnnamedAddr(true)
-		global.SetGlobalConstant(true)
 	}
 	if state.needsStructNamesSidetable {
-		global := replaceGlobalIntWithArray(mod, "reflect.structNamesSidetable", state.structNamesSidetable)
+		global := c.replaceGlobalIntWithArray("reflect.structNamesSidetable", state.structNamesSidetable)
 		global.SetLinkage(llvm.InternalLinkage)
 		global.SetUnnamedAddr(true)
-		global.SetGlobalConstant(true)
 	}
 }

@@ -10,13 +10,13 @@ import (
 // The original license can be found here:
 //     https://golang.org/LICENSE

-type stdSizes struct {
+type StdSizes struct {
 	IntSize  int64
 	PtrSize  int64
 	MaxAlign int64
 }

-func (s *stdSizes) Alignof(T types.Type) int64 {
+func (s *StdSizes) Alignof(T types.Type) int64 {
 	// For arrays and structs, alignment is defined in terms
 	// of alignment of the elements and fields, respectively.
 	switch t := T.Underlying().(type) {
@@ -61,8 +61,14 @@ func (s *stdSizes) Alignof(T types.Type) int64 {
 	return a
 }

-func (s *stdSizes) Offsetsof(fields []*types.Var) []int64 {
+func (s *StdSizes) Offsetsof(fields []*types.Var) []int64 {
 	offsets := make([]int64, len(fields))
+	if len(fields) > 1 && fields[0].Name() == "C union" {
+		// This struct contains the magic "C union" field which indicates that
+		// this is actually a union from CGo.
+		// All fields in the union start at 0 so return that.
+		return offsets // all fields are still set to 0
+	}
 	var o int64
 	for i, f := range fields {
 		a := s.Alignof(f.Type())
@@ -89,7 +95,7 @@ var basicSizes = [...]byte{
 	types.Complex128: 16,
 }

-func (s *stdSizes) Sizeof(T types.Type) int64 {
+func (s *StdSizes) Sizeof(T types.Type) int64 {
 	switch t := T.Underlying().(type) {
 	case *types.Basic:
 		k := t.Kind()
@@ -110,9 +116,6 @@ func (s *stdSizes) Sizeof(T types.Type) int64 {
 		if k == types.UnsafePointer {
 			return s.PtrSize
 		}
-		if k == types.Invalid {
-			return 0 // only relevant when there is a type error somewhere
-		}
 		panic("unknown basic type: " + t.String())
 	case *types.Array:
 		n := t.Len()
@@ -140,12 +143,29 @@ func (s *stdSizes) Sizeof(T types.Type) int64 {
 				maxAlign = al
 			}
 		}
-		// Pick the size that fits this struct and add some alignment. Some
-		// structs have some extra padding at the end which should also be taken
-		// care of:
-		//     struct { int32 n; byte b }
-		offsets := s.Offsetsof(fields)
-		return align(offsets[n-1]+s.Sizeof(fields[n-1].Type()), maxAlign)
+		if fields[0].Name() == "C union" {
+			// Magic field that indicates this is a CGo union and not a struct.
+			// The size is the biggest element, aligned to the element with the
+			// biggest alignment. This is not necessarily the same, for example
+			// in the following union:
+			//     union { int32_t l; int16_t s[3] }
+			maxSize := int64(0)
+			for _, field := range fields[1:] {
+				si := s.Sizeof(field.Type())
+				if si > maxSize {
+					maxSize = si
+				}
+			}
+			return align(maxSize, maxAlign)
+		} else {
+			// This is a regular struct.
+			// Pick the size that fits this struct and add some alignment. Some
+			// structs have some extra padding at the end which should also be
+			// taken care of:
+			//     struct { int32 n; byte b }
+			offsets := s.Offsetsof(fields)
+			return align(offsets[n-1]+s.Sizeof(fields[n-1].Type()), maxAlign)
+		}
 	case *types.Interface:
 		return s.PtrSize * 2
 	case *types.Pointer:
@@ -7,7 +7,6 @@ import (
 	"go/ast"
 	"go/token"
 	"go/types"
-	"strconv"
 	"strings"

 	"github.com/tinygo-org/tinygo/loader"
@@ -21,12 +20,11 @@ import (
 type globalInfo struct {
 	linkName string // go:extern
 	extern   bool   // go:extern
-	align    int    // go:align
 }

 // loadASTComments loads comments on globals from the AST, for use later in the
 // program. In particular, they are required for //go:extern pragmas on globals.
-func (c *compilerContext) loadASTComments(lprogram *loader.Program) {
+func (c *Compiler) loadASTComments(lprogram *loader.Program) {
 	c.astComments = map[string]*ast.CommentGroup{}
 	for _, pkgInfo := range lprogram.Sorted() {
 		for _, file := range pkgInfo.Files {
@@ -56,55 +54,22 @@ func (c *compilerContext) loadASTComments(lprogram *loader.Program) {

 // getGlobal returns a LLVM IR global value for a Go SSA global. It is added to
 // the LLVM IR if it has not been added already.
-func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
+func (c *Compiler) getGlobal(g *ssa.Global) llvm.Value {
 	info := c.getGlobalInfo(g)
 	llvmGlobal := c.mod.NamedGlobal(info.linkName)
 	if llvmGlobal.IsNil() {
-		typ := g.Type().(*types.Pointer).Elem()
-		llvmType := c.getLLVMType(typ)
+		llvmType := c.getLLVMType(g.Type().(*types.Pointer).Elem())
 		llvmGlobal = llvm.AddGlobal(c.mod, llvmType, info.linkName)
 		if !info.extern {
-			llvmGlobal.SetInitializer(llvm.ConstNull(llvmType))
+			llvmGlobal.SetInitializer(c.getZeroValue(llvmType))
 			llvmGlobal.SetLinkage(llvm.InternalLinkage)
 		}
-
-		// Set alignment from the //go:align comment.
-		var alignInBits uint32
-		if info.align < 0 || info.align&(info.align-1) != 0 {
-			// Check for power-of-two (or 0).
-			// See: https://stackoverflow.com/a/108360
-			c.addError(g.Pos(), "global variable alignment must be a positive power of two")
-		} else {
-			// Set the alignment only when it is a power of two.
-			alignInBits = uint32(info.align) ^ uint32(info.align-1)
-			if info.align > c.targetData.ABITypeAlignment(llvmType) {
-				llvmGlobal.SetAlignment(info.align)
-			}
-		}
-
-		if c.Debug() && !info.extern {
-			// Add debug info.
-			// TODO: this should be done for every global in the program, not just
-			// the ones that are referenced from some code.
-			pos := c.ir.Program.Fset.Position(g.Pos())
-			diglobal := c.dibuilder.CreateGlobalVariableExpression(c.difiles[pos.Filename], llvm.DIGlobalVariableExpression{
-				Name:        g.RelString(nil),
-				LinkageName: info.linkName,
-				File:        c.getDIFile(pos.Filename),
-				Line:        pos.Line,
-				Type:        c.getDIType(typ),
-				LocalToUnit: false,
-				Expr:        c.dibuilder.CreateExpression(nil),
-				AlignInBits: alignInBits,
-			})
-			llvmGlobal.AddMetadata(0, diglobal)
-		}
 	}
 	return llvmGlobal
 }

