main: add -json flag support to go env

This is needed for VS Code support.
loader: load packages using Go modules
2026-07-27 23:28:42 +00:00 · 2020-05-08 14:50:37 +02:00 · 2020-05-08 14:50:26 +02:00 · 2020-05-08 14:50:26 +02:00 · 2020-05-05 00:06:53 +02:00 · 2020-05-04 21:58:27 +02:00
594 changed files with 8301 additions and 34257 deletions
@@ -28,7 +28,6 @@ commands:
                qemu-user \
                gcc-avr \
                avr-libc
-            sudo apt-get install --no-install-recommends libc6-dev-i386 lib32gcc-8-dev
  install-node:
    steps:
      - run:
@@ -38,54 +37,28 @@ commands:
            sudo tar -C /usr/local -xf node-v10.15.1-linux-x64.tar.xz
            sudo ln -s /usr/local/node-v10.15.1-linux-x64/bin/node /usr/bin/node
            rm node-v10.15.1-linux-x64.tar.xz
-  install-chrome:
-    steps:
-      - run:
-          name: "Install Chrome"
-          command: |
-            wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
-            sudo apt install ./google-chrome-stable_current_amd64.deb
-  install-wasmtime:
-    steps:
-      - run:
-          name: "Install wasmtime"
-          command: |
-            curl https://wasmtime.dev/install.sh -sSf | bash
-            sudo ln -s ~/.wasmtime/bin/wasmtime /usr/local/bin/wasmtime
-  install-xtensa-toolchain:
-    parameters:
-      variant:
-        type: string
-    steps:
-      - run:
-          name: "Install Xtensa toolchain"
-          command: |
-            curl -L https://github.com/espressif/crosstool-NG/releases/download/esp-2020r2/xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz -o xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz
-            sudo tar -C /usr/local -xf xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz
-            sudo ln -s /usr/local/xtensa-esp32-elf/bin/xtensa-esp32-elf-ld /usr/local/bin/xtensa-esp32-elf-ld
-            rm xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz
  llvm-source-linux:
    steps:
      - restore_cache:
          keys:
-            - llvm-source-11-v1
+            - llvm-source-10-v0
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-11-v1
+          key: llvm-source-10-v0
          paths:
            - llvm-project
  build-wasi-libc:
    steps:
      - restore_cache:
          keys:
-            - wasi-libc-sysroot-v4
+            - wasi-libc-sysroot-v2
      - run:
          name: "Build wasi-libc"
          command: make wasi-libc
      - save_cache:
-          key: wasi-libc-sysroot-v4
+          key: wasi-libc-sysroot-v2
          paths:
            - lib/wasi-libc/sysroot
  test-linux:
@@ -98,8 +71,6 @@ commands:
      - apt-dependencies:
          llvm: "<<parameters.llvm>>"
      - install-node
-      - install-chrome
-      - install-wasmtime
      - restore_cache:
          keys:
            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
@@ -108,21 +79,20 @@ commands:
      - run: go install -tags=llvm<<parameters.llvm>> .
      - restore_cache:
          keys:
-            - wasi-libc-sysroot-systemclang-v3
+            - wasi-libc-sysroot-systemclang-v1
      - run: make wasi-libc
      - save_cache:
-          key: wasi-libc-sysroot-systemclang-v3
+          key: wasi-libc-sysroot-systemclang-v1
          paths:
            - lib/wasi-libc/sysroot
-      - run: go test -v -tags=llvm<<parameters.llvm>> ./cgo ./compileopts ./compiler ./interp ./transform .
+      - run: go test -v -tags=llvm<<parameters.llvm>> ./cgo ./compileopts ./interp ./transform .
      - run: make gen-device -j4
-      - run: make smoketest XTENSA=0
-      - run: make tinygo-test
-      - run: make wasmtest
+      - run: make smoketest
      - save_cache:
          key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
          paths:
            - ~/.cache/go-build
+            - ~/.cache/tinygo
            - /go/pkg/mod
      - run: make fmt-check
  assert-test-linux:
@@ -132,9 +102,9 @@ commands:
      - run:
          name: "Install apt dependencies"
          command: |
-            sudo apt-get update
            sudo apt-get install \
                gcc-arm-linux-gnueabihf \
+                binutils-arm-none-eabi \
                libc6-dev-armel-cross \
                gcc-aarch64-linux-gnu \
                libc6-dev-arm64-cross \
@@ -142,11 +112,7 @@ commands:
                qemu-user \
                gcc-avr \
                avr-libc
-            sudo apt-get install --no-install-recommends libc6-dev-i386 lib32gcc-6-dev
      - install-node
-      - install-wasmtime
-      - install-xtensa-toolchain:
-          variant: "linux-amd64"
      - restore_cache:
          keys:
            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
@@ -154,14 +120,17 @@ commands:
      - llvm-source-linux
      - restore_cache:
          keys:
-            - llvm-build-11-linux-v2-assert
+            - 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 ninja-build
+              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
@@ -169,7 +138,7 @@ commands:
              make ASSERT=1 llvm-build
            fi
      - save_cache:
-          key: llvm-build-11-linux-v2-assert
+          key: llvm-build-10-linux-v0-assert
          paths:
            llvm-build
      - run: make ASSERT=1
@@ -181,6 +150,7 @@ commands:
          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
@@ -191,9 +161,9 @@ commands:
      - run:
          name: "Install apt dependencies"
          command: |
-            sudo apt-get update
            sudo apt-get install \
                gcc-arm-linux-gnueabihf \
+                binutils-arm-none-eabi \
                libc6-dev-armel-cross \
                gcc-aarch64-linux-gnu \
                libc6-dev-arm64-cross \
@@ -201,11 +171,7 @@ commands:
                qemu-user \
                gcc-avr \
                avr-libc
-            sudo apt-get install --no-install-recommends libc6-dev-i386 lib32gcc-6-dev
      - install-node
-      - install-wasmtime
-      - install-xtensa-toolchain:
-          variant: "linux-amd64"
      - restore_cache:
          keys:
            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
@@ -213,14 +179,17 @@ commands:
      - llvm-source-linux
      - restore_cache:
          keys:
-            - llvm-build-11-linux-v2-noassert
+            - llvm-build-10-linux-v0
      - run:
          name: "Build LLVM"
          command: |
            if [ ! -f llvm-build/lib/liblldELF.a ]
            then
              # install dependencies
-              sudo apt-get install cmake ninja-build
+              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
@@ -228,32 +197,25 @@ commands:
              make llvm-build
            fi
      - save_cache:
-          key: llvm-build-11-linux-v2-noassert
+          key: llvm-build-10-linux-v0
          paths:
            llvm-build
      - build-wasi-libc
      - run:
          name: "Test TinyGo"
          command: make test
-      - run:
-          name: "Install fpm"
-          command: |
-            sudo apt-get install ruby ruby-dev
-            sudo gem install --no-document fpm
      - run:
          name: "Build TinyGo release"
          command: |
-            make release deb -j3
+            make release -j3
            cp -p build/release.tar.gz /tmp/tinygo.linux-amd64.tar.gz
-            cp -p build/release.deb    /tmp/tinygo_amd64.deb
      - store_artifacts:
          path: /tmp/tinygo.linux-amd64.tar.gz
-      - store_artifacts:
-          path: /tmp/tinygo_amd64.deb
      - save_cache:
          key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
          paths:
            - ~/.cache/go-build
+            - ~/.cache/tinygo
            - /go/pkg/mod
      - run:
          name: "Extract release tarball"
@@ -270,29 +232,27 @@ commands:
      - run:
          name: "Install dependencies"
          command: |
-            curl https://dl.google.com/go/go1.16.darwin-amd64.tar.gz -o go1.16.darwin-amd64.tar.gz
-            sudo tar -C /usr/local -xzf go1.16.darwin-amd64.tar.gz
+            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
            ln -s /usr/local/go/bin/go /usr/local/bin/go
            HOMEBREW_NO_AUTO_UPDATE=1 brew install qemu
-      - install-xtensa-toolchain:
-          variant: "macos"
      - 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-11-macos-v1
+            - llvm-source-10-macos-v0
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-11-macos-v1
+          key: llvm-source-10-macos-v0
          paths:
            - llvm-project
      - restore_cache:
          keys:
-            - llvm-build-11-macos-v2
+            - llvm-build-10-macos-v0
      - run:
          name: "Build LLVM"
          command: |
@@ -304,17 +264,17 @@ commands:
              make llvm-build
            fi
      - save_cache:
-          key: llvm-build-11-macos-v2
+          key: llvm-build-10-macos-v0
          paths:
            llvm-build
      - restore_cache:
          keys:
-            - wasi-libc-sysroot-macos-v3
+            - wasi-libc-sysroot-macos-v1
      - run:
          name: "Build wasi-libc"
          command: make wasi-libc
      - save_cache:
-          key: wasi-libc-sysroot-macos-v3
+          key: wasi-libc-sysroot-macos-v1
          paths:
            - lib/wasi-libc/sysroot
      - run:
@@ -334,14 +294,33 @@ commands:
            tar -C /usr/local/opt -xf /tmp/tinygo.darwin-amd64.tar.gz
            ln -s /usr/local/opt/tinygo/bin/tinygo /usr/local/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-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:
+    docker:
+      - image: circleci/golang:1.11-buster
+    steps:
+      - test-linux:
+          llvm: "9"
+  test-llvm10-go112:
+    docker:
+      - image: circleci/golang:1.12-buster
+    steps:
+      - test-linux:
+          llvm: "10"
  test-llvm10-go113:
    docker:
      - image: circleci/golang:1.13-buster
@@ -354,18 +333,6 @@ jobs:
    steps:
      - test-linux:
          llvm: "10"
-  test-llvm11-go115:
-    docker:
-      - image: circleci/golang:1.15-buster
-    steps:
-      - test-linux:
-          llvm: "11"
-  test-llvm11-go116:
-    docker:
-      - image: circleci/golang:1.16-buster
-    steps:
-      - test-linux:
-          llvm: "11"
  assert-test-linux:
    docker:
      - image: circleci/golang:1.14-stretch
@@ -384,13 +351,14 @@ jobs:



+
 workflows:
  test-all:
    jobs:
+      - test-llvm9-go111
+      - test-llvm10-go112
      - test-llvm10-go113
      - test-llvm10-go114
-      - test-llvm11-go115
-      - test-llvm11-go116
      - build-linux
      - build-macos
      - assert-test-linux
@@ -3,26 +3,14 @@ docs/_build
 src/device/avr/*.go
 src/device/avr/*.ld
 src/device/avr/*.s
-src/device/esp/*.go
 src/device/nrf/*.go
 src/device/nrf/*.s
-src/device/nxp/*.go
-src/device/nxp/*.s
 src/device/sam/*.go
 src/device/sam/*.s
 src/device/sifive/*.go
 src/device/sifive/*.s
 src/device/stm32/*.go
 src/device/stm32/*.s
-src/device/kendryte/*.go
-src/device/kendryte/*.s
 vendor
 llvm-build
 llvm-project
-
-# Ignore files generated by smoketest
-test.gba
-test.hex
-test.nro
-test.wasm
-wasm.wasm
@@ -9,7 +9,7 @@
 	url = https://github.com/avr-rust/avr-mcu.git
 [submodule "lib/cmsis-svd"]
 	path = lib/cmsis-svd
-	url = https://github.com/tinygo-org/cmsis-svd
+	url = https://github.com/posborne/cmsis-svd
 [submodule "lib/compiler-rt"]
 	path = lib/compiler-rt
 	url = https://github.com/llvm-mirror/compiler-rt.git
@@ -20,6 +20,3 @@
 [submodule "lib/picolibc"]
 	path = lib/picolibc
 	url = https://github.com/keith-packard/picolibc.git
-[submodule "lib/stm32-svd"]
-	path = lib/stm32-svd
-	url = https://github.com/tinygo-org/stm32-svd
@@ -10,20 +10,12 @@ This guide describes how to statically link TinyGo against LLVM, libclang and
 lld so that the binary can be easily moved between systems. It also shows how to
 build a release tarball that includes this binary and all necessary extra files.

-**Note**: this documentation describes how to build a statically linked release
-tarball. If you want to develop TinyGo, you will probably want to follow a
-different guide:
-
-  * [Linux](https://tinygo.org/getting-started/linux/#source-install)
-  * [macOS](https://tinygo.org/getting-started/macos/#source-install)
-  * [Windows](https://tinygo.org/getting-started/windows/#source-install)
-
 ## Dependencies

 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 (1.13+)
+  * Go (1.11+)
  * Standard build tools (gcc/clang)
  * git
  * CMake
@@ -43,6 +35,11 @@ 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
@@ -87,10 +84,6 @@ Now that we have a working static build, it's time to make a release tarball:

    make release

-If you did not clone the repository with the `--recursive` option, you will get errors until you initialize the project submodules:
-
-    git submodule update --init
-
 The release tarball is stored in build/release.tar.gz, and can be extracted with
 the following command (for example in ~/lib):

@@ -1,316 +1,3 @@
-0.17.0
-
---
-* **command line**
-  - switch to LLVM 11 for static builds
-  - support gdb debugging with AVR
-  - add support for additional openocd commands
-  - add `-x` flag to print commands
-  - use LLVM 11 by default when linking LLVM dynamically
-  - update go-llvm to use LLVM 11 on macOS
-  - bump go.bug.st/serial to version 1.1.2
-  - do not build LLVM with libxml to work around a bugo on macOS
-  - add support for Go 1.16
-  - support gdb daemonization on Windows
-  - remove support for LLVM 9, to fix CI
-  - kill OpenOCD if it does not exit with a regular quit signal
-  - support `-ocd-output` on Windows
-* **compiler**
-  - `builder`: parallelize most of the build
-  - `builder`: remove unused cacheKey parameter
-  - `builder`: add -mcpu flag while building libraries
-  - `builder`: wait for running jobs to finish
-  - `cgo`: add support for variadic functions
-  - `compiler`: fix undefined behavior in wordpack
-  - `compiler`: fix incorrect "exported function" panic
-  - `compiler`: fix non-int integer constants (fixing a crash)
-  - `compiler`: refactor and add tests
-  - `compiler`: emit a nil check when slicing an array pointer
-  - `compiler`: saturate float-to-int conversions
-  - `compiler`: test float to int conversions and fix upper-bound calculation
-  - `compiler`: support all kinds of deferred builtins
-  - `compiler`: remove ir package
-  - `compiler`: remove unnecessary main.main call workaround
-  - `compiler`: move the setting of attributes to getFunction
-  - `compiler`: create runtime types lazily when needed
-  - `compiler`: move settings to a separate Config struct
-  - `compiler`: work around an ARM backend bug in LLVM
-  - `interp`: rewrite entire package
-  - `interp`: fix alignment of untyped globals
-  - `loader`: use name "main" for the main package
-  - `loader`: support imports from vendor directories
-  - `stacksize`: add support for DW_CFA_offset_extended
-  - `transform`: show better error message in coroutines lowering
-* **standard library**
-  - `machine`: accept configuration struct for ADC parameters
-  - `machine`: make I2C.Configure signature consistent
-  - `reflect`: implement PtrTo
-  - `runtime`: refactor to simplify stack switching
-  - `runtime`: put metadata at the top end of the heap
-* **targets**
-  - `atsam`: add a length check to findPinPadMapping
-  - `atsam`: improve USBCDC
-  - `atsam`: avoid infinite loop when USBCDC is disconnected
-  - `avr`: add SPI support for Atmega based chips
-  - `avr`: use Clang for compiling C and assembly files
-  - `esp32`: implement task based scheduler
-  - `esp32`: enable the FPU
-  - `esp8266`: implement task based scheduler
-  - `esp`: add compiler-rt library
-  - `esp`: add picolibc
-  - `nrf`: refactor code a bit to reduce duplication
-  - `nrf`: use SPIM peripheral instead of the legacy SPI peripheral
-  - `nrf`: update nrfx submodule to latest commit
-  - `nrf52840`: ensure that USB CDC interface is only initialized once
-  - `nrf52840`: improve USBCDC
-  - `stm32`: use stm32-rs SVDs which are of much higher quality
-  - `stm32`: harmonization of UART logic
-  - `stm32`: replace I2C addressable interface with simpler type
-  - `stm32`: fix i2c and add stm32f407 i2c
-  - `stm32`: revert change that adds support for channels in interrupts
-  - `wasm`: implement a growable heap
-  - `wasm`: fix typo in wasm_exec.js, syscall/js.valueLoadString()
-  - `wasm`: Namespaced Wasm Imports so they don't conflict across modules, or reserved LLVM IR
-  - `wasi`: support env variables based on libc
-  - `wasi`: specify wasi-libc in a different way, to improve error message
-* **boards**
-  - `matrixportal-m4`: add support for board Adafruit Matrix Portal M4
-  - `mkr1000`: add this board
-  - `nucleo-f722ze`: add this board
-  - `clue`: correct volume name and add alias for release version of Adafruit Clue board
-  - `p1am-100`: add support for the P1AM-100 (similar to Arduino MKR)
-  - `microbit-v2`: add initial support based on work done by @alankrantas thank you!
-  - `lgt92`: support for STM32L0 MCUs and Dragino LGT92 device
-  - `nicenano`: nice!nano board support
-  - `circuitplay-bluefruit`: correct internal I2C pin mapping
-  - `clue`: correct for lack of low frequency crystal
-  - `digispark`: split off attiny85 target
-  - `nucleo-l552ze`: implementation with CLOCK, LED, and UART
-  - `nrf52840-mdk-usb-dongle`: add this board
-
-0.16.0
---
-
-* **command-line**
-  - add initial support for LLVM 11
-  - make lib64 clang include path check more robust
-  - `build`: improve support for GOARCH=386 and add tests
-  - `gdb`: add support for qemu-user targets
-  - `test`: support non-host tests
-  - `test`: add support for -c and -o flags
-  - `test`: implement some benchmark stubs
-* **compiler**
-  - `builder`: improve detection of clang on Fedora
-  - `compiler`: fix floating point comparison bugs
-  - `compiler`: implement negate for complex numbers
-  - `loader`: fix linkname in test binaries
-  - `transform`: add missing return pointer restore for regular coroutine tail
-    calls
-* **standard library**
-  - `machine`: switch default frequency to 4MHz
-  - `machine`: clarify caller's responsibility in `SetInterrupt`
-  - `os`: add `LookupEnv()` stub
-  - `reflect`: implement `Swapper`
-  - `runtime`: fix UTF-8 decoding
-  - `runtime`: gc: use raw stack access whenever possible
-  - `runtime`: use dedicated printfloat32
-  - `runtime`: allow ranging over a nil map
-  - `runtime`: avoid device/nxp dependency in HardFault handler
-  - `testing`: implement dummy Helper method
-  - `testing`: add Run method
-* **targets**
-  - `arm64`: add support for SVCall intrinsic
-  - `atsamd51`: avoid panic when configuring SPI with SDI=NoPin
-  - `avr`: properly support the `.rodata` section
-  - `esp8266`: implement `Pin.Get` function
-  - `nintendoswitch`: fix crash when printing long lines (> 120)
-  - `nintendoswitch`: add env parser and removed unused stuff
-  - `nrf`: add I2C error checking
-  - `nrf`: give more flexibility in picking SPI speeds
-  - `nrf`: fix nrf52832 flash size
-  - `stm32f103`: support wakeups from interrupts
-  - `stm32f405`: add SPI support
-  - `stm32f405`: add I2C support
-  - `wasi`: add support for this target
-  - `wasi`: use 'generic' ABI by default
-  - `wasi`: remove --no-threads flag from wasm-ld
-  - `wasm`: add instanceof support for WebAssembly
-  - `wasm`: use fixed length buffer for putchar
-* **boards**
-  - `d1mini`: add this ESP8266 based board
-  - `esp32`: use board definitions instead of chip names
-  - `qtpy`: add board definition for Adafruit QTPy
-  - `teensy40`: add this board
-
-0.15.0
---
-
-* **command-line**
-  - add cached GOROOT to info subcommand
-  - embed git-hash in tinygo-dev executable
-  - implement tinygo targets to list usable targets
-  - use simpler file copy instead of file renaming to avoid issues on nrf52840 UF2 bootloaders
-  - use ToSlash() to specify program path
-  - support flashing esp32/esp8266 directly from tinygo
-  - when flashing call PortReset only on other than openocd
-* **compiler**
-  - `compileopts`: add support for custom binary formats
-  - `compiler`: improve display of goroutine wrappers
-  - `interp`: don't panic in the Store method
-  - `interp`: replace some panics with error messages
-  - `interp`: show error line in first line of the traceback
-  - `loader`: be more robust when creating the cached GOROOT
-  - `loader`: rewrite/refactor much of the code to use go list directly
-  - `loader`: use ioutil.TempDir to create a temporary directory
-  - `stacksize`: deal with DW_CFA_advance_loc1
-* **standard library**
-  - `runtime`: use waitForEvents when appropriate
-* **wasm**
-  - `wasm`: Remove --no-threads from wasm-ld calls.
-  - `wasm`: update wasi-libc dependency
-* **targets**
-  - `arduino-mega2560`: fix flashing on Windows
-  - `arm`: automatically determine stack sizes
-  - `arm64`: make dynamic loader structs and constants private
-  - `avr`: configure emulator in board files
-  - `cortexm`: fix stack size calculation with interrupts
-  - `flash`: add openocd settings to atsamd21 / atsamd51
-  - `flash`: add openocd settings to nrf5
-  - `microbit`: reelboard: flash using OpenOCD when needed
-  - `nintendoswitch`: Add dynamic loader for runtime loading PIE sections
-  - `nintendoswitch`: fix import cycle on dynamic_arm64.go
-  - `nintendoswitch`: Fix invalid memory read / write in print calls
-  - `nintendoswitch`: simplified assembly code
-  - `nintendoswitch`: support outputting .nro files directly
-* **boards**
-  - `arduino-zero`: Adding support for the Arduino Zero (#1365)
-  - `atsamd2x`: fix BAUD value
-  - `atsamd5x`: fix BAUD value
-  - `bluepill`: Enable stm32's USART2 for the board and map it to UART1 tinygo's device
-  - `device/atsamd51x`: add all remaining bitfield values for PCHCTRLm Mapping
-  - `esp32`: add libgcc ROM functions to linker script
-  - `esp32`: add SPI support
-  - `esp32`: add support for basic GPIO
-  - `esp32`: add support for the Espressif ESP32 chip
-  - `esp32`: configure the I/O matrix for GPIO pins
-  - `esp32`: export machine.PortMask* for bitbanging implementations
-  - `esp8266`: add support for this chip
-  - `machine/atsamd51x,runtime/atsamd51x`: fixes needed for full support for all PWM pins. Also adds some useful constants to clarify peripheral clock usage
-  - `machine/itsybitsy-nrf52840`: add support for Adafruit Itsybitsy nrf52840 (#1243)
-  - `machine/stm32f4`: refactor common code and add new build tag stm32f4 (#1332)
-  - `nrf`: add SoftDevice support for the Circuit Playground Bluefruit
-  - `nrf`: call sd_app_evt_wait when the SoftDevice is enabled
-  - `nrf52840`: add build tags for SoftDevice support
-  - `nrf52840`: use higher priority for USB-CDC code
-  - `runtime/atsamd51x`: use PCHCTRL_GCLK_SERCOMX_SLOW for setting clocks on all SERCOM ports
-  - `stm32f405`: add basic UART handler
-  - `stm32f405`: add STM32F405 machine/runtime, and new board/target feather-stm32f405
-* **build**
-  - `all`: run test binaries in the correct directory
-  - `build`: Fix arch release job
-  - `ci`: run `tinygo test` for known-working packages
-  - `ci`: set git-fetch-depth to 1
-  - `docker`: fix the problem with the wasm build (#1357)
-  - `Makefile`: check whether submodules have been downloaded in some common cases
-* **docs**
-  - add ESP32, ESP8266, and Adafruit Feather STM32F405 to list of supported boards
-
-0.14.1
---
-* **command-line**
-  - support for Go 1.15
-* **compiler**
-  - loader:  work around Windows symlink limitation
-
-0.14.0
---
-* **command-line**
-  - fix `getDefaultPort()` on non-English Windows locales
-  - compileopts: improve error reporting of unsupported flags
-  - fix test subcommand
-  - use auto-retry to locate MSD for UF2 and HEX flashing
-  - fix touchSerialPortAt1200bps on Windows
-  - support package names with backslashes on Windows
-* **compiler**
-  - fix a few crashes due to named types
-  - add support for atomic operations
-  - move the channel blocked list onto the stack
-  - fix -gc=none
-  - fix named string to `[]byte` slice conversion
-  - implement func value and builtin defers
-  - add proper parameter names to runtime.initAll, to fix a panic
-  - builder: fix picolibc include path
-  - builder: use newer version of gohex
-  - builder: try to determine stack size information at compile time
-  - builder: remove -opt=0
-  - interp: fix sync/atomic.Value load/store methods
-  - loader: add Go module support
-  - transform: fix debug information in func lowering pass
-  - transform: do not special-case zero or one implementations of a method call
-  - transform: introduce check for method calls on nil interfaces
-  - transform: gc: track 0-index GEPs to fix miscompilation
-* **cgo**
-  - Add LDFlags support
-* **standard library**
-  - extend stdlib to allow import of more packages
-  - replace master/slave terminology with appropriate alternatives (MOSI->SDO
-    etc)
-  - `internal/bytealg`: reimplement bytealg in pure Go
-  - `internal/task`: fix nil panic in (*internal/task.Stack).Pop
-  - `os`: add Args and stub it with mock data
-  - `os`: implement virtual filesystem support
-  - `reflect`: add Cap and Len support for map and chan
-  - `runtime`: fix return address in scheduler on RISC-V
-  - `runtime`: avoid recursion in printuint64 function
-  - `runtime`: replace ReadRegister with AsmFull inline assembly
-  - `runtime`: fix compilation errors when using gc.extalloc
-  - `runtime`: add cap and len support for chans
-  - `runtime`: refactor time handling (improving accuracy)
-  - `runtime`: make channels work in interrupts
-  - `runtime/interrupt`: add cross-chip disable/restore interrupt support
-  - `sync`: implement `sync.Cond`
-  - `sync`: add WaitGroup
-* **targets**
-  - `arm`: allow nesting in DisableInterrupts and EnableInterrupts
-  - `arm`: make FPU configuraton consistent
-  - `arm`: do not mask fault handlers in critical sections
-  - `atmega2560`: fix pin mapping for pins D2, D5 and the L port
-  - `atsamd`: return an error when an incorrect PWM pin is used
-  - `atsamd`: add support for pin change interrupts
-  - `atsamd`: add DAC support
-  - `atsamd21`: add more ADC pins
-  - `atsamd51`: fix ROM / RAM size on atsamd51j20
-  - `atsamd51`: add more pins
-  - `atsamd51`: add more ADC pins
-  - `atsamd51`: add pin change interrupt settings
-  - `atsamd51`: extend pinPadMapping
-  - `arduino-nano33`: use (U)SB flag to ensure that device can be found when
-     not on default port
-  - `arduino-nano33`: remove (d)ebug flag to reduce console noise when flashing
-  - `avr`: use standard pin numbering
-  - `avr`: unify GPIO pin/port code
-  - `avr`: add support for PinInputPullup
-  - `avr`: work around codegen bug in LLVM 10
-  - `avr`: fix target triple
-  - `fe310`: remove extra println left in by mistake
-  - `feather-nrf52840`: add support for the Feather nRF52840
-  - `maixbit`: add board definition and dummy runtime
-  - `nintendoswitch`: Add experimental Nintendo Switch support without CRT
-  - `nrf`: expose the RAM base address
-  - `nrf`: add support for pin change interrupts
-  - `nrf`: add microbit-s110v8 target
-  - `nrf`: fix bug in SPI.Tx
-  - `nrf`: support debugging the PCA10056
-  - `pygamer`: add Adafruit PyGamer suport
-  - `riscv`: fix interrupt configuration bug
-  - `riscv`: disable linker relaxations during gp init
-  - `stm32f4disco`: add new target with ST-Link v2.1 debugger
-  - `teensy36`: add Teensy 3.6 support
-  - `wasm`: fix event handling
-  - `wasm`: add --no-demangle linker option
-  - `wioterminal`: add support for the Seeed Wio Terminal
-  - `xiao`: add support for the Seeed XIAO
-
 0.13.1
 ---
 * **standard library**
@@ -32,7 +32,7 @@ Microcontrollers have lots of peripherals (I2C, SPI, ADC, etc.) and many don't h

 ## How to use our Github repository

-The `release` branch of this repo will always have the latest released version of TinyGo. All of the active development work for the next release will take place in the `dev` branch. TinyGo will use semantic versioning and will create a tag/release for each release.
+The `master` branch of this repo will always have the latest released version of TinyGo. All of the active development work for the next release will take place in the `dev` branch. TinyGo will use semantic versioning and will create a tag/release for each release.

 Here is how to contribute back some code or documentation:

@@ -15,4 +15,4 @@ Ayke van Laethem <aykevanlaethem@gmail.com>
 Daniel Esteban <conejo@conejo.me>
 Loon, LLC.
 Ron Evans <ron@hybridgroup.com>
-Nia Weiss <niaow1234@gmail.com>
+Jaden Weiss <jaden@jadendw.dev>
@@ -1,10 +1,10 @@
-# TinyGo base stage installs the most recent Go 1.15.x, LLVM 11 and the TinyGo compiler itself.
-FROM golang:1.15 AS tinygo-base
+# TinyGo base stage installs Go 1.14, LLVM 10 and the TinyGo compiler itself.
+FROM golang:1.14 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-11 main" >> /etc/apt/sources.list && \
+    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main" >> /etc/apt/sources.list && \
    apt-get update && \
-    apt-get install -y llvm-11-dev libclang-11-dev lld-11 git
+    apt-get install -y llvm-10-dev libclang-10-dev git

 COPY . /tinygo

@@ -27,10 +27,10 @@ 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

-RUN cd /tinygo/ && \
+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 && \
    apt-get update && \
-    apt-get install -y make clang-11 libllvm11 lld-11 && \
-    make wasi-libc
+    apt-get install -y libllvm10 lld-10

 # tinygo-avr stage installs the needed dependencies to compile TinyGo programs for AVR microcontrollers.
 FROM tinygo-base AS tinygo-avr
@@ -61,7 +61,7 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

 RUN cd /tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make clang-11 && \
+    apt-get install -y apt-utils make clang-10 && \
    make gen-device-nrf && make gen-device-stm32

 # tinygo-all stage installs the needed dependencies to compile TinyGo programs for all platforms.
@@ -73,7 +73,7 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

 RUN cd /tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make clang-11 binutils-avr gcc-avr avr-libc && \
+    apt-get install -y apt-utils make clang-10 binutils-avr gcc-avr avr-libc && \
    make gen-device

 CMD ["tinygo"]
@@ -1,7 +1,7 @@
-Copyright (c) 2018-2021 TinyGo Authors. All rights reserved.
+Copyright (c) 2018-2020 TinyGo Authors. All rights reserved.

 TinyGo includes portions of the Go standard library.
-Copyright (c) 2009-2021 The Go Authors. All rights reserved.
+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.
@@ -9,10 +9,25 @@ CLANG_SRC ?= $(LLVM_PROJECTDIR)/clang
 LLD_SRC ?= $(LLVM_PROJECTDIR)/lld

 # Try to autodetect LLVM build tools.
-detect = $(shell command -v $(1) 2> /dev/null && echo $(1))
-CLANG ?= $(word 1,$(abspath $(call detect,llvm-build/bin/clang))$(call detect,clang-11)$(call detect,clang-10)$(call detect,clang))
-LLVM_AR ?= $(word 1,$(abspath $(call detect,llvm-build/bin/llvm-ar))$(call detect,llvm-ar-11)$(call detect,llvm-ar-10)$(call detect,llvm-ar))
-LLVM_NM ?= $(word 1,$(abspath $(call detect,llvm-build/bin/llvm-nm))$(call detect,llvm-nm-11)$(call detect,llvm-nm-10)$(call detect,llvm-nm))
+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

 # Go binary and GOROOT to select
 GO ?= go
@@ -22,7 +37,7 @@ export GOROOT = $(shell $(GO) env GOROOT)
 MD5SUM = md5sum

 # tinygo binary for tests
-TINYGO ?= $(word 1,$(call detect,tinygo)$(call detect,build/tinygo))
+TINYGO ?= tinygo

 # Use CCACHE for LLVM if possible
 ifneq (, $(shell command -v ccache 2> /dev/null))
@@ -36,7 +51,7 @@ 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-nxp gen-device-avr
+.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

@@ -48,69 +63,64 @@ ifeq ($(OS),Windows_NT)
    # 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 -DLLVM_ENABLE_PIC=OFF
+    LLVM_OPTION += -DLLVM_ENABLE_THREADS=OFF

-    CGO_CPPFLAGS += -DCINDEX_NO_EXPORTS
    CGO_LDFLAGS += -static -static-libgcc -static-libstdc++
    CGO_LDFLAGS_EXTRA += -lversion

-    LIBCLANG_NAME = libclang
+    # 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_NAME = clang
+    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
 else ifeq ($(shell uname -s),FreeBSD)
    MD5SUM = md5
-    LIBCLANG_NAME = clang
+    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
    START_GROUP = -Wl,--start-group
    END_GROUP = -Wl,--end-group
 else
-    LIBCLANG_NAME = clang
+    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
    START_GROUP = -Wl,--start-group
    END_GROUP = -Wl,--end-group
 endif

-# Libraries that should be linked in for the statically linked Clang.
-CLANG_LIB_NAMES = clangAnalysis clangARCMigrate clangAST clangASTMatchers clangBasic clangCodeGen clangCrossTU clangDriver clangDynamicASTMatchers clangEdit clangFormat clangFrontend clangFrontendTool clangHandleCXX clangHandleLLVM clangIndex clangLex clangParse clangRewrite clangRewriteFrontend clangSema clangSerialization clangStaticAnalyzerCheckers clangStaticAnalyzerCore clangStaticAnalyzerFrontend clangTooling clangToolingASTDiff clangToolingCore clangToolingInclusions
-CLANG_LIBS = $(START_GROUP) $(addprefix -l,$(CLANG_LIB_NAMES)) $(END_GROUP) -lstdc++
+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++

-# Libraries that should be linked in for the statically linked LLD.
-LLD_LIB_NAMES = lldCOFF lldCommon lldCore lldDriver lldELF lldMachO lldMinGW lldReaderWriter lldWasm lldYAML
-LLD_LIBS = $(START_GROUP) $(addprefix -l,$(LLD_LIB_NAMES)) $(END_GROUP)
+LLD_LIBS = $(START_GROUP) -llldCOFF -llldCommon -llldCore -llldDriver -llldELF -llldMachO -llldMinGW -llldReaderWriter -llldWasm -llldYAML $(END_GROUP)

-# Other libraries that are needed to link TinyGo.
-EXTRA_LIB_NAMES = LLVMInterpreter
-
-# These build targets appear to be the only ones necessary to build all TinyGo
-# dependencies. Only building a subset significantly speeds up rebuilding LLVM.
-# The Makefile rules convert a name like lldELF to lib/liblldELF.a to match the
-# library path (for ninja).
-# This list also includes a few tools that are necessary as part of the full
-# TinyGo build.
-NINJA_BUILD_TARGETS = clang llvm-config llvm-ar llvm-nm $(addprefix lib/lib,$(addsuffix .a,$(LIBCLANG_NAME) $(CLANG_LIB_NAMES) $(LLD_LIB_NAMES) $(EXTRA_LIB_NAMES)))

 # 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 $(LLD_SRC))/include
+    CGO_CPPFLAGS=$(shell $(LLVM_BUILDDIR)/bin/llvm-config --cppflags) -I$(abspath $(LLVM_BUILDDIR))/tools/clang/include -I$(abspath $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
    CGO_CXXFLAGS=-std=c++14
-    CGO_LDFLAGS+=$(abspath $(LLVM_BUILDDIR))/lib/lib$(LIBCLANG_NAME).a -L$(abspath $(LLVM_BUILDDIR)/lib) $(CLANG_LIBS) $(LLD_LIBS) $(shell $(LLVM_BUILDDIR)/bin/llvm-config --ldflags --libs --system-libs $(LLVM_COMPONENTS)) -lstdc++ $(CGO_LDFLAGS_EXTRA)
+    CGO_LDFLAGS+=$(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)
 endif


 clean:
 	@rm -rf build

-FMT_PATHS = ./*.go builder cgo compiler interp 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 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:
 	@gofmt -l -w $(FMT_PATHS)
 fmt-check:
 	@unformatted=$$(gofmt -l $(FMT_PATHS)); [ -z "$$unformatted" ] && exit 0; echo "Unformatted:"; for fn in $$unformatted; do echo "  $$fn"; done; exit 1


-gen-device: gen-device-avr gen-device-esp gen-device-nrf gen-device-sam gen-device-sifive gen-device-stm32 gen-device-kendryte gen-device-nxp
+gen-device: gen-device-avr gen-device-nrf gen-device-sam gen-device-sifive gen-device-stm32

 gen-device-avr:
-	@if [ ! -e lib/avr/README.md ]; then echo "Submodules have not been downloaded. Please download them using:\n  git submodule update --init"; exit 1; fi
 	$(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/
@@ -119,18 +129,10 @@ gen-device-avr:
 build/gen-device-svd: ./tools/gen-device-svd/*.go
 	$(GO) build -o $@ ./tools/gen-device-svd/

-gen-device-esp: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/Espressif-Community -interrupts=software lib/cmsis-svd/data/Espressif-Community/ src/device/esp/
-	GO111MODULE=off $(GO) fmt ./src/device/esp
-
 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-nxp: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/NXP lib/cmsis-svd/data/NXP/ src/device/nxp/
-	GO111MODULE=off $(GO) fmt ./src/device/nxp
-
 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
@@ -139,70 +141,48 @@ 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-kendryte: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/Kendryte-Community -interrupts=software lib/cmsis-svd/data/Kendryte-Community/ src/device/kendryte/
-	GO111MODULE=off $(GO) fmt ./src/device/kendryte
-
 gen-device-stm32: build/gen-device-svd
-	./build/gen-device-svd -source=https://github.com/tinygo-org/stm32-svd lib/stm32-svd/svd src/device/stm32/
+	./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


 # Get LLVM sources.
 $(LLVM_PROJECTDIR)/README.md:
-	git clone -b xtensa_release_11.0.0 --depth=1 https://github.com/tinygo-org/llvm-project $(LLVM_PROJECTDIR)
+	git clone -b release/10.x https://github.com/llvm/llvm-project $(LLVM_PROJECTDIR)
 llvm-source: $(LLVM_PROJECTDIR)/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;Xtensa" -DCMAKE_BUILD_TYPE=Release -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_LIBEDIT=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_LIBXML2=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_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)

 # Build LLVM.
 $(LLVM_BUILDDIR): $(LLVM_BUILDDIR)/build.ninja
-	cd $(LLVM_BUILDDIR); ninja $(NINJA_BUILD_TARGETS)
+	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:
-	@if [ ! -e lib/wasi-libc/Makefile ]; then echo "Submodules have not been downloaded. Please download them using:\n  git submodule update --init"; exit 1; fi
 	cd lib/wasi-libc && make -j4 WASM_CC=$(CLANG) WASM_AR=$(LLVM_AR) WASM_NM=$(LLVM_NM)


 # Build the Go compiler.
 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)" $(GO) build -buildmode exe -o build/tinygo$(EXE) -tags byollvm -ldflags="-X main.gitSha1=`git rev-parse --short HEAD`" .
+	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) build -o build/tinygo$(EXE) -tags byollvm .