 // getGlobalInfo returns some information about a specific global.
-func (c *compilerContext) getGlobalInfo(g *ssa.Global) globalInfo {
+func (c *Compiler) getGlobalInfo(g *ssa.Global) globalInfo {
 	info := globalInfo{}
 	if strings.HasPrefix(g.Name(), "C.") {
 		// Created by CGo: such a name cannot be created by regular C code.
@@ -137,11 +102,6 @@ func (info *globalInfo) parsePragmas(doc *ast.CommentGroup) {
 			if len(parts) == 2 {
 				info.linkName = parts[1]
 			}
-		case "//go:align":
-			align, err := strconv.Atoi(parts[1])
-			if err == nil {
-				info.align = align
-			}
 		}
 	}
 }
@@ -10,14 +10,14 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// createSyscall emits an inline system call instruction, depending on the
-// target OS/arch.
-func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
-	num := b.getValue(call.Args[0])
+// emitSyscall emits an inline system call instruction, depending on the target
+// OS/arch.
+func (c *Compiler) emitSyscall(frame *Frame, call *ssa.CallCommon) (llvm.Value, error) {
+	num := c.getValue(frame, call.Args[0])
 	var syscallResult llvm.Value
 	switch {
-	case b.GOARCH() == "amd64":
-		if b.GOOS() == "darwin" {
+	case c.GOARCH == "amd64":
+		if c.GOOS == "darwin" {
 			// Darwin adds this magic number to system call numbers:
 			//
 			// > Syscall classes for 64-bit system call entry.
@@ -28,13 +28,13 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 			// > All system classes enter the kernel via the syscall instruction.
 			//
 			// Source: https://opensource.apple.com/source/xnu/xnu-792.13.8/osfmk/mach/i386/syscall_sw.h
-			num = b.CreateOr(num, llvm.ConstInt(b.uintptrType, 0x2000000, false), "")
+			num = c.builder.CreateOr(num, llvm.ConstInt(c.uintptrType, 0x2000000, false), "")
 		}
 		// Sources:
 		//   https://stackoverflow.com/a/2538212
 		//   https://en.wikibooks.org/wiki/X86_Assembly/Interfacing_with_Linux#syscall
 		args := []llvm.Value{num}
-		argTypes := []llvm.Type{b.uintptrType}
+		argTypes := []llvm.Type{c.uintptrType}
 		// Constraints will look something like:
 		//   "={rax},0,{rdi},{rsi},{rdx},{r10},{r8},{r9},~{rcx},~{r11}"
 		constraints := "={rax},0"
@@ -50,21 +50,21 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"{r12}",
 				"{r13}",
 			}[i]
-			llvmValue := b.getValue(arg)
+			llvmValue := c.getValue(frame, arg)
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		constraints += ",~{rcx},~{r11}"
-		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
+		fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "syscall", constraints, true, false, llvm.InlineAsmDialectIntel)
-		syscallResult = b.CreateCall(target, args, "")
-	case b.GOARCH() == "386" && b.GOOS() == "linux":
+		syscallResult = c.builder.CreateCall(target, args, "")
+	case c.GOARCH == "386" && c.GOOS == "linux":
 		// Sources:
 		//   syscall(2) man page
 		//   https://stackoverflow.com/a/2538212
 		//   https://en.wikibooks.org/wiki/X86_Assembly/Interfacing_with_Linux#int_0x80
 		args := []llvm.Value{num}
-		argTypes := []llvm.Type{b.uintptrType}
+		argTypes := []llvm.Type{c.uintptrType}
 		// Constraints will look something like:
 		//   "={eax},0,{ebx},{ecx},{edx},{esi},{edi},{ebp}"
 		constraints := "={eax},0"
@@ -77,14 +77,14 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"{edi}",
 				"{ebp}",
 			}[i]
-			llvmValue := b.getValue(arg)
+			llvmValue := c.getValue(frame, arg)
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
-		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
+		fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "int 0x80", constraints, true, false, llvm.InlineAsmDialectIntel)
-		syscallResult = b.CreateCall(target, args, "")
-	case b.GOARCH() == "arm" && b.GOOS() == "linux":
+		syscallResult = c.builder.CreateCall(target, args, "")
+	case c.GOARCH == "arm" && c.GOOS == "linux":
 		// Implement the EABI system call convention for Linux.
 		// Source: syscall(2) man page.
 		args := []llvm.Value{}
@@ -102,21 +102,21 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"{r5}",
 				"{r6}",
 			}[i]
-			llvmValue := b.getValue(arg)
+			llvmValue := c.getValue(frame, arg)
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		args = append(args, num)
-		argTypes = append(argTypes, b.uintptrType)
+		argTypes = append(argTypes, c.uintptrType)
 		constraints += ",{r7}" // syscall number
 		for i := len(call.Args) - 1; i < 4; i++ {
 			// r0-r3 get clobbered after the syscall returns
 			constraints += ",~{r" + strconv.Itoa(i) + "}"
 		}
-		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
+		fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
-		syscallResult = b.CreateCall(target, args, "")
-	case b.GOARCH() == "arm64" && b.GOOS() == "linux":
+		syscallResult = c.builder.CreateCall(target, args, "")
+	case c.GOARCH == "arm64" && c.GOOS == "linux":
 		// Source: syscall(2) man page.
 		args := []llvm.Value{}
 		argTypes := []llvm.Type{}
@@ -132,12 +132,12 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 				"{x4}",
 				"{x5}",
 			}[i]
-			llvmValue := b.getValue(arg)
+			llvmValue := c.getValue(frame, arg)
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
 		args = append(args, num)
-		argTypes = append(argTypes, b.uintptrType)
+		argTypes = append(argTypes, c.uintptrType)
 		constraints += ",{x8}" // syscall number
 		for i := len(call.Args) - 1; i < 8; i++ {
 			// x0-x7 may get clobbered during the syscall following the aarch64
@@ -145,14 +145,14 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 			constraints += ",~{x" + strconv.Itoa(i) + "}"
 		}
 		constraints += ",~{x16},~{x17}" // scratch registers
-		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
+		fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
-		syscallResult = b.CreateCall(target, args, "")
+		syscallResult = c.builder.CreateCall(target, args, "")
 	default:
-		return llvm.Value{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS()+"/"+b.GOARCH())
+		return llvm.Value{}, c.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+c.GOOS+"/"+c.GOARCH)
 	}
-	switch b.GOOS() {
-	case "linux", "freebsd":
+	switch c.GOOS {
+	case "linux":
 		// Return values: r0, r1 uintptr, err Errno
 		// Pseudocode:
 		//     var err uintptr
@@ -160,15 +160,15 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		//         err = -syscallResult
 		//     }
 		//     return syscallResult, 0, err
-		zero := llvm.ConstInt(b.uintptrType, 0, false)
-		inrange1 := b.CreateICmp(llvm.IntSLT, syscallResult, llvm.ConstInt(b.uintptrType, 0, false), "")
-		inrange2 := b.CreateICmp(llvm.IntSGT, syscallResult, llvm.ConstInt(b.uintptrType, 0xfffffffffffff000, true), "") // -4096
-		hasError := b.CreateAnd(inrange1, inrange2, "")
-		errResult := b.CreateSelect(hasError, b.CreateSub(zero, syscallResult, ""), zero, "syscallError")
-		retval := llvm.Undef(b.ctx.StructType([]llvm.Type{b.uintptrType, b.uintptrType, b.uintptrType}, false))
-		retval = b.CreateInsertValue(retval, syscallResult, 0, "")
-		retval = b.CreateInsertValue(retval, zero, 1, "")
-		retval = b.CreateInsertValue(retval, errResult, 2, "")
+		zero := llvm.ConstInt(c.uintptrType, 0, false)
+		inrange1 := c.builder.CreateICmp(llvm.IntSLT, syscallResult, llvm.ConstInt(c.uintptrType, 0, false), "")
+		inrange2 := c.builder.CreateICmp(llvm.IntSGT, syscallResult, llvm.ConstInt(c.uintptrType, 0xfffffffffffff000, true), "") // -4096
+		hasError := c.builder.CreateAnd(inrange1, inrange2, "")
+		errResult := c.builder.CreateSelect(hasError, c.builder.CreateSub(zero, syscallResult, ""), zero, "syscallError")
+		retval := llvm.Undef(c.ctx.StructType([]llvm.Type{c.uintptrType, c.uintptrType, c.uintptrType}, false))
+		retval = c.builder.CreateInsertValue(retval, syscallResult, 0, "")
+		retval = c.builder.CreateInsertValue(retval, zero, 1, "")
+		retval = c.builder.CreateInsertValue(retval, errResult, 2, "")
 		return retval, nil
 	case "darwin":
 		// Return values: r0, r1 uintptr, err Errno
@@ -178,15 +178,15 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		//         err = syscallResult
 		//     }
 		//     return syscallResult, 0, err
-		zero := llvm.ConstInt(b.uintptrType, 0, false)
-		hasError := b.CreateICmp(llvm.IntNE, syscallResult, llvm.ConstInt(b.uintptrType, 0, false), "")
-		errResult := b.CreateSelect(hasError, syscallResult, zero, "syscallError")
-		retval := llvm.Undef(b.ctx.StructType([]llvm.Type{b.uintptrType, b.uintptrType, b.uintptrType}, false))
-		retval = b.CreateInsertValue(retval, syscallResult, 0, "")
-		retval = b.CreateInsertValue(retval, zero, 1, "")
-		retval = b.CreateInsertValue(retval, errResult, 2, "")
+		zero := llvm.ConstInt(c.uintptrType, 0, false)
+		hasError := c.builder.CreateICmp(llvm.IntNE, syscallResult, llvm.ConstInt(c.uintptrType, 0, false), "")
+		errResult := c.builder.CreateSelect(hasError, syscallResult, zero, "syscallError")
+		retval := llvm.Undef(c.ctx.StructType([]llvm.Type{c.uintptrType, c.uintptrType, c.uintptrType}, false))
+		retval = c.builder.CreateInsertValue(retval, syscallResult, 0, "")
+		retval = c.builder.CreateInsertValue(retval, zero, 1, "")
+		retval = c.builder.CreateInsertValue(retval, errResult, 2, "")
 		return retval, nil
 	default:
-		return llvm.Value{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS()+"/"+b.GOARCH())
+		return llvm.Value{}, c.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+c.GOOS+"/"+c.GOARCH)
 	}
 }
@@ -8,23 +8,19 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// createVolatileLoad is the implementation of the intrinsic function
-// runtime/volatile.LoadT().
-func (b *builder) createVolatileLoad(instr *ssa.CallCommon) (llvm.Value, error) {
-	addr := b.getValue(instr.Args[0])
-	b.createNilCheck(instr.Args[0], addr, "deref")
-	val := b.CreateLoad(addr, "")
+func (c *Compiler) emitVolatileLoad(frame *Frame, instr *ssa.CallCommon) (llvm.Value, error) {
+	addr := c.getValue(frame, instr.Args[0])
+	c.emitNilCheck(frame, addr, "deref")
+	val := c.builder.CreateLoad(addr, "")
 	val.SetVolatile(true)
 	return val, nil
 }

-// createVolatileStore is the implementation of the intrinsic function
-// runtime/volatile.StoreT().
-func (b *builder) createVolatileStore(instr *ssa.CallCommon) (llvm.Value, error) {
-	addr := b.getValue(instr.Args[0])
-	val := b.getValue(instr.Args[1])
-	b.createNilCheck(instr.Args[0], addr, "deref")
-	store := b.CreateStore(val, addr)
+func (c *Compiler) emitVolatileStore(frame *Frame, instr *ssa.CallCommon) (llvm.Value, error) {
+	addr := c.getValue(frame, instr.Args[0])
+	val := c.getValue(frame, instr.Args[1])
+	c.emitNilCheck(frame, addr, "deref")
+	store := c.builder.CreateStore(val, addr)
 	store.SetVolatile(true)
 	return llvm.Value{}, nil
 }
@@ -0,0 +1,120 @@
+package compiler
+
+// This file contains utility functions to pack and unpack sets of values. It
+// can take in a list of values and tries to store it efficiently in the pointer
+// itself if possible and legal.
+
+import (
+	"tinygo.org/x/go-llvm"
+)
+
+// emitPointerPack packs the list of values into a single pointer value using
+// bitcasts, or else allocates a value on the heap if it cannot be packed in the
+// pointer value directly. It returns the pointer with the packed data.
+func (c *Compiler) emitPointerPack(values []llvm.Value) llvm.Value {
+	valueTypes := make([]llvm.Type, len(values))
+	for i, value := range values {
+		valueTypes[i] = value.Type()
+	}
+	packedType := c.ctx.StructType(valueTypes, false)
+
+	// Allocate memory for the packed data.
+	var packedAlloc, packedHeapAlloc llvm.Value
+	size := c.targetData.TypeAllocSize(packedType)
+	if size == 0 {
+		return llvm.ConstPointerNull(c.i8ptrType)
+	} else if len(values) == 1 && values[0].Type().TypeKind() == llvm.PointerTypeKind {
+		return c.builder.CreateBitCast(values[0], c.i8ptrType, "pack.ptr")
+	} else if size <= c.targetData.TypeAllocSize(c.i8ptrType) {
+		// Packed data fits in a pointer, so store it directly inside the
+		// pointer.
+		if len(values) == 1 && values[0].Type().TypeKind() == llvm.IntegerTypeKind {
+			// Try to keep this cast in SSA form.
+			return c.builder.CreateIntToPtr(values[0], c.i8ptrType, "pack.int")
+		}
+		// Because packedType is a struct and we have to cast it to a *i8, store
+		// it in an alloca first for bitcasting (store+bitcast+load).
+		packedAlloc, _, _ = c.createTemporaryAlloca(packedType, "")
+	} else {
+		// Packed data is bigger than a pointer, so allocate it on the heap.
+		sizeValue := llvm.ConstInt(c.uintptrType, size, false)
+		packedHeapAlloc = c.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "")
+		if c.needsStackObjects() {
+			c.trackPointer(packedHeapAlloc)
+		}
+		packedAlloc = c.builder.CreateBitCast(packedHeapAlloc, llvm.PointerType(packedType, 0), "")
+	}
+	// Store all values in the alloca or heap pointer.
+	for i, value := range values {
+		indices := []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
+		}
+		gep := c.builder.CreateInBoundsGEP(packedAlloc, indices, "")
+		c.builder.CreateStore(value, gep)
+	}
+
+	if packedHeapAlloc.IsNil() {
+		// Load value (as *i8) from the alloca.
+		packedAlloc = c.builder.CreateBitCast(packedAlloc, llvm.PointerType(c.i8ptrType, 0), "")
+		result := c.builder.CreateLoad(packedAlloc, "")
+		packedPtr := c.builder.CreateBitCast(packedAlloc, c.i8ptrType, "")
+		packedSize := llvm.ConstInt(c.ctx.Int64Type(), c.targetData.TypeAllocSize(packedAlloc.Type()), false)
+		c.emitLifetimeEnd(packedPtr, packedSize)
+		return result
+	} else {
+		// Get the original heap allocation pointer, which already is an *i8.
+		return packedHeapAlloc
+	}
+}
+
+// emitPointerUnpack extracts a list of values packed using emitPointerPack.
+func (c *Compiler) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
+	packedType := c.ctx.StructType(valueTypes, false)
+
+	// Get a correctly-typed pointer to the packed data.
+	var packedAlloc, packedRawAlloc llvm.Value
+	size := c.targetData.TypeAllocSize(packedType)
+	if size == 0 {
+		// No data to unpack.
+	} else if len(valueTypes) == 1 && valueTypes[0].TypeKind() == llvm.PointerTypeKind {
+		// A single pointer is always stored directly.
+		return []llvm.Value{c.builder.CreateBitCast(ptr, valueTypes[0], "unpack.ptr")}
+	} else if size <= c.targetData.TypeAllocSize(c.i8ptrType) {
+		// Packed data stored directly in pointer.
+		if len(valueTypes) == 1 && valueTypes[0].TypeKind() == llvm.IntegerTypeKind {
+			// Keep this cast in SSA form.
+			return []llvm.Value{c.builder.CreatePtrToInt(ptr, valueTypes[0], "unpack.int")}
+		}
+		// Fallback: load it using an alloca.
+		packedRawAlloc, _, _ = c.createTemporaryAlloca(llvm.PointerType(c.i8ptrType, 0), "unpack.raw.alloc")
+		packedRawValue := c.builder.CreateBitCast(ptr, llvm.PointerType(c.i8ptrType, 0), "unpack.raw.value")
+		c.builder.CreateStore(packedRawValue, packedRawAlloc)
+		packedAlloc = c.builder.CreateBitCast(packedRawAlloc, llvm.PointerType(packedType, 0), "unpack.alloc")
+	} else {
+		// Packed data stored on the heap. Bitcast the passed-in pointer to the
+		// correct pointer type.
+		packedAlloc = c.builder.CreateBitCast(ptr, llvm.PointerType(packedType, 0), "unpack.raw.ptr")
+	}
+	// Load each value from the packed data.
+	values := make([]llvm.Value, len(valueTypes))
+	for i, valueType := range valueTypes {
+		if c.targetData.TypeAllocSize(valueType) == 0 {
+			// This value has length zero, so there's nothing to load.
+			values[i] = c.getZeroValue(valueType)
+			continue
+		}
+		indices := []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
+		}
+		gep := c.builder.CreateInBoundsGEP(packedAlloc, indices, "")
+		values[i] = c.builder.CreateLoad(gep, "")
+	}
+	if !packedRawAlloc.IsNil() {
+		allocPtr := c.builder.CreateBitCast(packedRawAlloc, c.i8ptrType, "")
+		allocSize := llvm.ConstInt(c.ctx.Int64Type(), c.targetData.TypeAllocSize(c.uintptrType), false)
+		c.emitLifetimeEnd(allocPtr, allocSize)
+	}
+	return values
+}
@@ -4,10 +4,7 @@ go 1.11