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

-# Test known-working standard library packages.
-# TODO: do this in one command, parallelize, and only show failing tests (no
-# implied -v flag).
-.PHONY: tinygo-test
 tinygo-test:
-	$(TINYGO) test container/heap
-	$(TINYGO) test container/list
-	$(TINYGO) test container/ring
-	$(TINYGO) test crypto/des
-	$(TINYGO) test encoding/ascii85
-	$(TINYGO) test encoding/base32
-	$(TINYGO) test encoding/hex
-	$(TINYGO) test hash/adler32
-	$(TINYGO) test hash/fnv
-	$(TINYGO) test hash/crc64
-	$(TINYGO) test math
-	$(TINYGO) test math/cmplx
-	$(TINYGO) test text/scanner
-	$(TINYGO) test unicode/utf8
+	cd tests/tinygotest && tinygo test

 .PHONY: smoketest
 smoketest:
 	$(TINYGO) version
-	# test all examples (except pwm)
+	# test all examples
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/adc
@@ -223,9 +203,7 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=microbit            examples/microbit-blink
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=microbit-v2         examples/microbit-blink
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/pininterrupt
+	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/pwm
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/serial
 	@$(MD5SUM) test.hex
@@ -236,6 +214,8 @@ smoketest:
 	# 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
 	$(TINYGO) build             -o test.wasm -tags=reelboard            examples/blinky1
@@ -251,8 +231,6 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=microbit            examples/echo
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=microbit-s110v8     examples/echo
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nrf52840-mdk        examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10031            examples/blinky1
@@ -279,15 +257,11 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=stm32f4disco        examples/blinky2
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=stm32f4disco-1      examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=feather-stm32f405   examples/blinky1
-	@$(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
+	$(TINYGO) build -size short -o test.hex -target=clue_alpha          examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.gba -target=gameboy-advance     examples/gba-display
 	@$(MD5SUM) test.gba
@@ -311,56 +285,17 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pinetime-devkit0    examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=lgt92    examples/blinky1
-	@$(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
-	$(TINYGO) build -size short -o test.hex -target=wioterminal         examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pygamer             examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=xiao                examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/dac
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pyportal            examples/dac
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=feather-nrf52840  	examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=itsybitsy-nrf52840  examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=qtpy  				examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=teensy40            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=teensy36            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=nucleo-f722ze       examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=nucleo-l552ze       examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=p1am-100            examples/blinky1
-	@$(MD5SUM) test.hex
-	# test pwm
-	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/pwm
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m4        examples/pwm
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=feather-m4          examples/pwm
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pyportal            examples/pwm
-	@$(MD5SUM) test.hex
 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
-	$(TINYGO) build -size short -o test.hex -target=arduino             examples/pwm
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino -scheduler=tasks  examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino-nano        examples/blinky1
@@ -369,35 +304,13 @@ ifneq ($(AVR), 0)
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=digispark -gc=leaking examples/blinky1
 	@$(MD5SUM) test.hex
-endif
-ifneq ($(XTENSA), 0)
-	$(TINYGO) build -size short -o test.bin -target=esp32-mini32      	examples/blinky1
-	@$(MD5SUM) test.bin
-	$(TINYGO) build -size short -o test.bin -target=nodemcu             examples/blinky1
-	@$(MD5SUM) test.bin
 endif
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=hifive1-qemu        examples/serial
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=maixbit             examples/blinky1
-	@$(MD5SUM) test.hex
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/export
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/main
-	# test various compiler flags
-	$(TINYGO) build -size short -o test.hex -target=pca10040 -gc=none -scheduler=none examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=1     examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build             -o test.nro -target=nintendoswitch      examples/serial
-	@$(MD5SUM) test.nro
-	$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=0     ./testdata/stdlib.go
-	@$(MD5SUM) test.hex

-wasmtest:
-	$(GO) test ./tests/wasm
-
-build/release: tinygo gen-device wasi-libc
+release: tinygo gen-device wasi-libc
 	@mkdir -p build/release/tinygo/bin
 	@mkdir -p build/release/tinygo/lib/clang/include
 	@mkdir -p build/release/tinygo/lib/CMSIS/CMSIS
@@ -432,13 +345,4 @@ build/release: tinygo gen-device wasi-libc
 	./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
-
-release: build/release
 	tar -czf build/release.tar.gz -C build/release tinygo
-
-deb: build/release
-	@mkdir -p build/release-deb/usr/local/bin
-	@mkdir -p build/release-deb/usr/local/lib
-	cp -ar build/release/tinygo build/release-deb/usr/local/lib/tinygo
-	ln -sf ../lib/tinygo/bin/tinygo build/release-deb/usr/local/bin/tinygo
-	fpm -f -s dir -t deb -n tinygo -v $(shell grep "const Version = " goenv/version.go | awk '{print $$NF}') -m '@tinygo-org' --description='TinyGo is a Go compiler for small places.' --license='BSD 3-Clause' --url=https://tinygo.org/ --deb-changelog CHANGELOG.md -p build/release.deb -C ./build/release-deb
@@ -43,42 +43,27 @@ See the [getting started instructions](https://tinygo.org/getting-started/) for

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

-The following 55 microcontroller boards are currently supported:
+The following 32 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](https://www.adafruit.com/product/4500)
+* [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 Feather nRF52840 Express](https://www.adafruit.com/product/4062)
-* [Adafruit Feather STM32F405 Express](https://www.adafruit.com/product/4382)
 * [Adafruit ItsyBitsy M0](https://www.adafruit.com/product/3727)
 * [Adafruit ItsyBitsy M4](https://www.adafruit.com/product/3800)
-* [Adafruit ItsyBitsy nRF52840](https://www.adafruit.com/product/4481)
-* [Adafruit Matrix Portal M4](https://www.adafruit.com/product/4745)
 * [Adafruit Metro M4 Express Airlift](https://www.adafruit.com/product/4000)
 * [Adafruit PyBadge](https://www.adafruit.com/product/4200)
-* [Adafruit PyGamer](https://www.adafruit.com/product/4242)
 * [Adafruit PyPortal](https://www.adafruit.com/product/4116)
-* [Adafruit QT Py](https://www.adafruit.com/product/4600)
 * [Adafruit Trinket M0](https://www.adafruit.com/product/3500)
 * [Arduino Mega 2560](https://store.arduino.cc/arduino-mega-2560-rev3)
-* [Arduino MKR1000](https://store.arduino.cc/arduino-mkr1000-wifi)
 * [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)
-* [Arduino Zero](https://store.arduino.cc/usa/arduino-zero)
 * [BBC micro:bit](https://microbit.org/)
-* [BBC micro:bit v2](https://microbit.org/new-microbit/)
 * [Digispark](http://digistump.com/products/1)
-* [Dragino LoRaWAN GPS Tracker LGT-92](http://www.dragino.com/products/lora-lorawan-end-node/item/142-lgt-92.html)
-* [ESP32](https://www.espressif.com/en/products/socs/esp32)
-* [ESP8266](https://www.espressif.com/en/products/socs/esp8266)
 * [Game Boy Advance](https://en.wikipedia.org/wiki/Game_Boy_Advance)
 * [Makerdiary nRF52840-MDK](https://wiki.makerdiary.com/nrf52840-mdk/)
-* [Makerdiary nRF52840-MDK USB Dongle](https://wiki.makerdiary.com/nrf52840-mdk-usb-dongle/)
-* [nice!nano](https://docs.nicekeyboards.com/#/nice!nano/)
-* [Nintendo Switch](https://www.nintendo.com/switch/)
 * [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)
@@ -87,17 +72,9 @@ The following 55 microcontroller boards are currently supported:
 * [Particle Xenon](https://docs.particle.io/datasheets/discontinued/xenon-datasheet/)
 * [Phytec reel board](https://www.phytec.eu/product-eu/internet-of-things/reelboard/)
 * [PineTime DevKit](https://www.pine64.org/pinetime/)
-* [PJRC Teensy 3.6](https://www.pjrc.com/store/teensy36.html)
-* [PJRC Teensy 4.0](https://www.pjrc.com/store/teensy40.html)
-* [ProductivityOpen P1AM-100](https://facts-engineering.github.io/modules/P1AM-100/P1AM-100.html)
-* [Seeed Wio Terminal](https://www.seeedstudio.com/Wio-Terminal-p-4509.html)
-* [Seeed Seeeduino XIAO](https://www.seeedstudio.com/Seeeduino-XIAO-Arduino-Microcontroller-SAMD21-Cortex-M0+-p-4426.html)
-* [Seeed Sipeed MAix BiT](https://www.seeedstudio.com/Sipeed-MAix-BiT-for-RISC-V-AI-IoT-p-2872.html)
 * [SiFIve HiFive1](https://www.sifive.com/boards/hifive1)
-* [ST Micro "Nucleo" F103RB](https://www.st.com/en/evaluation-tools/nucleo-f103rb.html)
-* [ST Micro "Nucleo" F722ZE](https://www.st.com/en/evaluation-tools/nucleo-f722ze.html)
-* [ST Micro "Nucleo" L552ZE](https://www.st.com/en/evaluation-tools/nucleo-l552ze-q.html)
-* [ST Micro STM32F103XX "Bluepill"](https://stm32-base.org/boards/STM32F103C8T6-Blue-Pill)
+* [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/)

@@ -159,6 +136,4 @@ The original reasoning was: if [Python](https://micropython.org/) can run on mic

 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/11.0.0/LICENSE.TXT). This has been clearly indicated in the header of these files.
-
-Some code has been copied and/or ported from Paul Stoffregen's Teensy libraries and is therefore licensed under PJRC's license. This has been clearly indicated in the header of these files.
+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.
@@ -1,7 +1,7 @@
 # Avoid lengthy LLVM rebuilds on each newly pushed branch. Pull requests will
 # be built anyway.
 trigger:
- release
+- master
 - dev

 jobs:
@@ -12,13 +12,12 @@ jobs:
  steps:
    - task: GoTool@0
      inputs:
-        version: '1.16'
+        version: '1.14.1'
    - checkout: self
-      fetchDepth: 1
-    - task: Cache@2
+    - task: CacheBeta@0
      displayName: Cache LLVM source
      inputs:
-        key: llvm-source-11-windows-v1
+        key: llvm-source-10-windows-v0
        path: llvm-project
    - task: Bash@3
      displayName: Download LLVM source
@@ -28,7 +27,7 @@ jobs:
    - task: CacheBeta@0
      displayName: Cache LLVM build
      inputs:
-        key: llvm-build-11-windows-v4
+        key: llvm-build-10-windows-v0
        path: llvm-build
    - task: Bash@3
      displayName: Build LLVM
@@ -37,22 +36,18 @@ jobs:
        script: |
          if [ ! -f llvm-build/lib/liblldELF.a ]
          then
-            # install dependencies
            choco install ninja
-            # hack ninja to use fewer jobs
-            echo -e 'C:\\ProgramData\\Chocolatey\\bin\\ninja -j4 %*' > /usr/bin/ninja.bat
-            # build!
            make llvm-build
          fi
    - task: Bash@3
      displayName: Install QEMU
      inputs:
        targetType: inline
-        script: choco install qemu --version=2020.06.12
+        script: choco install qemu
    - task: CacheBeta@0
      displayName: Cache wasi-libc sysroot
      inputs:
-        key: wasi-libc-sysroot-v4
+        key: wasi-libc-sysroot-v2
        path: lib/wasi-libc/sysroot
    - task: Bash@3
      displayName: Build wasi-libc
@@ -74,7 +69,7 @@ jobs:
        script: |
          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
          unset GOROOT
-          make build/release -j4
+          make release -j4
    - publish: $(System.DefaultWorkingDirectory)/build/release/tinygo
      displayName: Publish zip as artifact
      artifact: tinygo
@@ -85,4 +80,4 @@ jobs:
        script: |
          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
          unset GOROOT
-          make smoketest TINYGO=build/tinygo AVR=0 XTENSA=0
+          make smoketest TINYGO=build/tinygo AVR=0
@@ -4,19 +4,11 @@
 package builder

 import (
-	"crypto/sha512"
-	"debug/elf"
-	"encoding/binary"
-	"encoding/hex"
-	"encoding/json"
 	"errors"
 	"fmt"
-	"go/types"
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"runtime"
-	"sort"
 	"strconv"
 	"strings"

@@ -24,554 +16,36 @@ import (
 	"github.com/tinygo-org/tinygo/compiler"
 	"github.com/tinygo-org/tinygo/goenv"
 	"github.com/tinygo-org/tinygo/interp"
-	"github.com/tinygo-org/tinygo/loader"
-	"github.com/tinygo-org/tinygo/stacksize"
 	"github.com/tinygo-org/tinygo/transform"
 	"tinygo.org/x/go-llvm"
 )

-// BuildResult is the output of a build. This includes the binary itself and
-// some other metadata that is obtained while building the binary.
-type BuildResult struct {
-	// A path to the output binary. It will be removed after Build returns, so
-	// if it should be kept it must be copied or moved away.
-	Binary string
-
-	// The directory of the main package. This is useful for testing as the test
-	// binary must be run in the directory of the tested package.
-	MainDir string
-}
-
-// packageAction is the struct that is serialized to JSON and hashed, to work as
-// a cache key of compiled packages. It should contain all the information that
-// goes into a compiled package to avoid using stale data.
-//
-// Right now it's still important to include a hash of every import, because a
-// dependency might have a public constant that this package uses and thus this
-// package will need to be recompiled if that constant changes. In the future,
-// the type data should be serialized to disk which can then be used as cache
-// key, avoiding the need for recompiling all dependencies when only the
-// implementation of an imported package changes.
-type packageAction struct {
-	ImportPath      string
-	CompilerVersion int // compiler.Version
-	LLVMVersion     string
-	Config          *compiler.Config
-	CFlags          []string
-	FileHashes      map[string]string // hash of every file that's part of the package
-	Imports         map[string]string // map from imported package to action ID hash
-}
-
 // 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(BuildResult) error) error {
-	// Create a temporary directory for intermediary files.
-	dir, err := ioutil.TempDir("", "tinygo")
+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
 	}
-	defer os.RemoveAll(dir)
-
-	compilerConfig := &compiler.Config{
-		Triple:          config.Triple(),
-		CPU:             config.CPU(),
-		Features:        config.Features(),
-		GOOS:            config.GOOS(),
-		GOARCH:          config.GOARCH(),
-		CodeModel:       config.CodeModel(),
-		RelocationModel: config.RelocationModel(),
-
-		Scheduler:          config.Scheduler(),
-		FuncImplementation: config.FuncImplementation(),
-		AutomaticStackSize: config.AutomaticStackSize(),
-		DefaultStackSize:   config.Target.DefaultStackSize,
-		NeedsStackObjects:  config.NeedsStackObjects(),
-		Debug:              config.Debug(),
+	mod, extraFiles, errs := compiler.Compile(pkgName, machine, config)
+	if errs != nil {
+		return newMultiError(errs)
 	}

-	// Load the target machine, which is the LLVM object that contains all
-	// details of a target (alignment restrictions, pointer size, default
-	// address spaces, etc).
-	machine, err := compiler.NewTargetMachine(compilerConfig)
-	if err != nil {
-		return err
+	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")
 	}

-	// Load entire program AST into memory.
-	lprogram, err := loader.Load(config, []string{pkgName}, config.ClangHeaders, types.Config{
-		Sizes: compiler.Sizes(machine),
-	})
-	if err != nil {
-		return err
-	}
-	err = lprogram.Parse()
-	if err != nil {
-		return err
-	}
-
-	// The slice of jobs that orchestrates most of the build.
-	// This is somewhat like an in-memory Makefile with each job being a
-	// Makefile target.
-	var jobs []*compileJob
-
-	// Create the *ssa.Program. This does not yet build the entire SSA of the
-	// program so it's pretty fast and doesn't need to be parallelized.
-	program := lprogram.LoadSSA()
-
-	// Add jobs to compile each package.
-	// Packages that have a cache hit will not be compiled again.
-	var packageJobs []*compileJob
-	packageBitcodePaths := make(map[string]string)
-	packageActionIDs := make(map[string]string)
-	for _, pkg := range lprogram.Sorted() {
-		pkg := pkg // necessary to avoid a race condition
-
-		// Create a cache key: a hash from the action ID below that contains all
-		// the parameters for the build.
-		actionID := packageAction{
-			ImportPath:      pkg.ImportPath,
-			CompilerVersion: compiler.Version,
-			LLVMVersion:     llvm.Version,
-			Config:          compilerConfig,
-			CFlags:          pkg.CFlags,
-			FileHashes:      make(map[string]string, len(pkg.FileHashes)),
-			Imports:         make(map[string]string, len(pkg.Pkg.Imports())),
-		}
-		for filePath, hash := range pkg.FileHashes {
-			actionID.FileHashes[filePath] = hex.EncodeToString(hash)
-		}
-		for _, imported := range pkg.Pkg.Imports() {
-			hash, ok := packageActionIDs[imported.Path()]
-			if !ok {
-				return fmt.Errorf("package %s imports %s but couldn't find dependency", pkg.ImportPath, imported.Path())
-			}
-			actionID.Imports[imported.Path()] = hash
-		}
-		buf, err := json.Marshal(actionID)
-		if err != nil {
-			panic(err) // shouldn't happen
-		}
-		hash := sha512.Sum512_224(buf)
-		packageActionIDs[pkg.ImportPath] = hex.EncodeToString(hash[:])
-
-		// Determine the path of the bitcode file (which is a serialized version
-		// of a LLVM module).
-		cacheDir := goenv.Get("GOCACHE")
-		if cacheDir == "off" {
-			// Use temporary build directory instead, effectively disabling the
-			// build cache.
-			cacheDir = dir
-		}
-		bitcodePath := filepath.Join(cacheDir, "pkg-"+hex.EncodeToString(hash[:])+".bc")
-		packageBitcodePaths[pkg.ImportPath] = bitcodePath
-
-		// Check whether this package has been compiled before, and if so don't
-		// compile it again.
-		if _, err := os.Stat(bitcodePath); err == nil {
-			// Already cached, don't recreate this package.
-			continue
-		}
-
-		// The package has not yet been compiled, so create a job to do so.
-		job := &compileJob{
-			description: "compile package " + pkg.ImportPath,
-			run: func() error {
-				// Compile AST to IR. The compiler.CompilePackage function will
-				// build the SSA as needed.
-				mod, errs := compiler.CompilePackage(pkg.ImportPath, pkg, program.Package(pkg.Pkg), machine, compilerConfig, config.DumpSSA())
-				if errs != nil {
-					return newMultiError(errs)
-				}
-				if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
-					return errors.New("verification error after compiling package " + pkg.ImportPath)
-				}
-
-				// Serialize the LLVM module as a bitcode file.
-				// Write to a temporary path that is renamed to the destination
-				// file to avoid race conditions with other TinyGo invocatiosn
-				// that might also be compiling this package at the same time.
-				f, err := ioutil.TempFile(filepath.Dir(bitcodePath), filepath.Base(bitcodePath))
-				if err != nil {
-					return err
-				}
-				if runtime.GOOS == "windows" {
-					// Work around a problem on Windows.
-					// For some reason, WriteBitcodeToFile causes TinyGo to
-					// exit with the following message:
-					//   LLVM ERROR: IO failure on output stream: Bad file descriptor
-					buf := llvm.WriteBitcodeToMemoryBuffer(mod)
-					defer buf.Dispose()
-					_, err = f.Write(buf.Bytes())
-				} else {
-					// Otherwise, write bitcode directly to the file (probably
-					// faster).
-					err = llvm.WriteBitcodeToFile(mod, f)
-				}
-				if err != nil {
-					// WriteBitcodeToFile doesn't produce a useful error on its
-					// own, so create a somewhat useful error message here.
-					return fmt.Errorf("failed to write bitcode for package %s to file %s", pkg.ImportPath, bitcodePath)
-				}
-				err = f.Close()
-				if err != nil {
-					return err
-				}
-				return os.Rename(f.Name(), bitcodePath)
-			},
-		}
-		jobs = append(jobs, job)
-		packageJobs = append(packageJobs, job)
-	}
-
-	// Add job that links and optimizes all packages together.
-	var mod llvm.Module
-	var stackSizeLoads []string
-	programJob := &compileJob{
-		description:  "link+optimize packages (LTO)",
-		dependencies: packageJobs,
-		run: func() error {
-			// Load and link all the bitcode files. This does not yet optimize
-			// anything, it only links the bitcode files together.
-			ctx := llvm.NewContext()
-			mod = ctx.NewModule("")
-			for _, pkg := range lprogram.Sorted() {
-				pkgMod, err := ctx.ParseBitcodeFile(packageBitcodePaths[pkg.ImportPath])
-				if err != nil {
-					return fmt.Errorf("failed to load bitcode file: %w", err)
-				}
-				err = llvm.LinkModules(mod, pkgMod)
-				if err != nil {
-					return fmt.Errorf("failed to link module: %w", err)
-				}
-			}
-
-			// Create runtime.initAll function that calls the runtime
-			// initializer of each package.
-			llvmInitFn := mod.NamedFunction("runtime.initAll")
-			llvmInitFn.SetLinkage(llvm.InternalLinkage)
-			llvmInitFn.SetUnnamedAddr(true)
-			llvmInitFn.Param(0).SetName("context")
-			llvmInitFn.Param(1).SetName("parentHandle")
-			block := mod.Context().AddBasicBlock(llvmInitFn, "entry")
-			irbuilder := mod.Context().NewBuilder()
-			defer irbuilder.Dispose()
-			irbuilder.SetInsertPointAtEnd(block)
-			i8ptrType := llvm.PointerType(mod.Context().Int8Type(), 0)
-			for _, pkg := range lprogram.Sorted() {
-				pkgInit := mod.NamedFunction(pkg.Pkg.Path() + ".init")
-				if pkgInit.IsNil() {
-					panic("init not found for " + pkg.Pkg.Path())
-				}
-				irbuilder.CreateCall(pkgInit, []llvm.Value{llvm.Undef(i8ptrType), llvm.Undef(i8ptrType)}, "")
-			}
-			irbuilder.CreateRetVoid()
-
-			// After linking, functions should (as far as possible) be set to
-			// private linkage or internal linkage. The compiler package marks
-			// non-exported functions by setting the visibility to hidden or
-			// (for thunks) to linkonce_odr linkage. Change the linkage here to
-			// internal to benefit much more from interprocedural optimizations.
-			for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-				if fn.Visibility() == llvm.HiddenVisibility {
-					fn.SetVisibility(llvm.DefaultVisibility)
-					fn.SetLinkage(llvm.InternalLinkage)
-				} else if fn.Linkage() == llvm.LinkOnceODRLinkage {
-					fn.SetLinkage(llvm.InternalLinkage)
-				}
-			}
-
-			// Do the same for globals.
-			for global := mod.FirstGlobal(); !global.IsNil(); global = llvm.NextGlobal(global) {
-				if global.Visibility() == llvm.HiddenVisibility {
-					global.SetVisibility(llvm.DefaultVisibility)
-					global.SetLinkage(llvm.InternalLinkage)
-				} else if global.Linkage() == llvm.LinkOnceODRLinkage {
-					global.SetLinkage(llvm.InternalLinkage)
-				}
-			}
-
-			if config.Options.PrintIR {
-				fmt.Println("; Generated LLVM IR:")
-				fmt.Println(mod.String())
-			}
-
-			// Run all optimization passes, which are much more effective now
-			// that the optimizer can see the whole program at once.
-			err := optimizeProgram(mod, config)
-			if err != nil {
-				return err
-			}
-
-			// Make sure stack sizes are loaded from a separate section so they can be
-			// modified after linking.
-			if config.AutomaticStackSize() {
-				stackSizeLoads = transform.CreateStackSizeLoads(mod, config)
-			}
-			return nil
-		},
-	}
-	jobs = append(jobs, programJob)
-
-	// Check whether we only need to create an object file.
-	// If so, we don't need to link anything and will be finished quickly.
-	outext := filepath.Ext(outpath)
-	if outext == ".o" || outext == ".bc" || outext == ".ll" {
-		// Run jobs to produce the LLVM module.
-		err := runJobs(jobs)
-		if err != nil {
-			return err
-		}
-		// Generate output.
-		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:
-			panic("unreachable")
-		}
-	}
-
-	// Act as a compiler driver, as we need to produce a complete executable.
-	// First add all jobs necessary to build this object file, then afterwards
-	// run all jobs in parallel as far as possible.
-
-	// Add job to write the output object file.
-	objfile := filepath.Join(dir, "main.o")
-	outputObjectFileJob := &compileJob{
-		description:  "generate output file",
-		dependencies: []*compileJob{programJob},
-		run: func() error {
-			llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
-			if err != nil {
-				return err
-			}
-			return ioutil.WriteFile(objfile, llvmBuf.Bytes(), 0666)
-		},
-	}
-	jobs = append(jobs, outputObjectFileJob)
-
-	// Prepare link command.
-	linkerDependencies := []*compileJob{outputObjectFileJob}
-	executable := filepath.Join(dir, "main")
-	tmppath := executable // final file
-	ldflags := append(config.LDFlags(), "-o", executable, objfile)
-
-	// Add compiler-rt dependency if needed. Usually this is a simple load from
-	// a cache.
-	if config.Target.RTLib == "compiler-rt" {
-		path, job, err := CompilerRT.load(config.Triple(), config.CPU(), dir)
-		if err != nil {
-			return err
-		}
-		if job != nil {
-			// The library was not loaded from cache so needs to be compiled
-			// (and then stored in the cache).
-			jobs = append(jobs, job.dependencies...)
-			jobs = append(jobs, job)
-			linkerDependencies = append(linkerDependencies, job)
-		}
-		ldflags = append(ldflags, path)
-	}
-
-	// Add libc dependency if needed.
-	root := goenv.Get("TINYGOROOT")
-	switch config.Target.Libc {
-	case "picolibc":
-		path, job, err := Picolibc.load(config.Triple(), config.CPU(), dir)
-		if err != nil {
-			return err
-		}
-		if job != nil {
-			// The library needs to be compiled (cache miss).
-			jobs = append(jobs, job.dependencies...)
-			jobs = append(jobs, job)
-			linkerDependencies = append(linkerDependencies, job)
-		}
-		ldflags = append(ldflags, path)
-	case "wasi-libc":
-		path := filepath.Join(root, "lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a")
-		if _, err := os.Stat(path); os.IsNotExist(err) {
-			return errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
-		}
-		ldflags = append(ldflags, path)
-	case "":
-		// no library specified, so nothing to do
-	default:
-		return fmt.Errorf("unknown libc: %s", config.Target.Libc)
-	}
-
-	// Add jobs to compile extra files. These files are in C or assembly and
-	// contain things like the interrupt vector table and low level operations
-	// such as stack switching.
-	for i, path := range config.ExtraFiles() {
-		abspath := filepath.Join(root, path)
-		outpath := filepath.Join(dir, "extra-"+strconv.Itoa(i)+"-"+filepath.Base(path)+".o")
-		job := &compileJob{
-			description: "compile extra file " + path,
-			run: func() error {
-				err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, abspath)...)
-				if err != nil {
-					return &commandError{"failed to build", path, err}
-				}
-				return nil
-			},
-		}
-		jobs = append(jobs, job)
-		linkerDependencies = append(linkerDependencies, job)
-		ldflags = append(ldflags, outpath)
-	}
-
-	// Add jobs to compile C files in all packages. This is part of CGo.
-	// TODO: do this as part of building the package to be able to link the
-	// bitcode files together.
-	for i, pkg := range lprogram.Sorted() {
-		for j, filename := range pkg.CFiles {
-			file := filepath.Join(pkg.Dir, filename)
-			outpath := filepath.Join(dir, "pkg"+strconv.Itoa(i)+"."+strconv.Itoa(j)+"-"+filepath.Base(file)+".o")
-			job := &compileJob{
-				description: "compile CGo file " + file,
-				run: func() error {
-					err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, file)...)
-					if err != nil {
-						return &commandError{"failed to build", file, err}
-					}
-					return nil
-				},
-			}
-			jobs = append(jobs, job)
-			linkerDependencies = append(linkerDependencies, job)
-			ldflags = append(ldflags, outpath)
-		}
-	}
-
-	// Linker flags from CGo lines:
-	//     #cgo LDFLAGS: foo
-	if len(lprogram.LDFlags) > 0 {
-		ldflags = append(ldflags, lprogram.LDFlags...)
-	}
-
-	// Create a linker job, which links all object files together and does some
-	// extra stuff that can only be done after linking.
-	jobs = append(jobs, &compileJob{
-		description:  "link",
-		dependencies: linkerDependencies,
-		run: func() error {
-			err = link(config.Target.Linker, ldflags...)
-			if err != nil {
-				return &commandError{"failed to link", executable, err}
-			}
-
-			var calculatedStacks []string
-			var stackSizes map[string]functionStackSize
-			if config.Options.PrintStacks || config.AutomaticStackSize() {
-				// Try to determine stack sizes at compile time.
-				// Don't do this by default as it usually doesn't work on
-				// unsupported architectures.
-				calculatedStacks, stackSizes, err = determineStackSizes(mod, executable)
-				if err != nil {
-					return err
-				}
-			}
-			if config.AutomaticStackSize() {
-				// Modify the .tinygo_stacksizes section that contains a stack size
-				// for each goroutine.
-				err = modifyStackSizes(executable, stackSizeLoads, stackSizes)
-				if err != nil {
-					return fmt.Errorf("could not modify stack sizes: %w", 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)
-				}
-			}
-
-			// Print goroutine stack sizes, as far as possible.
-			if config.Options.PrintStacks {
-				printStacks(calculatedStacks, stackSizes)
-			}
-
-			return nil
-		},
-	})
-
-	// Run all jobs to compile and link the program.
-	// Do this now (instead of after elf-to-hex and similar conversions) as it
-	// is simpler and cannot be parallelized.
-	err = runJobs(jobs)
-	if err != nil {
-		return err
-	}
-
-	// Get an Intel .hex file or .bin file from the .elf file.
-	outputBinaryFormat := config.BinaryFormat(outext)
-	switch outputBinaryFormat {
-	case "elf":
-		// do nothing, file is already in ELF format
-	case "hex", "bin":
-		// Extract raw binary, either encoding it as a hex file or as a raw
-		// firmware file.
-		tmppath = filepath.Join(dir, "main"+outext)
-		err := objcopy(executable, tmppath, outputBinaryFormat)
-		if err != nil {
-			return err
-		}
-	case "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
-		}
-	case "esp32", "esp8266":
-		// Special format for the ESP family of chips (parsed by the ROM
-		// bootloader).
-		tmppath = filepath.Join(dir, "main"+outext)
-		err := makeESPFirmareImage(executable, tmppath, outputBinaryFormat)
-		if err != nil {
-			return err
-		}
-	default:
-		return fmt.Errorf("unknown output binary format: %s", outputBinaryFormat)
-	}
-	return action(BuildResult{
-		Binary:  tmppath,
-		MainDir: lprogram.MainPkg().Dir,
-	})
-}
-
-// optimizeProgram runs a series of optimizations and transformations that are
-// needed to convert a program to its final form. Some transformations are not
-// optional and must be run as the compiler expects them to run.
-func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
-	err := interp.Run(mod, config.DumpSSA())
+	err = interp.Run(mod, config.DumpSSA())
 	if err != nil {
 		return err
 	}
@@ -588,7 +62,7 @@ func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
 	// keep functions interoperable, pass int64 types as pointers to
 	// stack-allocated values.
 	// Use -wasm-abi=generic to disable this behaviour.
-	if config.WasmAbi() == "js" {
+	if config.Options.WasmAbi == "js" && strings.HasPrefix(config.Triple(), "wasm") {
 		err := transform.ExternalInt64AsPtr(mod)
 		if err != nil {
 			return err
@@ -597,7 +71,7 @@ func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {

 	// Optimization levels here are roughly the same as Clang, but probably not
 	// exactly.
-	var errs []error
+	errs = nil
 	switch config.Options.Opt {
 	case "none", "0":
 		errs = transform.Optimize(mod, config, 0, 0, 0) // -O0
@@ -610,7 +84,7 @@ func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
 	case "z":
 		errs = transform.Optimize(mod, config, 2, 2, 5) // -Oz, default
 	default:
-		return errors.New("unknown optimization level: -opt=" + config.Options.Opt)
+		errs = []error{errors.New("unknown optimization level: -opt=" + config.Options.Opt)}
 	}
 	if len(errs) > 0 {
 		return newMultiError(errs)
@@ -619,249 +93,140 @@ func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
 		return errors.New("verification failure after LLVM optimization passes")
 	}

-	// LLVM 11 by default tries to emit tail calls (even with the target feature
-	// disabled) unless it is explicitly disabled with a function attribute.
-	// This is a problem, as it tries to emit them and prints an error when it
-	// can't with this feature disabled.
-	// Because as of september 2020 tail calls are not yet widely supported,
-	// they need to be disabled until they are widely supported (at which point
-	// the +tail-call target feautre can be set).
-	if strings.HasPrefix(config.Triple(), "wasm") {
-		transform.DisableTailCalls(mod)
+	// 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")
+		}
 	}

-	return nil
-}
+	// 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.