 require (
 	github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2
-	github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf
 	github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46
-	go.bug.st/serial v1.0.0
-	golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2
-	google.golang.org/appengine v1.4.0 // indirect
-	tinygo.org/x/go-llvm v0.0.0-20200401165421-8d120882fc7a
+	golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef
+	tinygo.org/x/go-llvm v0.0.0-20190224120431-7707ae5d1261
 )
@@ -1,59 +1,14 @@
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2 h1:oMCHnXa6CCCafdPDbMh/lWRhRByN0VFLvv+g+ayx1SI=
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2/go.mod h1:PkYb9DJNAwrSvRx5DYA+gUcOIgTGVMNkfSCbZM8cWpI=
-github.com/creack/goselect v0.1.1 h1:tiSSgKE1eJtxs1h/VgGQWuXUP0YS4CDIFMp6vaI1ls0=
-github.com/creack/goselect v0.1.1/go.mod h1:a/NhLweNvqIYMuxcMOuWY516Cimucms3DglDzQP3hKY=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
-github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf h1:7+FW5aGwISbqUtkfmIpZJGRgNFg2ioYPvFaUxdqpDsg=
-github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE=
 github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46 h1:wXG2bA8fO7Vv7lLk2PihFMTqmbT173Tje39oKzQ50Mo=
 github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46/go.mod h1:Pb6XcsXyropB9LNHhnqaknG/vEwYztLkQzVCHv8sQ3M=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-go.bug.st/serial v1.0.0 h1:ogEPzrllCsnG00EqKRjeYvPRsO7NJW6DqykzkdD6E/k=
-go.bug.st/serial v1.0.0/go.mod h1:rpXPISGjuNjPTRTcMlxi9lN6LoIPxd1ixVjBd8aSk/Q=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee h1:WG0RUwxtNT4qqaXX3DPA8zHFNm/D9xaBpxzHt1WcA/E=
-golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20191128015809-6d18c012aee9 h1:ZBzSG/7F4eNKz2L3GE9o300RX0Az1Bw5HF7PDraD+qU=
-golang.org/x/sys v0.0.0-20191128015809-6d18c012aee9/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef h1:ymc9FeDom3RIEA3coKokSllBB1hRcMT0tZ1W3Jf9Ids=
 golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
-golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2 h1:0sfSpGSa544Fwnbot3Oxq/U6SXqjty6Jy/3wRhVS7ig=
-golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbOeHJjicWYPqR9bpxqxYG2pA=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 tinygo.org/x/go-llvm v0.0.0-20190224120431-7707ae5d1261 h1:rJS2Hga39YAnm7DE4qrPm6Dr/67EOojL0XPzvbEeBiw=
 tinygo.org/x/go-llvm v0.0.0-20190224120431-7707ae5d1261/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20190818154551-95bc4ffe1add h1:dFjMH1sLhYADg8UQm7DB56B7e+TfvAmWmEZLhyv3r/w=
-tinygo.org/x/go-llvm v0.0.0-20190818154551-95bc4ffe1add/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20191103182207-90b6e4bdc0b9 h1:d6rAX39a3C0pKrY5HcojEGyN8w9ocU0v7X28lC/TRKU=
-tinygo.org/x/go-llvm v0.0.0-20191103182207-90b6e4bdc0b9/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20191103200204-37e93e3f04e2 h1:Q5Hv3e5cLMGkiYwYgZL1Zrv6nb/EY+DJpRWrdO6ws6o=
-tinygo.org/x/go-llvm v0.0.0-20191103200204-37e93e3f04e2/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20191113125529-bad6d01809e8 h1:9Bfvso+tTVQg16UzOA614NaYA4x8vsRBNtd3eBrXwp0=
-tinygo.org/x/go-llvm v0.0.0-20191113125529-bad6d01809e8/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20191124211856-b2db3df3f257 h1:o8VDylrMN7gWemBMu8rEyuogKPhcLTdx5KrUAp9macc=
-tinygo.org/x/go-llvm v0.0.0-20191124211856-b2db3df3f257/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20191215173731-ad71f3d24aae h1:s8J5EyxCkHxXB08UI3gk9W9IS/ekizRvSX+PfZxnAB0=
-tinygo.org/x/go-llvm v0.0.0-20191215173731-ad71f3d24aae/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20200104190746-1ff21df33566 h1:a4y30bTf7U0zDA75v2PTL+XQ2OzJetj19gK8XwQpUNY=
-tinygo.org/x/go-llvm v0.0.0-20200104190746-1ff21df33566/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20200226165415-53522ab6713d h1:mtgZh/e8a3wxneQFuLXoQYO//1mvlki02yZ1JCwMKp4=
-tinygo.org/x/go-llvm v0.0.0-20200226165415-53522ab6713d/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
-tinygo.org/x/go-llvm v0.0.0-20200401165421-8d120882fc7a h1:Ugje2Lxuv8CFncHzs5W+hWfJvPsM+W4K0zRvzFbLvoE=
-tinygo.org/x/go-llvm v0.0.0-20200401165421-8d120882fc7a/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
@@ -1,197 +0,0 @@
-// Package goenv returns environment variables that are used in various parts of
-// the compiler. You can query it manually with the `tinygo env` subcommand.
-package goenv
-
-import (
-	"fmt"
-	"os"
-	"os/exec"
-	"os/user"
-	"path/filepath"
-	"runtime"
-)
-
-// Keys is a slice of all available environment variable keys.
-var Keys = []string{
-	"GOOS",
-	"GOARCH",
-	"GOROOT",
-	"GOPATH",
-	"GOCACHE",
-	"CGO_ENABLED",
-	"TINYGOROOT",
-}
-
-// TINYGOROOT is the path to the final location for checking tinygo files. If
-// unset (by a -X ldflag), then sourceDir() will fallback to the original build
-// directory.
-var TINYGOROOT string
-
-// Get returns a single environment variable, possibly calculating it on-demand.
-// The empty string is returned for unknown environment variables.
-func Get(name string) string {
-	switch name {
-	case "GOOS":
-		if dir := os.Getenv("GOOS"); dir != "" {
-			return dir
-		}
-		return runtime.GOOS
-	case "GOARCH":
-		if dir := os.Getenv("GOARCH"); dir != "" {
-			return dir
-		}
-		return runtime.GOARCH
-	case "GOROOT":
-		return getGoroot()
-	case "GOPATH":
-		if dir := os.Getenv("GOPATH"); dir != "" {
-			return dir
-		}
-
-		// fallback
-		home := getHomeDir()
-		return filepath.Join(home, "go")
-	case "GOCACHE":
-		// Get the cache directory, usually ~/.cache/tinygo
-		dir, err := os.UserCacheDir()
-		if err != nil {
-			panic("could not find cache dir: " + err.Error())
-		}
-		return filepath.Join(dir, "tinygo")
-	case "CGO_ENABLED":
-		val := os.Getenv("CGO_ENABLED")
-		if val == "1" || val == "0" {
-			return val
-		}
-		// Default to enabling CGo.
-		return "1"
-	case "TINYGOROOT":
-		return sourceDir()
-	default:
-		return ""
-	}
-}
-
-// Return the TINYGOROOT, or exit with an error.
-func sourceDir() string {
-	// Use $TINYGOROOT as root, if available.
-	root := os.Getenv("TINYGOROOT")
-	if root != "" {
-		if !isSourceDir(root) {
-			fmt.Fprintln(os.Stderr, "error: $TINYGOROOT was not set to the correct root")
-			os.Exit(1)
-		}
-		return root
-	}
-
-	if TINYGOROOT != "" {
-		if !isSourceDir(TINYGOROOT) {
-			fmt.Fprintln(os.Stderr, "error: TINYGOROOT was not set to the correct root")
-			os.Exit(1)
-		}
-		return TINYGOROOT
-	}
-
-	// Find root from executable path.
-	path, err := os.Executable()
-	if err != nil {
-		// Very unlikely. Bail out if it happens.
-		panic("could not get executable path: " + err.Error())
-	}
-	root = filepath.Dir(filepath.Dir(path))
-	if isSourceDir(root) {
-		return root
-	}
-
-	// Fallback: use the original directory from where it was built
-	// https://stackoverflow.com/a/32163888/559350
-	_, path, _, _ = runtime.Caller(0)
-	root = filepath.Dir(filepath.Dir(path))
-	if isSourceDir(root) {
-		return root
-	}
-
-	fmt.Fprintln(os.Stderr, "error: could not autodetect root directory, set the TINYGOROOT environment variable to override")
-	os.Exit(1)
-	panic("unreachable")
-}
-
-// isSourceDir returns true if the directory looks like a TinyGo source directory.
-func isSourceDir(root string) bool {
-	_, err := os.Stat(filepath.Join(root, "src/runtime/internal/sys/zversion.go"))
-	if err != nil {
-		return false
-	}
-	_, err = os.Stat(filepath.Join(root, "src/device/arm/arm.go"))
-	return err == nil
-}
-
-func getHomeDir() string {
-	u, err := user.Current()
-	if err != nil {
-		panic("cannot get current user: " + err.Error())
-	}
-	if u.HomeDir == "" {
-		// This is very unlikely, so panic here.
-		// Not the nicest solution, however.
-		panic("could not find home directory")
-	}
-	return u.HomeDir
-}
-
-// getGoroot returns an appropriate GOROOT from various sources. If it can't be
-// found, it returns an empty string.
-func getGoroot() string {
-	goroot := os.Getenv("GOROOT")
-	if goroot != "" {
-		// An explicitly set GOROOT always has preference.
-		return goroot
-	}
-
-	// Check for the location of the 'go' binary and base GOROOT on that.
-	binpath, err := exec.LookPath("go")
-	if err == nil {
-		binpath, err = filepath.EvalSymlinks(binpath)
-		if err == nil {
-			goroot := filepath.Dir(filepath.Dir(binpath))
-			if isGoroot(goroot) {
-				return goroot
-			}
-		}
-	}
-
-	// Check what GOROOT was at compile time.
-	if isGoroot(runtime.GOROOT()) {
-		return runtime.GOROOT()
-	}
-
-	// Check for some standard locations, as a last resort.
-	var candidates []string
-	switch runtime.GOOS {
-	case "linux":
-		candidates = []string{
-			"/usr/local/go", // manually installed
-			"/usr/lib/go",   // from the distribution
-		}
-	case "darwin":
-		candidates = []string{
-			"/usr/local/go",             // manually installed
-			"/usr/local/opt/go/libexec", // from Homebrew
-		}
-	}
-
-	for _, candidate := range candidates {
-		if isGoroot(candidate) {
-			return candidate
-		}
-	}
-
-	// Can't find GOROOT...
-	return ""
-}
-
-// isGoroot checks whether the given path looks like a GOROOT.
-func isGoroot(goroot string) bool {
-	_, err := os.Stat(filepath.Join(goroot, "src", "runtime", "internal", "sys", "zversion.go"))
-	return err == nil
-}
@@ -1,64 +0,0 @@
-package goenv
-
-import (
-	"errors"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"path/filepath"
-	"regexp"
-	"strings"
-)
-
-// GetGorootVersion returns the major and minor version for a given GOROOT path.
-// If the goroot cannot be determined, (0, 0) is returned.
-func GetGorootVersion(goroot string) (major, minor int, err error) {
-	s, err := GorootVersionString(goroot)
-	if err != nil {
-		return 0, 0, err
-	}
-
-	if s == "" || s[:2] != "go" {
-		return 0, 0, errors.New("could not parse Go version: version does not start with 'go' prefix")
-	}
-
-	parts := strings.Split(s[2:], ".")
-	if len(parts) < 2 {
-		return 0, 0, errors.New("could not parse Go version: version has less than two parts")
-	}
-
-	// Ignore the errors, we don't really handle errors here anyway.
-	var trailing string
-	n, err := fmt.Sscanf(s, "go%d.%d%s", &major, &minor, &trailing)
-	if n == 2 && err == io.EOF {
-		// Means there were no trailing characters (i.e., not an alpha/beta)
-		err = nil
-	}
-	if err != nil {
-		return 0, 0, fmt.Errorf("failed to parse version: %s", err)
-	}
-	return
-}
-
-// GorootVersionString returns the version string as reported by the Go
-// toolchain for the given GOROOT path. It is usually of the form `go1.x.y` but
-// can have some variations (for beta releases, for example).
-func GorootVersionString(goroot string) (string, error) {
-	if data, err := ioutil.ReadFile(filepath.Join(
-		goroot, "src", "runtime", "internal", "sys", "zversion.go")); err == nil {
-
-		r := regexp.MustCompile("const TheVersion = `(.*)`")
-		matches := r.FindSubmatch(data)
-		if len(matches) != 2 {
-			return "", errors.New("Invalid go version output:\n" + string(data))
-		}
-
-		return string(matches[1]), nil
-
-	} else if data, err := ioutil.ReadFile(filepath.Join(goroot, "VERSION")); err == nil {
-		return string(data), nil
-
-	} else {
-		return "", err
-	}
-}
@@ -3,81 +3,15 @@ package interp
 // This file provides useful types for errors encountered during IR evaluation.

 import (
-	"errors"
-	"go/scanner"
-	"go/token"
-	"path/filepath"
-
 	"tinygo.org/x/go-llvm"
 )

-// errUnreachable is returned when an unreachable instruction is executed. This
-// error should not be visible outside of the interp package.
-var errUnreachable = &Error{Err: errors.New("interp: unreachable executed")}
-
-// unsupportedInstructionError returns a new "unsupported instruction" error for
-// the given instruction. It includes source location information, when
-// available.
-func (e *evalPackage) unsupportedInstructionError(inst llvm.Value) *Error {
-	return e.errorAt(inst, errors.New("interp: unsupported instruction"))
-}
-
-// ErrorLine is one line in a traceback. The position may be missing.
-type ErrorLine struct {
-	Pos  token.Position
+type Unsupported struct {
 	Inst llvm.Value
 }

-// Error encapsulates compile-time interpretation errors with an associated
-// import path. The errors may not have a precise location attached.
-type Error struct {
-	ImportPath string
-	Inst       llvm.Value
-	Pos        token.Position
-	Err        error
-	Traceback  []ErrorLine
-}
-
-// Error returns the string of the first error in the list of errors.
-func (e *Error) Error() string {
-	return e.Pos.String() + ": " + e.Err.Error()
-}
-
-// errorAt returns an error value for the currently interpreted package at the
-// location of the instruction. The location information may not be complete as
-// it depends on debug information in the IR.
-func (e *evalPackage) errorAt(inst llvm.Value, err error) *Error {
-	return &Error{
-		ImportPath: e.packagePath,
-		Pos:        getPosition(inst),
-		Err:        err,
-	}
-}
-
-// errorAt returns an error value at the location of the instruction.
-// The location information may not be complete as it depends on debug
-// information in the IR.
-func errorAt(inst llvm.Value, msg string) scanner.Error {
-	return scanner.Error{
-		Pos: getPosition(inst),
-		Msg: msg,
-	}
-}
-
-// getPosition returns the position information for the given instruction, as
-// far as it is available.
-func getPosition(inst llvm.Value) token.Position {
-	if inst.IsAInstruction().IsNil() {
-		return token.Position{}
-	}
-	loc := inst.InstructionDebugLoc()
-	if loc.IsNil() {
-		return token.Position{}
-	}
-	file := loc.LocationScope().ScopeFile()
-	return token.Position{
-		Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-		Line:     int(loc.LocationLine()),
-		Column:   int(loc.LocationColumn()),
-	}
+func (e Unsupported) Error() string {
+	// TODO: how to return the actual instruction string?
+	// It looks like LLVM provides no function for that...
+	return "interp: unsupported instruction"
 }
@@ -11,18 +11,21 @@ import (
 )

 type frame struct {
-	*evalPackage
-	fn     llvm.Value
-	locals map[llvm.Value]Value
+	*Eval
+	fn      llvm.Value
+	pkgName string
+	locals  map[llvm.Value]Value
 }

+var ErrUnreachable = errors.New("interp: unreachable executed")
+
 // evalBasicBlock evaluates a single basic block, returning the return value (if
 // ending with a ret instruction), a list of outgoing basic blocks (if not
 // ending with a ret instruction), or an error on failure.
 // Most of it works at compile time. Some calls get translated into calls to be
 // executed at runtime: calls to functions with side effects, external calls,
 // and operations on the result of such instructions.
-func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (retval Value, outgoing []llvm.Value, err *Error) {
+func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (retval Value, outgoing []llvm.Value, err error) {
 	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
 		if fr.Debug {
 			print(indent)
@@ -76,14 +79,14 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateXor(lhs, rhs, "")}

 			default:
-				return nil, nil, fr.unsupportedInstructionError(inst)
+				return nil, nil, &Unsupported{inst}
 			}

 		// Memory operators
 		case !inst.IsAAllocaInst().IsNil():
 			allocType := inst.Type().ElementType()
-			alloca := llvm.AddGlobal(fr.Mod, allocType, fr.packagePath+"$alloca")
-			alloca.SetInitializer(llvm.ConstNull(allocType))
+			alloca := llvm.AddGlobal(fr.Mod, allocType, fr.pkgName+"$alloca")
+			alloca.SetInitializer(getZeroValue(allocType))
 			alloca.SetLinkage(llvm.InternalLinkage)
 			fr.locals[inst] = &LocalValue{
 				Underlying: alloca,
@@ -98,7 +101,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				value = operand.Load()
 			}
 			if value.Type() != inst.Type() {
-				return nil, nil, fr.errorAt(inst, errors.New("interp: load: type does not match"))
+				panic("interp: load: type does not match")
 			}
 			fr.locals[inst] = fr.getValue(value)
 		case !inst.IsAStoreInst().IsNil():
@@ -122,16 +125,15 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					// Not a constant operation.
 					// This should be detected by the scanner, but isn't at the
 					// moment.
-					return nil, nil, fr.errorAt(inst, errors.New("todo: non-const gep"))
+					panic("todo: non-const gep")
 				}
 				indices[i] = uint32(operand.Value().ZExtValue())
 			}
-			result, err := value.GetElementPtr(indices)
-			if err != nil {
-				return nil, nil, fr.errorAt(inst, err)
-			}
+			result := value.GetElementPtr(indices)
 			if result.Type() != inst.Type() {
-				return nil, nil, fr.errorAt(inst, errors.New("interp: gep: type does not match"))
+				println(" expected:", inst.Type().String())
+				println(" actual:  ", result.Type().String())
+				panic("interp: gep: type does not match")
 			}
 			fr.locals[inst] = result

@@ -186,7 +188,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					}
 				}
 				// It is not possible in Go to bitcast a map value to a pointer.
-				return nil, nil, fr.errorAt(inst, errors.New("unimplemented: bitcast of map"))
+				panic("unimplemented: bitcast of map")
 			}
 			value := fr.getLocal(operand).(*LocalValue)
 			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateBitCast(value.Value(), inst.Type(), "")}
@@ -196,28 +198,20 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 			lhs := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
 			rhs := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
 			predicate := inst.IntPredicate()
-			if predicate == llvm.IntEQ {
-				var lhsZero, rhsZero bool
-				var ok1, ok2 bool
-				if lhs.Type().TypeKind() == llvm.PointerTypeKind {
-					// Unfortunately, the const propagation in the IR builder
-					// doesn't handle pointer compares of inttoptr values. So we
-					// implement it manually here.
-					lhsZero, ok1 = isPointerNil(lhs)
-					rhsZero, ok2 = isPointerNil(rhs)
-				}
-				if lhs.Type().TypeKind() == llvm.IntegerTypeKind {
-					lhsZero, ok1 = isZero(lhs)
-					rhsZero, ok2 = isZero(rhs)
-				}
+			if predicate == llvm.IntEQ && lhs.Type().TypeKind() == llvm.PointerTypeKind {
+				// Unfortunately, the const propagation in the IR builder
+				// doesn't handle pointer compares of inttoptr values. So we
+				// implement it manually here.
+				lhsNil, ok1 := isPointerNil(lhs)
+				rhsNil, ok2 := isPointerNil(rhs)
 				if ok1 && ok2 {
-					if lhsZero && rhsZero {
-						// Both are zero, so this icmp is always evaluated to true.
+					if lhsNil && rhsNil {
+						// Both are nil, so this icmp is always evaluated to true.
 						fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), 1, false)}
 						continue
 					}
-					if lhsZero != rhsZero {
-						// Only one of them is zero, so this comparison must return false.
+					if lhsNil != rhsNil {
+						// Only one of them is nil, so this comparison must return false.
 						fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false)}
 						continue
 					}
@@ -253,13 +247,13 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				if size != typeSize {
 					// allocate an array
 					if size%typeSize != 0 {
-						return nil, nil, fr.unsupportedInstructionError(inst)
+						return nil, nil, &Unsupported{inst}
 					}
 					elementCount = int(size / typeSize)
 					allocType = llvm.ArrayType(allocType, elementCount)
 				}
-				alloc := llvm.AddGlobal(fr.Mod, allocType, fr.packagePath+"$alloc")
-				alloc.SetInitializer(llvm.ConstNull(allocType))
+				alloc := llvm.AddGlobal(fr.Mod, allocType, fr.pkgName+"$alloc")
+				alloc.SetInitializer(getZeroValue(allocType))
 				alloc.SetLinkage(llvm.InternalLinkage)
 				result := &LocalValue{
 					Underlying: alloc,
@@ -268,11 +262,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				if elementCount == 1 {
 					fr.locals[resultInst] = result
 				} else {
-					result, err := result.GetElementPtr([]uint32{0, 0})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					fr.locals[resultInst] = result
+					fr.locals[resultInst] = result.GetElementPtr([]uint32{0, 0})
 				}
 			case callee.Name() == "runtime.hashmapMake":
 				// create a map
@@ -280,55 +270,24 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				valueSize := inst.Operand(1).ZExtValue()
 				fr.locals[inst] = &MapValue{
 					Eval:      fr.Eval,
-					PkgName:   fr.packagePath,
+					PkgName:   fr.pkgName,
 					KeySize:   int(keySize),
 					ValueSize: int(valueSize),
 				}
 			case callee.Name() == "runtime.hashmapStringSet":
 				// set a string key in the map
+				m := fr.getLocal(inst.Operand(0)).(*MapValue)
+				// "key" is a Go string value, which in the TinyGo calling convention is split up
+				// into separate pointer and length parameters.
 				keyBuf := fr.getLocal(inst.Operand(1)).(*LocalValue)
 				keyLen := fr.getLocal(inst.Operand(2)).(*LocalValue)
 				valPtr := fr.getLocal(inst.Operand(3)).(*LocalValue)
-				m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
-				if !ok || !keyBuf.IsConstant() || !keyLen.IsConstant() || !valPtr.IsConstant() {
-					// The mapassign operation could not be done at compile
-					// time. Do it at runtime instead.
-					m := fr.getLocal(inst.Operand(0)).Value()
-					fr.markDirty(m)
-					llvmParams := []llvm.Value{
-						m,                                    // *runtime.hashmap
-						fr.getLocal(inst.Operand(1)).Value(), // key.ptr
-						fr.getLocal(inst.Operand(2)).Value(), // key.len
-						fr.getLocal(inst.Operand(3)).Value(), // value (unsafe.Pointer)
-						fr.getLocal(inst.Operand(4)).Value(), // context
-						fr.getLocal(inst.Operand(5)).Value(), // parentHandle
-					}
-					fr.builder.CreateCall(callee, llvmParams, "")
-					continue
-				}
-				// "key" is a Go string value, which in the TinyGo calling convention is split up
-				// into separate pointer and length parameters.
 				m.PutString(keyBuf, keyLen, valPtr)
 			case callee.Name() == "runtime.hashmapBinarySet":
 				// set a binary (int etc.) key in the map
+				m := fr.getLocal(inst.Operand(0)).(*MapValue)
 				keyBuf := fr.getLocal(inst.Operand(1)).(*LocalValue)
 				valPtr := fr.getLocal(inst.Operand(2)).(*LocalValue)
-				m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
-				if !ok || !keyBuf.IsConstant() || !valPtr.IsConstant() {
-					// The mapassign operation could not be done at compile
-					// time. Do it at runtime instead.
-					m := fr.getLocal(inst.Operand(0)).Value()
-					fr.markDirty(m)
-					llvmParams := []llvm.Value{
-						m,                                    // *runtime.hashmap
-						fr.getLocal(inst.Operand(1)).Value(), // key
-						fr.getLocal(inst.Operand(2)).Value(), // value
-						fr.getLocal(inst.Operand(3)).Value(), // context
-						fr.getLocal(inst.Operand(4)).Value(), // parentHandle
-					}
-					fr.builder.CreateCall(callee, llvmParams, "")
-					continue
-				}
 				m.PutBinary(keyBuf, valPtr)
 			case callee.Name() == "runtime.stringConcat":
 				// adding two strings together
@@ -345,7 +304,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				}
 				globalType := llvm.ArrayType(fr.Mod.Context().Int8Type(), len(result))
 				globalValue := llvm.ConstArray(fr.Mod.Context().Int8Type(), vals)
-				global := llvm.AddGlobal(fr.Mod, globalType, fr.packagePath+"$stringconcat")
+				global := llvm.AddGlobal(fr.Mod, globalType, fr.pkgName+"$stringconcat")
 				global.SetInitializer(globalValue)
 				global.SetLinkage(llvm.InternalLinkage)
 				global.SetGlobalConstant(true)
@@ -353,70 +312,10 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				stringType := fr.Mod.GetTypeByName("runtime._string")
 				retPtr := llvm.ConstGEP(global, getLLVMIndices(fr.Mod.Context().Int32Type(), []uint32{0, 0}))
 				retLen := llvm.ConstInt(stringType.StructElementTypes()[1], uint64(len(result)), false)
-				ret := llvm.ConstNull(stringType)
+				ret := getZeroValue(stringType)
 				ret = llvm.ConstInsertValue(ret, retPtr, []uint32{0})
 				ret = llvm.ConstInsertValue(ret, retLen, []uint32{1})
 				fr.locals[inst] = &LocalValue{fr.Eval, ret}
-			case callee.Name() == "runtime.sliceCopy":
-				elementSize := fr.getLocal(inst.Operand(4)).(*LocalValue).Value().ZExtValue()
-				dstArray := fr.getLocal(inst.Operand(0)).(*LocalValue).stripPointerCasts()
-				srcArray := fr.getLocal(inst.Operand(1)).(*LocalValue).stripPointerCasts()
-				dstLen := fr.getLocal(inst.Operand(2)).(*LocalValue)
-				srcLen := fr.getLocal(inst.Operand(3)).(*LocalValue)
-				if elementSize != 1 && dstArray.Type().ElementType().TypeKind() == llvm.ArrayTypeKind && srcArray.Type().ElementType().TypeKind() == llvm.ArrayTypeKind {
-					// Slice data pointers are created by adding a global array
-					// and getting the address of the first element using a GEP.
-					// However, before the compiler can pass it to
-					// runtime.sliceCopy, it has to perform a bitcast to a *i8,
-					// to make it a unsafe.Pointer. Now, when the IR builder
-					// sees a bitcast of a GEP with zero indices, it will make
-					// a bitcast of the original array instead of the GEP,
-					// which breaks our assumptions.
-					// Re-add this GEP, in the hope that it it is then of the correct type...
-					dstArrayValue, err := dstArray.GetElementPtr([]uint32{0, 0})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					dstArray = dstArrayValue.(*LocalValue)
-					srcArrayValue, err := srcArray.GetElementPtr([]uint32{0, 0})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					srcArray = srcArrayValue.(*LocalValue)
-				}
-				if fr.Eval.TargetData.TypeAllocSize(dstArray.Type().ElementType()) != elementSize {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: slice dst element size does not match pointer type"))
-				}
-				if fr.Eval.TargetData.TypeAllocSize(srcArray.Type().ElementType()) != elementSize {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: slice src element size does not match pointer type"))
-				}
-				if dstArray.Type() != srcArray.Type() {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: slice element types don't match"))
-				}
-				length := dstLen.Value().SExtValue()
-				if srcLength := srcLen.Value().SExtValue(); srcLength < length {
-					length = srcLength
-				}
-				if length < 0 {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: trying to copy a slice with negative length?"))
-				}
-				for i := int64(0); i < length; i++ {
-					var err error
-					// *dst = *src
-					dstArray.Store(srcArray.Load())
-					// dst++
-					dstArrayValue, err := dstArray.GetElementPtr([]uint32{1})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					dstArray = dstArrayValue.(*LocalValue)
-					// src++
-					srcArrayValue, err := srcArray.GetElementPtr([]uint32{1})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					srcArray = srcArrayValue.(*LocalValue)
-				}
 			case callee.Name() == "runtime.stringToBytes":
 				// convert a string to a []byte
 				bufPtr := fr.getLocal(inst.Operand(0))
@@ -428,7 +327,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				}
 				globalType := llvm.ArrayType(fr.Mod.Context().Int8Type(), len(result))
 				globalValue := llvm.ConstArray(fr.Mod.Context().Int8Type(), vals)
-				global := llvm.AddGlobal(fr.Mod, globalType, fr.packagePath+"$bytes")
+				global := llvm.AddGlobal(fr.Mod, globalType, fr.pkgName+"$bytes")
 				global.SetInitializer(globalValue)
 				global.SetLinkage(llvm.InternalLinkage)
 				global.SetGlobalConstant(true)
@@ -436,40 +335,25 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				sliceType := inst.Type()
 				retPtr := llvm.ConstGEP(global, getLLVMIndices(fr.Mod.Context().Int32Type(), []uint32{0, 0}))
 				retLen := llvm.ConstInt(sliceType.StructElementTypes()[1], uint64(len(result)), false)
-				ret := llvm.ConstNull(sliceType)
+				ret := getZeroValue(sliceType)
 				ret = llvm.ConstInsertValue(ret, retPtr, []uint32{0}) // ptr
 				ret = llvm.ConstInsertValue(ret, retLen, []uint32{1}) // len
 				ret = llvm.ConstInsertValue(ret, retLen, []uint32{2}) // cap
 				fr.locals[inst] = &LocalValue{fr.Eval, ret}
-			case callee.Name() == "runtime.typeAssert":
-				actualTypeInt := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
-				assertedType := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
-				if actualTypeInt.IsAConstantExpr().IsNil() || actualTypeInt.Opcode() != llvm.PtrToInt {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: expected typecode in runtime.typeAssert to be a ptrtoint"))
-				}
-				actualType := actualTypeInt.Operand(0)
-				if actualType.IsAConstant().IsNil() || assertedType.IsAConstant().IsNil() {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: unimplemented: type assert with non-constant interface value"))
-				}
-				assertOk := uint64(0)
-				if llvm.ConstExtractValue(actualType.Initializer(), []uint32{0}) == assertedType {
-					assertOk = 1
-				}
-				fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), assertOk, false)}
 			case callee.Name() == "runtime.interfaceImplements":
 				typecode := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
 				interfaceMethodSet := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
 				if typecode.IsAConstantExpr().IsNil() || typecode.Opcode() != llvm.PtrToInt {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: expected typecode to be a ptrtoint"))
+					panic("interp: expected typecode to be a ptrtoint")
 				}
 				typecode = typecode.Operand(0)
 				if interfaceMethodSet.IsAConstantExpr().IsNil() || interfaceMethodSet.Opcode() != llvm.GetElementPtr {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: expected method set in runtime.interfaceImplements to be a constant gep"))
+					panic("interp: expected method set in runtime.interfaceImplements to be a constant gep")
 				}
 				interfaceMethodSet = interfaceMethodSet.Operand(0).Initializer()
 				methodSet := llvm.ConstExtractValue(typecode.Initializer(), []uint32{1})
 				if methodSet.IsAConstantExpr().IsNil() || methodSet.Opcode() != llvm.GetElementPtr {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: expected method set to be a constant gep"))
+					panic("interp: expected method set to be a constant gep")
 				}
 				methodSet = methodSet.Operand(0).Initializer()