-// functionStackSizes keeps stack size information about a single function
-// (usually a goroutine).
-type functionStackSize struct {
-	humanName        string
-	stackSize        uint64
-	stackSizeType    stacksize.SizeType
-	missingStackSize *stacksize.CallNode
-}
+		// Create a temporary directory for intermediary files.
+		dir, err := ioutil.TempDir("", "tinygo")
+		if err != nil {
+			return err
+		}
+		defer os.RemoveAll(dir)

-// determineStackSizes tries to determine the stack sizes of all started
-// goroutines and of the reset vector. The LLVM module is necessary to find
-// functions that call a function pointer.
-func determineStackSizes(mod llvm.Module, executable string) ([]string, map[string]functionStackSize, error) {
-	var callsIndirectFunction []string
-	gowrappers := []string{}
-	gowrapperNames := make(map[string]string)
-	for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-		// Determine which functions call a function pointer.
-		for bb := fn.FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
-			for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
-				if inst.IsACallInst().IsNil() {
-					continue
-				}
-				if callee := inst.CalledValue(); callee.IsAFunction().IsNil() && callee.IsAInlineAsm().IsNil() {
-					callsIndirectFunction = append(callsIndirectFunction, fn.Name())
+		// 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 a list of "go wrappers", small wrapper functions that decode
-		// parameters when starting a new goroutine.
-		attr := fn.GetStringAttributeAtIndex(-1, "tinygo-gowrapper")
-		if !attr.IsNil() {
-			gowrappers = append(gowrappers, fn.Name())
-			gowrapperNames[fn.Name()] = attr.GetStringValue()
-		}
-	}
-	sort.Strings(gowrappers)
-
-	// Load the ELF binary.
-	f, err := elf.Open(executable)
-	if err != nil {
-		return nil, nil, fmt.Errorf("could not load executable for stack size analysis: %w", err)
-	}
-	defer f.Close()
-
-	// Determine the frame size of each function (if available) and the callgraph.
-	functions, err := stacksize.CallGraph(f, callsIndirectFunction)
-	if err != nil {
-		return nil, nil, fmt.Errorf("could not parse executable for stack size analysis: %w", err)
-	}
-
-	// Goroutines need to be started and finished and take up some stack space
-	// that way. This can be measured by measuing the stack size of
-	// tinygo_startTask.
-	if numFuncs := len(functions["tinygo_startTask"]); numFuncs != 1 {
-		return nil, nil, fmt.Errorf("expected exactly one definition of tinygo_startTask, got %d", numFuncs)
-	}
-	baseStackSize, baseStackSizeType, baseStackSizeFailedAt := functions["tinygo_startTask"][0].StackSize()
-
-	sizes := make(map[string]functionStackSize)
-
-	// Add the reset handler function, for convenience. The reset handler runs
-	// startup code and the scheduler. The listed stack size is not the full
-	// stack size: interrupts are not counted.
-	var resetFunction string
-	switch f.Machine {
-	case elf.EM_ARM:
-		// Note: all interrupts happen on this stack so the real size is bigger.
-		resetFunction = "Reset_Handler"
-	}
-	if resetFunction != "" {
-		funcs := functions[resetFunction]
-		if len(funcs) != 1 {
-			return nil, nil, fmt.Errorf("expected exactly one definition of %s in the callgraph, found %d", resetFunction, len(funcs))
-		}
-		stackSize, stackSizeType, missingStackSize := funcs[0].StackSize()
-		sizes[resetFunction] = functionStackSize{
-			stackSize:        stackSize,
-			stackSizeType:    stackSizeType,
-			missingStackSize: missingStackSize,
-			humanName:        resetFunction,
-		}
-	}
-
-	// Add all goroutine wrapper functions.
-	for _, name := range gowrappers {
-		funcs := functions[name]
-		if len(funcs) != 1 {
-			return nil, nil, fmt.Errorf("expected exactly one definition of %s in the callgraph, found %d", name, len(funcs))
-		}
-		humanName := gowrapperNames[name]
-		if humanName == "" {
-			humanName = name // fallback
-		}
-		stackSize, stackSizeType, missingStackSize := funcs[0].StackSize()
-		if baseStackSizeType != stacksize.Bounded {
-			// It was not possible to determine the stack size at compile time
-			// because tinygo_startTask does not have a fixed stack size. This
-			// can happen when using -opt=1.
-			stackSizeType = baseStackSizeType
-			missingStackSize = baseStackSizeFailedAt
-		} else if stackSize < baseStackSize {
-			// This goroutine has a very small stack, but still needs to fit all
-			// registers to start and suspend the goroutine. Otherwise a stack
-			// overflow will occur even before the goroutine is started.
-			stackSize = baseStackSize
-		}
-		sizes[name] = functionStackSize{
-			stackSize:        stackSize,
-			stackSizeType:    stackSizeType,
-			missingStackSize: missingStackSize,
-			humanName:        humanName,
-		}
-	}
-
-	if resetFunction != "" {
-		return append([]string{resetFunction}, gowrappers...), sizes, nil
-	}
-	return gowrappers, sizes, nil
-}
-
-// modifyStackSizes modifies the .tinygo_stacksizes section with the updated
-// stack size information. Before this modification, all stack sizes in the
-// section assume the default stack size (which is relatively big).
-func modifyStackSizes(executable string, stackSizeLoads []string, stackSizes map[string]functionStackSize) error {
-	fp, err := os.OpenFile(executable, os.O_RDWR, 0)
-	if err != nil {
-		return err
-	}
-	defer fp.Close()
-
-	elfFile, err := elf.NewFile(fp)
-	if err != nil {
-		return err
-	}
-
-	section := elfFile.Section(".tinygo_stacksizes")
-	if section == nil {
-		return errors.New("could not find .tinygo_stacksizes section")
-	}
-
-	if section.Size != section.FileSize {
-		// Sanity check.
-		return fmt.Errorf("expected .tinygo_stacksizes to have identical size and file size, got %d and %d", section.Size, section.FileSize)
-	}
-
-	// Read all goroutine stack sizes.
-	data := make([]byte, section.Size)
-	_, err = fp.ReadAt(data, int64(section.Offset))
-	if err != nil {
-		return err
-	}
-
-	if len(stackSizeLoads)*4 != len(data) {
-		// Note: while AVR should use 2 byte stack sizes, even 64-bit platforms
-		// should probably stick to 4 byte stack sizes as a larger than 4GB
-		// stack doesn't make much sense.
-		return errors.New("expected 4 byte stack sizes")
-	}
-
-	// Modify goroutine stack sizes with a compile-time known worst case stack
-	// size.
-	for i, name := range stackSizeLoads {
-		fn, ok := stackSizes[name]
-		if !ok {
-			return fmt.Errorf("could not find symbol %s in ELF file", name)
-		}
-		if fn.stackSizeType == stacksize.Bounded {
-			stackSize := uint32(fn.stackSize)
-
-			// Adding 4 for the stack canary. Even though the size may be
-			// automatically determined, stack overflow checking is still
-			// important as the stack size cannot be determined for all
-			// goroutines.
-			stackSize += 4
-
-			// Add stack size used by interrupts.
-			switch elfFile.Machine {
-			case elf.EM_ARM:
-				// On Cortex-M (assumed here), this stack size is 8 words or 32
-				// bytes. This is only to store the registers that the interrupt
-				// may modify, the interrupt will switch to the interrupt stack
-				// (MSP).
-				// Some background:
-				// https://interrupt.memfault.com/blog/cortex-m-rtos-context-switching
-				stackSize += 32
+		// 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
 			}
-
-			// Finally write the stack size to the binary.
-			binary.LittleEndian.PutUint32(data[i*4:], stackSize)
-		}
-	}
-
-	// Write back the modified stack sizes.
-	_, err = fp.WriteAt(data, int64(section.Offset))
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// printStacks prints the maximum stack depth for functions that are started as
-// goroutines. Stack sizes cannot always be determined statically, in particular
-// recursive functions and functions that call interface methods or function
-// pointers may have an unknown stack depth (depending on what the optimizer
-// manages to optimize away).
-//
-// It might print something like the following:
-//
-//     function                         stack usage (in bytes)
-//     Reset_Handler                    316
-//     examples/blinky2.led1            92
-//     runtime.run$1                    300
-func printStacks(calculatedStacks []string, stackSizes map[string]functionStackSize) {
-	// Print the sizes of all stacks.
-	fmt.Printf("%-32s %s\n", "function", "stack usage (in bytes)")
-	for _, name := range calculatedStacks {
-		fn := stackSizes[name]
-		switch fn.stackSizeType {
-		case stacksize.Bounded:
-			fmt.Printf("%-32s %d\n", fn.humanName, fn.stackSize)
-		case stacksize.Unknown:
-			fmt.Printf("%-32s unknown, %s does not have stack frame information\n", fn.humanName, fn.missingStackSize)
-		case stacksize.Recursive:
-			fmt.Printf("%-32s recursive, %s may call itself\n", fn.humanName, fn.missingStackSize)
-		case stacksize.IndirectCall:
-			fmt.Printf("%-32s unknown, %s calls a function pointer\n", fn.humanName, fn.missingStackSize)
 		}
+		return action(tmppath)
 	}
 }
@@ -30,7 +30,10 @@ func cacheTimestamp(paths []string) (time.Time, error) {
 // Try to load a given file from the cache. Return "", nil if no cached file can
 // be found (or the file is stale), return the absolute path if there is a cache
 // and return an error on I/O errors.
-func cacheLoad(name string, sourceFiles []string) (string, 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)
 	cacheStat, err := os.Stat(cachepath)
 	if os.IsNotExist(err) {
@@ -55,7 +58,9 @@ func cacheLoad(name string, sourceFiles []string) (string, error) {

 // Store the file located at tmppath in the cache with the given name. The
 // tmppath may or may not be gone afterwards.
-func cacheStore(tmppath, name string, sourceFiles []string) (string, error) {
+//
+// Note: the configKey is ignored, see cacheLoad.
+func cacheStore(tmppath, name, configKey string, sourceFiles []string) (string, error) {
 	// get the last modified time
 	if len(sourceFiles) == 0 {
 		panic("cache: no source files")
@@ -69,16 +74,24 @@ func cacheStore(tmppath, name string, sourceFiles []string) (string, error) {
 		return "", err
 	}
 	cachepath := filepath.Join(dir, name)
-	err = copyFile(tmppath, cachepath)
+	err = moveFile(tmppath, cachepath)
 	if err != nil {
 		return "", err
 	}
 	return cachepath, nil
 }

-// copyFile copies the given file from src to dst. It can copy over
-// a possibly already existing file at the destination.
-func copyFile(src, dst string) error {
+// moveFile renames the file from src to dst. If renaming doesn't work (for
+// example, the rename crosses a filesystem boundary), the file is copied and
+// the old file is removed.
+func moveFile(src, dst string) error {
+	err := os.Rename(src, dst)
+	if err == nil {
+		// Success!
+		return nil
+	}
+	// Failed to move, probably a different filesystem.
+	// Do a copy + remove.
 	inf, err := os.Open(src)
 	if err != nil {
 		return err
@@ -101,7 +101,7 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,

  // Target Options
  Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
-  Opts.CPU = std::string(Args.getLastArgValue(OPT_target_cpu));
+  Opts.CPU = Args.getLastArgValue(OPT_target_cpu);
  Opts.Features = Args.getAllArgValues(OPT_target_feature);

  // Use the default target triple if unspecified.
@@ -132,19 +132,13 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,

  Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
  Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
-  Opts.DwarfDebugFlags =
-      std::string(Args.getLastArgValue(OPT_dwarf_debug_flags));
-  Opts.DwarfDebugProducer =
-      std::string(Args.getLastArgValue(OPT_dwarf_debug_producer));
-  Opts.DebugCompilationDir =
-      std::string(Args.getLastArgValue(OPT_fdebug_compilation_dir));
-  Opts.MainFileName = std::string(Args.getLastArgValue(OPT_main_file_name));
+  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)) {
-    auto Split = StringRef(Arg).split('=');
-    Opts.DebugPrefixMap.insert(
-        {std::string(Split.first), std::string(Split.second)});
-  }
+  for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
+    Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));

  // Frontend Options
  if (Args.hasArg(OPT_INPUT)) {
@@ -160,9 +154,8 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
    }
  }
  Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
-  Opts.OutputPath = std::string(Args.getLastArgValue(OPT_o));
-  Opts.SplitDwarfOutput =
-      std::string(Args.getLastArgValue(OPT_split_dwarf_output));
+  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)
@@ -190,9 +183,8 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
  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 =
-      std::string(Args.getLastArgValue(OPT_mrelocation_model, "pic"));
-  Opts.TargetABI = std::string(Args.getLastArgValue(OPT_target_abi));
+  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);
@@ -322,7 +314,12 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
                            SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());

  // Build up the feature string from the target feature list.
-  std::string FS = llvm::join(Opts.Features, ",");
+  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;

@@ -386,7 +383,7 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
    MCSection *AsmLabel = Ctx.getMachOSection(
        "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
    Str.get()->SwitchSection(AsmLabel);
-    Str.get()->emitZeros(1);
+    Str.get()->EmitZeros(1);
  }

  // Assembly to object compilation should leverage assembly info.
@@ -11,7 +11,6 @@
 #include <clang/FrontendTool/Utils.h>
 #include <llvm/ADT/IntrusiveRefCntPtr.h>
 #include <llvm/Option/Option.h>
-#include <llvm/Support/Host.h>

 using namespace llvm;
 using namespace clang;
@@ -25,8 +25,8 @@ func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
 	if err != nil {
 		return nil, fmt.Errorf("could not read version from GOROOT (%v): %v", goroot, err)
 	}
-	if major != 1 || minor < 13 || minor > 16 {
-		return nil, fmt.Errorf("requires go version 1.13 through 1.16, got go%d.%d", major, minor)
+	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{
@@ -6,9 +6,6 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sort"
-	"strings"
-
-	"tinygo.org/x/go-llvm"
 )

 // getClangHeaderPath returns the path to the built-in Clang headers. It tries
@@ -29,7 +26,6 @@ func getClangHeaderPath(TINYGOROOT string) string {

 	// 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.
-	llvmMajor := strings.Split(llvm.Version, ".")[0]
 	for _, cmdName := range commands["clang"] {
 		binpath, err := exec.LookPath(cmdName)
 		if err == nil {
@@ -44,38 +40,22 @@ func getClangHeaderPath(TINYGOROOT string) string {
 			// Example executable:
 			//     /usr/lib/llvm-9/bin/clang
 			// Example include path:
-			//     /usr/lib/llvm-9/lib64/clang/9.0.1/include/
-			llvmRoot := filepath.Dir(filepath.Dir(binpath))
-			clangVersionRoot := filepath.Join(llvmRoot, "lib64", "clang")
-			dirs64, err64 := ioutil.ReadDir(clangVersionRoot)
-			// Example include path:
 			//     /usr/lib/llvm-9/lib/clang/9.0.1/include/
-			clangVersionRoot = filepath.Join(llvmRoot, "lib", "clang")
-			dirs32, err32 := ioutil.ReadDir(clangVersionRoot)
-			if err64 != nil && err32 != nil {
+			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(dirs64)+len(dirs32))
-			dirCount := 0
-			for _, d := range dirs32 {
-				name := d.Name()
-				if name == llvmMajor || strings.HasPrefix(name, llvmMajor+".") {
-					dirnames[dirCount] = filepath.Join(llvmRoot, "lib", "clang", name)
-					dirCount++
-				}
-			}
-			for _, d := range dirs64 {
-				name := d.Name()
-				if name == llvmMajor || strings.HasPrefix(name, llvmMajor+".") {
-					dirnames[dirCount] = filepath.Join(llvmRoot, "lib64", "clang", name)
-					dirCount++
-				}
+			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 := dirCount - 1; i >= 0; i-- {
-				path := filepath.Join(dirnames[i], "include")
+			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
@@ -1,153 +0,0 @@
-package builder
-
-// This file implements support for writing ESP image files. These image files
-// are read by the ROM bootloader so have to be in a particular format.
-//
-// In the future, it may be necessary to implement support for other image
-// formats, such as the ESP8266 image formats (again, used by the ROM bootloader
-// to load the firmware).
-
-import (
-	"bytes"
-	"crypto/sha256"
-	"debug/elf"
-	"encoding/binary"
-	"fmt"
-	"io/ioutil"
-	"sort"
-)
-
-type espImageSegment struct {
-	addr uint32
-	data []byte
-}
-
-// makeESPFirmare converts an input ELF file to an image file for an ESP32 or
-// ESP8266 chip. This is a special purpose image format just for the ESP chip
-// family, and is parsed by the on-chip mask ROM bootloader.
-//
-// The following documentation has been used:
-// https://github.com/espressif/esptool/wiki/Firmware-Image-Format
-// https://github.com/espressif/esp-idf/blob/8fbb63c2a701c22ccf4ce249f43aded73e134a34/components/bootloader_support/include/esp_image_format.h#L58
-// https://github.com/espressif/esptool/blob/master/esptool.py
-func makeESPFirmareImage(infile, outfile, format string) error {
-	inf, err := elf.Open(infile)
-	if err != nil {
-		return err
-	}
-	defer inf.Close()
-
-	// Load all segments to be written to the image. These are actually ELF
-	// sections, not true ELF segments (similar to how esptool does it).
-	var segments []*espImageSegment
-	for _, section := range inf.Sections {
-		if section.Type != elf.SHT_PROGBITS || section.Size == 0 || section.Flags&elf.SHF_ALLOC == 0 {
-			continue
-		}
-		data, err := section.Data()
-		if err != nil {
-			return fmt.Errorf("failed to read section data: %w", err)
-		}
-		for len(data)%4 != 0 {
-			// Align segment to 4 bytes.
-			data = append(data, 0)
-		}
-		if uint64(uint32(section.Addr)) != section.Addr {
-			return fmt.Errorf("section address too big: 0x%x", section.Addr)
-		}
-		segments = append(segments, &espImageSegment{
-			addr: uint32(section.Addr),
-			data: data,
-		})
-	}
-
-	// Sort the segments by address. This is what esptool does too.
-	sort.SliceStable(segments, func(i, j int) bool { return segments[i].addr < segments[j].addr })
-
-	// Calculate checksum over the segment data. This is used in the image
-	// footer.
-	checksum := uint8(0xef)
-	for _, segment := range segments {
-		for _, b := range segment.data {
-			checksum ^= b
-		}
-	}
-
-	// Write first to an in-memory buffer, primarily so that we can easily
-	// calculate a hash over the entire image.
-	// An added benefit is that we don't need to check for errors all the time.
-	outf := &bytes.Buffer{}
-
-	// Image header.
-	switch format {
-	case "esp32":
-		// Header format:
-		// https://github.com/espressif/esp-idf/blob/8fbb63c2/components/bootloader_support/include/esp_image_format.h#L58
-		binary.Write(outf, binary.LittleEndian, struct {
-			magic          uint8
-			segment_count  uint8
-			spi_mode       uint8
-			spi_speed_size uint8
-			entry_addr     uint32
-			wp_pin         uint8
-			spi_pin_drv    [3]uint8
-			reserved       [11]uint8
-			hash_appended  bool
-		}{
-			magic:          0xE9,
-			segment_count:  byte(len(segments)),
-			spi_mode:       0, // irrelevant, replaced by esptool when flashing
-			spi_speed_size: 0, // spi_speed, spi_size: replaced by esptool when flashing
-			entry_addr:     uint32(inf.Entry),
-			wp_pin:         0xEE, // disable WP pin
-			hash_appended:  true, // add a SHA256 hash
-		})
-	case "esp8266":
-		// Header format:
-		// https://github.com/espressif/esptool/wiki/Firmware-Image-Format
-		// Basically a truncated version of the ESP32 header.
-		binary.Write(outf, binary.LittleEndian, struct {
-			magic          uint8
-			segment_count  uint8
-			spi_mode       uint8
-			spi_speed_size uint8
-			entry_addr     uint32
-		}{
-			magic:          0xE9,
-			segment_count:  byte(len(segments)),
-			spi_mode:       0,    // irrelevant, replaced by esptool when flashing
-			spi_speed_size: 0x20, // spi_speed, spi_size: replaced by esptool when flashing
-			entry_addr:     uint32(inf.Entry),
-		})
-	default:
-		return fmt.Errorf("builder: unknown binary format %#v, expected esp32 or esp8266", format)
-	}
-
-	// Write all segments to the image.
-	// https://github.com/espressif/esptool/wiki/Firmware-Image-Format#segment
-	for _, segment := range segments {
-		binary.Write(outf, binary.LittleEndian, struct {
-			addr   uint32
-			length uint32
-		}{
-			addr:   segment.addr,
-			length: uint32(len(segment.data)),
-		})
-		outf.Write(segment.data)
-	}
-
-	// Footer, including checksum.
-	// The entire image size must be a multiple of 16, so pad the image to one
-	// byte less than that before writing the checksum.
-	outf.Write(make([]byte, 15-outf.Len()%16))
-	outf.WriteByte(checksum)
-
-	if format == "esp32" {
-		// SHA256 hash (to protect against image corruption, not for security).
-		hash := sha256.Sum256(outf.Bytes())
-		outf.Write(hash[:])
-	}
-
-	// Write the image to the output file.
-	return ioutil.WriteFile(outfile, outf.Bytes(), 0666)
-}
@@ -1,160 +0,0 @@
-package builder
-
-// This file implements a job runner for the compiler, which runs jobs in
-// parallel while taking care of dependencies.
-
-import (
-	"fmt"
-	"runtime"
-	"time"
-)
-
-// Set to true to enable logging in the job runner. This may help to debug
-// concurrency or performance issues.
-const jobRunnerDebug = false
-
-type jobState uint8
-
-const (
-	jobStateQueued   jobState = iota // not yet running
-	jobStateRunning                  // running
-	jobStateFinished                 // finished running
-)
-
-// compileJob is a single compiler job, comparable to a single Makefile target.
-// It is used to orchestrate various compiler tasks that can be run in parallel
-// but that have dependencies and thus have limitations in how they can be run.
-type compileJob struct {
-	description  string // description, only used for logging
-	dependencies []*compileJob
-	run          func() error
-	state        jobState
-	err          error         // error if finished
-	duration     time.Duration // how long it took to run this job (only set after finishing)
-}
-
-// readyToRun returns whether this job is ready to run: it is itself not yet
-// started and all dependencies are finished.
-func (job *compileJob) readyToRun() bool {
-	if job.state != jobStateQueued {
-		// Already running or finished, so shouldn't be run again.
-		return false
-	}
-
-	// Check dependencies.
-	for _, dep := range job.dependencies {
-		if dep.state != jobStateFinished {
-			// A dependency is not finished, so this job has to wait until it
-			// is.
-			return false
-		}
-	}
-
-	// All conditions are satisfied.
-	return true
-}
-
-// runJobs runs all the jobs indicated in the jobs slice and returns the error
-// of the first job that fails to run.
-// It runs all jobs in the order of the slice, as long as all dependencies have
-// already run. Therefore, if some jobs are preferred to run before others, they
-// should be ordered as such in this slice.
-func runJobs(jobs []*compileJob) error {
-	// Create channels to communicate with the workers.
-	doneChan := make(chan *compileJob)
-	workerChan := make(chan *compileJob)
-	defer close(workerChan)
-
-	// Start a number of workers.
-	for i := 0; i < runtime.NumCPU(); i++ {
-		if jobRunnerDebug {
-			fmt.Println("## starting worker", i)
-		}
-		go jobWorker(workerChan, doneChan)
-	}
-
-	// Send each job in the jobs slice to a worker, taking care of job
-	// dependencies.
-	numRunningJobs := 0
-	var totalTime time.Duration
-	start := time.Now()
-	for {
-		// If there are free workers, try starting a new job (if one is
-		// available). If it succeeds, try again to fill the entire worker pool.
-		if numRunningJobs < runtime.NumCPU() {
-			jobToRun := nextJob(jobs)
-			if jobToRun != nil {
-				// Start job.
-				if jobRunnerDebug {
-					fmt.Println("## start:   ", jobToRun.description)
-				}
-				jobToRun.state = jobStateRunning
-				workerChan <- jobToRun
-				numRunningJobs++
-				continue
-			}
-		}
-
-		// When there are no jobs running, all jobs in the jobs slice must have
-		// been finished. Therefore, the work is done.
-		if numRunningJobs == 0 {
-			break
-		}
-
-		// Wait until a job is finished.
-		job := <-doneChan
-		job.state = jobStateFinished
-		numRunningJobs--
-		totalTime += job.duration
-		if jobRunnerDebug {
-			fmt.Println("## finished:", job.description, "(time "+job.duration.String()+")")
-		}
-		if job.err != nil {
-			// Wait for running jobs to finish.
-			for numRunningJobs != 0 {
-				<-doneChan
-				numRunningJobs--
-			}
-			// Return error of first failing job.
-			return job.err
-		}
-	}
-
-	// Some statistics, if debugging.
-	if jobRunnerDebug {
-		// Total duration of running all jobs.
-		duration := time.Since(start)
-		fmt.Println("## total:   ", duration)
-
-		// The individual time of each job combined. On a multicore system, this
-		// should be lower than the total above.
-		fmt.Println("## job sum: ", totalTime)
-	}
-
-	return nil
-}
-
-// nextJob returns the first ready-to-run job.
-// This is an implementation detail of runJobs.
-func nextJob(jobs []*compileJob) *compileJob {
-	for _, job := range jobs {
-		if job.readyToRun() {
-			return job
-		}
-	}
-	return nil
-}
-
-// jobWorker is the goroutine that runs received jobs.
-// This is an implementation detail of runJobs.
-func jobWorker(workerChan, doneChan chan *compileJob) {
-	for job := range workerChan {
-		start := time.Now()
-		err := job.run()
-		if err != nil {
-			job.err = err
-		}
-		job.duration = time.Since(start)
-		doneChan <- job
-	}
-}
@@ -1,6 +1,7 @@
 package builder

 import (
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -39,112 +40,63 @@ func (l *Library) sourcePaths(target string) []string {
 }

 // Load the library archive, possibly generating and caching it if needed.
-// The resulting file is stored in the provided tmpdir, which is expected to be
-// removed after the Load call.
-func (l *Library) Load(target, tmpdir string) (path string, err error) {
-	path, job, err := l.load(target, "", tmpdir)
-	if err != nil {
-		return "", err
-	}
-	if job != nil {
-		jobs := append([]*compileJob{job}, job.dependencies...)
-		err = runJobs(jobs)
-	}
-	return path, err
-}
-
-// load returns a path to the library file for the given target, loading it from
-// cache if possible. It will return a non-zero compiler job if the library
-// wasn't cached, this job (and its dependencies) must be run before the library
-// path is valid.
-// The provided tmpdir will be used to store intermediary files and possibly the
-// output archive file, it is expected to be removed after use.
-func (l *Library) load(target, cpu, tmpdir string) (path string, job *compileJob, err error) {
+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, nil
+		return precompiledPath, nil
 	}

-	var outfile string
-	if cpu != "" {
-		outfile = l.name + "-" + target + "-" + cpu + ".a"
-	} else {
-		outfile = l.name + "-" + target + ".a"
-	}
+	outfile := l.name + "-" + target + ".a"

 	// Try to fetch this library from the cache.
-	if path, err := cacheLoad(outfile, l.sourcePaths(target)); path != "" || err != nil {
+	if path, err := cacheLoad(outfile, commands["clang"][0], l.sourcePaths(target)); path != "" || err != nil {
 		// Cache hit.
-		return path, nil, err
+		return path, err
 	}
 	// Cache miss, build it now.

-	remapDir := filepath.Join(os.TempDir(), "tinygo-"+l.name)
-	dir := filepath.Join(tmpdir, "build-lib-"+l.name)
-	err = os.Mkdir(dir, 0777)
+	dirPrefix := "tinygo-" + l.name
+	remapDir := filepath.Join(os.TempDir(), dirPrefix)
+	dir, err := ioutil.TempDir(os.TempDir(), dirPrefix)
 	if err != nil {
-		return "", nil, err
+		return "", err
 	}
+	defer os.RemoveAll(dir)

 	// Precalculate the flags to the compiler invocation.
-	// 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.
 	args := append(l.cflags(), "-c", "-Oz", "-g", "-ffunction-sections", "-fdata-sections", "-Wno-macro-redefined", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir)
-	if cpu != "" {
-		args = append(args, "-mcpu="+cpu)
-	}
 	if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
-		args = append(args, "-fshort-enums", "-fomit-frame-pointer", "-mfloat-abi=soft")
+		args = append(args, "-fshort-enums", "-fomit-frame-pointer")
 	}
 	if strings.HasPrefix(target, "riscv32-") {
 		args = append(args, "-march=rv32imac", "-mabi=ilp32", "-fforce-enable-int128")
 	}
-	if strings.HasPrefix(target, "riscv64-") {
-		args = append(args, "-march=rv64gc", "-mabi=lp64")
-	}

-	// Create job to put all the object files in a single archive. This archive
-	// file is the (static) library file.
+	// Compile all sources.
 	var objs []string
-	arpath := filepath.Join(dir, l.name+".a")
-	job = &compileJob{
-		description: "ar " + l.name + ".a",
-		run: func() error {
-			// Create an archive of all object files.
-			err := makeArchive(arpath, objs)
-			if err != nil {
-				return err
-			}
-			// Store this archive in the cache.
-			_, err = cacheStore(arpath, outfile, l.sourcePaths(target))
-			return err
-		},
-	}
-
-	// Create jobs to compile all sources. These jobs are depended upon by the
-	// archive job above, so must be run first.
 	for _, srcpath := range l.sourcePaths(target) {
-		srcpath := srcpath // avoid concurrency issues by redefining inside the loop
 		objpath := filepath.Join(dir, filepath.Base(srcpath)+".o")
 		objs = append(objs, objpath)
-		job.dependencies = append(job.dependencies, &compileJob{
-			description: "compile " + srcpath,
-			run: func() error {
-				var compileArgs []string
-				compileArgs = append(compileArgs, args...)
-				compileArgs = append(compileArgs, "-o", objpath, srcpath)
-				err := runCCompiler("clang", compileArgs...)
-				if err != nil {
-					return &commandError{"failed to build", srcpath, err}
-				}
-				return nil
-			},
-		})
+		// 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}
+		}
 	}

-	return arpath, job, nil
+	// 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))
 }
@@ -4,15 +4,12 @@ import (
 	"debug/elf"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"sort"

 	"github.com/marcinbor85/gohex"
 )

-// maxPadBytes is the maximum allowed bytes to be padded in a rom extraction
-// this value is currently defined by Nintendo Switch Page Alignment (4096 bytes)
-const maxPadBytes = 4095
-
 // objcopyError is an error returned by functions that act like objcopy.
 type objcopyError struct {
 	Op  string
@@ -61,7 +58,7 @@ func extractROM(path string) (uint64, []byte, error) {

 	progs := make(progSlice, 0, 2)
 	for _, prog := range f.Progs {
-		if prog.Type != elf.PT_LOAD || prog.Filesz == 0 || prog.Off == 0 {
+		if prog.Type != elf.PT_LOAD || prog.Filesz == 0 {
 			continue
 		}
 		progs = append(progs, prog)
@@ -73,19 +70,8 @@ func extractROM(path string) (uint64, []byte, error) {

 	var rom []byte
 	for _, prog := range progs {
-		romEnd := progs[0].Paddr + uint64(len(rom))
-		if prog.Paddr > romEnd && prog.Paddr < romEnd+16 {
-			// Sometimes, the linker seems to insert a bit of padding between
-			// segments. Simply zero-fill these parts.
-			rom = append(rom, make([]byte, prog.Paddr-romEnd)...)
-		}
 		if prog.Paddr != progs[0].Paddr+uint64(len(rom)) {
-			diff := prog.Paddr - (progs[0].Paddr + uint64(len(rom)))
-			if diff > maxPadBytes {
-				return 0, nil, objcopyError{"ROM segments are non-contiguous: " + path, nil}
-			}
-			// Pad the difference
-			rom = append(rom, make([]byte, diff)...)
+			return 0, nil, objcopyError{"ROM segments are non-contiguous: " + path, nil}
 		}
 		data, err := ioutil.ReadAll(prog.Open())
 		if err != nil {
@@ -107,7 +93,7 @@ func extractROM(path string) (uint64, []byte, error) {

 // objcopy converts an ELF file to a different (simpler) output file format:
 // .bin or .hex. It extracts only the .text section.
-func objcopy(infile, outfile, binaryFormat string) error {
+func objcopy(infile, outfile string) error {
 	f, err := os.OpenFile(outfile, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
 	if err != nil {
 		return err
@@ -121,20 +107,24 @@ func objcopy(infile, outfile, binaryFormat string) error {
 	}

 	// Write to the file, in the correct format.
-	switch binaryFormat {
-	case "hex":
-		// Intel hex file, includes the firmware start address.
+	switch filepath.Ext(outfile) {
+	case ".gba":
+		// The address is not stored in a .gba file.
+		_, err := f.Write(data)
+		return err
+	case ".bin":
+		// The address is not stored in a .bin file (therefore you
+		// should use .hex files in most cases).
+		_, err := f.Write(data)
+		return err
+	case ".hex":
 		mem := gohex.NewMemory()
 		err := mem.AddBinary(uint32(addr), data)
 		if err != nil {
 			return objcopyError{"failed to create .hex file", err}
 		}
-		return mem.DumpIntelHex(f, 16)
-	case "bin":
-		// The start address is not stored in raw firmware files (therefore you
-		// should use .hex files in most cases).
-		_, err := f.Write(data)
-		return err
+		mem.DumpIntelHex(f, 16) // TODO: handle error
+		return nil
 	default:
 		panic("unreachable")
 	}
@@ -41,8 +41,6 @@ type cgoPackage struct {
 	elaboratedTypes map[string]*elaboratedTypeInfo
 	enums           map[string]enumInfo
 	anonStructNum   int
-	ldflags         []string
-	visitedFiles    map[string][]byte
 }

 // constantInfo stores some information about a CGo constant found by libclang
@@ -55,10 +53,9 @@ type constantInfo struct {
 // functionInfo stores some information about a CGo function found by libclang
 // and declared in the AST.
 type functionInfo struct {
-	args     []paramInfo
-	results  *ast.FieldList
-	pos      token.Pos
-	variadic bool
+	args    []paramInfo
+	results *ast.FieldList
+	pos     token.Pos
 }

 // paramInfo is a parameter of a CGo function (see functionInfo).
@@ -157,10 +154,9 @@ typedef unsigned long long  _Cgo_ulonglong;
 // Process extracts `import "C"` statements from the AST, parses the comment
 // with libclang, and modifies the AST to use this information. It returns a
 // newly created *ast.File that should be added to the list of to-be-parsed
-// files, the LDFLAGS for this package, and a map of file hashes of the accessed
-// C header files. If there is one or more error, it returns these in the
-// []error slice but still modifies the AST.
-func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string) (*ast.File, []string, map[string][]byte, []error) {
+// files. If there is one or more error, it returns these in the []error slice
+// but still modifies the AST.
+func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string) (*ast.File, []error) {
 	p := &cgoPackage{
 		dir:             dir,
 		fset:            fset,
@@ -172,7 +168,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		typedefs:        map[string]*typedefInfo{},
 		elaboratedTypes: map[string]*elaboratedTypeInfo{},
 		enums:           map[string]enumInfo{},
-		visitedFiles:    map[string][]byte{},
 	}

 	// Disable _FORTIFY_SOURCE as it causes problems on macOS.
@@ -188,7 +183,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	// Find the absolute path for this package.
 	packagePath, err := filepath.Abs(fset.File(files[0].Pos()).Name())
 	if err != nil {
-		return nil, nil, nil, []error{
+		return nil, []error{
 			scanner.Error{
 				Pos: fset.Position(files[0].Pos()),
 				Msg: "cgo: cannot find absolute path: " + err.Error(), // TODO: wrap this error
@@ -364,19 +359,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 					}
 					makePathsAbsolute(flags, packagePath)
 					cflags = append(cflags, flags...)
-				case "LDFLAGS":
-					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 := checkLinkerFlags(name, flags); err != nil {
-						p.addErrorAfter(comment.Slash, comment.Text[:lineStart+colon+1], err.Error())
-						continue
-					}
-					makePathsAbsolute(flags, packagePath)
-					p.ldflags = append(p.ldflags, flags...)
 				default:
 					startPos := strings.LastIndex(line[4:colon], name) + 4
 					p.addErrorAfter(comment.Slash, comment.Text[:lineStart+startPos], "invalid #cgo line: "+name)
@@ -430,7 +412,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	// Print the newly generated in-memory AST, for debugging.
 	//ast.Print(fset, p.generated)

-	return p.generated, p.ldflags, p.visitedFiles, p.errors
+	return p.generated, p.errors
 }

 // makePathsAbsolute converts some common path compiler flags (-I, -L) from
@@ -488,16 +470,6 @@ func (p *cgoPackage) addFuncDecls() {
 				Results: fn.results,
 			},
 		}
-		if fn.variadic {
-			decl.Doc = &ast.CommentGroup{
-				List: []*ast.Comment{
-					&ast.Comment{
-						Slash: fn.pos,
-						Text:  "//go:variadic",
-					},
-				},
-			}
-		}
 		obj.Decl = decl
 		for i, arg := range fn.args {
 			args[i] = &ast.Field{
@@ -5,7 +5,6 @@ import (
 	"flag"
 	"fmt"
 	"go/ast"
-	"go/build"
 	"go/format"
 	"go/parser"
 	"go/token"
@@ -24,7 +23,7 @@ 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.ReplaceAll(result, "\r\n", "\n")
+	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
@@ -42,20 +41,6 @@ func TestCGo(t *testing.T) {
 	for _, name := range []string{"basic", "errors", "types", "flags", "const"} {
 		name := name // avoid a race condition
 		t.Run(name, func(t *testing.T) {
-			// Skip tests that require specific Go version.
-			if name == "errors" {
-				ok := false
-				for _, version := range build.Default.ReleaseTags {
-					if version == "go1.16" {
-						ok = true
-						break
-					}
-				}
-				if !ok {
-					t.Skip("Results for errors test are only valid for Go 1.16+")
-				}
-			}
-
 			// Read the AST in memory.
 			path := filepath.Join("testdata", name+".go")
 			fset := token.NewFileSet()
@@ -65,7 +50,7 @@ func TestCGo(t *testing.T) {
 			}

 			// Process the AST with CGo.
-			cgoAST, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", fset, cflags)
+			cgoAST, cgoErrors := Process([]*ast.File{f}, "testdata", fset, cflags)

 			// Check the AST for type errors.
 			var typecheckErrors []error
@@ -113,7 +98,7 @@ func TestCGo(t *testing.T) {
 			if err != nil {
 				t.Fatalf("could not read expected output: %v", err)
 			}
-			expected := strings.ReplaceAll(string(expectedBytes), "\r\n", "\n")
+			expected := strings.Replace(string(expectedBytes), "\r\n", "\n", -1)

 			// Check whether the output is as expected.
 			if expected != actual {
@@ -154,7 +139,7 @@ func formatDiagnostic(err error) string {
 	msg := err.Error()
 	if runtime.GOOS == "windows" {
 		// Fix Windows path slashes.
-		msg = strings.ReplaceAll(msg, "testdata\\", "testdata/")
+		msg = strings.Replace(msg, "testdata\\", "testdata/", -1)
 	}
 	return "//     " + msg + "\n"
 }
@@ -4,7 +4,6 @@ package cgo
 // modification. It does not touch the AST itself.

 import (
-	"crypto/sha512"
 	"fmt"
 	"go/ast"
 	"go/scanner"
@@ -57,7 +56,6 @@ unsigned tinygo_clang_Cursor_isBitField(GoCXCursor c);
 int tinygo_clang_globals_visitor(GoCXCursor c, GoCXCursor parent, CXClientData client_data);
 int tinygo_clang_struct_visitor(GoCXCursor c, GoCXCursor parent, CXClientData client_data);
 int tinygo_clang_enum_visitor(GoCXCursor c, GoCXCursor parent, CXClientData client_data);
-void tinygo_clang_inclusion_visitor(CXFile included_file, CXSourceLocation *inclusion_stack, unsigned include_len, CXClientData client_data);
 */
 import "C"

@@ -116,7 +114,6 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, posFilename
 	}
 	defer C.clang_disposeTranslationUnit(unit)

-	// Report parser and type errors.
 	if numDiagnostics := int(C.clang_getNumDiagnostics(unit)); numDiagnostics != 0 {
 		addDiagnostic := func(diagnostic C.CXDiagnostic) {
 			spelling := getString(C.clang_getDiagnosticSpelling(diagnostic))
@@ -137,36 +134,10 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, posFilename
 		}
 	}

-	// Extract information required by CGo.
 	ref := storedRefs.Put(p)
 	defer storedRefs.Remove(ref)
 	cursor := C.tinygo_clang_getTranslationUnitCursor(unit)
 	C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_globals_visitor), C.CXClientData(ref))
-
-	// Determine files read during CGo processing, for caching.
-	inclusionCallback := func(includedFile C.CXFile) {
-		// Get full file path.
-		path := getString(C.clang_getFileName(includedFile))
-
-		// Get contents of file (that should be in-memory).
-		size := C.size_t(0)
-		rawData := C.clang_getFileContents(unit, includedFile, &size)
-		if rawData == nil {
-			// Sanity check. This should (hopefully) never trigger.
-			panic("libclang: file contents was not loaded")
-		}
-		data := (*[1 << 24]byte)(unsafe.Pointer(rawData))[:size]
-
-		// Hash the contents if it isn't hashed yet.
-		if _, ok := p.visitedFiles[path]; !ok {
-			// already stored
-			sum := sha512.Sum512_224(data)
-			p.visitedFiles[path] = sum[:]
-		}
-	}
-	inclusionCallbackRef := storedRefs.Put(inclusionCallback)
-	defer storedRefs.Remove(inclusionCallbackRef)
-	C.clang_getInclusions(unit, C.CXInclusionVisitor(C.tinygo_clang_inclusion_visitor), C.CXClientData(inclusionCallbackRef))
 }