@@ -498,8 +382,6 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int64Type(), 0, false)}
 			case callee.Name() == "llvm.dbg.value":
 				// do nothing
-			case strings.HasPrefix(callee.Name(), "llvm.lifetime."):
-				// do nothing
 			case callee.Name() == "runtime.trackPointer":
 				// do nothing
 			case strings.HasPrefix(callee.Name(), "runtime.print") || callee.Name() == "runtime._panic":
@@ -541,10 +423,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					params = append(params, local)
 				}
 				var ret Value
-				scanResult, err := fr.hasSideEffects(callee)
-				if err != nil {
-					return nil, nil, err
-				}
+				scanResult := fr.Eval.hasSideEffects(callee)
 				if scanResult.severity == sideEffectLimited || dirtyParams && scanResult.severity != sideEffectAll {
 					// Side effect is bounded. This means the operation invokes
 					// side effects (like calling an external function) but it
@@ -567,13 +446,8 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					//     compile time.
 					//   * Unbounded: cannot call at runtime so we'll try to
 					//     interpret anyway and hope for the best.
-					ret, err = fr.function(callee, params, indent+"    ")
+					ret, err = fr.function(callee, params, fr.pkgName, indent+"    ")
 					if err != nil {
-						// Record this function call in the backtrace.
-						err.Traceback = append(err.Traceback, ErrorLine{
-							Pos:  getPosition(inst),
-							Inst: inst,
-						})
 						return nil, nil, err
 					}
 				}
@@ -582,7 +456,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				}
 			default:
 				// function pointers, etc.
-				return nil, nil, fr.unsupportedInstructionError(inst)
+				return nil, nil, &Unsupported{inst}
 			}
 		case !inst.IsAExtractValueInst().IsNil():
 			agg := fr.getLocal(inst.Operand(0)).(*LocalValue) // must be constant
@@ -592,7 +466,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = fr.getValue(newValue)
 			} else {
 				if len(indices) != 1 {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: cannot handle extractvalue with not exactly 1 index"))
+					return nil, nil, errors.New("cannot handle extractvalue with not exactly 1 index")
 				}
 				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateExtractValue(agg.Underlying, int(indices[0]), inst.Name())}
 			}
@@ -605,22 +479,10 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = &LocalValue{fr.Eval, newValue}
 			} else {
 				if len(indices) != 1 {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: cannot handle insertvalue with not exactly 1 index"))
+					return nil, nil, errors.New("cannot handle insertvalue with not exactly 1 index")
 				}
 				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateInsertValue(agg.Underlying, val.Value(), int(indices[0]), inst.Name())}
 			}
-		case !inst.IsASelectInst().IsNil():
-			// var result T
-			// if cond {
-			//   result = x
-			// } else {
-			//   result = y
-			// }
-			// return result
-			cond := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
-			x := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
-			y := fr.getLocal(inst.Operand(2)).(*LocalValue).Underlying
-			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSelect(cond, x, y, "")}

 		case !inst.IsAReturnInst().IsNil() && inst.OperandsCount() == 0:
 			return nil, nil, nil // ret void
@@ -630,17 +492,17 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 			// conditional branch (if/then/else)
 			cond := fr.getLocal(inst.Operand(0)).Value()
 			if cond.Type() != fr.Mod.Context().Int1Type() {
-				return nil, nil, fr.errorAt(inst, errors.New("expected an i1 in a branch instruction"))
+				panic("expected an i1 in a branch instruction")
 			}
 			thenBB := inst.Operand(1)
 			elseBB := inst.Operand(2)
 			if !cond.IsAInstruction().IsNil() {
-				return nil, nil, fr.errorAt(inst, errors.New("interp: branch on a non-constant"))
+				return nil, nil, errors.New("interp: branch on a non-constant")
 			}
 			if !cond.IsAConstantExpr().IsNil() {
 				// This may happen when the instruction builder could not
 				// const-fold some instructions.
-				return nil, nil, fr.errorAt(inst, errors.New("interp: branch on a non-const-propagated constant expression"))
+				return nil, nil, errors.New("interp: branch on a non-const-propagated constant expression")
 			}
 			switch cond {
 			case llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false): // false
@@ -648,7 +510,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 			case llvm.ConstInt(fr.Mod.Context().Int1Type(), 1, false): // true
 				return nil, []llvm.Value{elseBB}, nil // else
 			default:
-				return nil, nil, fr.errorAt(inst, errors.New("branch was not true or false"))
+				panic("branch was not true or false")
 			}
 		case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 1:
 			// unconditional branch (goto)
@@ -656,11 +518,10 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 		case !inst.IsAUnreachableInst().IsNil():
 			// Unreachable was reached (e.g. after a call to panic()).
 			// Report this as an error, as it is not supposed to happen.
-			// This is a sentinel error value.
-			return nil, nil, errUnreachable
+			return nil, nil, ErrUnreachable

 		default:
-			return nil, nil, fr.unsupportedInstructionError(inst)
+			return nil, nil, &Unsupported{inst}
 		}
 	}