 //export tinygo_clang_globals_visitor
@@ -181,10 +152,12 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 			return C.CXChildVisit_Continue
 		}
 		cursorType := C.tinygo_clang_getCursorType(c)
+		if C.clang_isFunctionTypeVariadic(cursorType) != 0 {
+			return C.CXChildVisit_Continue // not supported
+		}
 		numArgs := int(C.tinygo_clang_Cursor_getNumArguments(c))
 		fn := &functionInfo{
-			pos:      pos,
-			variadic: C.clang_isFunctionTypeVariadic(cursorType) != 0,
+			pos: pos,
 		}
 		p.functions[name] = fn
 		for i := 0; i < numArgs; i++ {
@@ -273,9 +246,9 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 		}
 		value := source[len(name):]
 		// Try to convert this #define into a Go constant expression.
-		expr, scannerError := parseConst(pos+token.Pos(len(name)), p.fset, value)
-		if scannerError != nil {
-			p.errors = append(p.errors, *scannerError)
+		expr, err := parseConst(pos+token.Pos(len(name)), p.fset, value)
+		if err != nil {
+			p.errors = append(p.errors, err)
 		}
 		if expr != nil {
 			// Parsing was successful.
@@ -801,9 +774,3 @@ func tinygo_clang_enum_visitor(c, parent C.GoCXCursor, client_data C.CXClientDat
 	}
 	return C.CXChildVisit_Continue
 }
-
-//export tinygo_clang_inclusion_visitor
-func tinygo_clang_inclusion_visitor(includedFile C.CXFile, inclusionStack *C.CXSourceLocation, includeLen C.unsigned, clientData C.CXClientData) {
-	callback := storedRefs.Get(unsafe.Pointer(clientData)).(func(C.CXFile))
-	callback(includedFile)
-}
@@ -1,14 +1,14 @@
 // +build !byollvm
-// +build !llvm10
+// +build !llvm9

 package cgo

 /*
-#cgo linux   CFLAGS:  -I/usr/lib/llvm-11/include
-#cgo darwin  CFLAGS:  -I/usr/local/opt/llvm@11/include
-#cgo freebsd CFLAGS:  -I/usr/local/llvm11/include
-#cgo linux   LDFLAGS: -L/usr/lib/llvm-11/lib -lclang
-#cgo darwin  LDFLAGS: -L/usr/local/opt/llvm@11/lib -lclang -lffi
-#cgo freebsd LDFLAGS: -L/usr/local/llvm11/lib -lclang
+#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
 */
 import "C"
@@ -1,14 +0,0 @@
-// +build !byollvm
-// +build llvm10
-
-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
-*/
-import "C"
@@ -0,0 +1,14 @@
+// +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"
@@ -4,10 +4,10 @@
 //     testdata/errors.go:13:23: unexpected token )

 // Type checking errors after CGo processing:
-//     testdata/errors.go:102: cannot use 2 << 10 (untyped int constant 2048) as uint8 value in variable declaration (overflows)
+//     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: cannot use C.SOME_CONST_3 (untyped int constant 1234) as byte value in variable declaration (overflows)
+//     testdata/errors.go:110: C.SOME_CONST_3 (untyped int constant 1234) overflows byte

 package main

@@ -21,13 +21,6 @@ package main
 #if defined(NOTDEFINED)
 #warning flag must not be defined
 #endif
-
-// Check Compiler flags
-#cgo LDFLAGS: -lc
-
-// This flag is not valid ldflags
-#cgo LDFLAGS: -does-not-exists
-
 */
 import "C"

@@ -1,7 +1,6 @@
 // CGo errors:
 //     testdata/flags.go:5:7: invalid #cgo line: NOFLAGS
 //     testdata/flags.go:8:13: invalid flag: -fdoes-not-exist
-//     testdata/flags.go:29:14: invalid flag: -does-not-exists

 package main

@@ -104,10 +104,6 @@ typedef struct {
 	unsigned char e : 3;
 	// Note that C++ allows bitfields bigger than the underlying type.
 } bitfield_t;
-
-// Function signatures.
-void variadic0();
-void variadic2(int x, int y, ...);
 */
 import "C"

@@ -167,9 +163,3 @@ func accessUnion() {
 	var _ *C.int = union2d.unionfield_i()
 	var _ *[2]float64 = union2d.unionfield_d()
 }
-
-// Test function signatures.
-func accessFunctions() {
-	C.variadic0()
-	C.variadic2(3, 5)
-}
@@ -4,11 +4,6 @@ import "unsafe"

 var _ unsafe.Pointer

-func C.variadic0() //go:variadic
-func C.variadic2(x C.int, y C.int) //go:variadic
-var C.variadic0$funcaddr unsafe.Pointer
-var C.variadic2$funcaddr unsafe.Pointer
-
 const C.option2A = 20
 const C.optionA = 0
 const C.optionB = 1
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"

 	"github.com/tinygo-org/tinygo/goenv"
@@ -21,6 +22,29 @@ type Config struct {
 	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
@@ -94,19 +118,19 @@ func (c *Config) NeedsStackObjects() bool {
 	switch c.GC() {
 	case "conservative", "extalloc":
 		for _, tag := range c.BuildTags() {
-			if tag == "wasm" {
-				return true
+			if tag == "baremetal" {
+				return false
 			}
 		}

-		return false
+		return true
 	default:
 		return false
 	}
 }

-// Scheduler returns the scheduler implementation. Valid values are "none",
-//"coroutines" and "tasks".
+// Scheduler returns the scheduler implementation. Valid values are "coroutines"
+// and "tasks".
 func (c *Config) Scheduler() string {
 	if c.Options.Scheduler != "" {
 		return c.Options.Scheduler
@@ -120,24 +144,14 @@ func (c *Config) Scheduler() string {

 // FuncImplementation picks an appropriate func value implementation for the
 // target.
-func (c *Config) FuncImplementation() string {
+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 "tasks":
-		// 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.
-		return "doubleword"
 	case "none", "coroutines":
-		// As "doubleword", 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.
-		// Pick the switch implementation with the coroutines scheduler, as it
-		// allows the use of blocking inside a function that is used as a func
-		// value.
-		return "switch"
+		return FuncValueSwitch
+	case "tasks":
+		return FuncValueDoubleword
 	default:
 		panic("unknown scheduler type")
 	}
@@ -150,31 +164,18 @@ func (c *Config) PanicStrategy() string {
 	return c.Options.PanicStrategy
 }

-// AutomaticStackSize returns whether goroutine stack sizes should be determined
-// automatically at compile time, if possible. If it is false, no attempt is
-// made.
-func (c *Config) AutomaticStackSize() bool {
-	if c.Target.AutoStackSize != nil && c.Scheduler() == "tasks" {
-		return *c.Target.AutoStackSize
-	}
-	return false
-}
-
 // 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.ReplaceAll(flag, "{root}", goenv.Get("TINYGOROOT")))
+		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"))
 	}
-	if c.Debug() {
-		cflags = append(cflags, "-g")
-	}
 	return cflags
 }

@@ -186,9 +187,15 @@ func (c *Config) LDFlags() []string {
 	// Merge and adjust LDFlags.
 	ldflags := append([]string{}, c.Options.LDFlags...)
 	for _, flag := range c.Target.LDFlags {
-		ldflags = append(ldflags, strings.ReplaceAll(flag, "{root}", root))
+		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)
 	}
@@ -219,31 +226,6 @@ func (c *Config) Debug() bool {
 	return c.Options.Debug
 }

-// BinaryFormat returns an appropriate binary format, based on the file
-// extension and the configured binary format in the target JSON file.
-func (c *Config) BinaryFormat(ext string) string {
-	switch ext {
-	case ".bin", ".gba", ".nro":
-		// The simplest format possible: dump everything in a raw binary file.
-		if c.Target.BinaryFormat != "" {
-			return c.Target.BinaryFormat
-		}
-		return "bin"
-	case ".hex":
-		// Similar to bin, but includes the start address and is thus usually a
-		// better format.
-		return "hex"
-	case ".uf2":
-		// Special purpose firmware format, mainly used on Adafruit boards.
-		// More information:
-		// https://github.com/Microsoft/uf2
-		return "uf2"
-	default:
-		// Use the ELF format for unrecognized file formats.
-		return "elf"
-	}
-}
-
 // 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.
@@ -283,9 +265,6 @@ func (c *Config) OpenOCDConfiguration() (args []string, err error) {
 		return nil, fmt.Errorf("unknown OpenOCD transport: %#v", c.Target.OpenOCDTransport)
 	}
 	args = []string{"-f", "interface/" + openocdInterface + ".cfg"}
-	for _, cmd := range c.Target.OpenOCDCommands {
-		args = append(args, "-c", cmd)
-	}
 	if c.Target.OpenOCDTransport != "" {
 		args = append(args, "-c", "transport select "+c.Target.OpenOCDTransport)
 	}
@@ -293,34 +272,6 @@ func (c *Config) OpenOCDConfiguration() (args []string, err error) {
 	return args, nil
 }

-// CodeModel returns the code model used on this platform.
-func (c *Config) CodeModel() string {
-	if c.Target.CodeModel != "" {
-		return c.Target.CodeModel
-	}
-
-	return "default"
-}
-
-// RelocationModel returns the relocation model in use on this platform. Valid
-// values are "static", "pic", "dynamicnopic".
-func (c *Config) RelocationModel() string {
-	if c.Target.RelocationModel != "" {
-		return c.Target.RelocationModel
-	}
-
-	return "static"
-}
-
-// WasmAbi returns the WASM ABI which is specified in the target JSON file, and
-// the value is overridden by `-wasm-abi` flag if it is provided
-func (c *Config) WasmAbi() string {
-	if c.Options.WasmAbi != "" {
-		return c.Options.WasmAbi
-	}
-	return c.Target.WasmAbi
-}
-
 type TestConfig struct {
 	CompileTestBinary bool
 	// TODO: Filter the test functions to run, include verbose flag, etc
@@ -1,17 +1,5 @@
 package compileopts

-import (
-	"fmt"
-	"strings"
-)
-
-var (
-	validGCOptions            = []string{"none", "leaking", "extalloc", "conservative"}
-	validSchedulerOptions     = []string{"none", "tasks", "coroutines"}
-	validPrintSizeOptions     = []string{"none", "short", "full"}
-	validPanicStrategyOptions = []string{"print", "trap"}
-)
-
 // Options contains extra options to give to the compiler. These options are
 // usually passed from the command line.
 type Options struct {
@@ -23,64 +11,13 @@ type Options struct {
 	PrintIR       bool
 	DumpSSA       bool
 	VerifyIR      bool
-	PrintCommands bool
 	Debug         bool
 	PrintSizes    string
-	PrintStacks   bool
 	CFlags        []string
 	LDFlags       []string
 	Tags          string
 	WasmAbi       string
+	HeapSize      int64
 	TestConfig    TestConfig
 	Programmer    string
 }
-
-// Verify performs a validation on the given options, raising an error if options are not valid.
-func (o *Options) Verify() error {
-	if o.GC != "" {
-		valid := isInArray(validGCOptions, o.GC)
-		if !valid {
-			return fmt.Errorf(`invalid gc option '%s': valid values are %s`,
-				o.GC,
-				strings.Join(validGCOptions, ", "))
-		}
-	}
-
-	if o.Scheduler != "" {
-		valid := isInArray(validSchedulerOptions, o.Scheduler)
-		if !valid {
-			return fmt.Errorf(`invalid scheduler option '%s': valid values are %s`,
-				o.Scheduler,
-				strings.Join(validSchedulerOptions, ", "))
-		}
-	}
-
-	if o.PrintSizes != "" {
-		valid := isInArray(validPrintSizeOptions, o.PrintSizes)
-		if !valid {
-			return fmt.Errorf(`invalid size option '%s': valid values are %s`,
-				o.PrintSizes,
-				strings.Join(validPrintSizeOptions, ", "))
-		}
-	}
-
-	if o.PanicStrategy != "" {
-		valid := isInArray(validPanicStrategyOptions, o.PanicStrategy)
-		if !valid {
-			return fmt.Errorf(`invalid panic option '%s': valid values are %s`,
-				o.PanicStrategy,
-				strings.Join(validPanicStrategyOptions, ", "))
-		}
-	}
-
-	return nil
-}
-
-func isInArray(arr []string, item string) bool {
-	for _, i := range arr {
-		if i == item {
-			return true
-		}
-	}
-	return false
-}
@@ -1,138 +0,0 @@
-package compileopts_test
-
-import (
-	"errors"
-	"testing"
-
-	"github.com/tinygo-org/tinygo/compileopts"
-)
-
-func TestVerifyOptions(t *testing.T) {
-
-	expectedGCError := errors.New(`invalid gc option 'incorrect': valid values are none, leaking, extalloc, conservative`)
-	expectedSchedulerError := errors.New(`invalid scheduler option 'incorrect': valid values are none, tasks, coroutines`)
-	expectedPrintSizeError := errors.New(`invalid size option 'incorrect': valid values are none, short, full`)
-	expectedPanicStrategyError := errors.New(`invalid panic option 'incorrect': valid values are print, trap`)
-
-	testCases := []struct {
-		name          string
-		opts          compileopts.Options
-		expectedError error
-	}{
-		{
-			name: "OptionsEmpty",
-			opts: compileopts.Options{},
-		},
-		{
-			name: "InvalidGCOption",
-			opts: compileopts.Options{
-				GC: "incorrect",
-			},
-			expectedError: expectedGCError,
-		},
-		{
-			name: "GCOptionNone",
-			opts: compileopts.Options{
-				GC: "none",
-			},
-		},
-		{
-			name: "GCOptionLeaking",
-			opts: compileopts.Options{
-				GC: "leaking",
-			},
-		},
-		{
-			name: "GCOptionExtalloc",
-			opts: compileopts.Options{
-				GC: "extalloc",
-			},
-		},
-		{
-			name: "GCOptionConservative",
-			opts: compileopts.Options{
-				GC: "conservative",
-			},
-		},
-		{
-			name: "InvalidSchedulerOption",
-			opts: compileopts.Options{
-				Scheduler: "incorrect",
-			},
-			expectedError: expectedSchedulerError,
-		},
-		{
-			name: "SchedulerOptionNone",
-			opts: compileopts.Options{
-				Scheduler: "none",
-			},
-		},
-		{
-			name: "SchedulerOptionTasks",
-			opts: compileopts.Options{
-				Scheduler: "tasks",
-			},
-		},
-		{
-			name: "SchedulerOptionCoroutines",
-			opts: compileopts.Options{
-				Scheduler: "coroutines",
-			},
-		},
-		{
-			name: "InvalidPrintSizeOption",
-			opts: compileopts.Options{
-				PrintSizes: "incorrect",
-			},
-			expectedError: expectedPrintSizeError,
-		},
-		{
-			name: "PrintSizeOptionNone",
-			opts: compileopts.Options{
-				PrintSizes: "none",
-			},
-		},
-		{
-			name: "PrintSizeOptionShort",
-			opts: compileopts.Options{
-				PrintSizes: "short",
-			},
-		},
-		{
-			name: "PrintSizeOptionFull",
-			opts: compileopts.Options{
-				PrintSizes: "full",
-			},
-		},
-		{
-			name: "InvalidPanicOption",
-			opts: compileopts.Options{
-				PanicStrategy: "incorrect",
-			},
-			expectedError: expectedPanicStrategyError,
-		},
-		{
-			name: "PanicOptionPrint",
-			opts: compileopts.Options{
-				PanicStrategy: "print",
-			},
-		},
-		{
-			name: "PanicOptionTrap",
-			opts: compileopts.Options{
-				PanicStrategy: "trap",
-			},
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			err := tc.opts.Verify()
-			if tc.expectedError != err {
-				if tc.expectedError.Error() != err.Error() {
-					t.Errorf("expected %v, got %v", tc.expectedError, err)
-				}
-			}
-		})
-	}
-}
@@ -8,7 +8,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"reflect"
 	"runtime"
 	"strings"

@@ -34,13 +33,11 @@ type TargetSpec struct {
 	Linker           string   `json:"linker"`
 	RTLib            string   `json:"rtlib"` // compiler runtime library (libgcc, compiler-rt)
 	Libc             string   `json:"libc"`
-	AutoStackSize    *bool    `json:"automatic-stack-size"` // Determine stack size automatically at compile time.
-	DefaultStackSize uint64   `json:"default-stack-size"`   // Default stack size if the size couldn't be determined at compile time.
 	CFlags           []string `json:"cflags"`
 	LDFlags          []string `json:"ldflags"`
 	LinkerScript     string   `json:"linkerscript"`
 	ExtraFiles       []string `json:"extra-files"`
-	Emulator         []string `json:"emulator" override:"copy"` // inherited Emulator must not be append
+	Emulator         []string `json:"emulator"`
 	FlashCommand     string   `json:"flash-command"`
 	GDB              string   `json:"gdb"`
 	PortReset        string   `json:"flash-1200-bps-reset"`
@@ -48,57 +45,90 @@ type TargetSpec struct {
 	FlashVolume      string   `json:"msd-volume-name"`
 	FlashFilename    string   `json:"msd-firmware-name"`
 	UF2FamilyID      string   `json:"uf2-family-id"`
-	BinaryFormat     string   `json:"binary-format"`
 	OpenOCDInterface string   `json:"openocd-interface"`
 	OpenOCDTarget    string   `json:"openocd-target"`
 	OpenOCDTransport string   `json:"openocd-transport"`
-	OpenOCDCommands  []string `json:"openocd-commands"`
 	JLinkDevice      string   `json:"jlink-device"`
-	CodeModel        string   `json:"code-model"`
-	RelocationModel  string   `json:"relocation-model"`
-	WasmAbi          string   `json:"wasm-abi"`
 }

-// overrideProperties overrides all properties that are set in child into itself using reflection.
-func (spec *TargetSpec) overrideProperties(child *TargetSpec) {
-	specType := reflect.TypeOf(spec).Elem()
-	specValue := reflect.ValueOf(spec).Elem()
-	childValue := reflect.ValueOf(child).Elem()
-
-	for i := 0; i < specType.NumField(); i++ {
-		field := specType.Field(i)
-		src := childValue.Field(i)
-		dst := specValue.Field(i)
-
-		switch kind := field.Type.Kind(); kind {
-		case reflect.String: // for strings, just copy the field of child to spec if not empty
-			if src.Len() > 0 {
-				dst.Set(src)
-			}
-		case reflect.Uint, reflect.Uint32, reflect.Uint64: // for Uint, copy if not zero
-			if src.Uint() != 0 {
-				dst.Set(src)
-			}
-		case reflect.Ptr: // for pointers, copy if not nil
-			if !src.IsNil() {
-				dst.Set(src)
-			}
-		case reflect.Slice: // for slices...
-			if src.Len() > 0 { // ... if not empty ...
-				switch tag := field.Tag.Get("override"); tag {
-				case "copy":
-					// copy the field of child to spec
-					dst.Set(src)
-				case "append", "":
-					// or append the field of child to spec
-					dst.Set(reflect.AppendSlice(src, dst))
-				default:
-					panic("override mode must be 'copy' or 'append' (default). I don't know how to '" + tag + "'.")
-				}
-			}
-		default:
-			panic("unknown field type : " + kind.String())
-		}
+// 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
 	}
 }

@@ -147,11 +177,11 @@ func (spec *TargetSpec) resolveInherits() error {
 		if err != nil {
 			return err
 		}
-		newSpec.overrideProperties(subtarget)
+		newSpec.copyProperties(subtarget)
 	}

 	// When all properties are loaded, make sure they are properly inherited.
-	newSpec.overrideProperties(spec)
+	newSpec.copyProperties(spec)
 	*spec = *newSpec

 	return nil
@@ -217,7 +247,6 @@ func LoadTarget(target string) (*TargetSpec, error) {
 		}
 		goarch := map[string]string{ // map from LLVM arch to Go arch
 			"i386":    "386",
-			"i686":    "386",
 			"x86_64":  "amd64",
 			"aarch64": "arm64",
 			"armv7":   "arm",
@@ -233,40 +262,39 @@ 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",
+		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 != "wasm" {
-		spec.ExtraFiles = append(spec.ExtraFiles, "src/runtime/gc_"+goarch+".S")
-	}
 	if goarch != runtime.GOARCH {
 		// Some educated guesses as to how to invoke helper programs.
-		spec.GDB = "gdb-multiarch"
 		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" && runtime.GOARCH == "amd64" {
-			spec.CFlags = append(spec.CFlags, "-m32")
-			spec.LDFlags = append(spec.LDFlags, "-m32")
+		if goarch == "386" {
+			spec.CFlags = []string{"-m32"}
+			spec.LDFlags = []string{"-m32"}
 		}
 	}
 	return &spec, nil
@@ -1,9 +1,6 @@
 package compileopts

-import (
-	"reflect"
-	"testing"
-)
+import "testing"

 func TestLoadTarget(t *testing.T) {
 	_, err := LoadTarget("arduino")
@@ -20,67 +17,3 @@ func TestLoadTarget(t *testing.T) {
 		t.Error("LoadTarget failed for wrong reason:", err)
 	}
 }
-
-func TestOverrideProperties(t *testing.T) {
-	baseAutoStackSize := true
-	base := &TargetSpec{
-		GOOS:             "baseGoos",
-		CPU:              "baseCpu",
-		Features:         []string{"bf1", "bf2"},
-		BuildTags:        []string{"bt1", "bt2"},
-		Emulator:         []string{"be1", "be2"},
-		DefaultStackSize: 42,
-		AutoStackSize:    &baseAutoStackSize,
-	}
-	childAutoStackSize := false
-	child := &TargetSpec{
-		GOOS:             "",
-		CPU:              "chlidCpu",
-		Features:         []string{"cf1", "cf2"},
-		Emulator:         []string{"ce1", "ce2"},
-		AutoStackSize:    &childAutoStackSize,
-		DefaultStackSize: 64,
-	}
-
-	base.overrideProperties(child)
-
-	if base.GOOS != "baseGoos" {
-		t.Errorf("Overriding failed : got %v", base.GOOS)
-	}
-	if base.CPU != "chlidCpu" {
-		t.Errorf("Overriding failed : got %v", base.CPU)
-	}
-	if !reflect.DeepEqual(base.Features, []string{"cf1", "cf2", "bf1", "bf2"}) {
-		t.Errorf("Overriding failed : got %v", base.Features)
-	}
-	if !reflect.DeepEqual(base.BuildTags, []string{"bt1", "bt2"}) {
-		t.Errorf("Overriding failed : got %v", base.BuildTags)
-	}
-	if !reflect.DeepEqual(base.Emulator, []string{"ce1", "ce2"}) {
-		t.Errorf("Overriding failed : got %v", base.Emulator)
-	}
-	if *base.AutoStackSize != false {
-		t.Errorf("Overriding failed : got %v", base.AutoStackSize)
-	}
-	if base.DefaultStackSize != 64 {
-		t.Errorf("Overriding failed : got %v", base.DefaultStackSize)
-	}
-
-	baseAutoStackSize = true
-	base = &TargetSpec{
-		AutoStackSize:    &baseAutoStackSize,
-		DefaultStackSize: 42,
-	}
-	child = &TargetSpec{
-		AutoStackSize:    nil,
-		DefaultStackSize: 0,
-	}
-	base.overrideProperties(child)
-	if *base.AutoStackSize != true {
-		t.Errorf("Overriding failed : got %v", base.AutoStackSize)
-	}
-	if base.DefaultStackSize != 42 {
-		t.Errorf("Overriding failed : got %v", base.DefaultStackSize)
-	}
-
-}
@@ -16,7 +16,7 @@ import (
 // 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.info.nobounds {
+	if b.fn.IsNoBounds() {
 		// The //go:nobounds pragma was added to the function to avoid bounds
 		// checking.
 		return
@@ -48,7 +48,7 @@ func (b *builder) createLookupBoundsCheck(arrayLen, index llvm.Value, indexType
 // 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.info.nobounds {
+	if b.fn.IsNoBounds() {
 		// The //go:nobounds pragma was added to the function to avoid bounds
 		// checking.
 		return
@@ -104,7 +104,7 @@ func (b *builder) createSliceBoundsCheck(capacity, low, high, max llvm.Value, lo
 // 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.info.nobounds {
+	if b.fn.IsNoBounds() {
 		// The //go:nobounds pragma was added to the function to avoid bounds
 		// checking.
 		return
@@ -189,7 +189,7 @@ func (b *builder) createNilCheck(inst ssa.Value, ptr llvm.Value, blockPrefix str
 // 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.info.nobounds {
+	if b.fn.IsNoBounds() {
 		// Function disabled bounds checking - skip shift check.
 		return
 	}
@@ -212,8 +212,8 @@ func (b *builder) createRuntimeAssert(assert llvm.Value, blockPrefix, assertFunc
 		}
 	}

-	faultBlock := b.ctx.AddBasicBlock(b.llvmFn, blockPrefix+".throw")
-	nextBlock := b.ctx.AddBasicBlock(b.llvmFn, blockPrefix+".next")
+	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.
@@ -1,84 +0,0 @@
-package compiler
-
-import (
-	"strings"
-
-	"golang.org/x/tools/go/ssa"
-	"tinygo.org/x/go-llvm"
-)
-
-// createAtomicOp lowers an atomic library call by lowering it as an LLVM atomic
-// operation. It returns the result of the operation and true if the call could
-// be lowered inline, and false otherwise.
-func (b *builder) createAtomicOp(call *ssa.CallCommon) (llvm.Value, bool) {
-	name := call.Value.(*ssa.Function).Name()
-	switch name {
-	case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr":
-		ptr := b.getValue(call.Args[0])
-		val := b.getValue(call.Args[1])
-		oldVal := b.CreateAtomicRMW(llvm.AtomicRMWBinOpAdd, ptr, val, llvm.AtomicOrderingSequentiallyConsistent, true)
-		// Return the new value, not the original value returned by atomicrmw.
-		return b.CreateAdd(oldVal, val, ""), true
-	case "SwapInt32", "SwapInt64", "SwapUint32", "SwapUint64", "SwapUintptr", "SwapPointer":
-		ptr := b.getValue(call.Args[0])
-		val := b.getValue(call.Args[1])
-		isPointer := val.Type().TypeKind() == llvm.PointerTypeKind
-		if isPointer {
-			// atomicrmw only supports integers, so cast to an integer.
-			val = b.CreatePtrToInt(val, b.uintptrType, "")
-			ptr = b.CreateBitCast(ptr, llvm.PointerType(val.Type(), 0), "")
-		}
-		oldVal := b.CreateAtomicRMW(llvm.AtomicRMWBinOpXchg, ptr, val, llvm.AtomicOrderingSequentiallyConsistent, true)
-		if isPointer {
-			oldVal = b.CreateIntToPtr(oldVal, b.i8ptrType, "")
-		}
-		return oldVal, true
-	case "CompareAndSwapInt32", "CompareAndSwapInt64", "CompareAndSwapUint32", "CompareAndSwapUint64", "CompareAndSwapUintptr", "CompareAndSwapPointer":
-		ptr := b.getValue(call.Args[0])
-		old := b.getValue(call.Args[1])
-		newVal := b.getValue(call.Args[2])
-		if strings.HasSuffix(name, "64") {
-			arch := strings.Split(b.Triple, "-")[0]
-			if strings.HasPrefix(arch, "arm") && strings.HasSuffix(arch, "m") {
-				// Work around a bug in LLVM, at least LLVM 11:
-				// https://reviews.llvm.org/D95891
-				// Check for armv6m, armv7, armv7em, and perhaps others.
-				// See also: https://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html
-				compareAndSwap := b.mod.NamedFunction("__sync_val_compare_and_swap_8")
-				if compareAndSwap.IsNil() {
-					// Declare the function if it isn't already declared.
-					i64Type := b.ctx.Int64Type()
-					fnType := llvm.FunctionType(i64Type, []llvm.Type{llvm.PointerType(i64Type, 0), i64Type, i64Type}, false)
-					compareAndSwap = llvm.AddFunction(b.mod, "__sync_val_compare_and_swap_8", fnType)
-				}
-				actualOldValue := b.CreateCall(compareAndSwap, []llvm.Value{ptr, old, newVal}, "")
-				// The __sync_val_compare_and_swap_8 function returns the old
-				// value. However, we shouldn't return the old value, we should
-				// return whether the compare/exchange was successful. This is
-				// easily done by comparing the returned (actual) old value with
-				// the expected old value passed to
-				// __sync_val_compare_and_swap_8.
-				swapped := b.CreateICmp(llvm.IntEQ, old, actualOldValue, "")
-				return swapped, true
-			}
-		}
-		tuple := b.CreateAtomicCmpXchg(ptr, old, newVal, llvm.AtomicOrderingSequentiallyConsistent, llvm.AtomicOrderingSequentiallyConsistent, true)
-		swapped := b.CreateExtractValue(tuple, 1, "")
-		return swapped, true
-	case "LoadInt32", "LoadInt64", "LoadUint32", "LoadUint64", "LoadUintptr", "LoadPointer":
-		ptr := b.getValue(call.Args[0])
-		val := b.CreateLoad(ptr, "")
-		val.SetOrdering(llvm.AtomicOrderingSequentiallyConsistent)
-		val.SetAlignment(b.targetData.PrefTypeAlignment(val.Type())) // required
-		return val, true
-	case "StoreInt32", "StoreInt64", "StoreUint32", "StoreUint64", "StoreUintptr", "StorePointer":
-		ptr := b.getValue(call.Args[0])
-		val := b.getValue(call.Args[1])
-		store := b.CreateStore(val, ptr)
-		store.SetOrdering(llvm.AtomicOrderingSequentiallyConsistent)
-		store.SetAlignment(b.targetData.PrefTypeAlignment(val.Type())) // required
-		return store, true
-	default:
-		return llvm.Value{}, false
-	}
-}
@@ -4,7 +4,6 @@ import (
 	"go/types"
 	"strconv"

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

@@ -35,14 +34,14 @@ const (

 // 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 {
-	fn := b.program.ImportedPackage("runtime").Members[fnName].(*ssa.Function)
-	llvmFn := b.getFunction(fn)
-	if llvmFn.IsNil() {
-		panic("trying to call non-existent function: " + fn.RelString(nil))
+	fullName := "runtime." + fnName
+	fn := b.mod.NamedFunction(fullName)
+	if fn.IsNil() {
+		panic("trying to call non-existent function: " + fullName)
 	}
 	args = append(args, llvm.Undef(b.i8ptrType))            // unused context parameter
 	args = append(args, llvm.ConstPointerNull(b.i8ptrType)) // coroutine handle
-	return b.createCall(llvmFn, args, name)
+	return b.createCall(fn, args, name)
 }

 // createCall creates a call to the given function with the arguments possibly
@@ -12,7 +12,7 @@ import (
 )

 func (b *builder) createMakeChan(expr *ssa.MakeChan) llvm.Value {
-	elementSize := b.targetData.TypeAllocSize(b.getLLVMType(expr.Type().Underlying().(*types.Chan).Elem()))
+	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())
@@ -35,37 +35,27 @@ func (b *builder) createChanSend(instr *ssa.Send) {
 	valueAlloca, valueAllocaCast, valueAllocaSize := b.createTemporaryAlloca(valueType, "chan.value")
 	b.CreateStore(chanValue, valueAlloca)

-	// Allocate blockedlist buffer.
-	channelBlockedList := b.mod.GetTypeByName("runtime.channelBlockedList")
-	channelBlockedListAlloca, channelBlockedListAllocaCast, channelBlockedListAllocaSize := b.createTemporaryAlloca(channelBlockedList, "chan.blockedList")
-
 	// Do the send.
-	b.createRuntimeCall("chanSend", []llvm.Value{ch, valueAllocaCast, channelBlockedListAlloca}, "")
+	b.createRuntimeCall("chanSend", []llvm.Value{ch, valueAllocaCast}, "")

-	// End the lifetime of the allocas.
+	// 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(channelBlockedListAllocaCast, channelBlockedListAllocaSize)
 	b.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)
 }

 // createChanRecv 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().Underlying().(*types.Chan).Elem())
+	valueType := b.getLLVMType(unop.X.Type().(*types.Chan).Elem())
 	ch := b.getValue(unop.X)

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

-	// Allocate blockedlist buffer.
-	channelBlockedList := b.mod.GetTypeByName("runtime.channelBlockedList")
-	channelBlockedListAlloca, channelBlockedListAllocaCast, channelBlockedListAllocaSize := b.createTemporaryAlloca(channelBlockedList, "chan.blockedList")
-
 	// Do the receive.
-	commaOk := b.createRuntimeCall("chanRecv", []llvm.Value{ch, valueAllocaCast, channelBlockedListAlloca}, "")
+	commaOk := b.createRuntimeCall("chanRecv", []llvm.Value{ch, valueAllocaCast}, "")
 	received := b.CreateLoad(valueAlloca, "chan.received")
-	b.emitLifetimeEnd(channelBlockedListAllocaCast, channelBlockedListAllocaSize)
 	b.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)

 	if unop.CommaOk {
@@ -79,7 +69,8 @@ func (b *builder) createChanRecv(unop *ssa.UnOp) llvm.Value {
 }

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

@@ -126,7 +117,7 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 		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().Underlying().(*types.Chan).Elem())
+			llvmType := b.getLLVMType(state.Chan.Type().(*types.Chan).Elem())
 			if size := b.targetData.TypeAllocSize(llvmType); size > recvbufSize {
 				recvbufSize = size
 			}
@@ -1,173 +0,0 @@
-package compiler
-
-import (
-	"flag"
-	"go/types"
-	"io/ioutil"
-	"regexp"
-	"strconv"
-	"strings"
-	"testing"
-
-	"github.com/tinygo-org/tinygo/compileopts"
-	"github.com/tinygo-org/tinygo/loader"
-	"tinygo.org/x/go-llvm"
-)
-
-// Pass -update to go test to update the output of the test files.
-var flagUpdate = flag.Bool("update", false, "update tests based on test output")
-
-// Basic tests for the compiler. Build some Go files and compare the output with
-// the expected LLVM IR for regression testing.
-func TestCompiler(t *testing.T) {
-	target, err := compileopts.LoadTarget("i686--linux")
-	if err != nil {
-		t.Fatal("failed to load target:", err)
-	}
-	config := &compileopts.Config{
-		Options: &compileopts.Options{},
-		Target:  target,
-	}
-	compilerConfig := &Config{
-		Triple:             config.Triple(),
-		GOOS:               config.GOOS(),
-		GOARCH:             config.GOARCH(),
-		CodeModel:          config.CodeModel(),
-		RelocationModel:    config.RelocationModel(),
-		Scheduler:          config.Scheduler(),
-		FuncImplementation: config.FuncImplementation(),
-		AutomaticStackSize: config.AutomaticStackSize(),
-	}
-	machine, err := NewTargetMachine(compilerConfig)
-	if err != nil {
-		t.Fatal("failed to create target machine:", err)
-	}
-
-	tests := []string{
-		"basic.go",
-		"pointer.go",
-		"slice.go",
-		"float.go",
-	}
-
-	for _, testCase := range tests {
-		t.Run(testCase, func(t *testing.T) {
-			// Load entire program AST into memory.
-			lprogram, err := loader.Load(config, []string{"./testdata/" + testCase}, config.ClangHeaders, types.Config{
-				Sizes: Sizes(machine),
-			})
-			if err != nil {
-				t.Fatal("failed to create target machine:", err)
-			}
-			err = lprogram.Parse()
-			if err != nil {
-				t.Fatalf("could not parse test case %s: %s", testCase, err)
-			}
-
-			// Compile AST to IR.
-			program := lprogram.LoadSSA()
-			pkg := lprogram.MainPkg()
-			mod, errs := CompilePackage(testCase, pkg, program.Package(pkg.Pkg), machine, compilerConfig, false)
-			if errs != nil {
-				for _, err := range errs {
-					t.Log("error:", err)
-				}
-				return
-			}
-
-			// Optimize IR a little.
-			funcPasses := llvm.NewFunctionPassManagerForModule(mod)
-			defer funcPasses.Dispose()
-			funcPasses.AddInstructionCombiningPass()
-			funcPasses.InitializeFunc()
-			for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-				funcPasses.RunFunc(fn)
-			}
-			funcPasses.FinalizeFunc()
-
-			outfile := "./testdata/" + testCase[:len(testCase)-3] + ".ll"
-
-			// Update test if needed. Do not check the result.
-			if *flagUpdate {
-				err := ioutil.WriteFile(outfile, []byte(mod.String()), 0666)
-				if err != nil {
-					t.Error("failed to write updated output file:", err)
-				}
-				return
-			}
-
-			expected, err := ioutil.ReadFile(outfile)
-			if err != nil {
-				t.Fatal("failed to read golden file:", err)
-			}
-
-			if !fuzzyEqualIR(mod.String(), string(expected)) {
-				t.Errorf("output does not match expected output:\n%s", mod.String())
-			}
-		})
-	}
-}
-
-var alignRegexp = regexp.MustCompile(", align [0-9]+$")
-
-// 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, line1 := range lines1 {
-		line2 := lines2[i]
-		match1 := alignRegexp.MatchString(line1)
-		match2 := alignRegexp.MatchString(line2)
-		if match1 != match2 {
-			// Only one of the lines has the align keyword. Remove it.
-			// This is a change to make the test work in both LLVM 10 and LLVM
-			// 11 (LLVM 11 appears to automatically add alignment everywhere).
-			line1 = alignRegexp.ReplaceAllString(line1, "")
-			line2 = alignRegexp.ReplaceAllString(line2, "")
-		}
-		if line1 != line2 {
-			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
-	llvmVersion, err := strconv.Atoi(strings.Split(llvm.Version, ".")[0])
-	if err != nil {
-		// Note: this should never happen and if it does, it will always happen
-		// for a particular build because llvm.Version is a constant.
-		panic(err)
-	}
-	for _, line := range lines {
-		line = strings.Split(line, ";")[0]    // strip out comments/info
-		line = strings.TrimRight(line, "\r ") // drop '\r' on Windows and remove trailing spaces from comments
-		if line == "" {
-			continue
-		}
-		if strings.HasPrefix(line, "source_filename = ") {
-			continue
-		}
-		if llvmVersion < 10 && strings.HasPrefix(line, "attributes ") {
-			// Ignore attribute groups. These may change between LLVM versions.
-			// Right now test outputs are for LLVM 10.
-			continue
-		}
-		if llvmVersion < 10 && strings.HasPrefix(line, "target datalayout ") {
-			// Ignore the target layout. This may change between LLVM versions.
-			continue
-		}
-		out = append(out, line)
-	}
-	return out
-}
@@ -14,9 +14,8 @@ package compiler
 //     frames.