@@ -674,7 +535,6 @@ func (fr *frame) getLocal(v llvm.Value) Value {
 	} else if value := fr.getValue(v); value != nil {
 		return value
 	} else {
-		// This should not happen under normal circumstances.
 		panic("cannot find value")
 	}
 }
@@ -7,6 +7,7 @@ package interp
 // methods.

 import (
+	"errors"
 	"strings"

 	"tinygo.org/x/go-llvm"
@@ -21,17 +22,9 @@ type Eval struct {
 	sideEffectFuncs map[llvm.Value]*sideEffectResult // cache of side effect scan results
 }

-// evalPackage encapsulates the Eval type for just a single package. The Eval
-// type keeps state across the whole program, the evalPackage type keeps extra
-// state for the currently interpreted package.
-type evalPackage struct {
-	*Eval
-	packagePath string
-}
-
 // Run evaluates the function with the given name and then eliminates all
 // callers.
-func Run(mod llvm.Module, debug bool) error {
+func Run(mod llvm.Module, targetData llvm.TargetData, debug bool) error {
 	if debug {
 		println("\ncompile-time evaluation:")
 	}
@@ -39,7 +32,7 @@ func Run(mod llvm.Module, debug bool) error {
 	name := "runtime.initAll"
 	e := &Eval{
 		Mod:          mod,
-		TargetData:   llvm.NewTargetData(mod.DataLayout()),
+		TargetData:   targetData,
 		Debug:        debug,
 		dirtyGlobals: map[llvm.Value]struct{}{},
 	}
@@ -63,7 +56,7 @@ func Run(mod llvm.Module, debug bool) error {
 			break // ret void
 		}
 		if inst.IsACallInst().IsNil() || inst.CalledValue().IsAFunction().IsNil() {
-			return errorAt(inst, "interp: expected all instructions in "+name+" to be direct calls")
+			return errors.New("expected all instructions in " + name + " to be direct calls")
 		}
 		initCalls = append(initCalls, inst)
 	}
@@ -73,17 +66,13 @@ func Run(mod llvm.Module, debug bool) error {
 	for _, call := range initCalls {
 		initName := call.CalledValue().Name()
 		if !strings.HasSuffix(initName, ".init") {
-			return errorAt(call, "interp: expected all instructions in "+name+" to be *.init() calls")
+			return errors.New("expected all instructions in " + name + " to be *.init() calls")
 		}
 		pkgName := initName[:len(initName)-5]
 		fn := call.CalledValue()
 		call.EraseFromParentAsInstruction()
-		evalPkg := evalPackage{
-			Eval:        e,
-			packagePath: pkgName,
-		}
-		_, err := evalPkg.function(fn, []Value{&LocalValue{e, undefPtr}, &LocalValue{e, undefPtr}}, "")
-		if err == errUnreachable {
+		_, err := e.Function(fn, []Value{&LocalValue{e, undefPtr}, &LocalValue{e, undefPtr}}, pkgName)
+		if err == ErrUnreachable {
 			break
 		}
 		if err != nil {
@@ -94,14 +83,16 @@ func Run(mod llvm.Module, debug bool) error {
 	return nil
 }

-// function interprets the given function. The params are the function params
-// and the indent is the string indentation to use when dumping all interpreted
-// instructions.
-func (e *evalPackage) function(fn llvm.Value, params []Value, indent string) (Value, *Error) {
+func (e *Eval) Function(fn llvm.Value, params []Value, pkgName string) (Value, error) {
+	return e.function(fn, params, pkgName, "")
+}
+
+func (e *Eval) function(fn llvm.Value, params []Value, pkgName, indent string) (Value, error) {
 	fr := frame{
-		evalPackage: e,
-		fn:          fn,
-		locals:      make(map[llvm.Value]Value),
+		Eval:    e,
+		fn:      fn,
+		pkgName: pkgName,
+		locals:  make(map[llvm.Value]Value),
 	}
 	for i, param := range fn.Params() {
 		fr.locals[param] = params[i]
@@ -1,103 +0,0 @@
-package interp
-
-import (
-	"io/ioutil"
-	"os"
-	"strings"
-	"testing"
-
-	"tinygo.org/x/go-llvm"
-)
-
-func TestInterp(t *testing.T) {
-	for _, name := range []string{
-		"basic",
-		"slice-copy",
-		"consteval",
-		"map",
-		"interface",
-	} {
-		name := name // make tc local to this closure
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-			runTest(t, "testdata/"+name)
-		})
-	}
-}
-
-func runTest(t *testing.T, pathPrefix string) {
-	// Read the input IR.
-	ctx := llvm.NewContext()
-	buf, err := llvm.NewMemoryBufferFromFile(pathPrefix + ".ll")
-	os.Stat(pathPrefix + ".ll") // make sure this file is tracked by `go test` caching
-	if err != nil {
-		t.Fatalf("could not read file %s: %v", pathPrefix+".ll", err)
-	}
-	mod, err := ctx.ParseIR(buf)
-	if err != nil {
-		t.Fatalf("could not load module:\n%v", err)
-	}
-
-	// Perform the transform.
-	err = Run(mod, false)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// Run some cleanup passes to get easy-to-read outputs.
-	pm := llvm.NewPassManager()
-	defer pm.Dispose()
-	pm.AddGlobalOptimizerPass()
-	pm.AddDeadStoreEliminationPass()
-	pm.Run(mod)
-
-	// Read the expected output IR.
-	out, err := ioutil.ReadFile(pathPrefix + ".out.ll")
-	if err != nil {
-		t.Fatalf("could not read output file %s: %v", pathPrefix+".out.ll", err)
-	}
-
-	// See whether the transform output matches with the expected output IR.
-	expected := string(out)
-	actual := mod.String()
-	if !fuzzyEqualIR(expected, actual) {
-		t.Logf("output does not match expected output:\n%s", actual)
-		t.Fail()
-	}
-}
-
-// fuzzyEqualIR returns true if the two LLVM IR strings passed in are roughly
-// equal. That means, only relevant lines are compared (excluding comments
-// etc.).
-func fuzzyEqualIR(s1, s2 string) bool {
-	lines1 := filterIrrelevantIRLines(strings.Split(s1, "\n"))
-	lines2 := filterIrrelevantIRLines(strings.Split(s2, "\n"))
-	if len(lines1) != len(lines2) {
-		return false
-	}
-	for i, line := range lines1 {
-		if line != lines2[i] {
-			return false
-		}
-	}
-
-	return true
-}
-
-// filterIrrelevantIRLines removes lines from the input slice of strings that
-// are not relevant in comparing IR. For example, empty lines and comments are
-// stripped out.
-func filterIrrelevantIRLines(lines []string) []string {
-	var out []string
-	for _, line := range lines {
-		line = strings.TrimSpace(line) // drop '\r' on Windows
-		if line == "" || line[0] == ';' {
-			continue
-		}
-		if strings.HasPrefix(line, "source_filename = ") {
-			continue
-		}
-		out = append(out, line)
-	}
-	return out
-}
@@ -1,29 +1,11 @@
 package interp

 import (
-	"errors"
-	"strings"
-
 	"tinygo.org/x/go-llvm"
 )

 type sideEffectSeverity int

-func (severity sideEffectSeverity) String() string {
-	switch severity {
-	case sideEffectInProgress:
-		return "in progress"
-	case sideEffectNone:
-		return "none"
-	case sideEffectLimited:
-		return "limited"
-	case sideEffectAll:
-		return "all"
-	default:
-		return "unknown"
-	}
-}
-
 const (
 	sideEffectInProgress sideEffectSeverity = iota // computing side effects is in progress (for recursive functions)
 	sideEffectNone                                 // no side effects at all (pure)
@@ -41,38 +23,28 @@ type sideEffectResult struct {
 // hasSideEffects scans this function and all descendants, recursively. It
 // returns whether this function has side effects and if it does, which globals
 // it mentions anywhere in this function or any called functions.
-func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error) {
-	name := fn.Name()
-	switch {
-	case name == "runtime.alloc":
+func (e *Eval) hasSideEffects(fn llvm.Value) *sideEffectResult {
+	switch fn.Name() {
+	case "runtime.alloc":
 		// Cannot be scanned but can be interpreted.
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case name == "runtime.nanotime":
+		return &sideEffectResult{severity: sideEffectNone}
+	case "runtime.nanotime":
 		// Fixed value at compile time.
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case name == "runtime._panic":
-		return &sideEffectResult{severity: sideEffectLimited}, nil
-	case name == "runtime.typeAssert":
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case name == "runtime.interfaceImplements":
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case name == "runtime.sliceCopy":
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case name == "runtime.trackPointer":
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case name == "llvm.dbg.value":
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	case strings.HasPrefix(name, "llvm.lifetime."):
-		return &sideEffectResult{severity: sideEffectNone}, nil
-	}
-	if fn.IsDeclaration() {
-		return &sideEffectResult{severity: sideEffectLimited}, nil
+		return &sideEffectResult{severity: sideEffectNone}
+	case "runtime._panic":
+		return &sideEffectResult{severity: sideEffectLimited}
+	case "runtime.interfaceImplements":
+		return &sideEffectResult{severity: sideEffectNone}
+	case "runtime.trackPointer":
+		return &sideEffectResult{severity: sideEffectNone}
+	case "llvm.dbg.value":
+		return &sideEffectResult{severity: sideEffectNone}
 	}
 	if e.sideEffectFuncs == nil {
 		e.sideEffectFuncs = make(map[llvm.Value]*sideEffectResult)
 	}
 	if se, ok := e.sideEffectFuncs[fn]; ok {
-		return se, nil
+		return se
 	}
 	result := &sideEffectResult{
 		severity:        sideEffectInProgress,
@@ -83,7 +55,6 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 	for bb := fn.EntryBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
 		for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
 			if inst.IsAInstruction().IsNil() {
-				// Should not happen in valid IR.
 				panic("not an instruction")
 			}