 import (
-	"go/types"
-
 	"github.com/tinygo-org/tinygo/compiler/llvmutil"
+	"github.com/tinygo-org/tinygo/ir"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )
@@ -26,11 +25,9 @@ import (
 // calls.
 func (b *builder) deferInitFunc() {
 	// Some setup.
-	b.deferFuncs = make(map[*ssa.Function]int)
+	b.deferFuncs = make(map[*ir.Function]int)
 	b.deferInvokeFuncs = make(map[string]int)
-	b.deferClosureFuncs = make(map[*ssa.Function]int)
-	b.deferExprFuncs = make(map[ssa.Value]int)
-	b.deferBuiltinFuncs = make(map[ssa.Value]deferBuiltin)
+	b.deferClosureFuncs = make(map[*ir.Function]int)

 	// Create defer list pointer.
 	deferType := llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)
@@ -107,11 +104,13 @@ func (b *builder) createDefer(instr *ssa.Defer) {

 	} else if callee, ok := instr.Call.Value.(*ssa.Function); ok {
 		// Regular function call.
-		if _, ok := b.deferFuncs[callee]; !ok {
-			b.deferFuncs[callee] = len(b.allDeferFuncs)
-			b.allDeferFuncs = append(b.allDeferFuncs, callee)
+		fn := b.ir.GetFunction(callee)
+
+		if _, ok := b.deferFuncs[fn]; !ok {
+			b.deferFuncs[fn] = len(b.allDeferFuncs)
+			b.allDeferFuncs = append(b.allDeferFuncs, fn)
 		}
-		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferFuncs[callee]), false)
+		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferFuncs[fn]), false)

 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields).
@@ -133,7 +132,7 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		context := b.CreateExtractValue(closure, 0, "")

 		// Get the callback number.
-		fn := makeClosure.Fn.(*ssa.Function)
+		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)
@@ -152,53 +151,9 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		values = append(values, context)
 		valueTypes = append(valueTypes, context.Type())

-	} else if builtin, ok := instr.Call.Value.(*ssa.Builtin); ok {
-		var argTypes []types.Type
-		var argValues []llvm.Value
-		for _, arg := range instr.Call.Args {
-			argTypes = append(argTypes, arg.Type())
-			argValues = append(argValues, b.getValue(arg))
-		}
-
-		if _, ok := b.deferBuiltinFuncs[instr.Call.Value]; !ok {
-			b.deferBuiltinFuncs[instr.Call.Value] = deferBuiltin{
-				callName: builtin.Name(),
-				pos:      builtin.Pos(),
-				argTypes: argTypes,
-				callback: len(b.allDeferFuncs),
-			}
-			b.allDeferFuncs = append(b.allDeferFuncs, instr.Call.Value)
-		}
-		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferBuiltinFuncs[instr.Call.Value].callback), false)
-
-		// Collect all values to be put in the struct (starting with
-		// runtime._defer fields).
-		values = []llvm.Value{callback, next}
-		for _, param := range argValues {
-			values = append(values, param)
-			valueTypes = append(valueTypes, param.Type())
-		}
-
 	} else {
-		funcValue := b.getValue(instr.Call.Value)
-
-		if _, ok := b.deferExprFuncs[instr.Call.Value]; !ok {
-			b.deferExprFuncs[instr.Call.Value] = len(b.allDeferFuncs)
-			b.allDeferFuncs = append(b.allDeferFuncs, &instr.Call)
-		}
-
-		callback := llvm.ConstInt(b.uintptrType, uint64(b.deferExprFuncs[instr.Call.Value]), 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, funcValue}
-		valueTypes = append(valueTypes, funcValue.Type())
-		for _, param := range instr.Call.Args {
-			llvmParam := b.getValue(param)
-			values = append(values, llvmParam)
-			valueTypes = append(valueTypes, llvmParam.Type())
-		}
+		b.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.
@@ -220,7 +175,7 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		allocCall := b.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "defer.alloc.call")
 		alloca = b.CreateBitCast(allocCall, llvm.PointerType(deferFrameType, 0), "defer.alloc")
 	}
-	if b.NeedsStackObjects {
+	if b.NeedsStackObjects() {
 		b.trackPointer(alloca)
 	}
 	b.CreateStore(deferFrame, alloca)
@@ -248,10 +203,10 @@ func (b *builder) createRunDefers() {
 	//     }

 	// Create loop.
-	loophead := b.ctx.AddBasicBlock(b.llvmFn, "rundefers.loophead")
-	loop := b.ctx.AddBasicBlock(b.llvmFn, "rundefers.loop")
-	unreachable := b.ctx.AddBasicBlock(b.llvmFn, "rundefers.default")
-	end := b.ctx.AddBasicBlock(b.llvmFn, "rundefers.end")
+	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)

 	// Create loop head:
@@ -283,28 +238,21 @@ func (b *builder) createRunDefers() {
 		// Create switch case, for example:
 		//     case 0:
 		//         // run first deferred call
-		block := b.ctx.AddBasicBlock(b.llvmFn, "rundefers.callback")
+		block := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.callback")
 		sw.AddCase(llvm.ConstInt(b.uintptrType, uint64(i), false), block)
 		b.SetInsertPointAtEnd(block)
 		switch callback := callback.(type) {
 		case *ssa.CallCommon:
-			// Call on an value or interface value.
-
-			// Get the real defer struct type and cast to it.
-			valueTypes := []llvm.Type{b.uintptrType, llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)}
-
+			// Call on an interface value.
 			if !callback.IsInvoke() {
-				//Expect funcValue to be passed through the defer frame.
-				valueTypes = append(valueTypes, b.getFuncType(callback.Signature()))
-			} else {
-				//Expect typecode
-				valueTypes = append(valueTypes, b.uintptrType, b.i8ptrType)
+				panic("expected an invoke call, not a direct call")
 			}

+			// 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}
 			for _, arg := range callback.Args {
 				valueTypes = append(valueTypes, b.getLLVMType(arg.Type()))
 			}
-
 			deferFrameType := b.ctx.StructType(valueTypes, false)
 			deferFramePtr := b.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")

@@ -317,42 +265,26 @@ func (b *builder) createRunDefers() {
 				forwardParams = append(forwardParams, forwardParam)
 			}

-			var fnPtr llvm.Value
+			// Isolate the typecode.
+			typecode, forwardParams := forwardParams[0], forwardParams[1:]

-			if !callback.IsInvoke() {
-				// Isolate the func value.
-				funcValue := forwardParams[0]
-				forwardParams = forwardParams[1:]
-
-				//Get function pointer and context
-				fp, context := b.decodeFuncValue(funcValue, callback.Signature())
-				fnPtr = fp
-
-				//Pass context
-				forwardParams = append(forwardParams, context)
-			} else {
-				// Isolate the typecode.
-				typecode := forwardParams[0]
-				forwardParams = forwardParams[1:]
-				fnPtr = b.getInvokePtr(callback, typecode)
-
-				// 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))
-			}
+			// 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))

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

+			fnPtr := b.getInvokePtr(callback, typecode)
 			b.createCall(fnPtr, forwardParams, "")

-		case *ssa.Function:
+		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)}
-			for _, param := range getParams(callback.Signature) {
+			for _, param := range callback.Params {
 				valueTypes = append(valueTypes, b.getLLVMType(param.Type()))
 			}
 			deferFrameType := b.ctx.StructType(valueTypes, false)
@@ -361,7 +293,7 @@ func (b *builder) createRunDefers() {
 			// Extract the params from the struct.
 			forwardParams := []llvm.Value{}
 			zero := llvm.ConstInt(b.ctx.Int32Type(), 0, false)
-			for i := range getParams(callback.Signature) {
+			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")
 				forwardParams = append(forwardParams, forwardParam)
@@ -369,7 +301,7 @@ func (b *builder) createRunDefers() {

 			// 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 !b.getFunctionInfo(callback).exported {
+			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))
@@ -379,11 +311,11 @@ func (b *builder) createRunDefers() {
 			}

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

 		case *ssa.MakeClosure:
 			// Get the real defer struct type and cast to it.
-			fn := callback.Fn.(*ssa.Function)
+			fn := b.ir.GetFunction(callback.Fn.(*ssa.Function))
 			valueTypes := []llvm.Type{b.uintptrType, llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)}
 			params := fn.Signature.Params()
 			for i := 0; i < params.Len(); i++ {
@@ -406,35 +338,8 @@ func (b *builder) createRunDefers() {
 			forwardParams = append(forwardParams, llvm.Undef(b.i8ptrType))

 			// Call deferred function.
-			b.createCall(b.getFunction(fn), forwardParams, "")
-		case *ssa.Builtin:
-			db := b.deferBuiltinFuncs[callback]
+			b.createCall(fn.LLVMFn, forwardParams, "")

-			//Get parameter types
-			valueTypes := []llvm.Type{b.uintptrType, llvm.PointerType(b.getLLVMRuntimeType("_defer"), 0)}
-
-			//Get signature from call results
-			params := callback.Type().Underlying().(*types.Signature).Params()
-			for i := 0; i < params.Len(); i++ {
-				valueTypes = append(valueTypes, b.getLLVMType(params.At(i).Type()))
-			}
-
-			deferFrameType := b.ctx.StructType(valueTypes, false)
-			deferFramePtr := b.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")
-
-			// Extract the params from the struct.
-			var argValues []llvm.Value
-			zero := llvm.ConstInt(b.ctx.Int32Type(), 0, false)
-			for i := 0; i < params.Len(); i++ {
-				gep := b.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(b.ctx.Int32Type(), uint64(i+2), false)}, "gep")
-				forwardParam := b.CreateLoad(gep, "param")
-				argValues = append(argValues, forwardParam)
-			}
-
-			_, err := b.createBuiltin(db.argTypes, argValues, db.callName, db.pos)
-			if err != nil {
-				b.diagnostics = append(b.diagnostics, err)
-			}
 		default:
 			panic("unknown deferred function type")
 		}
@@ -14,7 +14,7 @@ import (
 // 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 {
 	return types.Error{
-		Fset: c.program.Fset,
+		Fset: c.ir.Program.Fset,
 		Pos:  pos,
 		Msg:  msg,
 	}
@@ -6,6 +6,7 @@ package compiler
 import (
 	"go/types"

+	"github.com/tinygo-org/tinygo/compileopts"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )
@@ -20,11 +21,11 @@ func (b *builder) createFuncValue(funcPtr, context llvm.Value, sig *types.Signat
 // context.
 func (c *compilerContext) createFuncValue(builder llvm.Builder, funcPtr, context llvm.Value, sig *types.Signature) llvm.Value {
 	var funcValueScalar llvm.Value
-	switch c.FuncImplementation {
-	case "doubleword":
+	switch c.FuncImplementation() {
+	case compileopts.FuncValueDoubleword:
 		// Closure is: {context, function pointer}
 		funcValueScalar = funcPtr
-	case "switch":
+	case compileopts.FuncValueSwitch:
 		sigGlobal := c.getTypeCode(sig)
 		funcValueWithSignatureGlobalName := funcPtr.Name() + "$withSignature"
 		funcValueWithSignatureGlobal := c.mod.NamedGlobal(funcValueWithSignatureGlobalName)
@@ -37,7 +38,7 @@ func (c *compilerContext) createFuncValue(builder llvm.Builder, funcPtr, context
 			funcValueWithSignatureGlobal = llvm.AddGlobal(c.mod, funcValueWithSignatureType, funcValueWithSignatureGlobalName)
 			funcValueWithSignatureGlobal.SetInitializer(funcValueWithSignature)
 			funcValueWithSignatureGlobal.SetGlobalConstant(true)
-			funcValueWithSignatureGlobal.SetLinkage(llvm.LinkOnceODRLinkage)
+			funcValueWithSignatureGlobal.SetLinkage(llvm.InternalLinkage)
 		}
 		funcValueScalar = llvm.ConstPtrToInt(funcValueWithSignatureGlobal, c.uintptrType)
 	default:
@@ -66,10 +67,10 @@ func (b *builder) extractFuncContext(funcValue llvm.Value) llvm.Value {
 // 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 "doubleword":
+	switch b.FuncImplementation() {
+	case compileopts.FuncValueDoubleword:
 		funcPtr = b.CreateExtractValue(funcValue, 1, "")
-	case "switch":
+	case compileopts.FuncValueSwitch:
 		llvmSig := b.getRawFuncType(sig)
 		sigGlobal := b.getTypeCode(sig)
 		funcPtr = b.createRuntimeCall("getFuncPtr", []llvm.Value{funcValue, sigGlobal}, "")
@@ -82,11 +83,11 @@ 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 "doubleword":
+	switch c.FuncImplementation() {
+	case compileopts.FuncValueDoubleword:
 		rawPtr := c.getRawFuncType(typ)
 		return c.ctx.StructType([]llvm.Type{c.i8ptrType, rawPtr}, false)
-	case "switch":
+	case compileopts.FuncValueSwitch:
 		return c.getLLVMRuntimeType("funcValue")
 	default:
 		panic("unimplemented func value variant")
@@ -148,7 +149,7 @@ func (b *builder) parseMakeClosure(expr *ssa.MakeClosure) (llvm.Value, error) {
 	if len(expr.Bindings) == 0 {
 		panic("unexpected: MakeClosure without bound variables")
 	}
-	f := expr.Fn.(*ssa.Function)
+	f := b.ir.GetFunction(expr.Fn.(*ssa.Function))

 	// Collect all bound variables.
 	boundVars := make([]llvm.Value, len(expr.Bindings))
@@ -163,5 +164,5 @@ func (b *builder) parseMakeClosure(expr *ssa.MakeClosure) (llvm.Value, error) {
 	context := b.emitPointerPack(boundVars)

 	// Create the closure.
-	return b.createFuncValue(b.getFunction(f), context, f.Signature), nil
+	return b.createFuncValue(f.LLVMFn, context, f.Signature), nil
 }
@@ -7,7 +7,6 @@ import (
 	"go/token"

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

@@ -20,32 +19,16 @@ import (
 // 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, stackSize llvm.Value
-	switch b.Scheduler {
+	var callee llvm.Value
+	switch b.Scheduler() {
 	case "none", "tasks":
 		callee = b.createGoroutineStartWrapper(funcPtr, prefix, pos)
-		if b.AutomaticStackSize {
-			// The stack size is not known until after linking. Call a dummy
-			// function that will be replaced with a load from a special ELF
-			// section that contains the stack size (and is modified after
-			// linking).
-			stackSizeFn := b.getFunction(b.program.ImportedPackage("internal/task").Members["getGoroutineStackSize"].(*ssa.Function))
-			stackSize = b.createCall(stackSizeFn, []llvm.Value{callee, llvm.Undef(b.i8ptrType), llvm.Undef(b.i8ptrType)}, "stacksize")
-		} else {
-			// The stack size is fixed at compile time. By emitting it here as a
-			// constant, it can be optimized.
-			stackSize = llvm.ConstInt(b.uintptrType, b.DefaultStackSize, false)
-		}
 	case "coroutines":
 		callee = b.CreatePtrToInt(funcPtr, b.uintptrType, "")
-		// There is no goroutine stack size: coroutines are used instead of
-		// stacks.
-		stackSize = llvm.Undef(b.uintptrType)
 	default:
 		panic("unreachable")
 	}
-	start := b.getFunction(b.program.ImportedPackage("internal/task").Members["start"].(*ssa.Function))
-	b.createCall(start, []llvm.Value{callee, paramBundle, stackSize, llvm.Undef(b.i8ptrType), llvm.ConstPointerNull(b.i8ptrType)}, "")
+	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())
 }

@@ -84,14 +67,13 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		// 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.LinkOnceODRLinkage)
+		wrapper.SetLinkage(llvm.PrivateLinkage)
 		wrapper.SetUnnamedAddr(true)
-		wrapper.AddAttributeAtIndex(-1, c.ctx.CreateStringAttribute("tinygo-gowrapper", name))
 		entry := c.ctx.AddBasicBlock(wrapper, "entry")
 		builder.SetInsertPointAtEnd(entry)

-		if c.Debug {
-			pos := c.program.Fset.Position(pos)
+		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
@@ -141,14 +123,13 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		// Create the wrapper.
 		wrapperType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.i8ptrType}, false)
 		wrapper = llvm.AddFunction(c.mod, prefix+".gowrapper", wrapperType)
-		wrapper.SetLinkage(llvm.LinkOnceODRLinkage)
+		wrapper.SetLinkage(llvm.InternalLinkage)
 		wrapper.SetUnnamedAddr(true)
-		wrapper.AddAttributeAtIndex(-1, c.ctx.CreateStringAttribute("tinygo-gowrapper", ""))
 		entry := c.ctx.AddBasicBlock(wrapper, "entry")
 		builder.SetInsertPointAtEnd(entry)

-		if c.Debug {
-			pos := c.program.Fset.Position(pos)
+		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
@@ -163,44 +163,6 @@ func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
 	return b.CreateCall(target, llvmArgs, ""), nil
 }

-// This is a compiler builtin which emits an inline SVCall instruction. It can
-// be one of:
-//
-//     func SVCall0(num uintptr) uintptr
-//     func SVCall1(num uintptr, a1 interface{}) uintptr
-//     func SVCall2(num uintptr, a1, a2 interface{}) uintptr
-//     func SVCall3(num uintptr, a1, a2, a3 interface{}) uintptr
-//     func SVCall4(num uintptr, a1, a2, a3, a4 interface{}) uintptr
-//
-// The num parameter must be a constant. All other parameters may be any scalar
-// value supported by LLVM inline assembly.
-// Same as emitSVCall but for AArch64
-func (b *builder) emitSV64Call(args []ssa.Value) (llvm.Value, error) {
-	num, _ := constant.Uint64Val(args[0].(*ssa.Const).Value)
-	llvmArgs := []llvm.Value{}
-	argTypes := []llvm.Type{}
-	asm := "svc #" + strconv.FormatUint(num, 10)
-	constraints := "={x0}"
-	for i, arg := range args[1:] {
-		arg = arg.(*ssa.MakeInterface).X
-		if i == 0 {
-			constraints += ",0"
-		} else {
-			constraints += ",{x" + strconv.Itoa(i) + "}"
-		}
-		llvmValue := b.getValue(arg)
-		llvmArgs = append(llvmArgs, llvmValue)
-		argTypes = append(argTypes, llvmValue.Type())
-	}
-	// Implement the ARM64 calling convention by marking x1-x7 as
-	// clobbered. x0 is used as an output register so doesn't have to be
-	// marked as clobbered.
-	constraints += ",~{x1},~{x2},~{x3},~{x4},~{x5},~{x6},~{x7}"
-	fnType := llvm.FunctionType(b.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
@@ -11,6 +11,7 @@ import (
 	"strconv"
 	"strings"

+	"github.com/tinygo-org/tinygo/ir"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )
@@ -31,7 +32,7 @@ func (b *builder) createMakeInterface(val llvm.Value, typ types.Type, pos token.
 		itfConcreteTypeGlobal = llvm.AddGlobal(b.mod, typeInInterface, "typeInInterface:"+itfTypeCodeGlobal.Name())
 		itfConcreteTypeGlobal.SetInitializer(llvm.ConstNamedStruct(typeInInterface, []llvm.Value{itfTypeCodeGlobal, itfMethodSetGlobal}))
 		itfConcreteTypeGlobal.SetGlobalConstant(true)
-		itfConcreteTypeGlobal.SetLinkage(llvm.LinkOnceODRLinkage)
+		itfConcreteTypeGlobal.SetLinkage(llvm.PrivateLinkage)
 	}
 	itfTypeCode := b.CreatePtrToInt(itfConcreteTypeGlobal, b.uintptrType, "")
 	itf := llvm.Undef(b.getLLVMRuntimeType("_interface"))
@@ -80,7 +81,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				globalValue = llvm.ConstInsertValue(globalValue, lengthValue, []uint32{1})
 			}
 			global.SetInitializer(globalValue)
-			global.SetLinkage(llvm.LinkOnceODRLinkage)
+			global.SetLinkage(llvm.PrivateLinkage)
 		}
 		global.SetGlobalConstant(true)
 	}
@@ -235,7 +236,7 @@ func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
 		return llvm.ConstGEP(global, []llvm.Value{zero, zero})
 	}

-	ms := c.program.MethodSets.MethodSet(typ)
+	ms := c.ir.Program.MethodSets.MethodSet(typ)
 	if ms.Len() == 0 {
 		// no methods, so can leave that one out
 		return llvm.ConstPointerNull(llvm.PointerType(c.getLLVMRuntimeType("interfaceMethodInfo"), 0))
@@ -246,16 +247,15 @@ func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
 	for i := 0; i < ms.Len(); i++ {
 		method := ms.At(i)
 		signatureGlobal := c.getMethodSignature(method.Obj().(*types.Func))
-		fn := c.program.MethodValue(method)
-		llvmFn := c.getFunction(fn)
-		if llvmFn.IsNil() {
+		f := c.ir.GetFunction(c.ir.Program.MethodValue(method))
+		if f.LLVMFn.IsNil() {
 			// compiler error, so panic
-			panic("cannot find function: " + c.getFunctionInfo(fn).linkName)
+			panic("cannot find function: " + f.LinkName())
 		}
-		wrapper := c.getInterfaceInvokeWrapper(fn, llvmFn)
+		fn := c.getInterfaceInvokeWrapper(f)
 		methodInfo := llvm.ConstNamedStruct(interfaceMethodInfoType, []llvm.Value{
 			signatureGlobal,
-			llvm.ConstPtrToInt(wrapper, c.uintptrType),
+			llvm.ConstPtrToInt(fn, c.uintptrType),
 		})
 		methods[i] = methodInfo
 	}
@@ -264,7 +264,7 @@ func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
 	global = llvm.AddGlobal(c.mod, arrayType, typ.String()+"$methodset")
 	global.SetInitializer(value)
 	global.SetGlobalConstant(true)
-	global.SetLinkage(llvm.LinkOnceODRLinkage)
+	global.SetLinkage(llvm.PrivateLinkage)
 	return llvm.ConstGEP(global, []llvm.Value{zero, zero})
 }

@@ -295,7 +295,7 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 	global = llvm.AddGlobal(c.mod, value.Type(), name+"$interface")
 	global.SetInitializer(value)
 	global.SetGlobalConstant(true)
-	global.SetLinkage(llvm.LinkOnceODRLinkage)
+	global.SetLinkage(llvm.PrivateLinkage)
 	return llvm.ConstGEP(global, []llvm.Value{zero, zero})
 }

@@ -303,7 +303,7 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 // external *i8 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 {
-	signature := methodSignature(method)
+	signature := ir.MethodSignature(method)
 	signatureGlobal := c.mod.NamedGlobal("func " + signature)
 	if signatureGlobal.IsNil() {
 		signatureGlobal = llvm.AddGlobal(c.mod, c.ctx.Int8Type(), "func "+signature)
@@ -357,8 +357,8 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 	// value.

 	prevBlock := b.GetInsertBlock()
-	okBlock := b.ctx.AddBasicBlock(b.llvmFn, "typeassert.ok")
-	nextBlock := b.ctx.AddBasicBlock(b.llvmFn, "typeassert.next")
+	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)

@@ -436,8 +436,8 @@ func (b *builder) getInvokeCall(instr *ssa.CallCommon) (llvm.Value, []llvm.Value
 // 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(fn *ssa.Function, llvmFn llvm.Value) llvm.Value {
-	wrapperName := llvmFn.Name() + "$invoke"
+func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
+	wrapperName := f.LinkName() + "$invoke"
 	wrapper := c.mod.NamedFunction(wrapperName)
 	if !wrapper.IsNil() {
 		// Wrapper already created. Return it directly.
@@ -445,7 +445,7 @@ func (c *compilerContext) getInterfaceInvokeWrapper(fn *ssa.Function, llvmFn llv
 	}

 	// Get the expanded receiver type.
-	receiverType := c.getLLVMType(fn.Signature.Recv().Type())
+	receiverType := c.getLLVMType(f.Params[0].Type())
 	var expandedReceiverType []llvm.Type
 	for _, info := range expandFormalParamType(receiverType, "", nil) {
 		expandedReceiverType = append(expandedReceiverType, info.llvmType)
@@ -457,17 +457,19 @@ func (c *compilerContext) getInterfaceInvokeWrapper(fn *ssa.Function, llvmFn llv
 		// Casting a function signature to a different signature and calling it
 		// with a receiver pointer bitcasted to *i8 (as done in calls on an
 		// interface) is hopefully a safe (defined) operation.
-		return llvmFn
+		return f.LLVMFn
 	}

 	// create wrapper function
-	fnType := llvmFn.Type().ElementType()
+	fnType := f.LLVMFn.Type().ElementType()
 	paramTypes := append([]llvm.Type{c.i8ptrType}, fnType.ParamTypes()[len(expandedReceiverType):]...)
 	wrapFnType := llvm.FunctionType(fnType.ReturnType(), paramTypes, false)
 	wrapper = llvm.AddFunction(c.mod, wrapperName, wrapFnType)
-	wrapper.LastParam().SetName("parentHandle")
+	if f.LLVMFn.LastParam().Name() == "parentHandle" {
+		wrapper.LastParam().SetName("parentHandle")
+	}

-	wrapper.SetLinkage(llvm.LinkOnceODRLinkage)
+	wrapper.SetLinkage(llvm.InternalLinkage)
 	wrapper.SetUnnamedAddr(true)

 	// Create a new builder just to create this wrapper.
@@ -478,9 +480,9 @@ func (c *compilerContext) getInterfaceInvokeWrapper(fn *ssa.Function, llvmFn llv
 	defer b.Builder.Dispose()

 	// add debug info if needed
-	if c.Debug {
-		pos := c.program.Fset.Position(fn.Pos())
-		difunc := c.attachDebugInfoRaw(fn, wrapper, "$invoke", pos.Filename, pos.Line)
+	if c.Debug() {
+		pos := c.ir.Program.Fset.Position(f.Pos())
+		difunc := c.attachDebugInfoRaw(f, wrapper, "$invoke", pos.Filename, pos.Line)
 		b.SetCurrentDebugLocation(uint(pos.Line), uint(pos.Column), difunc, llvm.Metadata{})
 	}

@@ -490,60 +492,13 @@ func (c *compilerContext) getInterfaceInvokeWrapper(fn *ssa.Function, llvmFn llv

 	receiverValue := b.emitPointerUnpack(wrapper.Param(0), []llvm.Type{receiverType})[0]
 	params := append(b.expandFormalParam(receiverValue), wrapper.Params()[1:]...)
-	if llvmFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
-		b.CreateCall(llvmFn, params, "")
+	if f.LLVMFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
+		b.CreateCall(f.LLVMFn, params, "")
 		b.CreateRetVoid()
 	} else {
-		ret := b.CreateCall(llvmFn, params, "ret")
+		ret := b.CreateCall(f.LLVMFn, params, "ret")
 		b.CreateRet(ret)
 	}

 	return wrapper
 }
-
-// methodSignature creates a readable version of a method signature (including
-// the function name, excluding the receiver name). This string is used
-// internally to match interfaces and to call the correct method on an
-// interface. Examples:
-//
-//     String() string
-//     Read([]byte) (int, error)
-func methodSignature(method *types.Func) string {
-	return method.Name() + signature(method.Type().(*types.Signature))
-}
-
-// Make a readable version of a function (pointer) signature.
-// Examples:
-//
-//     () string
-//     (string, int) (int, error)
-func signature(sig *types.Signature) string {
-	s := ""
-	if sig.Params().Len() == 0 {
-		s += "()"
-	} else {
-		s += "("
-		for i := 0; i < sig.Params().Len(); i++ {
-			if i > 0 {
-				s += ", "
-			}
-			s += sig.Params().At(i).Type().String()
-		}
-		s += ")"
-	}
-	if sig.Results().Len() == 0 {
-		// keep as-is
-	} else if sig.Results().Len() == 1 {
-		s += " " + sig.Results().At(0).Type().String()
-	} else {
-		s += " ("
-		for i := 0; i < sig.Results().Len(); i++ {
-			if i > 0 {
-				s += ", "
-			}
-			s += sig.Results().At(i).Type().String()
-		}
-		s += ")"
-	}
-	return s
-}
@@ -39,14 +39,14 @@ func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, erro

 	// Create a new global of type runtime/interrupt.handle. Globals of this
 	// type are lowered in the interrupt lowering pass.
-	globalType := b.program.ImportedPackage("runtime/interrupt").Type("handle").Type()
+	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.SetVisibility(llvm.HiddenVisibility)
+	global.SetLinkage(llvm.PrivateLinkage)
 	global.SetGlobalConstant(true)
 	global.SetUnnamedAddr(true)
 	initializer := llvm.ConstNull(globalLLVMType)
@@ -55,8 +55,8 @@ func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, erro
 	global.SetInitializer(initializer)

 	// Add debug info to the interrupt global.
-	if b.Debug {
-		pos := b.program.Fset.Position(instr.Pos())
+	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,
@@ -79,7 +79,7 @@ func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, erro
 	// 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") {
+	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)
@@ -44,7 +44,7 @@ func (b *builder) emitLifetimeEnd(ptr, size llvm.Value) {
 // 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.NeedsStackObjects, values)
+	return llvmutil.EmitPointerPack(b.Builder, b.mod, b.Config, values)
 }

 // emitPointerUnpack extracts a list of values packed using emitPointerPack.
@@ -5,6 +5,7 @@ package llvmutil
 // itself if possible and legal.

 import (
+	"github.com/tinygo-org/tinygo/compileopts"
 	"tinygo.org/x/go-llvm"
 )

@@ -12,7 +13,7 @@ import (
 // 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, needsStackObjects bool, values []llvm.Value) llvm.Value {
+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)
@@ -25,6 +26,7 @@ func EmitPointerPack(builder llvm.Builder, mod llvm.Module, needsStackObjects bo
 	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)
@@ -37,39 +39,9 @@ func EmitPointerPack(builder llvm.Builder, mod llvm.Module, needsStackObjects bo
 			// 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 a *i8 alloca first and load the *i8 value from there. This is
-		// effectively a bitcast.
-		packedAlloc, _, _ := CreateTemporaryAlloca(builder, mod, i8ptrType, "")
-
-		if size < targetData.TypeAllocSize(i8ptrType) {
-			// The alloca is bigger than the value that will be stored in it.
-			// To avoid having some bits undefined, zero the alloca first.
-			// Hopefully this will get optimized away.
-			builder.CreateStore(llvm.ConstNull(i8ptrType), packedAlloc)
-		}
-
-		// Store all values in the alloca.
-		packedAllocCast := builder.CreateBitCast(packedAlloc, llvm.PointerType(packedType, 0), "")
-		for i, value := range values {
-			indices := []llvm.Value{
-				llvm.ConstInt(ctx.Int32Type(), 0, false),
-				llvm.ConstInt(ctx.Int32Type(), uint64(i), false),
-			}
-			gep := builder.CreateInBoundsGEP(packedAllocCast, indices, "")
-			builder.CreateStore(value, gep)
-		}
-
-		// Load value (the *i8) from the alloca.
-		result := builder.CreateLoad(packedAlloc, "")
-
-		// End the lifetime of the alloca, to help the optimizer.
-		packedPtr := builder.CreateBitCast(packedAlloc, i8ptrType, "")
-		packedSize := llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(packedAlloc.Type()), false)
-		EmitLifetimeEnd(builder, mod, packedPtr, packedSize)
-
-		return result
+		// 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
@@ -95,12 +67,12 @@ func EmitPointerPack(builder llvm.Builder, mod llvm.Module, needsStackObjects bo
 		// 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{
+		packedHeapAlloc = builder.CreateCall(alloc, []llvm.Value{
 			sizeValue,
 			llvm.Undef(i8ptrType),            // unused context parameter
 			llvm.ConstPointerNull(i8ptrType), // coroutine handle
 		}, "")
-		if needsStackObjects {
+		if config.NeedsStackObjects() {
 			trackPointer := mod.NamedFunction("runtime.trackPointer")
 			builder.CreateCall(trackPointer, []llvm.Value{
 				packedHeapAlloc,
@@ -108,19 +80,28 @@ func EmitPointerPack(builder llvm.Builder, mod llvm.Module, needsStackObjects bo
 				llvm.ConstPointerNull(i8ptrType), // coroutine handle
 			}, "")
 		}
-		packedAlloc := builder.CreateBitCast(packedHeapAlloc, llvm.PointerType(packedType, 0), "")
-
-		// Store all values in the 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)
+		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)
+	}

-		// Return the original heap allocation pointer, which already is an *i8.
+	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
 	}
 }
@@ -15,298 +15,6 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// functionInfo contains some information about a function or method. In
-// particular, it contains information obtained from pragmas.
-//
-// The linkName value contains a valid link name, even if //go:linkname is not
-// present.
-type functionInfo struct {
-	module     string     // go:wasm-module
-	importName string     // go:linkname, go:export - The name the developer assigns
-	linkName   string     // go:linkname, go:export - The name that we map for the particular module -> importName
-	exported   bool       // go:export, CGo
-	nobounds   bool       // go:nobounds
-	variadic   bool       // go:variadic (CGo only)
-	inline     inlineType // go:inline
-}
-
-type inlineType int
-
-// How much to inline.
-const (
-	// Default behavior. The compiler decides for itself whether any given
-	// function will be inlined. Whether any function is inlined depends on the
-	// optimization level.
-	inlineDefault inlineType = iota
-
-	// Inline hint, just like the C inline keyword (signalled using
-	// //go:inline). The compiler will be more likely to inline this function,
-	// but it is not a guarantee.
-	inlineHint
-
-	// Don't inline, just like the GCC noinline attribute. Signalled using
-	// //go:noinline.
-	inlineNone
-)
-
-// getFunction returns the LLVM function for the given *ssa.Function, creating
-// it if needed. It can later be filled with compilerContext.createFunction().
-func (c *compilerContext) getFunction(fn *ssa.Function) llvm.Value {
-	info := c.getFunctionInfo(fn)
-	llvmFn := c.mod.NamedFunction(info.linkName)
-	if !llvmFn.IsNil() {
-		return llvmFn
-	}
-
-	var retType llvm.Type
-	if fn.Signature.Results() == nil {
-		retType = c.ctx.VoidType()
-	} else if fn.Signature.Results().Len() == 1 {
-		retType = c.getLLVMType(fn.Signature.Results().At(0).Type())
-	} else {
-		results := make([]llvm.Type, 0, fn.Signature.Results().Len())
-		for i := 0; i < fn.Signature.Results().Len(); i++ {
-			results = append(results, c.getLLVMType(fn.Signature.Results().At(i).Type()))
-		}
-		retType = c.ctx.StructType(results, false)
-	}
-
-	var paramInfos []paramInfo
-	for _, param := range getParams(fn.Signature) {
-		paramType := c.getLLVMType(param.Type())
-		paramFragmentInfos := expandFormalParamType(paramType, param.Name(), param.Type())
-		paramInfos = append(paramInfos, paramFragmentInfos...)
-	}
-
-	// Add an extra parameter as the function context. This context is used in
-	// closures and bound methods, but should be optimized away when not used.
-	if !info.exported {
-		paramInfos = append(paramInfos, paramInfo{llvmType: c.i8ptrType, name: "context", flags: 0})
-		paramInfos = append(paramInfos, paramInfo{llvmType: c.i8ptrType, name: "parentHandle", flags: 0})
-	}
-
-	var paramTypes []llvm.Type
-	for _, info := range paramInfos {
-		paramTypes = append(paramTypes, info.llvmType)
-	}
-
-	fnType := llvm.FunctionType(retType, paramTypes, info.variadic)
-	llvmFn = llvm.AddFunction(c.mod, info.linkName, fnType)
-	if strings.HasPrefix(c.Triple, "wasm") {
-		// C functions without prototypes like this:
-		//   void foo();
-		// are actually variadic functions. However, it appears that it has been
-		// decided in WebAssembly that such prototype-less functions are not
-		// allowed in WebAssembly.
-		// In C, this can only happen when there are zero parameters, hence this
-		// check here. For more information:
-		// https://reviews.llvm.org/D48443
-		// https://github.com/WebAssembly/tool-conventions/issues/16
-		if info.variadic && len(fn.Params) == 0 {
-			attr := c.ctx.CreateStringAttribute("no-prototype", "")
-			llvmFn.AddFunctionAttr(attr)
-		}
-	}
-
-	dereferenceableOrNullKind := llvm.AttributeKindID("dereferenceable_or_null")
-	for i, info := range paramInfos {
-		if info.flags&paramIsDeferenceableOrNull == 0 {
-			continue
-		}
-		if info.llvmType.TypeKind() == llvm.PointerTypeKind {
-			el := info.llvmType.ElementType()
-			size := c.targetData.TypeAllocSize(el)
-			if size == 0 {
-				// dereferenceable_or_null(0) appears to be illegal in LLVM.
-				continue
-			}
-			dereferenceableOrNull := c.ctx.CreateEnumAttribute(dereferenceableOrNullKind, size)
-			llvmFn.AddAttributeAtIndex(i+1, dereferenceableOrNull)
-		}
-	}
-
-	// Set a number of function or parameter attributes, depending on the
-	// function. These functions are runtime functions that are known to have
-	// certain attributes that might not be inferred by the compiler.
-	switch info.linkName {
-	case "abort":
-		// On *nix systems, the "abort" functuion in libc is used to handle fatal panics.
-		// Mark it as noreturn so LLVM can optimize away code.
-		llvmFn.AddFunctionAttr(c.ctx.CreateEnumAttribute(llvm.AttributeKindID("noreturn"), 0))
-	case "runtime.alloc":
-		// Tell the optimizer that runtime.alloc is an allocator, meaning that it
-		// returns values that are never null and never alias to an existing value.
-		for _, attrName := range []string{"noalias", "nonnull"} {
-			llvmFn.AddAttributeAtIndex(0, c.ctx.CreateEnumAttribute(llvm.AttributeKindID(attrName), 0))
-		}
-	case "runtime.trackPointer":
-		// This function is necessary for tracking pointers on the stack in a
-		// portable way (see gc_stack_portable.go). Indicate to the optimizer
-		// that the only thing we'll do is read the pointer.
-		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
-		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("readonly"), 0))
-	}
-
-	// External/exported functions may not retain pointer values.
-	// https://golang.org/cmd/cgo/#hdr-Passing_pointers
-	if info.exported {
-		// Set the wasm-import-module attribute if the function's module is set.
-		if info.module != "" {
-
-			// We need to add the wasm-import-module and the wasm-import-name
-			wasmImportModuleAttr := c.ctx.CreateStringAttribute("wasm-import-module", info.module)
-			llvmFn.AddFunctionAttr(wasmImportModuleAttr)
-
-			// Add the Wasm Import Name, if we are a named wasm import
-			if info.importName != "" {
-				wasmImportNameAttr := c.ctx.CreateStringAttribute("wasm-import-name", info.importName)
-				llvmFn.AddFunctionAttr(wasmImportNameAttr)
-			}
-		}
-		nocaptureKind := llvm.AttributeKindID("nocapture")
-		nocapture := c.ctx.CreateEnumAttribute(nocaptureKind, 0)
-		for i, typ := range paramTypes {
-			if typ.TypeKind() == llvm.PointerTypeKind {
-				llvmFn.AddAttributeAtIndex(i+1, nocapture)
-			}
-		}
-	}
-
-	// Synthetic functions are functions that do not appear in the source code,
-	// they are artificially constructed. Usually they are wrapper functions
-	// that are not referenced anywhere except in a SSA call instruction so
-	// should be created right away.
-	// The exception is the package initializer, which does appear in the
-	// *ssa.Package members and so shouldn't be created here.
-	if fn.Synthetic != "" && fn.Synthetic != "package initializer" {
-		irbuilder := c.ctx.NewBuilder()
-		b := newBuilder(c, irbuilder, fn)
-		b.createFunction()
-		irbuilder.Dispose()
-		llvmFn.SetLinkage(llvm.LinkOnceODRLinkage)
-		llvmFn.SetUnnamedAddr(true)
-	}
-
-	return llvmFn
-}
-
-// getFunctionInfo returns information about a function that is not directly
-// present in *ssa.Function, such as the link name and whether it should be
-// exported.
-func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
-	info := functionInfo{}
-	if strings.HasPrefix(f.Name(), "C.") {
-		// Created by CGo: such a name cannot be created by regular C code.
-		info.linkName = f.Name()[2:]
-		info.exported = true
-	} else {
-		// Pick the default linkName.
-		info.linkName = f.RelString(nil)
-	}
-	// Check for //go: pragmas, which may change the link name (among others).
-	info.parsePragmas(f)
-	return info
-}
-
-// parsePragmas is used by getFunctionInfo to parse function pragmas such as
-// //export or //go:noinline.
-func (info *functionInfo) parsePragmas(f *ssa.Function) {
-	if f.Syntax() == nil {
-		return
-	}
-	if decl, ok := f.Syntax().(*ast.FuncDecl); ok && decl.Doc != nil {
-
-		// Our importName for a wasm module (if we are compiling to wasm), or llvm link name
-		var importName string
-
-		for _, comment := range decl.Doc.List {
-			text := comment.Text
-			if strings.HasPrefix(text, "//export ") {
-				// Rewrite '//export' to '//go:export' for compatibility with
-				// gc.
-				text = "//go:" + text[2:]
-			}
-			if !strings.HasPrefix(text, "//go:") {
-				continue
-			}
-			parts := strings.Fields(text)
-			switch parts[0] {
-			case "//go:export":
-				if len(parts) != 2 {
-					continue
-				}
-
-				importName = parts[1]
-				info.exported = true
-			case "//go:wasm-module":
-				// Alternative comment for setting the import module.
-				if len(parts) != 2 {
-					continue
-				}
-				info.module = parts[1]
-			case "//go:inline":
-				info.inline = inlineHint
-			case "//go:noinline":
-				info.inline = inlineNone
-			case "//go:linkname":
-				if len(parts) != 3 || parts[1] != f.Name() {
-					continue
-				}
-				// Only enable go:linkname when the package imports "unsafe".
-				// This is a slightly looser requirement than what gc uses: gc
-				// requires the file to import "unsafe", not the package as a
-				// whole.
-				if hasUnsafeImport(f.Pkg.Pkg) {
-					info.linkName = parts[2]
-				}
-			case "//go:nobounds":
-				// Skip bounds checking in this function. Useful for some
-				// runtime functions.
-				// This is somewhat dangerous and thus only imported in packages
-				// that import unsafe.
-				if hasUnsafeImport(f.Pkg.Pkg) {
-					info.nobounds = true
-				}
-			case "//go:variadic":
-				// The //go:variadic pragma is emitted by the CGo preprocessing
-				// pass for C variadic functions. This includes both explicit
-				// (with ...) and implicit (no parameters in signature)
-				// functions.
-				if strings.HasPrefix(f.Name(), "C.") {
-					// This prefix cannot naturally be created, it must have
-					// been created as a result of CGo preprocessing.
-					info.variadic = true
-				}
-			}
-		}
-
-		// Set the importName for our exported function if we have one
-		if importName != "" {
-			if info.module == "" {
-				info.linkName = importName
-			} else {
-				// WebAssembly import
-				info.importName = importName
-			}
-		}
-
-	}
-}
-
-// getParams returns the function parameters, including the receiver at the
-// start. This is an alternative to the Params member of *ssa.Function, which is
-// not yet populated when the package has not yet been built.
-func getParams(sig *types.Signature) []*types.Var {
-	params := []*types.Var{}
-	if sig.Recv() != nil {
-		params = append(params, sig.Recv())
-	}
-	for i := 0; i < sig.Params().Len(); i++ {
-		params = append(params, sig.Params().At(i))
-	}
-	return params
-}
-
 // globalInfo contains some information about a specific global. By default,
 // linkName is equal to .RelString(nil) on a global and extern is false, but for
 // some symbols this is different (due to //go:extern for example).
@@ -318,22 +26,25 @@ type globalInfo struct {

 // 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(pkg *loader.Package) {
-	for _, file := range pkg.Files {
-		for _, decl := range file.Decls {
-			switch decl := decl.(type) {
-			case *ast.GenDecl:
-				switch decl.Tok {
-				case token.VAR:
-					if len(decl.Specs) != 1 {
-						continue
-					}
-					for _, spec := range decl.Specs {
-						switch spec := spec.(type) {
-						case *ast.ValueSpec: // decl.Tok == token.VAR
-							for _, name := range spec.Names {
-								id := pkg.Pkg.Path() + "." + name.Name
-								c.astComments[id] = decl.Doc
+func (c *compilerContext) loadASTComments(lprogram *loader.Program) {
+	c.astComments = map[string]*ast.CommentGroup{}
+	for _, pkgInfo := range lprogram.Sorted() {
+		for _, file := range pkgInfo.Files {
+			for _, decl := range file.Decls {
+				switch decl := decl.(type) {
+				case *ast.GenDecl:
+					switch decl.Tok {
+					case token.VAR:
+						if len(decl.Specs) != 1 {
+							continue
+						}
+						for _, spec := range decl.Specs {
+							switch spec := spec.(type) {
+							case *ast.ValueSpec: // decl.Tok == token.VAR
+								for _, name := range spec.Names {
+									id := pkgInfo.Pkg.Path() + "." + name.Name
+									c.astComments[id] = decl.Doc
+								}
 							}
 						}
 					}
@@ -352,6 +63,10 @@ func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
 		typ := g.Type().(*types.Pointer).Elem()
 		llvmType := c.getLLVMType(typ)
 		llvmGlobal = llvm.AddGlobal(c.mod, llvmType, info.linkName)
+		if !info.extern {
+			llvmGlobal.SetInitializer(llvm.ConstNull(llvmType))
+			llvmGlobal.SetLinkage(llvm.InternalLinkage)
+		}

 		// Set alignment from the //go:align comment.
 		var alignInBits uint32
@@ -367,9 +82,11 @@ func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
 			}
 		}

-		if c.Debug && !info.extern {
+		if c.Debug() && !info.extern {
 			// Add debug info.
-			pos := c.program.Fset.Position(g.Pos())
+			// 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,
@@ -428,23 +145,3 @@ func (info *globalInfo) parsePragmas(doc *ast.CommentGroup) {
 		}
 	}
 }
-
-// Get all methods of a type.
-func getAllMethods(prog *ssa.Program, typ types.Type) []*types.Selection {
-	ms := prog.MethodSets.MethodSet(typ)
-	methods := make([]*types.Selection, ms.Len())
-	for i := 0; i < ms.Len(); i++ {
-		methods[i] = ms.At(i)
-	}
-	return methods
-}
-
-// Return true if this package imports "unsafe", false otherwise.
-func hasUnsafeImport(pkg *types.Package) bool {
-	for _, imp := range pkg.Imports() {
-		if imp == types.Unsafe {
-			return true
-		}
-	}
-	return false
-}
@@ -16,8 +16,8 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 	num := b.getValue(call.Args[0])
 	var syscallResult llvm.Value
 	switch {
-	case b.GOARCH == "amd64":
-		if b.GOOS == "darwin" {
+	case b.GOARCH() == "amd64":
+		if b.GOOS() == "darwin" {
 			// Darwin adds this magic number to system call numbers:
 			//
 			// > Syscall classes for 64-bit system call entry.
@@ -58,7 +58,7 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		fnType := llvm.FunctionType(b.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":
+	case b.GOARCH() == "386" && b.GOOS() == "linux":
 		// Sources:
 		//   syscall(2) man page
 		//   https://stackoverflow.com/a/2538212
@@ -84,7 +84,7 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		fnType := llvm.FunctionType(b.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":
+	case b.GOARCH() == "arm" && b.GOOS() == "linux":
 		// Implement the EABI system call convention for Linux.
 		// Source: syscall(2) man page.
 		args := []llvm.Value{}
@@ -116,7 +116,7 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		fnType := llvm.FunctionType(b.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":
+	case b.GOARCH() == "arm64" && b.GOOS() == "linux":
 		// Source: syscall(2) man page.
 		args := []llvm.Value{}
 		argTypes := []llvm.Type{}
@@ -149,9 +149,9 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
 		syscallResult = b.CreateCall(target, args, "")
 	default:
-		return llvm.Value{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS+"/"+b.GOARCH)
+		return llvm.Value{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS()+"/"+b.GOARCH())
 	}
-	switch b.GOOS {
+	switch b.GOOS() {
 	case "linux", "freebsd":
 		// Return values: r0, r1 uintptr, err Errno
 		// Pseudocode:
@@ -187,6 +187,6 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		retval = b.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{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS()+"/"+b.GOARCH())
 	}
 }
@@ -1,57 +0,0 @@
-package main
-
-// Basic tests that don't need to be split into a separate file.
-
-func addInt(x, y int) int {
-	return x + y
-}
-
-func equalInt(x, y int) bool {
-	return x == y
-}
-
-func floatEQ(x, y float32) bool {
-	return x == y
-}
-
-func floatNE(x, y float32) bool {
-	return x != y
-}
-
-func floatLower(x, y float32) bool {
-	return x < y
-}
-
-func floatLowerEqual(x, y float32) bool {
-	return x <= y
-}
-
-func floatGreater(x, y float32) bool {
-	return x > y
-}
-
-func floatGreaterEqual(x, y float32) bool {
-	return x >= y
-}
-
-func complexReal(x complex64) float32 {
-	return real(x)
-}
-
-func complexImag(x complex64) float32 {
-	return imag(x)
-}
-
-func complexAdd(x, y complex64) complex64 {
-	return x + y
-}
-
-func complexSub(x, y complex64) complex64 {
-	return x - y
-}
-
-func complexMul(x, y complex64) complex64 {
-	return x * y
-}
-
-// TODO: complexDiv (requires runtime call)
@@ -1,100 +0,0 @@
-; ModuleID = 'basic.go'
-source_filename = "basic.go"
-target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
-target triple = "i686--linux"
-
-declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
-
-define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret void
-}
-
-define hidden i32 @main.addInt(i32 %x, i32 %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = add i32 %x, %y
-  ret i32 %0
-}
-
-define hidden i1 @main.equalInt(i32 %x, i32 %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = icmp eq i32 %x, %y
-  ret i1 %0
-}
-
-define hidden i1 @main.floatEQ(float %x, float %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fcmp oeq float %x, %y
-  ret i1 %0
-}
-
-define hidden i1 @main.floatNE(float %x, float %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fcmp une float %x, %y
-  ret i1 %0
-}
-
-define hidden i1 @main.floatLower(float %x, float %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fcmp olt float %x, %y
-  ret i1 %0
-}
-
-define hidden i1 @main.floatLowerEqual(float %x, float %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fcmp ole float %x, %y
-  ret i1 %0
-}
-
-define hidden i1 @main.floatGreater(float %x, float %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fcmp ogt float %x, %y
-  ret i1 %0
-}
-
-define hidden i1 @main.floatGreaterEqual(float %x, float %y, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fcmp oge float %x, %y
-  ret i1 %0
-}
-
-define hidden float @main.complexReal(float %x.r, float %x.i, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret float %x.r
-}
-
-define hidden float @main.complexImag(float %x.r, float %x.i, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret float %x.i
-}
-
-define hidden { float, float } @main.complexAdd(float %x.r, float %x.i, float %y.r, float %y.i, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fadd float %x.r, %y.r
-  %1 = fadd float %x.i, %y.i
-  %2 = insertvalue { float, float } undef, float %0, 0
-  %3 = insertvalue { float, float } %2, float %1, 1
-  ret { float, float } %3
-}
-
-define hidden { float, float } @main.complexSub(float %x.r, float %x.i, float %y.r, float %y.i, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fsub float %x.r, %y.r
-  %1 = fsub float %x.i, %y.i
-  %2 = insertvalue { float, float } undef, float %0, 0
-  %3 = insertvalue { float, float } %2, float %1, 1
-  ret { float, float } %3
-}
-
-define hidden { float, float } @main.complexMul(float %x.r, float %x.i, float %y.r, float %y.i, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = fmul float %x.r, %y.r
-  %1 = fmul float %x.i, %y.i
-  %2 = fsub float %0, %1
-  %3 = fmul float %x.r, %y.i
-  %4 = fmul float %x.i, %y.r
-  %5 = fadd float %3, %4
-  %6 = insertvalue { float, float } undef, float %2, 0
-  %7 = insertvalue { float, float } %6, float %5, 1
-  ret { float, float } %7
-}
@@ -1,39 +0,0 @@
-package main
-
-// Test converting floats to ints.
-
-func f32tou32(v float32) uint32 {
-	return uint32(v)
-}
-
-func maxu32f() float32 {
-	return float32(^uint32(0))
-}
-
-func maxu32tof32() uint32 {
-	f := float32(^uint32(0))
-	return uint32(f)
-}
-
-func inftoi32() (uint32, uint32, int32, int32) {
-	inf := 1.0
-	inf /= 0.0
-
-	return uint32(inf), uint32(-inf), int32(inf), int32(-inf)
-}
-
-func u32tof32tou32(v uint32) uint32 {
-	return uint32(float32(v))
-}
-
-func f32tou32tof32(v float32) float32 {
-	return float32(uint32(v))
-}
-
-func f32tou8(v float32) uint8 {
-	return uint8(v)
-}
-
-func f32toi8(v float32) int8 {
-	return int8(v)
-}
@@ -1,82 +0,0 @@
-; ModuleID = 'float.go'
-source_filename = "float.go"
-target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
-target triple = "i686--linux"
-
-declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
-
-define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret void
-}
-
-define hidden i32 @main.f32tou32(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %positive = fcmp oge float %v, 0.000000e+00
-  %withinmax = fcmp ole float %v, 0x41EFFFFFC0000000
-  %inbounds = and i1 %positive, %withinmax
-  %saturated = sext i1 %positive to i32
-  %normal = fptoui float %v to i32
-  %0 = select i1 %inbounds, i32 %normal, i32 %saturated
-  ret i32 %0
-}
-
-define hidden float @main.maxu32f(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret float 0x41F0000000000000
-}
-
-define hidden i32 @main.maxu32tof32(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret i32 -1
-}
-
-define hidden { i32, i32, i32, i32 } @main.inftoi32(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret { i32, i32, i32, i32 } { i32 -1, i32 0, i32 2147483647, i32 -2147483648 }
-}
-
-define hidden i32 @main.u32tof32tou32(i32 %v, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = uitofp i32 %v to float
-  %withinmax = fcmp ole float %0, 0x41EFFFFFC0000000
-  %normal = fptoui float %0 to i32
-  %1 = select i1 %withinmax, i32 %normal, i32 -1
-  ret i32 %1
-}
-
-define hidden float @main.f32tou32tof32(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %positive = fcmp oge float %v, 0.000000e+00
-  %withinmax = fcmp ole float %v, 0x41EFFFFFC0000000
-  %inbounds = and i1 %positive, %withinmax
-  %saturated = sext i1 %positive to i32
-  %normal = fptoui float %v to i32
-  %0 = select i1 %inbounds, i32 %normal, i32 %saturated
-  %1 = uitofp i32 %0 to float
-  ret float %1
-}
-
-define hidden i8 @main.f32tou8(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %positive = fcmp oge float %v, 0.000000e+00
-  %withinmax = fcmp ole float %v, 2.550000e+02
-  %inbounds = and i1 %positive, %withinmax
-  %saturated = sext i1 %positive to i8
-  %normal = fptoui float %v to i8
-  %0 = select i1 %inbounds, i8 %normal, i8 %saturated
-  ret i8 %0
-}
-
-define hidden i8 @main.f32toi8(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %abovemin = fcmp oge float %v, -1.280000e+02
-  %belowmax = fcmp ole float %v, 1.270000e+02
-  %inbounds = and i1 %abovemin, %belowmax
-  %saturated = select i1 %abovemin, i8 127, i8 -128
-  %isnan = fcmp uno float %v, 0.000000e+00
-  %remapped = select i1 %isnan, i8 0, i8 %saturated
-  %normal = fptosi float %v to i8
-  %0 = select i1 %inbounds, i8 %normal, i8 %remapped
-  ret i8 %0
-}
@@ -1,41 +0,0 @@
-package main
-
-// This file tests various operations on pointers, such as pointer arithmetic
-// and dereferencing pointers.
-
-import "unsafe"
-
-// Dereference pointers.
-
-func pointerDerefZero(x *[0]int) [0]int {
-	return *x // This is a no-op, there is nothing to load.
-}
-
-// Unsafe pointer casts, they are sometimes a no-op.
-
-func pointerCastFromUnsafe(x unsafe.Pointer) *int {
-	return (*int)(x)
-}
-
-func pointerCastToUnsafe(x *int) unsafe.Pointer {
-	return unsafe.Pointer(x)
-}
-
-func pointerCastToUnsafeNoop(x *byte) unsafe.Pointer {
-	return unsafe.Pointer(x)
-}
-
-// The compiler has support for a few special cast+add patterns that are
-// transformed into a single GEP.
-
-func pointerUnsafeGEPFixedOffset(ptr *byte) *byte {
-	return (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + 10))
-}
-
-func pointerUnsafeGEPByteOffset(ptr *byte, offset uintptr) *byte {
-	return (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + offset))
-}
-
-func pointerUnsafeGEPIntOffset(ptr *int32, offset uintptr) *int32 {
-	return (*int32)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + offset*4))
-}
@@ -1,51 +0,0 @@
-; ModuleID = 'pointer.go'
-source_filename = "pointer.go"
-target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
-target triple = "i686--linux"
-
-declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
-
-define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret void
-}
-
-define hidden [0 x i32] @main.pointerDerefZero([0 x i32]* %x, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret [0 x i32] zeroinitializer
-}
-
-define hidden i32* @main.pointerCastFromUnsafe(i8* %x, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = bitcast i8* %x to i32*
-  ret i32* %0
-}
-
-define hidden i8* @main.pointerCastToUnsafe(i32* dereferenceable_or_null(4) %x, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = bitcast i32* %x to i8*
-  ret i8* %0
-}
-
-define hidden i8* @main.pointerCastToUnsafeNoop(i8* dereferenceable_or_null(1) %x, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret i8* %x
-}
-
-define hidden i8* @main.pointerUnsafeGEPFixedOffset(i8* dereferenceable_or_null(1) %ptr, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = getelementptr inbounds i8, i8* %ptr, i32 10
-  ret i8* %0
-}
-
-define hidden i8* @main.pointerUnsafeGEPByteOffset(i8* dereferenceable_or_null(1) %ptr, i32 %offset, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = getelementptr inbounds i8, i8* %ptr, i32 %offset
-  ret i8* %0
-}
-
-define hidden i32* @main.pointerUnsafeGEPIntOffset(i32* dereferenceable_or_null(4) %ptr, i32 %offset, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  %0 = getelementptr i32, i32* %ptr, i32 %offset
-  ret i32* %0
-}
@@ -1,9 +0,0 @@
-package main
-
-func sliceLen(ints []int) int {
-	return len(ints)
-}
-
-func sliceCap(ints []int) int {
-	return cap(ints)
-}
@@ -1,21 +0,0 @@
-; ModuleID = 'slice.go'
-source_filename = "slice.go"
-target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
-target triple = "i686--linux"
-
-declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
-
-define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret void
-}
-
-define hidden i32 @main.sliceLen(i32* %ints.data, i32 %ints.len, i32 %ints.cap, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret i32 %ints.len
-}
-
-define hidden i32 @main.sliceCap(i32* %ints.data, i32 %ints.len, i32 %ints.cap, i8* %context, i8* %parentHandle) unnamed_addr {
-entry:
-  ret i32 %ints.cap
-}
@@ -1,16 +1,13 @@
 module github.com/tinygo-org/tinygo

-go 1.13
+go 1.11

 require (
 	github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2
-	github.com/chromedp/cdproto v0.0.0-20210113043257-dabd2f2e7693
-	github.com/chromedp/chromedp v0.6.4
 	github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf
-	github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892
-	github.com/mattn/go-colorable v0.1.8
-	go.bug.st/serial v1.1.2
-	golang.org/x/sys v0.0.0-20210113181707-4bcb84eeeb78
+	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
-	tinygo.org/x/go-llvm v0.0.0-20210308112806-9ef958b6bed4
+	google.golang.org/appengine v1.4.0 // indirect
+	tinygo.org/x/go-llvm v0.0.0-20200401165421-8d120882fc7a
 )
@@ -1,61 +1,59 @@
 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/chromedp/cdproto v0.0.0-20210113043257-dabd2f2e7693 h1:11eq/RkpaotwdF6b1TRMcdgQUPNmyFEJOB7zLvh0O/Y=
-github.com/chromedp/cdproto v0.0.0-20210113043257-dabd2f2e7693/go.mod h1:55pim6Ht4LJKdVLlyFJV/g++HsEA1hQxPbB5JyNdZC0=
-github.com/chromedp/chromedp v0.6.4 h1:Gx7ZkRyrSVmbbDDja/ieNgNGJIvElroPOyeqYQGVDSY=
-github.com/chromedp/chromedp v0.6.4/go.mod h1:vodUdJf5dF/b8n0UBJv6NeM/QK28RjP3j+eM7fq4+84=
-github.com/chromedp/sysutil v1.0.0 h1:+ZxhTpfpZlmchB58ih/LBHX52ky7w2VhQVKQMucy3Ic=
-github.com/chromedp/sysutil v1.0.0/go.mod h1:kgWmDdq8fTzXYcKIBqIYvRRTnYb9aNS9moAV0xufSww=
 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/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
-github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
-github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
-github.com/gobwas/pool v0.2.1/go.mod h1:q8bcK0KcYlCgd9e7WYLm9LpyS+YeLd8JVDW6WezmKEw=
-github.com/gobwas/ws v1.0.4 h1:5eXU1CZhpQdq5kXbKb+sECH5Ia5KiO6CYzIzdlVx6Bs=
-github.com/gobwas/ws v1.0.4/go.mod h1:szmBTxLgaFppYjEmNtny/v3w89xOydFnnZMcgRRu/EM=
+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/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
-github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
-github.com/mailru/easyjson v0.7.6 h1:8yTIVnZgCoiM1TgqoeTl+LfU5Jg6/xL3QhGQnimLYnA=
-github.com/mailru/easyjson v0.7.6/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
-github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892 h1:6J+qramlHVLmiBOgRiBOnQkno8uprqG6YFFQTt6uYIw=
-github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892/go.mod h1:Pb6XcsXyropB9LNHhnqaknG/vEwYztLkQzVCHv8sQ3M=
-github.com/mattn/go-colorable v0.1.8 h1:c1ghPdyEDarC70ftn0y+A/Ee++9zz8ljHG1b13eJ0s8=
-github.com/mattn/go-colorable v0.1.8/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
-github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
-github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+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=
-go.bug.st/serial v1.1.2 h1:6xDpbta8KJ+VLRTeM8ghhxXRMLE/Lr8h9iDKwydarAY=
-go.bug.st/serial v1.1.2/go.mod h1:VmYBeyJWp5BnJ0tw2NUJHZdJTGl2ecBGABHlzRK1knY=
 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/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200909081042-eff7692f9009/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210113181707-4bcb84eeeb78 h1:nVuTkr9L6Bq62qpUqKo/RnZCFfzDBL0bYo6w9OJUqZY=
-golang.org/x/sys v0.0.0-20210113181707-4bcb84eeeb78/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 v0.0.0-20210308112806-9ef958b6bed4 h1:CMUHxVTb+UuUePuMf8vkWjZ3gTp9BBK91KrgOCwoNHs=
-tinygo.org/x/go-llvm v0.0.0-20210308112806-9ef958b6bed4/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
+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=
@@ -142,11 +142,10 @@ func getHomeDir() string {
 // getGoroot returns an appropriate GOROOT from various sources. If it can't be
 // found, it returns an empty string.
 func getGoroot() string {
-	// An explicitly set GOROOT always has preference.
 	goroot := os.Getenv("GOROOT")
 	if goroot != "" {
-		// Convert to the standard GOROOT being referenced, if it's a TinyGo cache.
-		return getStandardGoroot(goroot)
+		// An explicitly set GOROOT always has preference.
+		return goroot
 	}

 	// Check for the location of the 'go' binary and base GOROOT on that.
@@ -196,21 +195,3 @@ func isGoroot(goroot string) bool {
 	_, err := os.Stat(filepath.Join(goroot, "src", "runtime", "internal", "sys", "zversion.go"))
 	return err == nil
 }
-
-// getStandardGoroot returns the physical path to a real, standard Go GOROOT
-// implied by the given path.
-// If the given path appears to be a TinyGo cached GOROOT, it returns the path
-// referenced by symlinks contained in the cache. Otherwise, it returns the
-// given path as-is.
-func getStandardGoroot(path string) string {
-	// Check if the "bin" subdirectory of our given GOROOT is a symlink, and then
-	// return the _parent_ directory of its destination.
-	if dest, err := os.Readlink(filepath.Join(path, "bin")); nil == err {
-		// Clean the destination to remove any trailing slashes, so that
-		// filepath.Dir will always return the parent.
-		//   (because both "/foo" and "/foo/" are valid symlink destinations,
-		//   but filepath.Dir would return "/" and "/foo", respectively)
-		return filepath.Dir(filepath.Clean(dest))
-	}
-	return path
-}
@@ -10,10 +10,6 @@ import (
 	"strings"
 )

-// Version of TinyGo.
-// Update this value before release of new version of software.
-const Version = "0.18.0-dev"
-
 // 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) {
@@ -1,5 +0,0 @@
-# Hooks for Docker Hub
-
-Files in this directory are custom commands to be run during the different Docker Hub build phases.
-
-See https://docs.docker.com/docker-hub/builds/advanced/#custom-build-phase-hooks
@@ -1,4 +0,0 @@
-#!/bin/bash
-# Docker hub does a recursive clone, then checks the branch out,
-# so when a PR adds a submodule (or updates it), it fails.
-git submodule update --init
@@ -6,81 +6,50 @@ possible and only run unknown expressions (e.g. external calls) at runtime. This
 is in practice a partial evaluator of the `runtime.initAll` function, which
 calls each package initializer.

-This package is a rewrite of a previous partial evaluator that worked
-directly on LLVM IR and used the module and LLVM constants as intermediate
-values. This newer version instead uses a mostly Go intermediate form. It
-compiles functions and extracts relevant data first (compiler.go), then
-executes those functions (interpreter.go) in a memory space that can be
-rolled back per function (memory.go). This means that it is not necessary to
-scan functions to see whether they can be run at compile time, which was very
-error prone. Instead it just tries to execute everything and if it hits
-something it cannot interpret (such as a store to memory-mapped I/O) it rolls
-back the execution of that function and runs the function at runtime instead.
-All in all, this design provides several benefits:
+It works by directly interpreting LLVM IR:

-  * Much better error handling. By being able to revert to runtime execution
-    without the need for scanning functions, this version is able to
-    automatically work around many bugs in the previous implementation.
-  * More correct memory model. This is not inherent to the new design, but the
-    new design also made the memory model easier to reason about.
-  * Faster execution of initialization code. While it is not much faster for
-    normal interpretation (maybe 25% or so) due to the compilation overhead,
-    it should be a whole lot faster for loops as it doesn't have to call into
-    LLVM (via CGo) for every operation.
-
-As mentioned, this partial evaulator comes in three parts: a compiler, an
-interpreter, and a memory manager.
-
-## Compiler
-
-The main task of the compiler is that it extracts all necessary data from
-every instruction in a function so that when this instruction is interpreted,
-no additional CGo calls are necessary. This is not currently done for all
-instructions (`runtime.alloc` is a notable exception), but at least it does
-so for the vast majority of instructions.
-
-## Interpreter
-
-The interpreter runs an instruction just like it would if it were executed
-'for real'. The vast majority of instructions can be executed at compile
-time. As indicated above, some instructions need to be executed at runtime
-instead.
-
-## Memory
-
-Memory is represented as objects (the `object` type) that contains data that
-will eventually be stored in a global and values (the `value` interface) that
-can be worked with while running the interpreter. Values therefore are only
-used locally and are always passed by value (just like most LLVM constants)
-while objects represent the backing storage (like LLVM globals). Some values
-are pointer values, and point to an object.
-
-Importantly, this partial evaluator can roll back the execution of a
-function. This is implemented by creating a new memory view per function
-activation, which makes sure that any change to a global (such as a store
-instruction) is stored in the memory view. It creates a copy of the object
-and stores that in the memory view to be modified. Once the function has
-executed successfully, all these modified objects are then copied into the
-parent function, up to the root function invocation which (on successful
-execution) writes the values back into the LLVM module. This way, function
-invocations can be rolled back without leaving a trace.
-
-Pointer values point to memory objects, but not to a particular memory
-object. Every memory object is given an index, and pointers use that index to
-look up the current active object for the pointer to load from or to copy
-when storing to it.
-
-Rolling back a function should roll back everyting, including the few
-instructions emitted at runtime. This is done by treating instructions much
-like memory objects and removing the created instructions when necessary.
+  * Almost all operations work directly on constants, and are implemented using
+    the llvm.Const* set of functions that are evaluated directly.
+  * External function calls and some other operations (inline assembly, volatile
+    load, volatile store) are seen as having limited side effects. Limited in
+    the sense that it is known at compile time which globals it affects, which
+    then are marked 'dirty' (meaning, further operations on it must be done at
+    runtime). These operations are emitted directly in the `runtime.initAll`
+    function. Return values are also considered 'dirty'.
+  * Such 'dirty' objects and local values must be executed at runtime instead of
+    at compile time. This dirtyness propagates further through the IR, for
+    example storing a dirty local value to a global also makes the global dirty,
+    meaning that the global may not be read or written at compile time as it's
+    contents at that point during interpretation is unknown.
+  * There are some heuristics in place to avoid doing too much with dirty
+    values. For example, a branch based on a dirty local marks the whole
+    function itself as having side effect (as if it is an external function).
+    However, all globals it touches are still taken into account and when a call
+    is inserted in `runtime.initAll`, all globals it references are also marked
+    dirty.
+  * Heap allocation (`runtime.alloc`) is emulated by creating new objects. The
+    value in the allocation is the initializer of the global, the zero value is
+    the zero initializer.
+  * Stack allocation (`alloca`) is often emulated using a fake alloca object,
+    until the address of the alloca is taken in which case it is also created as
+    a real `alloca` in `runtime.initAll` and marked dirty. This may be necessary
+    when calling an external function with the given alloca as paramter.

 ## Why is this necessary?

 A partial evaluator is hard to get right, so why go through all the trouble of
 writing one?

-The answer is that globals with initializers are much easier to optimize by
-LLVM than initialization code. Also, there are a few other benefits:
+The main reason is that the previous attempt wasn't complete and wasn't sound.
+It simply tried to evaluate Go SSA directly, which was good but more difficult
+than necessary. An IR based interpreter needs to understand fewer instructions
+as the LLVM IR simply has less (complex) instructions than Go SSA. Also, LLVM
+provides some useful tools like easily getting all uses of a function or global,
+which Go SSA does not provide.
+
+But why is it necessary at all? The answer is that globals with initializers are
+much easier to optimize by LLVM than initialization code. Also, there are a few
+other benefits:

  * Dead globals are trivial to optimize away.
  * Constant globals are easier to detect. Remember that Go does not have global
@@ -91,29 +60,5 @@ LLVM than initialization code. Also, there are a few other benefits:
  * Constants are much more efficent on microcontrollers, as they can be
    allocated in flash instead of RAM.