@@ -100,7 +71,7 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 			switch inst.InstructionOpcode() {
 			case llvm.IndirectBr, llvm.Invoke:
 				// Not emitted by the compiler.
-				return nil, e.errorAt(inst, errors.New("unknown instructions"))
+				panic("unknown instructions")
 			case llvm.Call:
 				child := inst.CalledValue()
 				if !child.IsAInlineAsm().IsNil() {
@@ -121,21 +92,12 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 				if child.IsDeclaration() {
 					// External function call. Assume only limited side effects
 					// (no affected globals, etc.).
-					switch child.Name() {
-					case "runtime.typeAssert":
-						continue // implemented in interp
-					case "runtime.interfaceImplements":
-						continue // implemented in interp
-					}
 					if e.hasLocalSideEffects(dirtyLocals, inst) {
 						result.updateSeverity(sideEffectLimited)
 					}
 					continue
 				}
-				childSideEffects, err := e.hasSideEffects(child)
-				if err != nil {
-					return nil, err
-				}
+				childSideEffects := e.hasSideEffects(child)
 				switch childSideEffects.severity {
 				case sideEffectInProgress, sideEffectNone:
 					// no side effects or recursive function - continue scanning
@@ -177,7 +139,7 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 		// No side effect was reported for this function.
 		result.severity = sideEffectNone
 	}
-	return result, nil
+	return result
 }

 // hasLocalSideEffects checks whether the given instruction flows into a branch
@@ -192,7 +154,6 @@ func (e *Eval) hasLocalSideEffects(dirtyLocals map[llvm.Value]struct{}, inst llv
 	for use := inst.FirstUse(); !use.IsNil(); use = use.NextUse() {
 		user := use.User()
 		if user.IsAInstruction().IsNil() {
-			// Should not happen in valid IR.
 			panic("user not an instruction")
 		}
 		switch user.InstructionOpcode() {
@@ -212,13 +173,10 @@ func (e *Eval) hasLocalSideEffects(dirtyLocals map[llvm.Value]struct{}, inst llv
 				// Already handled in (*Eval).hasSideEffects.
 				continue
 			}
-			// This store might affect all kinds of values. While it is
-			// certainly possible to traverse through all of them, the easiest
-			// option right now is to just assume the worst and say that this
-			// function has side effects.
-			// TODO: traverse through all stores and mark all relevant allocas /
-			// globals dirty.
-			return true
+			// But a store might also store to an alloca, in which case all uses
+			// of the alloca (possibly indirect through a GEP, bitcast, etc.)
+			// must be marked dirty.
+			panic("todo: store")
 		default:
 			// All instructions that take 0 or more operands (1 or more if it
 			// was a use) and produce a result.
@@ -1,95 +0,0 @@
-package interp
-
-import (
-	"os"
-	"sort"
-	"testing"
-
-	"tinygo.org/x/go-llvm"
-)
-
-var scanTestTable = []struct {
-	name            string
-	severity        sideEffectSeverity
-	mentionsGlobals []string
-}{
-	{"returnsConst", sideEffectNone, nil},
-	{"returnsArg", sideEffectNone, nil},
-	{"externalCallOnly", sideEffectNone, nil},
-	{"externalCallAndReturn", sideEffectLimited, nil},
-	{"externalCallBranch", sideEffectLimited, nil},
-	{"readCleanGlobal", sideEffectNone, []string{"cleanGlobalInt"}},
-	{"readDirtyGlobal", sideEffectLimited, []string{"dirtyGlobalInt"}},
-	{"callFunctionPointer", sideEffectAll, []string{"functionPointer"}},
-	{"getDirtyPointer", sideEffectLimited, nil},
-	{"storeToPointer", sideEffectLimited, nil},
-	{"callTypeAssert", sideEffectNone, nil},
-	{"callInterfaceImplements", sideEffectNone, nil},
-}
-
-func TestScan(t *testing.T) {
-	t.Parallel()
-
-	// Read the input IR.
-	path := "testdata/scan.ll"
-	ctx := llvm.NewContext()
-	buf, err := llvm.NewMemoryBufferFromFile(path)
-	os.Stat(path) // make sure this file is tracked by `go test` caching
-	if err != nil {
-		t.Fatalf("could not read file %s: %v", path, err)
-	}
-	mod, err := ctx.ParseIR(buf)
-	if err != nil {
-		t.Fatalf("could not load module:\n%v", err)
-	}
-
-	// Check all to-be-tested functions.
-	for _, tc := range scanTestTable {
-		// Create an eval object, for testing.
-		e := &Eval{
-			Mod:          mod,
-			TargetData:   llvm.NewTargetData(mod.DataLayout()),
-			dirtyGlobals: map[llvm.Value]struct{}{},
-		}
-
-		// Mark some globals dirty, for testing.
-		e.markDirty(mod.NamedGlobal("dirtyGlobalInt"))
-
-		// Scan for side effects.
-		fn := mod.NamedFunction(tc.name)
-		if fn.IsNil() {
-			t.Errorf("scan test: could not find tested function %s in the IR", tc.name)
-			continue
-		}
-		evalPkg := &evalPackage{e, "testdata"}
-		result, err := evalPkg.hasSideEffects(fn)
-		if err != nil {
-			t.Errorf("scan test: failed to scan %s for side effects: %v", fn.Name(), err)
-		}
-
-		// Check whether the result is what we expect.
-		if result.severity != tc.severity {
-			t.Errorf("scan test: function %s should have severity %s but it has %s", tc.name, tc.severity, result.severity)
-		}
-
-		// Check whether the mentioned globals match with what we'd expect.
-		mentionsGlobalNames := make([]string, 0, len(result.mentionsGlobals))
-		for global := range result.mentionsGlobals {
-			mentionsGlobalNames = append(mentionsGlobalNames, global.Name())
-		}
-		sort.Strings(mentionsGlobalNames)
-		globalsMismatch := false
-		if len(result.mentionsGlobals) != len(tc.mentionsGlobals) {
-			globalsMismatch = true
-		} else {
-			for i, globalName := range mentionsGlobalNames {
-				if tc.mentionsGlobals[i] != globalName {
-					globalsMismatch = true
-				}
-			}
-		}
-		if globalsMismatch {
-			t.Errorf("scan test: expected %s to mention globals %v, but it mentions globals %v", tc.name, tc.mentionsGlobals, mentionsGlobalNames)
-		}
-	}
-}
@@ -1,60 +0,0 @@
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64--linux"
-
-@main.v1 = internal global i64 0
-@main.nonConst1 = global [4 x i64] zeroinitializer
-@main.nonConst2 = global i64 0
-
-declare void @runtime.printint64(i64) unnamed_addr
-
-declare void @runtime.printnl() unnamed_addr
-
-define void @runtime.initAll() unnamed_addr {
-entry:
-  call void @runtime.init()
-  call void @main.init()
-  ret void
-}
-
-define void @main() unnamed_addr {
-entry:
-  %0 = load i64, i64* @main.v1
-  call void @runtime.printint64(i64 %0)
-  call void @runtime.printnl()
-  ret void
-}
-
-define internal void @runtime.init() unnamed_addr {
-entry:
-  ret void
-}
-
-define internal void @main.init() unnamed_addr {
-entry:
-  store i64 3, i64* @main.v1
-  call void @"main.init#1"()
-
-  ; test the following pattern:
-  ;     func someValue() int // extern function
-  ;     var nonConst1 = [4]int{someValue(), 0, 0, 0}
-  %value1 = call i64 @someValue()
-  %gep1 = getelementptr [4 x i64], [4 x i64]* @main.nonConst1, i32 0, i32 0
-  store i64 %value1, i64* %gep1
-
-  ; Test that the global really is marked dirty:
-  ;     var nonConst2 = nonConst1[0]
-  %gep2 = getelementptr [4 x i64], [4 x i64]* @main.nonConst1, i32 0, i32 0
-  %value2 = load i64, i64* %gep2
-  store i64 %value2, i64* @main.nonConst2
-
-  ret void
-}
-
-define internal void @"main.init#1"() unnamed_addr {
-entry:
-  call void @runtime.printint64(i64 5)
-  call void @runtime.printnl()
-  ret void
-}
-
-declare i64 @someValue()
@@ -1,29 +0,0 @@
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64--linux"
-
-@main.nonConst1 = local_unnamed_addr global [4 x i64] zeroinitializer
-@main.nonConst2 = local_unnamed_addr global i64 0
-
-declare void @runtime.printint64(i64) unnamed_addr
-
-declare void @runtime.printnl() unnamed_addr
-
-define void @runtime.initAll() unnamed_addr {
-entry:
-  call void @runtime.printint64(i64 5)
-  call void @runtime.printnl()
-  %value1 = call i64 @someValue()
-  store i64 %value1, i64* getelementptr inbounds ([4 x i64], [4 x i64]* @main.nonConst1, i32 0, i32 0)
-  %value2 = load i64, i64* getelementptr inbounds ([4 x i64], [4 x i64]* @main.nonConst1, i32 0, i32 0)
-  store i64 %value2, i64* @main.nonConst2
-  ret void
-}
-
-define void @main() unnamed_addr {
-entry:
-  call void @runtime.printint64(i64 3)
-  call void @runtime.printnl()
-  ret void
-}
-
-declare i64 @someValue() local_unnamed_addr
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Ayke van Laethem	6272973d3f	optimize check function	2019-09-15 19:58:23 +02:00
Jaden Weiss	fee496ae79	fix bugs found by LLVM assertions	2019-09-15 12:51:54 -04:00
Jaden Weiss	d975ed9373	fix incorrect typing of globals bitmap	2019-09-12 16:42:37 -04:00