-The Go SSA package does not create constant initializers for globals.
-Instead, it emits initialization functions, so if you write the following:
-
-```go
-var foo = []byte{1, 2, 3, 4}
-```
-
-It would generate something like this:
-
-```go
-var foo []byte
-
-func init() {
-    foo = make([]byte, 4)
-    foo[0] = 1
-    foo[1] = 2
-    foo[2] = 3
-    foo[3] = 4
-}
-```
-
-This is of course hugely wasteful, it's much better to create `foo` as a
-global array instead of initializing it at runtime.
-
 For more details, see [this section of the
 documentation](https://tinygo.org/compiler-internals/differences-from-go/).
@@ -1,410 +0,0 @@
-package interp
-
-// This file compiles the LLVM IR to a form that's easy to efficiently
-// interpret.
-
-import (
-	"strings"
-
-	"tinygo.org/x/go-llvm"
-)
-
-// A function is a compiled LLVM function, which means that interpreting it
-// avoids most CGo calls necessary. This is done in a separate step so the
-// result can be cached.
-// Functions are in SSA form, just like the LLVM version if it. The first block
-// (blocks[0]) is the entry block.
-type function struct {
-	llvmFn llvm.Value
-	name   string       // precalculated llvmFn.Name()
-	params []llvm.Value // precalculated llvmFn.Params()
-	blocks []*basicBlock
-	locals map[llvm.Value]int
-}
-
-// basicBlock represents a LLVM basic block and contains a slice of
-// instructions. The last instruction must be a terminator instruction.
-type basicBlock struct {
-	instructions []instruction
-}
-
-// instruction is a precompiled LLVM IR instruction. The operands can be either
-// an already known value (such as literalValue or pointerValue) but can also be
-// the special localValue, which means that the value is a function parameter or
-// is produced by another instruction in the function. In that case, the
-// interpreter will replace the operand with that local value.
-type instruction struct {
-	opcode     llvm.Opcode
-	localIndex int
-	operands   []value
-	llvmInst   llvm.Value
-	name       string
-}
-
-// String returns a nice human-readable version of this instruction.
-func (inst *instruction) String() string {
-	operands := make([]string, len(inst.operands))
-	for i, op := range inst.operands {
-		operands[i] = op.String()
-	}
-
-	name := instructionNameMap[inst.opcode]
-	if name == "" {
-		name = "<unknown op>"
-	}
-	return name + " " + strings.Join(operands, " ")
-}
-
-// compileFunction compiles a given LLVM function to an easier to interpret
-// version of the function. As far as possible, all operands are preprocessed so
-// that the interpreter doesn't have to call into LLVM.
-func (r *runner) compileFunction(llvmFn llvm.Value) *function {
-	fn := &function{
-		llvmFn: llvmFn,
-		name:   llvmFn.Name(),
-		params: llvmFn.Params(),
-		locals: make(map[llvm.Value]int),
-	}
-	if llvmFn.IsDeclaration() {
-		// Nothing to do.
-		return fn
-	}
-
-	for i, param := range fn.params {
-		fn.locals[param] = i
-	}
-
-	// Make a map of all the blocks, to quickly find the block number for a
-	// given branch instruction.
-	blockIndices := make(map[llvm.Value]int)
-	for llvmBB := llvmFn.FirstBasicBlock(); !llvmBB.IsNil(); llvmBB = llvm.NextBasicBlock(llvmBB) {
-		index := len(blockIndices)
-		blockIndices[llvmBB.AsValue()] = index
-	}
-
-	// Compile every block.
-	for llvmBB := llvmFn.FirstBasicBlock(); !llvmBB.IsNil(); llvmBB = llvm.NextBasicBlock(llvmBB) {
-		bb := &basicBlock{}
-		fn.blocks = append(fn.blocks, bb)
-
-		// Compile every instruction in the block.
-		for llvmInst := llvmBB.FirstInstruction(); !llvmInst.IsNil(); llvmInst = llvm.NextInstruction(llvmInst) {
-			// Create instruction skeleton.
-			opcode := llvmInst.InstructionOpcode()
-			inst := instruction{
-				opcode:     opcode,
-				localIndex: len(fn.locals),
-				llvmInst:   llvmInst,
-			}
-			fn.locals[llvmInst] = len(fn.locals)
-
-			// Add operands specific for this instruction.
-			switch opcode {
-			case llvm.Ret:
-				// Return instruction, which can either be a `ret void` (no
-				// return value) or return a value.
-				numOperands := llvmInst.OperandsCount()
-				if numOperands != 0 {
-					inst.operands = []value{
-						r.getValue(llvmInst.Operand(0)),
-					}
-				}
-			case llvm.Br:
-				// Branch instruction. Can be either a conditional branch (with
-				// 3 operands) or unconditional branch (with just one basic
-				// block operand).
-				numOperands := llvmInst.OperandsCount()
-				switch numOperands {
-				case 3:
-					// Conditional jump to one of two blocks. Comparable to an
-					// if/else in procedural languages.
-					thenBB := llvmInst.Operand(2)
-					elseBB := llvmInst.Operand(1)
-					inst.operands = []value{
-						r.getValue(llvmInst.Operand(0)),
-						literalValue{uint32(blockIndices[thenBB])},
-						literalValue{uint32(blockIndices[elseBB])},
-					}
-				case 1:
-					// Unconditional jump to a target basic block. Comparable to
-					// a jump in C and Go.
-					jumpBB := llvmInst.Operand(0)
-					inst.operands = []value{
-						literalValue{uint32(blockIndices[jumpBB])},
-					}
-				default:
-					panic("unknown number of operands")
-				}
-			case llvm.PHI:
-				inst.name = llvmInst.Name()
-				incomingCount := inst.llvmInst.IncomingCount()
-				for i := 0; i < incomingCount; i++ {
-					incomingBB := inst.llvmInst.IncomingBlock(i)
-					incomingValue := inst.llvmInst.IncomingValue(i)
-					inst.operands = append(inst.operands,
-						literalValue{uint32(blockIndices[incomingBB.AsValue()])},
-						r.getValue(incomingValue),
-					)
-				}
-			case llvm.Select:
-				// Select is a special instruction that is much like a ternary
-				// operator. It produces operand 1 or 2 based on the boolean
-				// that is operand 0.
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					r.getValue(llvmInst.Operand(1)),
-					r.getValue(llvmInst.Operand(2)),
-				}
-			case llvm.Call:
-				// Call is a regular function call but could also be a runtime
-				// intrinsic. Some runtime intrinsics are treated specially by
-				// the interpreter, such as runtime.alloc. We don't
-				// differentiate between them here because these calls may also
-				// need to be run at runtime, in which case they should all be
-				// created in the same way.
-				llvmCalledValue := llvmInst.CalledValue()
-				if !llvmCalledValue.IsAFunction().IsNil() {
-					name := llvmCalledValue.Name()
-					if name == "llvm.dbg.value" || strings.HasPrefix(name, "llvm.lifetime.") {
-						// These intrinsics should not be interpreted, they are not
-						// relevant to the execution of this function.
-						continue
-					}
-				}
-				inst.name = llvmInst.Name()
-				numOperands := llvmInst.OperandsCount()
-				inst.operands = append(inst.operands, r.getValue(llvmCalledValue))
-				for i := 0; i < numOperands-1; i++ {
-					inst.operands = append(inst.operands, r.getValue(llvmInst.Operand(i)))
-				}
-			case llvm.Load:
-				// Load instruction. The interpreter will load from the
-				// appropriate memory view.
-				// Also provide the memory size to be loaded, which is necessary
-				// with a lack of type information.
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					literalValue{r.targetData.TypeAllocSize(llvmInst.Type())},
-				}
-			case llvm.Store:
-				// Store instruction. The interpreter will create a new object
-				// in the memory view of the function invocation and store to
-				// that, to make it possible to roll back this store.
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					r.getValue(llvmInst.Operand(1)),
-				}
-			case llvm.Alloca:
-				// Alloca allocates stack space for local variables.
-				numElements := r.getValue(inst.llvmInst.Operand(0)).(literalValue).value.(uint32)
-				elementSize := r.targetData.TypeAllocSize(inst.llvmInst.Type().ElementType())
-				inst.operands = []value{
-					literalValue{elementSize * uint64(numElements)},
-				}
-			case llvm.GetElementPtr:
-				// GetElementPtr does pointer arithmetic.
-				inst.name = llvmInst.Name()
-				ptr := llvmInst.Operand(0)
-				n := llvmInst.OperandsCount()
-				elementType := ptr.Type().ElementType()
-				// gep: [source ptr, dest value size, pairs of indices...]
-				inst.operands = []value{
-					r.getValue(ptr),
-					literalValue{r.targetData.TypeAllocSize(llvmInst.Type().ElementType())},
-					r.getValue(llvmInst.Operand(1)),
-					literalValue{r.targetData.TypeAllocSize(elementType)},
-				}
-				for i := 2; i < n; i++ {
-					operand := r.getValue(llvmInst.Operand(i))
-					if elementType.TypeKind() == llvm.StructTypeKind {
-						index := operand.(literalValue).value.(uint32)
-						elementOffset := r.targetData.ElementOffset(elementType, int(index))
-						// Encode operands in a special way. The elementOffset
-						// is just the offset in bytes. The elementSize is a
-						// negative number (when cast to a int64) by flipping
-						// all the bits. This allows the interpreter to detect
-						// this is a struct field and that it should not
-						// multiply it with the elementOffset to get the offset.
-						// It is important for the interpreter to know the
-						// struct field index for when the GEP must be done at
-						// runtime.
-						inst.operands = append(inst.operands, literalValue{elementOffset}, literalValue{^uint64(index)})
-						elementType = elementType.StructElementTypes()[index]
-					} else {
-						elementType = elementType.ElementType()
-						elementSize := r.targetData.TypeAllocSize(elementType)
-						elementSizeOperand := literalValue{elementSize}
-						// Add operand * elementSizeOperand bytes to the pointer.
-						inst.operands = append(inst.operands, operand, elementSizeOperand)
-					}
-				}
-			case llvm.BitCast, llvm.IntToPtr, llvm.PtrToInt:
-				// Bitcasts are ususally used to cast a pointer from one type to
-				// another leaving the pointer itself intact.
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-				}
-			case llvm.ExtractValue:
-				inst.name = llvmInst.Name()
-				agg := llvmInst.Operand(0)
-				var offset uint64
-				indexingType := agg.Type()
-				for _, index := range inst.llvmInst.Indices() {
-					switch indexingType.TypeKind() {
-					case llvm.StructTypeKind:
-						offset += r.targetData.ElementOffset(indexingType, int(index))
-						indexingType = indexingType.StructElementTypes()[index]
-					default: // ArrayTypeKind
-						indexingType = indexingType.ElementType()
-						elementSize := r.targetData.TypeAllocSize(indexingType)
-						offset += elementSize * uint64(index)
-					}
-				}
-				size := r.targetData.TypeAllocSize(inst.llvmInst.Type())
-				// extractvalue [agg, byteOffset, byteSize]
-				inst.operands = []value{
-					r.getValue(agg),
-					literalValue{offset},
-					literalValue{size},
-				}
-			case llvm.InsertValue:
-				inst.name = llvmInst.Name()
-				agg := llvmInst.Operand(0)
-				var offset uint64
-				indexingType := agg.Type()
-				for _, index := range inst.llvmInst.Indices() {
-					switch indexingType.TypeKind() {
-					case llvm.StructTypeKind:
-						offset += r.targetData.ElementOffset(indexingType, int(index))
-						indexingType = indexingType.StructElementTypes()[index]
-					default: // ArrayTypeKind
-						indexingType = indexingType.ElementType()
-						elementSize := r.targetData.TypeAllocSize(indexingType)
-						offset += elementSize * uint64(index)
-					}
-				}
-				// insertvalue [agg, elt, byteOffset]
-				inst.operands = []value{
-					r.getValue(agg),
-					r.getValue(llvmInst.Operand(1)),
-					literalValue{offset},
-				}
-			case llvm.ICmp:
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					r.getValue(llvmInst.Operand(1)),
-					literalValue{uint8(llvmInst.IntPredicate())},
-				}
-			case llvm.FCmp:
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					r.getValue(llvmInst.Operand(1)),
-					literalValue{uint8(llvmInst.FloatPredicate())},
-				}
-			case llvm.Add, llvm.Sub, llvm.Mul, llvm.UDiv, llvm.SDiv, llvm.URem, llvm.SRem, llvm.Shl, llvm.LShr, llvm.AShr, llvm.And, llvm.Or, llvm.Xor:
-				// Integer binary operations.
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					r.getValue(llvmInst.Operand(1)),
-				}
-			case llvm.SExt, llvm.ZExt, llvm.Trunc:
-				// Extend or shrink an integer size.
-				// No sign extension going on so easy to do.
-				// zext: [value, bitwidth]
-				// trunc: [value, bitwidth]
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					literalValue{uint64(llvmInst.Type().IntTypeWidth())},
-				}
-			case llvm.SIToFP, llvm.UIToFP:
-				// Convert an integer to a floating point instruction.
-				// opcode: [value, bitwidth]
-				inst.name = llvmInst.Name()
-				inst.operands = []value{
-					r.getValue(llvmInst.Operand(0)),
-					literalValue{uint64(r.targetData.TypeAllocSize(llvmInst.Type()) * 8)},
-				}
-			default:
-				// Unknown instruction, which is already set in inst.opcode so
-				// is detectable.
-				// This error is handled when actually trying to interpret this
-				// instruction (to not trigger on code that won't be executed).
-			}
-			bb.instructions = append(bb.instructions, inst)
-		}
-	}
-	return fn
-}
-
-// instructionNameMap maps from instruction opcodes to instruction names. This
-// can be useful for debug logging.
-var instructionNameMap = [...]string{
-	llvm.Ret:         "ret",
-	llvm.Br:          "br",
-	llvm.Switch:      "switch",
-	llvm.IndirectBr:  "indirectbr",
-	llvm.Invoke:      "invoke",
-	llvm.Unreachable: "unreachable",
-
-	// Standard Binary Operators
-	llvm.Add:  "add",
-	llvm.FAdd: "fadd",
-	llvm.Sub:  "sub",
-	llvm.FSub: "fsub",
-	llvm.Mul:  "mul",
-	llvm.FMul: "fmul",
-	llvm.UDiv: "udiv",
-	llvm.SDiv: "sdiv",
-	llvm.FDiv: "fdiv",
-	llvm.URem: "urem",
-	llvm.SRem: "srem",
-	llvm.FRem: "frem",
-
-	// Logical Operators
-	llvm.Shl:  "shl",
-	llvm.LShr: "lshr",
-	llvm.AShr: "ashr",
-	llvm.And:  "and",
-	llvm.Or:   "or",
-	llvm.Xor:  "xor",
-
-	// Memory Operators
-	llvm.Alloca:        "alloca",
-	llvm.Load:          "load",
-	llvm.Store:         "store",
-	llvm.GetElementPtr: "getelementptr",
-
-	// Cast Operators
-	llvm.Trunc:    "trunc",
-	llvm.ZExt:     "zext",
-	llvm.SExt:     "sext",
-	llvm.FPToUI:   "fptoui",
-	llvm.FPToSI:   "fptosi",
-	llvm.UIToFP:   "uitofp",
-	llvm.SIToFP:   "sitofp",
-	llvm.FPTrunc:  "fptrunc",
-	llvm.FPExt:    "fpext",
-	llvm.PtrToInt: "ptrtoint",
-	llvm.IntToPtr: "inttoptr",
-	llvm.BitCast:  "bitcast",
-
-	// Other Operators
-	llvm.ICmp:           "icmp",
-	llvm.FCmp:           "fcmp",
-	llvm.PHI:            "phi",
-	llvm.Call:           "call",
-	llvm.Select:         "select",
-	llvm.VAArg:          "vaarg",
-	llvm.ExtractElement: "extractelement",
-	llvm.InsertElement:  "insertelement",
-	llvm.ShuffleVector:  "shufflevector",
-	llvm.ExtractValue:   "extractvalue",
-	llvm.InsertValue:    "insertvalue",
-}
@@ -11,17 +11,15 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// These errors are expected during normal execution and can be recovered from
-// by running the affected function at runtime instead of compile time.
-var (
-	errIntegerAsPointer       = errors.New("interp: trying to use an integer as a pointer (memory-mapped I/O?)")
-	errUnsupportedInst        = errors.New("interp: unsupported instruction")
-	errUnsupportedRuntimeInst = errors.New("interp: unsupported instruction (to be emitted at runtime)")
-	errMapAlreadyCreated      = errors.New("interp: map already created")
-)
+// 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")}

-func isRecoverableError(err error) bool {
-	return err == errIntegerAsPointer || err == errUnsupportedInst || err == errUnsupportedRuntimeInst || err == errMapAlreadyCreated
+// 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.
@@ -48,13 +46,11 @@ func (e *Error) Error() string {
 // 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 (r *runner) errorAt(inst instruction, err error) *Error {
-	pos := getPosition(inst.llvmInst)
+func (e *evalPackage) errorAt(inst llvm.Value, err error) *Error {
 	return &Error{
-		ImportPath: r.pkgName,
-		Pos:        pos,
+		ImportPath: e.packagePath,
+		Pos:        getPosition(inst),
 		Err:        err,
-		Traceback:  []ErrorLine{{pos, inst.llvmInst}},
 	}
 }

@@ -0,0 +1,680 @@
+package interp
+
+// This file implements the core interpretation routines, interpreting single
+// functions.
+
+import (
+	"errors"
+	"strings"
+
+	"tinygo.org/x/go-llvm"
+)
+
+type frame struct {
+	*evalPackage
+	fn     llvm.Value
+	locals map[llvm.Value]Value
+}
+
+// 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) {
+	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
+		if fr.Debug {
+			print(indent)
+			inst.Dump()
+			println()
+		}
+		switch {
+		case !inst.IsABinaryOperator().IsNil():
+			lhs := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
+			rhs := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
+
+			switch inst.InstructionOpcode() {
+			// Standard binary operators
+			case llvm.Add:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateAdd(lhs, rhs, "")}
+			case llvm.FAdd:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFAdd(lhs, rhs, "")}
+			case llvm.Sub:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSub(lhs, rhs, "")}
+			case llvm.FSub:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFSub(lhs, rhs, "")}
+			case llvm.Mul:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateMul(lhs, rhs, "")}
+			case llvm.FMul:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFMul(lhs, rhs, "")}
+			case llvm.UDiv:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateUDiv(lhs, rhs, "")}
+			case llvm.SDiv:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSDiv(lhs, rhs, "")}
+			case llvm.FDiv:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFDiv(lhs, rhs, "")}
+			case llvm.URem:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateURem(lhs, rhs, "")}
+			case llvm.SRem:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSRem(lhs, rhs, "")}
+			case llvm.FRem:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFRem(lhs, rhs, "")}
+
+			// Logical operators
+			case llvm.Shl:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateShl(lhs, rhs, "")}
+			case llvm.LShr:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateLShr(lhs, rhs, "")}
+			case llvm.AShr:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateAShr(lhs, rhs, "")}
+			case llvm.And:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateAnd(lhs, rhs, "")}
+			case llvm.Or:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateOr(lhs, rhs, "")}
+			case llvm.Xor:
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateXor(lhs, rhs, "")}
+
+			default:
+				return nil, nil, fr.unsupportedInstructionError(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.SetLinkage(llvm.InternalLinkage)
+			fr.locals[inst] = &LocalValue{
+				Underlying: alloca,
+				Eval:       fr.Eval,
+			}
+		case !inst.IsALoadInst().IsNil():
+			operand := fr.getLocal(inst.Operand(0)).(*LocalValue)
+			var value llvm.Value
+			if !operand.IsConstant() || inst.IsVolatile() || (!operand.Underlying.IsAConstantExpr().IsNil() && operand.Underlying.Opcode() == llvm.BitCast) {
+				value = fr.builder.CreateLoad(operand.Value(), inst.Name())
+			} else {
+				value = operand.Load()
+			}
+			if value.Type() != inst.Type() {
+				return nil, nil, fr.errorAt(inst, errors.New("interp: load: type does not match"))
+			}
+			fr.locals[inst] = fr.getValue(value)
+		case !inst.IsAStoreInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			ptr := fr.getLocal(inst.Operand(1))
+			if inst.IsVolatile() {
+				fr.builder.CreateStore(value.Value(), ptr.Value())
+			} else {
+				ptr.Store(value.Value())
+			}
+		case !inst.IsAGetElementPtrInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			llvmIndices := make([]llvm.Value, inst.OperandsCount()-1)
+			for i := range llvmIndices {
+				llvmIndices[i] = inst.Operand(i + 1)
+			}
+			indices := make([]uint32, len(llvmIndices))
+			for i, llvmIndex := range llvmIndices {
+				operand := fr.getLocal(llvmIndex)
+				if !operand.IsConstant() {
+					// 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"))
+				}
+				indices[i] = uint32(operand.Value().ZExtValue())
+			}
+			result, err := value.GetElementPtr(indices)
+			if err != nil {
+				return nil, nil, fr.errorAt(inst, err)
+			}
+			if result.Type() != inst.Type() {
+				return nil, nil, fr.errorAt(inst, errors.New("interp: gep: type does not match"))
+			}
+			fr.locals[inst] = result
+
+		// Cast operators
+		case !inst.IsATruncInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateTrunc(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAZExtInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateZExt(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsASExtInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSExt(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAFPToUIInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPToUI(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAFPToSIInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPToSI(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAUIToFPInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateUIToFP(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsASIToFPInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSIToFP(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAFPTruncInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPTrunc(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAFPExtInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPExt(value.(*LocalValue).Value(), inst.Type(), "")}
+		case !inst.IsAPtrToIntInst().IsNil():
+			value := fr.getLocal(inst.Operand(0))
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreatePtrToInt(value.Value(), inst.Type(), "")}
+		case !inst.IsABitCastInst().IsNil() && inst.Type().TypeKind() == llvm.PointerTypeKind:
+			operand := inst.Operand(0)
+			if !operand.IsACallInst().IsNil() {
+				fn := operand.CalledValue()
+				if !fn.IsAFunction().IsNil() && fn.Name() == "runtime.alloc" {
+					continue // special case: bitcast of alloc
+				}
+			}
+			if _, ok := fr.getLocal(operand).(*MapValue); ok {
+				// Special case for runtime.trackPointer calls.
+				// Note: this might not be entirely sound in some rare cases
+				// where the map is stored in a dirty global.
+				uses := getUses(inst)
+				if len(uses) == 1 {
+					use := uses[0]
+					if !use.IsACallInst().IsNil() && !use.CalledValue().IsAFunction().IsNil() && use.CalledValue().Name() == "runtime.trackPointer" {
+						continue
+					}
+				}
+				// 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"))
+			}
+			value := fr.getLocal(operand).(*LocalValue)
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateBitCast(value.Value(), inst.Type(), "")}
+
+		// Other operators
+		case !inst.IsAICmpInst().IsNil():
+			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 ok1 && ok2 {
+					if lhsZero && rhsZero {
+						// Both are zero, 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.
+						fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false)}
+						continue
+					}
+				}
+			}
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateICmp(predicate, lhs, rhs, "")}
+		case !inst.IsAFCmpInst().IsNil():
+			lhs := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
+			rhs := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
+			predicate := inst.FloatPredicate()
+			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFCmp(predicate, lhs, rhs, "")}
+		case !inst.IsAPHINode().IsNil():
+			for i := 0; i < inst.IncomingCount(); i++ {
+				if inst.IncomingBlock(i) == incoming {
+					fr.locals[inst] = fr.getLocal(inst.IncomingValue(i))
+				}
+			}
+		case !inst.IsACallInst().IsNil():
+			callee := inst.CalledValue()
+			switch {
+			case callee.Name() == "runtime.alloc":
+				// heap allocation
+				users := getUses(inst)
+				var resultInst = inst
+				if len(users) == 1 && !users[0].IsABitCastInst().IsNil() {
+					// happens when allocating something other than i8*
+					resultInst = users[0]
+				}
+				size := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying.ZExtValue()
+				allocType := resultInst.Type().ElementType()
+				typeSize := fr.TargetData.TypeAllocSize(allocType)
+				elementCount := 1
+				if size != typeSize {
+					// allocate an array
+					if size%typeSize != 0 {
+						return nil, nil, fr.unsupportedInstructionError(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.SetLinkage(llvm.InternalLinkage)
+				result := &LocalValue{
+					Underlying: alloc,
+					Eval:       fr.Eval,
+				}
+				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
+				}
+			case callee.Name() == "runtime.hashmapMake":
+				// create a map
+				keySize := inst.Operand(0).ZExtValue()
+				valueSize := inst.Operand(1).ZExtValue()
+				fr.locals[inst] = &MapValue{
+					Eval:      fr.Eval,
+					PkgName:   fr.packagePath,
+					KeySize:   int(keySize),
+					ValueSize: int(valueSize),
+				}
+			case callee.Name() == "runtime.hashmapStringSet":
+				// set a string key in the map
+				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
+				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
+				buf1Ptr := fr.getLocal(inst.Operand(0))
+				buf1Len := fr.getLocal(inst.Operand(1))
+				buf2Ptr := fr.getLocal(inst.Operand(2))
+				buf2Len := fr.getLocal(inst.Operand(3))
+				buf1 := getStringBytes(buf1Ptr, buf1Len.Value())
+				buf2 := getStringBytes(buf2Ptr, buf2Len.Value())
+				result := []byte(string(buf1) + string(buf2))
+				vals := make([]llvm.Value, len(result))
+				for i := range vals {
+					vals[i] = llvm.ConstInt(fr.Mod.Context().Int8Type(), uint64(result[i]), false)
+				}
+				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.SetInitializer(globalValue)
+				global.SetLinkage(llvm.InternalLinkage)
+				global.SetGlobalConstant(true)
+				global.SetUnnamedAddr(true)
+				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 = 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))
+				bufLen := fr.getLocal(inst.Operand(1))
+				result := getStringBytes(bufPtr, bufLen.Value())
+				vals := make([]llvm.Value, len(result))
+				for i := range vals {
+					vals[i] = llvm.ConstInt(fr.Mod.Context().Int8Type(), uint64(result[i]), false)
+				}
+				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.SetInitializer(globalValue)
+				global.SetLinkage(llvm.InternalLinkage)
+				global.SetGlobalConstant(true)
+				global.SetUnnamedAddr(true)
+				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 = 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"))
+				}
+				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"))
+				}
+				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"))
+				}
+				methodSet = methodSet.Operand(0).Initializer()
+
+				// Make a set of all the methods on the concrete type, for
+				// easier checking in the next step.
+				definedMethods := map[string]struct{}{}
+				for i := 0; i < methodSet.Type().ArrayLength(); i++ {
+					methodInfo := llvm.ConstExtractValue(methodSet, []uint32{uint32(i)})
+					name := llvm.ConstExtractValue(methodInfo, []uint32{0}).Name()
+					definedMethods[name] = struct{}{}
+				}
+				// Check whether all interface methods are also in the list
+				// of defined methods calculated above.
+				implements := uint64(1) // i1 true
+				for i := 0; i < interfaceMethodSet.Type().ArrayLength(); i++ {
+					name := llvm.ConstExtractValue(interfaceMethodSet, []uint32{uint32(i)}).Name()
+					if _, ok := definedMethods[name]; !ok {
+						// There is a method on the interface that is not
+						// implemented by the type.
+						implements = 0 // i1 false
+						break
+					}
+				}
+				fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), implements, false)}
+			case callee.Name() == "runtime.nanotime":
+				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":
+				// This are all print instructions, which necessarily have side
+				// effects but no results.
+				// TODO: print an error when executing runtime._panic (with the
+				// exact error message it would print at runtime).
+				var params []llvm.Value
+				for i := 0; i < inst.OperandsCount()-1; i++ {
+					operand := fr.getLocal(inst.Operand(i)).Value()
+					fr.markDirty(operand)
+					params = append(params, operand)
+				}
+				// TODO: accurate debug info, including call chain
+				fr.builder.CreateCall(callee, params, inst.Name())
+			case !callee.IsAFunction().IsNil() && callee.IsDeclaration():
+				// external functions
+				var params []llvm.Value
+				for i := 0; i < inst.OperandsCount()-1; i++ {
+					operand := fr.getLocal(inst.Operand(i)).Value()
+					fr.markDirty(operand)
+					params = append(params, operand)
+				}
+				// TODO: accurate debug info, including call chain
+				result := fr.builder.CreateCall(callee, params, inst.Name())
+				if inst.Type().TypeKind() != llvm.VoidTypeKind {
+					fr.markDirty(result)
+					fr.locals[inst] = &LocalValue{fr.Eval, result}
+				}
+			case !callee.IsAFunction().IsNil():
+				// regular function
+				var params []Value
+				dirtyParams := false
+				for i := 0; i < inst.OperandsCount()-1; i++ {
+					local := fr.getLocal(inst.Operand(i))
+					if !local.IsConstant() {
+						dirtyParams = true
+					}
+					params = append(params, local)
+				}
+				var ret Value
+				scanResult, err := fr.hasSideEffects(callee)
+				if err != nil {
+					return nil, nil, err
+				}
+				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
+					// is known at compile time which side effects it invokes.
+					// This means the function can be called at runtime and the
+					// affected globals can be marked dirty at compile time.
+					llvmParams := make([]llvm.Value, len(params))
+					for i, param := range params {
+						llvmParams[i] = param.Value()
+					}
+					result := fr.builder.CreateCall(callee, llvmParams, inst.Name())
+					ret = &LocalValue{fr.Eval, result}
+					// mark all mentioned globals as dirty
+					for global := range scanResult.mentionsGlobals {
+						fr.markDirty(global)
+					}
+				} else {
+					// Side effect is one of:
+					//   * None: no side effects, can be fully interpreted at
+					//     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+"    ")
+					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
+					}
+				}
+				if inst.Type().TypeKind() != llvm.VoidTypeKind {
+					fr.locals[inst] = ret
+				}
+			default:
+				// function pointers, etc.
+				return nil, nil, fr.unsupportedInstructionError(inst)
+			}
+		case !inst.IsAExtractValueInst().IsNil():
+			agg := fr.getLocal(inst.Operand(0)).(*LocalValue) // must be constant
+			indices := inst.Indices()
+			if agg.Underlying.IsConstant() {
+				newValue := llvm.ConstExtractValue(agg.Underlying, indices)
+				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"))
+				}
+				fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateExtractValue(agg.Underlying, int(indices[0]), inst.Name())}
+			}
+		case !inst.IsAInsertValueInst().IsNil():
+			agg := fr.getLocal(inst.Operand(0)).(*LocalValue) // must be constant
+			val := fr.getLocal(inst.Operand(1))
+			indices := inst.Indices()
+			if agg.IsConstant() && val.IsConstant() {
+				newValue := llvm.ConstInsertValue(agg.Underlying, val.Value(), indices)
+				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"))
+				}
+				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
+		case !inst.IsAReturnInst().IsNil() && inst.OperandsCount() == 1:
+			return fr.getLocal(inst.Operand(0)), nil, nil
+		case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 3:
+			// 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"))
+			}
+			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"))
+			}
+			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"))
+			}
+			switch cond {
+			case llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false): // false
+				return nil, []llvm.Value{thenBB}, nil // then
+			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"))
+			}
+		case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 1:
+			// unconditional branch (goto)
+			return nil, []llvm.Value{inst.Operand(0)}, nil
+		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
+
+		default:
+			return nil, nil, fr.unsupportedInstructionError(inst)
+		}
+	}
+
+	panic("interp: reached end of basic block without terminator")
+}
+
+// Get the Value for an operand, which is a constant value of some sort.
+func (fr *frame) getLocal(v llvm.Value) Value {
+	if ret, ok := fr.locals[v]; ok {
+		return ret
+	} else if value := fr.getValue(v); value != nil {
+		return value
+	} else {
+		// This should not happen under normal circumstances.
+		panic("cannot find value")
+	}
+}
@@ -1,77 +1,59 @@
-// Package interp is a partial evaluator of code run at package init time. See
-// the README in this package for details.
+// Package interp interprets Go package initializers as much as possible. This
+// avoid running them at runtime, improving code size and making other
+// optimizations possible.
 package interp

+// This file provides the overarching Eval object with associated (utility)
+// methods.
+
 import (
-	"fmt"
-	"os"
 	"strings"
-	"time"

 	"tinygo.org/x/go-llvm"
 )

-// Enable extra checks, which should be disabled by default.
-// This may help track down bugs by adding a few more sanity checks.
-const checks = true
-
-// runner contains all state related to one interp run.
-type runner struct {
-	mod           llvm.Module
-	targetData    llvm.TargetData
-	builder       llvm.Builder
-	pointerSize   uint32                   // cached pointer size from the TargetData
-	i8ptrType     llvm.Type                // often used type so created in advance
-	maxAlign      int                      // maximum alignment of an object, alignment of runtime.alloc() result
-	debug         bool                     // log debug messages
-	pkgName       string                   // package name of the currently executing package
-	functionCache map[llvm.Value]*function // cache of compiled functions
-	objects       []object                 // slice of objects in memory
-	globals       map[llvm.Value]int       // map from global to index in objects slice
-	start         time.Time
-	callsExecuted uint64
+type Eval struct {
+	Mod             llvm.Module
+	TargetData      llvm.TargetData
+	Debug           bool
+	builder         llvm.Builder
+	dirtyGlobals    map[llvm.Value]struct{}
+	sideEffectFuncs map[llvm.Value]*sideEffectResult // cache of side effect scan results
 }

-// Run evaluates runtime.initAll function as much as possible at compile time.
-// Set debug to true if it should print output while running.
+// 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 {
-	r := runner{
-		mod:           mod,
-		targetData:    llvm.NewTargetData(mod.DataLayout()),
-		debug:         debug,
-		functionCache: make(map[llvm.Value]*function),
-		objects:       []object{{}},
-		globals:       make(map[llvm.Value]int),
-		start:         time.Now(),
+	if debug {
+		println("\ncompile-time evaluation:")
 	}
-	r.pointerSize = uint32(r.targetData.PointerSize())
-	r.i8ptrType = llvm.PointerType(mod.Context().Int8Type(), 0)
-	r.maxAlign = r.targetData.PrefTypeAlignment(r.i8ptrType) // assume pointers are maximally aligned (this is not always the case)

-	initAll := mod.NamedFunction("runtime.initAll")
+	name := "runtime.initAll"
+	e := &Eval{
+		Mod:          mod,
+		TargetData:   llvm.NewTargetData(mod.DataLayout()),
+		Debug:        debug,
+		dirtyGlobals: map[llvm.Value]struct{}{},
+	}
+	e.builder = mod.Context().NewBuilder()
+
+	initAll := mod.NamedFunction(name)
 	bb := initAll.EntryBasicBlock()
-
-	// Create a builder, to insert instructions that could not be evaluated at
-	// compile time.
-	r.builder = mod.Context().NewBuilder()
-	defer r.builder.Dispose()
-
 	// Create a dummy alloca in the entry block that we can set the insert point
 	// to. This is necessary because otherwise we might be removing the
 	// instruction (init call) that we are removing after successful
 	// interpretation.
-	r.builder.SetInsertPointBefore(bb.FirstInstruction())
-	dummy := r.builder.CreateAlloca(r.mod.Context().Int8Type(), "dummy")
-	r.builder.SetInsertPointBefore(dummy)
-	defer dummy.EraseFromParentAsInstruction()
-
-	// Get a list if init calls. A runtime.initAll might look something like this:
-	// func initAll() {
-	//     unsafe.init()
-	//     machine.init()
-	//     runtime.init()
-	// }
-	// This function gets a list of these call instructions.
+	e.builder.SetInsertPointBefore(bb.FirstInstruction())
+	dummy := e.builder.CreateAlloca(e.Mod.Context().Int8Type(), "dummy")
+	e.builder.SetInsertPointBefore(dummy)
 	var initCalls []llvm.Value
 	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
 		if inst == dummy {
@@ -81,67 +63,99 @@ 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 "+initAll.Name()+" to be direct calls")
+			return errorAt(inst, "interp: expected all instructions in "+name+" to be direct calls")
 		}
 		initCalls = append(initCalls, inst)
 	}

-	// Run initializers for each package. Once the package initializer is
-	// finished, the call to the package initializer can be removed.
+	// Do this in a separate step to avoid corrupting the iterator above.
+	undefPtr := llvm.Undef(llvm.PointerType(mod.Context().Int8Type(), 0))
 	for _, call := range initCalls {
 		initName := call.CalledValue().Name()
 		if !strings.HasSuffix(initName, ".init") {
-			return errorAt(call, "interp: expected all instructions in "+initAll.Name()+" to be *.init() calls")
+			return errorAt(call, "interp: expected all instructions in "+name+" to be *.init() calls")
 		}
-		r.pkgName = initName[:len(initName)-len(".init")]
+		pkgName := initName[:len(initName)-5]
 		fn := call.CalledValue()
-		if r.debug {
-			fmt.Fprintln(os.Stderr, "call:", fn.Name())
-		}
-		_, mem, callErr := r.run(r.getFunction(fn), nil, nil, "    ")
-		if callErr != nil {
-			if isRecoverableError(callErr.Err) {
-				if r.debug {
-					fmt.Fprintln(os.Stderr, "not interpreting", r.pkgName, "because of error:", callErr.Error())
-				}
-				mem.revert()
-				continue
-			}
-			return callErr
-		}
 		call.EraseFromParentAsInstruction()
-		for index, obj := range mem.objects {
-			r.objects[index] = obj
+		evalPkg := evalPackage{
+			Eval:        e,
+			packagePath: pkgName,
 		}
-	}
-	r.pkgName = ""
-
-	// Update all global variables in the LLVM module.
-	mem := memoryView{r: &r}
-	for _, obj := range r.objects {
-		if obj.llvmGlobal.IsNil() {
-			continue
+		_, err := evalPkg.function(fn, []Value{&LocalValue{e, undefPtr}, &LocalValue{e, undefPtr}}, "")
+		if err == errUnreachable {
+			break
 		}
-		if obj.buffer == nil {
-			continue
+		if err != nil {
+			return err
 		}
-		initializer := obj.buffer.toLLVMValue(obj.llvmGlobal.Type().ElementType(), &mem)
-		if checks && initializer.Type() != obj.llvmGlobal.Type().ElementType() {
-			panic("initializer type mismatch")
-		}
-		obj.llvmGlobal.SetInitializer(initializer)
 	}

 	return nil
 }

-// getFunction returns the compiled version of the given LLVM function. It
-// compiles the function if necessary and caches the result.
-func (r *runner) getFunction(llvmFn llvm.Value) *function {
-	if fn, ok := r.functionCache[llvmFn]; ok {
-		return fn
+// 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) {
+	fr := frame{
+		evalPackage: e,
+		fn:          fn,
+		locals:      make(map[llvm.Value]Value),
+	}
+	for i, param := range fn.Params() {
+		fr.locals[param] = params[i]
+	}
+
+	bb := fn.EntryBasicBlock()
+	var lastBB llvm.BasicBlock
+	for {
+		retval, outgoing, err := fr.evalBasicBlock(bb, lastBB, indent)
+		if outgoing == nil {
+			// returned something (a value or void, or an error)
+			return retval, err
+		}
+		if len(outgoing) > 1 {
+			panic("unimplemented: multiple outgoing blocks")
+		}
+		next := outgoing[0]
+		if next.IsABasicBlock().IsNil() {
+			panic("did not switch to a basic block")
+		}
+		lastBB = bb
+		bb = next.AsBasicBlock()
+	}
+}
+
+// getValue determines what kind of LLVM value it gets and returns the
+// appropriate Value type.
+func (e *Eval) getValue(v llvm.Value) Value {
+	return &LocalValue{e, v}
+}
+
+// markDirty marks the passed-in LLVM value dirty, recursively. For example,
+// when it encounters a constant GEP on a global, it marks the global dirty.
+func (e *Eval) markDirty(v llvm.Value) {
+	if !v.IsAGlobalVariable().IsNil() {
+		if v.IsGlobalConstant() {
+			return
+		}
+		if _, ok := e.dirtyGlobals[v]; !ok {
+			e.dirtyGlobals[v] = struct{}{}
+			e.sideEffectFuncs = nil // re-calculate all side effects
+		}
+	} else if v.IsConstant() {
+		if v.OperandsCount() >= 2 && !v.Operand(0).IsAGlobalVariable().IsNil() {
+			// looks like a constant getelementptr of a global.
+			// TODO: find a way to make sure it really is: v.Opcode() returns 0.
+			e.markDirty(v.Operand(0))
+			return
+		}
+		return // nothing to mark
+	} else if !v.IsAGetElementPtrInst().IsNil() {
+		panic("interp: todo: GEP")
+	} else {
+		// Not constant and not a global or GEP so doesn't have to be marked
+		// non-constant.
 	}
-	fn := r.compileFunction(llvmFn)
-	r.functionCache[llvmFn] = fn
-	return fn
 }
@@ -3,7 +3,6 @@ package interp
 import (
 	"io/ioutil"
 	"os"
-	"regexp"
 	"strings"
 	"testing"

@@ -42,29 +41,9 @@ func runTest(t *testing.T, pathPrefix string) {
 	// Perform the transform.
 	err = Run(mod, false)
 	if err != nil {
-		if err, match := err.(*Error); match {
-			println(err.Error())
-			if !err.Inst.IsNil() {
-				err.Inst.Dump()
-				println()
-			}
-			if len(err.Traceback) > 0 {
-				println("\ntraceback:")
-				for _, line := range err.Traceback {
-					println(line.Pos.String() + ":")
-					line.Inst.Dump()
-					println()
-				}
-			}
-		}
 		t.Fatal(err)
 	}

-	// To be sure, verify that the module is still valid.
-	if llvm.VerifyModule(mod, llvm.PrintMessageAction) != nil {
-		t.FailNow()
-	}
-
 	// Run some cleanup passes to get easy-to-read outputs.
 	pm := llvm.NewPassManager()
 	defer pm.Dispose()
@@ -87,8 +66,6 @@ func runTest(t *testing.T, pathPrefix string) {
 	}
 }

-var alignRegexp = regexp.MustCompile(", align [0-9]+$")
-
 // fuzzyEqualIR returns true if the two LLVM IR strings passed in are roughly
 // equal. That means, only relevant lines are compared (excluding comments
 // etc.).
@@ -98,18 +75,8 @@ func fuzzyEqualIR(s1, s2 string) bool {
 	if len(lines1) != len(lines2) {
 		return false
 	}
-	for i, line1 := range lines1 {
-		line2 := lines2[i]
-		match1 := alignRegexp.MatchString(line1)
-		match2 := alignRegexp.MatchString(line2)
-		if match1 != match2 {
-			// Only one of the lines has the align keyword. Remove it.
-			// This is a change to make the test work in both LLVM 10 and LLVM
-			// 11 (LLVM 11 appears to automatically add alignment everywhere).
-			line1 = alignRegexp.ReplaceAllString(line1, "")
-			line2 = alignRegexp.ReplaceAllString(line2, "")
-		}
-		if line1 != line2 {
+	for i, line := range lines1 {
+		if line != lines2[i] {
 			return false
 		}
 	}
@@ -1,932 +0,0 @@
-package interp
-
-import (
-	"errors"
-	"fmt"
-	"math"
-	"os"
-	"strings"
-	"time"
-
-	"tinygo.org/x/go-llvm"
-)
-
-func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent string) (value, memoryView, *Error) {
-	mem := memoryView{r: r, parent: parentMem}
-	locals := make([]value, len(fn.locals))
-	r.callsExecuted++
-
-	if time.Since(r.start) > time.Minute {
-		// Running for more than a minute. This should never happen.
-		return nil, mem, r.errorAt(fn.blocks[0].instructions[0], fmt.Errorf("interp: running for more than a minute, timing out (executed calls: %d)", r.callsExecuted))
-	}
-
-	// Parameters are considered a kind of local values.
-	for i, param := range params {
-		locals[i] = param
-	}
-
-	// Start with the first basic block and the first instruction.
-	// Branch instructions may modify both bb and instIndex when branching.
-	bb := fn.blocks[0]
-	currentBB := 0
-	lastBB := -1 // last basic block is undefined, only defined after a branch
-	var operands []value
-	for instIndex := 0; instIndex < len(bb.instructions); instIndex++ {
-		inst := bb.instructions[instIndex]
-		operands = operands[:0]
-		isRuntimeInst := false
-		if inst.opcode != llvm.PHI {
-			for _, v := range inst.operands {
-				if v, ok := v.(localValue); ok {
-					if localVal := locals[fn.locals[v.value]]; localVal == nil {
-						return nil, mem, r.errorAt(inst, errors.New("interp: local not defined"))
-					} else {
-						operands = append(operands, localVal)
-						if _, ok := localVal.(localValue); ok {
-							isRuntimeInst = true
-						}
-						continue
-					}
-				}
-				operands = append(operands, v)
-			}
-		}
-		if isRuntimeInst {
-			err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-			if err != nil {
-				return nil, mem, err
-			}
-			continue
-		}
-		switch inst.opcode {
-		case llvm.Ret:
-			if len(operands) != 0 {
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"ret", operands[0])
-				}
-				// Return instruction has a value to return.
-				return operands[0], mem, nil
-			}
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"ret")
-			}
-			// Return instruction doesn't return anything, it's just 'ret void'.
-			return nil, mem, nil
-		case llvm.Br:
-			switch len(operands) {
-			case 1:
-				// Unconditional branch: [nextBB]
-				lastBB = currentBB
-				currentBB = int(operands[0].(literalValue).value.(uint32))
-				bb = fn.blocks[currentBB]
-				instIndex = -1 // start at 0 the next cycle
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"br", operands, "->", currentBB)
-				}
-			case 3:
-				// Conditional branch: [cond, thenBB, elseBB]
-				lastBB = currentBB
-				switch operands[0].Uint() {
-				case 1: // true -> thenBB
-					currentBB = int(operands[1].(literalValue).value.(uint32))
-				case 0: // false -> elseBB
-					currentBB = int(operands[2].(literalValue).value.(uint32))
-				default:
-					panic("bool should be 0 or 1")
-				}
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"br", operands, "->", currentBB)
-				}
-				bb = fn.blocks[currentBB]
-				instIndex = -1 // start at 0 the next cycle
-			default:
-				panic("unknown operands length")
-			}
-			break // continue with next block
-		case llvm.PHI:
-			var result value
-			for i := 0; i < len(inst.operands); i += 2 {
-				if int(inst.operands[i].(literalValue).value.(uint32)) == lastBB {
-					incoming := inst.operands[i+1]
-					if local, ok := incoming.(localValue); ok {
-						result = locals[fn.locals[local.value]]
-					} else {
-						result = incoming
-					}
-					break
-				}
-			}
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"phi", inst.operands, "->", result)
-			}
-			if result == nil {
-				panic("could not find PHI input")
-			}
-			locals[inst.localIndex] = result
-		case llvm.Select:
-			// Select is much like a ternary operator: it picks a result from
-			// the second and third operand based on the boolean first operand.
-			var result value
-			switch operands[0].Uint() {
-			case 1:
-				result = operands[1]
-			case 0:
-				result = operands[2]
-			default:
-				panic("boolean must be 0 or 1")
-			}
-			locals[inst.localIndex] = result
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"select", operands, "->", result)
-			}
-		case llvm.Call:
-			// A call instruction can either be a regular call or a runtime intrinsic.
-			fnPtr, err := operands[0].asPointer(r)
-			if err != nil {
-				return nil, mem, r.errorAt(inst, err)
-			}
-			callFn := r.getFunction(fnPtr.llvmValue(&mem))
-			switch {
-			case callFn.name == "runtime.trackPointer":
-				// Allocas and such are created as globals, so don't need a
-				// runtime.trackPointer.
-				// Unless the object is allocated at runtime for example, in
-				// which case this call won't even get to this point but will
-				// already be emitted in initAll.
-				continue
-			case callFn.name == "(reflect.Type).Elem" || strings.HasPrefix(callFn.name, "runtime.print") || callFn.name == "runtime._panic" || callFn.name == "runtime.hashmapGet":
-				// These functions should be run at runtime. Specifically:
-				//   * (reflect.Type).Elem is a special function. It should
-				//     eventually be interpreted, but fall back to a runtime call
-				//     for now.
-				//   * Print and panic functions are best emitted directly without
-				//     interpreting them, otherwise we get a ton of putchar (etc.)
-				//     calls.
-				//   * runtime.hashmapGet tries to access the map value directly.
-				//     This is not possible as the map value is treated as a special
-				//     kind of object in this package.
-				err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-				if err != nil {
-					return nil, mem, err
-				}
-			case callFn.name == "runtime.nanotime" && r.pkgName == "time":
-				// The time package contains a call to runtime.nanotime.
-				// This appears to be to work around a limitation in Windows
-				// Server 2008:
-				//   > Monotonic times are reported as offsets from startNano.
-				//   > We initialize startNano to runtimeNano() - 1 so that on systems where
-				//   > monotonic time resolution is fairly low (e.g. Windows 2008
-				//   > which appears to have a default resolution of 15ms),
-				//   > we avoid ever reporting a monotonic time of 0.
-				//   > (Callers may want to use 0 as "time not set".)
-				// Simply let runtime.nanotime return 0 in this case, which
-				// should be fine and avoids a call to runtime.nanotime. It
-				// means that monotonic time in the time package is counted from
-				// time.Time{}.Sub(1), which should be fine.
-				locals[inst.localIndex] = literalValue{uint64(0)}
-			case callFn.name == "runtime.alloc":
-				// Allocate heap memory. At compile time, this is instead done
-				// by creating a global variable.
-
-				// Get the requested memory size to be allocated.
-				size := operands[1].Uint()
-
-				// Create the object.
-				alloc := object{
-					globalName: r.pkgName + "$alloc",
-					buffer:     newRawValue(uint32(size)),
-					size:       uint32(size),
-				}
-				index := len(r.objects)
-				r.objects = append(r.objects, alloc)
-
-				// And create a pointer to this object, for working with it (so
-				// that stores to it copy it, etc).
-				ptr := newPointerValue(r, index, 0)
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"runtime.alloc:", size, "->", ptr)
-				}
-				locals[inst.localIndex] = ptr
-			case callFn.name == "runtime.sliceCopy":
-				// sliceCopy implements the built-in copy function for slices.
-				// It is implemented here so that it can be used even if the
-				// runtime implementation is not available. Doing it this way
-				// may also be faster.
-				// Code:
-				// func sliceCopy(dst, src unsafe.Pointer, dstLen, srcLen uintptr, elemSize uintptr) int {
-				//     n := srcLen
-				//     if n > dstLen {
-				//         n = dstLen
-				//     }
-				//     memmove(dst, src, n*elemSize)
-				//     return int(n)
-				// }
-				dstLen := operands[3].Uint()
-				srcLen := operands[4].Uint()
-				elemSize := operands[5].Uint()
-				n := srcLen
-				if n > dstLen {
-					n = dstLen
-				}
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"copy:", operands[1], operands[2], n)
-				}
-				if n != 0 {
-					// Only try to copy bytes when there are any bytes to copy.
-					// This is not just an optimization. If one of the slices
-					// (or both) are nil, the asPointer method call will fail
-					// even though copying a nil slice is allowed.
-					dst, err := operands[1].asPointer(r)
-					if err != nil {
-						return nil, mem, r.errorAt(inst, err)
-					}
-					src, err := operands[2].asPointer(r)
-					if err != nil {
-						return nil, mem, r.errorAt(inst, err)
-					}
-					nBytes := uint32(n * elemSize)
-					dstObj := mem.getWritable(dst.index())
-					dstBuf := dstObj.buffer.asRawValue(r)
-					srcBuf := mem.get(src.index()).buffer.asRawValue(r)
-					copy(dstBuf.buf[dst.offset():dst.offset()+nBytes], srcBuf.buf[src.offset():])
-					dstObj.buffer = dstBuf
-					mem.put(dst.index(), dstObj)
-				}
-				switch inst.llvmInst.Type().IntTypeWidth() {
-				case 16:
-					locals[inst.localIndex] = literalValue{uint16(n)}
-				case 32:
-					locals[inst.localIndex] = literalValue{uint32(n)}
-				case 64:
-					locals[inst.localIndex] = literalValue{uint64(n)}
-				default:
-					panic("unknown integer type width")
-				}
-			case strings.HasPrefix(callFn.name, "llvm.memcpy.p0i8.p0i8.") || strings.HasPrefix(callFn.name, "llvm.memmove.p0i8.p0i8."):
-				// Copy a block of memory from one pointer to another.
-				dst, err := operands[1].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				src, err := operands[2].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				nBytes := uint32(operands[3].Uint())
-				dstObj := mem.getWritable(dst.index())
-				dstBuf := dstObj.buffer.asRawValue(r)
-				srcBuf := mem.get(src.index()).buffer.asRawValue(r)
-				copy(dstBuf.buf[dst.offset():dst.offset()+nBytes], srcBuf.buf[src.offset():])
-				dstObj.buffer = dstBuf
-				mem.put(dst.index(), dstObj)
-			case callFn.name == "runtime.typeAssert":
-				// This function must be implemented manually as it is normally
-				// implemented by the interface lowering pass.
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"typeassert:", operands[1:])
-				}
-				typeInInterfacePtr, err := operands[1].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				actualType, err := mem.load(typeInInterfacePtr, r.pointerSize).asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				assertedType, err := operands[2].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				result := assertedType.asRawValue(r).equal(actualType.asRawValue(r))
-				if result {
-					locals[inst.localIndex] = literalValue{uint8(1)}
-				} else {
-					locals[inst.localIndex] = literalValue{uint8(0)}
-				}
-			case callFn.name == "runtime.interfaceImplements":
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"interface assert:", operands[1:])
-				}
-
-				// Load various values for the interface implements check below.
-				typeInInterfacePtr, err := operands[1].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				methodSetPtr, err := mem.load(typeInInterfacePtr.addOffset(r.pointerSize), r.pointerSize).asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				methodSet := mem.get(methodSetPtr.index()).llvmGlobal.Initializer()
-				interfaceMethodSetPtr, err := operands[2].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				interfaceMethodSet := mem.get(interfaceMethodSetPtr.index()).llvmGlobal.Initializer()
-
-				// Make a set of all the methods on the concrete type, for
-				// easier checking in the next step.
-				concreteTypeMethods := map[string]struct{}{}
-				for i := 0; i < methodSet.Type().ArrayLength(); i++ {
-					methodInfo := llvm.ConstExtractValue(methodSet, []uint32{uint32(i)})
-					name := llvm.ConstExtractValue(methodInfo, []uint32{0}).Name()
-					concreteTypeMethods[name] = struct{}{}
-				}
-
-				// Check whether all interface methods are also in the list
-				// of defined methods calculated above. This is the interface
-				// assert itself.
-				assertOk := uint8(1) // i1 true
-				for i := 0; i < interfaceMethodSet.Type().ArrayLength(); i++ {
-					name := llvm.ConstExtractValue(interfaceMethodSet, []uint32{uint32(i)}).Name()
-					if _, ok := concreteTypeMethods[name]; !ok {
-						// There is a method on the interface that is not
-						// implemented by the type. The assertion will fail.
-						assertOk = 0 // i1 false
-						break
-					}
-				}
-				// If assertOk is still 1, the assertion succeeded.
-				locals[inst.localIndex] = literalValue{assertOk}
-			case callFn.name == "runtime.hashmapMake":
-				// Create a new map.
-				hashmapPointerType := inst.llvmInst.Type()
-				keySize := uint32(operands[1].Uint())
-				valueSize := uint32(operands[2].Uint())
-				m := newMapValue(r, hashmapPointerType, keySize, valueSize)
-				alloc := object{
-					llvmType:   hashmapPointerType,
-					globalName: r.pkgName + "$map",
-					buffer:     m,
-					size:       m.len(r),
-				}
-				index := len(r.objects)
-				r.objects = append(r.objects, alloc)
-
-				// Create a pointer to this map. Maps are reference types, so
-				// are implemented as pointers.
-				ptr := newPointerValue(r, index, 0)
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"runtime.hashmapMake:", keySize, valueSize, "->", ptr)
-				}
-				locals[inst.localIndex] = ptr
-			case callFn.name == "runtime.hashmapBinarySet":
-				// Do a mapassign operation with a binary key (that is, without
-				// a string key).
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"runtime.hashmapBinarySet:", operands[1:])
-				}
-				mapPtr, err := operands[1].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				m := mem.getWritable(mapPtr.index()).buffer.(*mapValue)
-				keyPtr, err := operands[2].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				valuePtr, err := operands[3].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				err = m.putBinary(&mem, keyPtr, valuePtr)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-			case callFn.name == "runtime.hashmapStringSet":
-				// Do a mapassign operation with a string key.
-				if r.debug {
-					fmt.Fprintln(os.Stderr, indent+"runtime.hashmapBinarySet:", operands[1:])
-				}
-				mapPtr, err := operands[1].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				m := mem.getWritable(mapPtr.index()).buffer.(*mapValue)
-				stringPtr, err := operands[2].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				stringLen := operands[3].Uint()
-				valuePtr, err := operands[4].asPointer(r)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				err = m.putString(&mem, stringPtr, stringLen, valuePtr)
-				if err != nil {
-					return nil, mem, r.errorAt(inst, err)
-				}
-			default:
-				if len(callFn.blocks) == 0 {
-					// Call to a function declaration without a definition
-					// available.
-					err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-					if err != nil {
-						return nil, mem, err
-					}
-					continue
-				}
-				// Call a function with a definition available. Run it as usual,
-				// possibly trying to recover from it if it failed to execute.
-				if r.debug {
-					argStrings := make([]string, len(operands)-1)
-					for i := range argStrings {
-						argStrings[i] = operands[i+1].String()
-					}
-					fmt.Fprintln(os.Stderr, indent+"call:", callFn.name+"("+strings.Join(argStrings, ", ")+")")
-				}
-				retval, callMem, callErr := r.run(callFn, operands[1:], &mem, indent+"    ")
-				if callErr != nil {
-					if isRecoverableError(callErr.Err) {
-						// This error can be recovered by doing the call at
-						// runtime instead of at compile time. But we need to
-						// revert any changes made by the call first.
-						if r.debug {
-							fmt.Fprintln(os.Stderr, indent+"!! revert because of error:", callErr.Err)
-						}
-						callMem.revert()
-						err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-						if err != nil {
-							return nil, mem, err
-						}
-						continue
-					}
-					// Add to the traceback, so that error handling code can see
-					// how this function got called.
-					callErr.Traceback = append(callErr.Traceback, ErrorLine{
-						Pos:  getPosition(inst.llvmInst),
-						Inst: inst.llvmInst,
-					})
-					return nil, mem, callErr
-				}
-				locals[inst.localIndex] = retval
-				mem.extend(callMem)
-			}
-		case llvm.Load:
-			// Load instruction, loading some data from the topmost memory view.
-			ptr, err := operands[0].asPointer(r)
-			if err != nil {
-				return nil, mem, r.errorAt(inst, err)
-			}
-			size := operands[1].(literalValue).value.(uint64)
-			if mem.hasExternalStore(ptr) {
-				// If there could be an external store (for example, because a
-				// pointer to the object was passed to a function that could not
-				// be interpreted at compile time) then the load must be done at
-				// runtime.
-				err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-				if err != nil {
-					return nil, mem, err
-				}
-				continue
-			}
-			result := mem.load(ptr, uint32(size))
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"load:", ptr, "->", result)
-			}
-			locals[inst.localIndex] = result
-		case llvm.Store:
-			// Store instruction. Create a new object in the memory view and
-			// store to that, to make it possible to roll back this store.
-			ptr, err := operands[1].asPointer(r)
-			if err != nil {
-				return nil, mem, r.errorAt(inst, err)
-			}
-			if mem.hasExternalLoadOrStore(ptr) {
-				err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-				if err != nil {
-					return nil, mem, err
-				}
-				continue
-			}
-			val := operands[0]
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"store:", val, ptr)
-			}
-			mem.store(val, ptr)
-		case llvm.Alloca:
-			// Alloca normally allocates some stack memory. In the interpreter,
-			// it allocates a global instead.
-			// This can likely be optimized, as all it really needs is an alloca
-			// in the initAll function and creating a global is wasteful for
-			// this purpose.
-
-			// Create the new object.
-			size := operands[0].(literalValue).value.(uint64)
-			alloca := object{
-				llvmType:   inst.llvmInst.Type(),
-				globalName: r.pkgName + "$alloca",
-				buffer:     newRawValue(uint32(size)),
-				size:       uint32(size),
-			}
-			index := len(r.objects)
-			r.objects = append(r.objects, alloca)
-
-			// Create a pointer to this object (an alloca produces a pointer).
-			ptr := newPointerValue(r, index, 0)
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"alloca:", operands, "->", ptr)
-			}
-			locals[inst.localIndex] = ptr
-		case llvm.GetElementPtr:
-			// GetElementPtr does pointer arithmetic, changing the offset of the
-			// pointer into the underlying object.
-			var offset uint64
-			var gepOperands []uint64
-			for i := 2; i < len(operands); i += 2 {
-				index := operands[i].Uint()
-				elementSize := operands[i+1].Uint()
-				if int64(elementSize) < 0 {
-					// This is a struct field.
-					// The field number is encoded by flipping all the bits.
-					gepOperands = append(gepOperands, ^elementSize)
-					offset += index
-				} else {
-					// This is a normal GEP, probably an array index.
-					gepOperands = append(gepOperands, index)
-					offset += elementSize * index
-				}
-			}
-			ptr, err := operands[0].asPointer(r)
-			if err != nil {
-				if err != errIntegerAsPointer {
-					return nil, mem, r.errorAt(inst, err)
-				}
-				// GEP on fixed pointer value (for example, memory-mapped I/O).
-				ptrValue := operands[0].Uint() + offset
-				switch operands[0].len(r) {
-				case 8:
-					locals[inst.localIndex] = literalValue{uint64(ptrValue)}
-				case 4:
-					locals[inst.localIndex] = literalValue{uint32(ptrValue)}
-				case 2:
-					locals[inst.localIndex] = literalValue{uint16(ptrValue)}
-				default:
-					panic("pointer operand is not of a known pointer size")
-				}
-				continue
-			}
-			ptr = ptr.addOffset(uint32(offset))
-			locals[inst.localIndex] = ptr
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"gep:", operands, "->", ptr)
-			}
-		case llvm.BitCast, llvm.IntToPtr, llvm.PtrToInt:
-			// Various bitcast-like instructions that all keep the same bits
-			// while changing the LLVM type.
-			// Because interp doesn't preserve the type, these operations are
-			// identity operations.
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+instructionNameMap[inst.opcode]+":", operands[0])
-			}
-			locals[inst.localIndex] = operands[0]
-		case llvm.ExtractValue:
-			agg := operands[0].asRawValue(r)
-			offset := operands[1].(literalValue).value.(uint64)
-			size := operands[2].(literalValue).value.(uint64)
-			elt := rawValue{
-				buf: agg.buf[offset : offset+size],
-			}
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"extractvalue:", operands, "->", elt)
-			}
-			locals[inst.localIndex] = elt
-		case llvm.InsertValue:
-			agg := operands[0].asRawValue(r)
-			elt := operands[1].asRawValue(r)
-			offset := int(operands[2].(literalValue).value.(uint64))
-			newagg := newRawValue(uint32(len(agg.buf)))
-			copy(newagg.buf, agg.buf)
-			copy(newagg.buf[offset:], elt.buf)
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"insertvalue:", operands, "->", newagg)
-			}
-			locals[inst.localIndex] = newagg
-		case llvm.ICmp:
-			predicate := llvm.IntPredicate(operands[2].(literalValue).value.(uint8))
-			var result bool
-			lhs := operands[0]
-			rhs := operands[1]
-			switch predicate {
-			case llvm.IntEQ, llvm.IntNE:
-				lhsPointer, lhsErr := lhs.asPointer(r)
-				rhsPointer, rhsErr := rhs.asPointer(r)
-				if (lhsErr == nil) != (rhsErr == nil) {
-					// Fast path: only one is a pointer, so they can't be equal.
-					result = false
-				} else if lhsErr == nil {
-					// Both must be nil, so both are pointers.
-					// Compare them directly.
-					result = lhsPointer.equal(rhsPointer)
-				} else {
-					// Fall back to generic comparison.
-					result = lhs.asRawValue(r).equal(rhs.asRawValue(r))
-				}
-				if predicate == llvm.IntNE {
-					result = !result
-				}
-			case llvm.IntUGT:
-				result = lhs.Uint() > rhs.Uint()
-			case llvm.IntUGE:
-				result = lhs.Uint() >= rhs.Uint()
-			case llvm.IntULT:
-				result = lhs.Uint() < rhs.Uint()
-			case llvm.IntULE:
-				result = lhs.Uint() <= rhs.Uint()
-			case llvm.IntSGT:
-				result = lhs.Int() > rhs.Int()
-			case llvm.IntSGE:
-				result = lhs.Int() >= rhs.Int()
-			case llvm.IntSLT:
-				result = lhs.Int() < rhs.Int()
-			case llvm.IntSLE:
-				result = lhs.Int() <= rhs.Int()
-			default:
-				return nil, mem, r.errorAt(inst, errors.New("interp: unsupported icmp"))
-			}
-			if result {
-				locals[inst.localIndex] = literalValue{uint8(1)}
-			} else {
-				locals[inst.localIndex] = literalValue{uint8(0)}
-			}
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"icmp:", operands[0], intPredicateString(predicate), operands[1], "->", result)
-			}
-		case llvm.FCmp:
-			predicate := llvm.FloatPredicate(operands[2].(literalValue).value.(uint8))
-			var result bool
-			var lhs, rhs float64
-			switch operands[0].len(r) {
-			case 8:
-				lhs = math.Float64frombits(operands[0].Uint())
-				rhs = math.Float64frombits(operands[1].Uint())
-			case 4:
-				lhs = float64(math.Float32frombits(uint32(operands[0].Uint())))
-				rhs = float64(math.Float32frombits(uint32(operands[1].Uint())))
-			default:
-				panic("unknown float type")
-			}
-			switch predicate {
-			case llvm.FloatOEQ:
-				result = lhs == rhs
-			case llvm.FloatUNE:
-				result = lhs != rhs
-			case llvm.FloatOGT:
-				result = lhs > rhs
-			case llvm.FloatOGE:
-				result = lhs >= rhs
-			case llvm.FloatOLT:
-				result = lhs < rhs
-			case llvm.FloatOLE:
-				result = lhs <= rhs
-			default:
-				return nil, mem, r.errorAt(inst, errors.New("interp: unsupported fcmp"))
-			}
-			if result {
-				locals[inst.localIndex] = literalValue{uint8(1)}
-			} else {
-				locals[inst.localIndex] = literalValue{uint8(0)}
-			}
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+"fcmp:", operands[0], predicate, operands[1], "->", result)
-			}
-		case llvm.Add, llvm.Sub, llvm.Mul, llvm.UDiv, llvm.SDiv, llvm.URem, llvm.SRem, llvm.Shl, llvm.LShr, llvm.AShr, llvm.And, llvm.Or, llvm.Xor:
-			// Integer binary operations.
-			lhs := operands[0]
-			rhs := operands[1]
-			lhsPtr, err := lhs.asPointer(r)
-			if err == nil {
-				// The lhs is a pointer. This sometimes happens for particular
-				// pointer tricks.
-				switch inst.opcode {
-				case llvm.Add:
-					// This likely means this is part of a
-					// unsafe.Pointer(uintptr(ptr) + offset) pattern.
-					lhsPtr = lhsPtr.addOffset(uint32(rhs.Uint()))
-					locals[inst.localIndex] = lhsPtr
-					continue
-				case llvm.Xor:
-					if rhs.Uint() == 0 {
-						// Special workaround for strings.noescape, see
-						// src/strings/builder.go in the Go source tree. This is
-						// the identity operator, so we can return the input.
-						locals[inst.localIndex] = lhs
-						continue
-					}
-				default:
-					// Catch-all for weird operations that should just be done
-					// at runtime.
-					err := r.runAtRuntime(fn, inst, locals, &mem, indent)
-					if err != nil {
-						return nil, mem, err
-					}
-					continue
-				}
-			}
-			var result uint64
-			switch inst.opcode {
-			case llvm.Add:
-				result = lhs.Uint() + rhs.Uint()
-			case llvm.Sub:
-				result = lhs.Uint() - rhs.Uint()
-			case llvm.Mul:
-				result = lhs.Uint() * rhs.Uint()
-			case llvm.UDiv:
-				result = lhs.Uint() / rhs.Uint()
-			case llvm.SDiv:
-				result = uint64(lhs.Int() / rhs.Int())
-			case llvm.URem:
-				result = lhs.Uint() % rhs.Uint()
-			case llvm.SRem:
-				result = uint64(lhs.Int() % rhs.Int())
-			case llvm.Shl:
-				result = lhs.Uint() << rhs.Uint()
-			case llvm.LShr:
-				result = lhs.Uint() >> rhs.Uint()
-			case llvm.AShr:
-				result = uint64(lhs.Int() >> rhs.Uint())
-			case llvm.And:
-				result = lhs.Uint() & rhs.Uint()
-			case llvm.Or:
-				result = lhs.Uint() | rhs.Uint()
-			case llvm.Xor:
-				result = lhs.Uint() ^ rhs.Uint()
-			default:
-				panic("unreachable")
-			}
-			switch lhs.len(r) {
-			case 8:
-				locals[inst.localIndex] = literalValue{result}
-			case 4:
-				locals[inst.localIndex] = literalValue{uint32(result)}
-			case 2:
-				locals[inst.localIndex] = literalValue{uint16(result)}
-			case 1:
-				locals[inst.localIndex] = literalValue{uint8(result)}
-			default:
-				panic("unknown integer size")
-			}
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+instructionNameMap[inst.opcode]+":", lhs, rhs, "->", result)
-			}
-		case llvm.SExt, llvm.ZExt, llvm.Trunc:
-			// Change the size of an integer to a larger or smaller bit width.
-			// We make use of the fact that the Uint() function already
-			// zero-extends the value and that Int() already sign-extends the
-			// value, so we only need to truncate it to the appropriate bit
-			// width. This means we can implement sext, zext and trunc in the
-			// same way, by first {zero,sign}extending all the way up to uint64
-			// and then truncating it as necessary.
-			var value uint64
-			if inst.opcode == llvm.SExt {
-				value = uint64(operands[0].Int())
-			} else {
-				value = operands[0].Uint()
-			}
-			bitwidth := operands[1].Uint()
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+instructionNameMap[inst.opcode]+":", value, bitwidth)
-			}
-			switch bitwidth {
-			case 64:
-				locals[inst.localIndex] = literalValue{value}
-			case 32:
-				locals[inst.localIndex] = literalValue{uint32(value)}
-			case 16:
-				locals[inst.localIndex] = literalValue{uint16(value)}
-			case 8:
-				locals[inst.localIndex] = literalValue{uint8(value)}
-			default:
-				panic("unknown integer size in sext/zext/trunc")
-			}
-		case llvm.SIToFP, llvm.UIToFP:
-			var value float64
-			switch inst.opcode {
-			case llvm.SIToFP:
-				value = float64(operands[0].Int())
-			case llvm.UIToFP:
-				value = float64(operands[0].Uint())
-			}
-			bitwidth := operands[1].Uint()
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+instructionNameMap[inst.opcode]+":", value, bitwidth)
-			}
-			switch bitwidth {
-			case 64:
-				locals[inst.localIndex] = literalValue{math.Float64bits(value)}
-			case 32:
-				locals[inst.localIndex] = literalValue{math.Float32bits(float32(value))}
-			default:
-				panic("unknown integer size in sitofp/uitofp")
-			}
-		default:
-			if r.debug {
-				fmt.Fprintln(os.Stderr, indent+inst.String())
-			}
-			return nil, mem, r.errorAt(inst, errUnsupportedInst)
-		}
-	}
-	return nil, mem, r.errorAt(bb.instructions[len(bb.instructions)-1], errors.New("interp: reached end of basic block without terminator"))
-}
-
-func (r *runner) runAtRuntime(fn *function, inst instruction, locals []value, mem *memoryView, indent string) *Error {
-	numOperands := inst.llvmInst.OperandsCount()
-	operands := make([]llvm.Value, numOperands)
-	for i := 0; i < numOperands; i++ {
-		operand := inst.llvmInst.Operand(i)
-		if !operand.IsAInstruction().IsNil() || !operand.IsAArgument().IsNil() {
-			operand = locals[fn.locals[operand]].toLLVMValue(operand.Type(), mem)
-		}
-		operands[i] = operand
-	}
-	if r.debug {
-		fmt.Fprintln(os.Stderr, indent+inst.String())
-	}
-	var result llvm.Value
-	switch inst.opcode {
-	case llvm.Call:
-		llvmFn := operands[len(operands)-1]
-		args := operands[:len(operands)-1]
-		for _, arg := range args {
-			if arg.Type().TypeKind() == llvm.PointerTypeKind {
-				mem.markExternalStore(arg)
-			}
-		}
-		result = r.builder.CreateCall(llvmFn, args, inst.name)
-	case llvm.Load:
-		mem.markExternalLoad(operands[0])
-		result = r.builder.CreateLoad(operands[0], inst.name)
-		if inst.llvmInst.IsVolatile() {
-			result.SetVolatile(true)
-		}
-	case llvm.Store:
-		mem.markExternalStore(operands[1])
-		result = r.builder.CreateStore(operands[0], operands[1])
-		if inst.llvmInst.IsVolatile() {
-			result.SetVolatile(true)
-		}
-	case llvm.BitCast:
-		result = r.builder.CreateBitCast(operands[0], inst.llvmInst.Type(), inst.name)
-	case llvm.ExtractValue:
-		indices := inst.llvmInst.Indices()
-		if len(indices) != 1 {
-			panic("expected exactly one index")
-		}
-		result = r.builder.CreateExtractValue(operands[0], int(indices[0]), inst.name)
-	case llvm.InsertValue:
-		indices := inst.llvmInst.Indices()
-		if len(indices) != 1 {
-			panic("expected exactly one index")
-		}
-		result = r.builder.CreateInsertValue(operands[0], operands[1], int(indices[0]), inst.name)
-	case llvm.Add:
-		result = r.builder.CreateAdd(operands[0], operands[1], inst.name)
-	case llvm.Sub:
-		result = r.builder.CreateSub(operands[0], operands[1], inst.name)
-	case llvm.Mul:
-		result = r.builder.CreateMul(operands[0], operands[1], inst.name)
-	case llvm.UDiv:
-		result = r.builder.CreateUDiv(operands[0], operands[1], inst.name)
-	case llvm.SDiv:
-		result = r.builder.CreateSDiv(operands[0], operands[1], inst.name)
-	case llvm.URem:
-		result = r.builder.CreateURem(operands[0], operands[1], inst.name)
-	case llvm.SRem:
-		result = r.builder.CreateSRem(operands[0], operands[1], inst.name)
-	case llvm.ZExt:
-		result = r.builder.CreateZExt(operands[0], inst.llvmInst.Type(), inst.name)
-	default:
-		return r.errorAt(inst, errUnsupportedRuntimeInst)
-	}
-	locals[inst.localIndex] = localValue{result}
-	mem.instructions = append(mem.instructions, result)
-	return nil
-}
-
-func intPredicateString(predicate llvm.IntPredicate) string {
-	switch predicate {
-	case llvm.IntEQ:
-		return "eq"
-	case llvm.IntNE:
-		return "ne"
-	case llvm.IntUGT:
-		return "ugt"
-	case llvm.IntUGE:
-		return "uge"
-	case llvm.IntULT:
-		return "ult"
-	case llvm.IntULE:
-		return "ule"
-	case llvm.IntSGT:
-		return "sgt"
-	case llvm.IntSGE:
-		return "sge"
-	case llvm.IntSLT:
-		return "slt"
-	case llvm.IntSLE:
-		return "sle"
-	default:
-		return "cmp?"
-	}
-}
@@ -0,0 +1,253 @@
+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)
+	sideEffectLimited                              // has side effects, but the effects are known
+	sideEffectAll                                  // has unknown side effects
+)
+
+// sideEffectResult contains the scan results after scanning a function for side
+// effects (recursively).
+type sideEffectResult struct {
+	severity        sideEffectSeverity
+	mentionsGlobals map[llvm.Value]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":
+		// Cannot be scanned but can be interpreted.
+		return &sideEffectResult{severity: sideEffectNone}, nil
+	case name == "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
+	}
+	if e.sideEffectFuncs == nil {
+		e.sideEffectFuncs = make(map[llvm.Value]*sideEffectResult)
+	}
+	if se, ok := e.sideEffectFuncs[fn]; ok {
+		return se, nil
+	}
+	result := &sideEffectResult{
+		severity:        sideEffectInProgress,
+		mentionsGlobals: map[llvm.Value]struct{}{},
+	}
+	e.sideEffectFuncs[fn] = result
+	dirtyLocals := map[llvm.Value]struct{}{}
+	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")
+			}
+
+			// Check for any globals mentioned anywhere in the function. Assume
+			// any mentioned globals may be read from or written to when
+			// executed, thus must be marked dirty with a call.
+			for i := 0; i < inst.OperandsCount(); i++ {
+				operand := inst.Operand(i)
+				if !operand.IsAGlobalVariable().IsNil() {
+					result.mentionsGlobals[operand] = struct{}{}
+				}
+			}
+
+			switch inst.InstructionOpcode() {
+			case llvm.IndirectBr, llvm.Invoke:
+				// Not emitted by the compiler.
+				return nil, e.errorAt(inst, errors.New("unknown instructions"))
+			case llvm.Call:
+				child := inst.CalledValue()
+				if !child.IsAInlineAsm().IsNil() {
+					// Inline assembly. This most likely has side effects.
+					// Assume they're only limited side effects, similar to
+					// external function calls.
+					result.updateSeverity(sideEffectLimited)
+					continue
+				}
+				if child.IsAFunction().IsNil() {
+					// Indirect call?
+					// In any case, we can't know anything here about what it
+					// affects exactly so mark this function as invoking all
+					// possible side effects.
+					result.updateSeverity(sideEffectAll)
+					continue
+				}
+				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
+				}
+				switch childSideEffects.severity {
+				case sideEffectInProgress, sideEffectNone:
+					// no side effects or recursive function - continue scanning
+				case sideEffectLimited:
+					// The return value may be problematic.
+					if e.hasLocalSideEffects(dirtyLocals, inst) {
+						result.updateSeverity(sideEffectLimited)
+					}
+				case sideEffectAll:
+					result.updateSeverity(sideEffectAll)
+				default:
+					panic("unreachable")
+				}
+			case llvm.Load:
+				if inst.IsVolatile() {
+					result.updateSeverity(sideEffectLimited)
+				}
+				if _, ok := e.dirtyGlobals[inst.Operand(0)]; ok {
+					if e.hasLocalSideEffects(dirtyLocals, inst) {
+						result.updateSeverity(sideEffectLimited)
+					}
+				}
+			case llvm.Store:
+				if inst.IsVolatile() {
+					result.updateSeverity(sideEffectLimited)
+				}
+			case llvm.IntToPtr:
+				// Pointer casts are not yet supported.
+				result.updateSeverity(sideEffectLimited)
+			default:
+				// Ignore most instructions.
+				// Check this list for completeness:
+				// https://godoc.org/github.com/llvm-mirror/llvm/bindings/go/llvm#Opcode
+			}
+		}
+	}
+
+	if result.severity == sideEffectInProgress {
+		// No side effect was reported for this function.
+		result.severity = sideEffectNone
+	}
+	return result, nil
+}
+
+// hasLocalSideEffects checks whether the given instruction flows into a branch
+// or return instruction, in which case the whole function must be marked as
+// having side effects and be called at runtime.
+func (e *Eval) hasLocalSideEffects(dirtyLocals map[llvm.Value]struct{}, inst llvm.Value) bool {
+	if _, ok := dirtyLocals[inst]; ok {
+		// It is already known that this local is dirty.
+		return true
+	}
+
+	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() {
+		case llvm.Br, llvm.Switch:
+			// A branch on a dirty value makes this function dirty: it cannot be
+			// interpreted at compile time so has to be run at runtime. It is
+			// marked as having side effects for this reason.
+			return true
+		case llvm.Ret:
+			// This function returns a dirty value so it is itself marked as
+			// dirty to make sure it is called at runtime.
+			return true
+		case llvm.Store:
+			ptr := user.Operand(1)
+			if !ptr.IsAGlobalVariable().IsNil() {
+				// Store to a global variable.
+				// 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
+		default:
+			// All instructions that take 0 or more operands (1 or more if it
+			// was a use) and produce a result.
+			// For a list:
+			// https://godoc.org/github.com/llvm-mirror/llvm/bindings/go/llvm#Opcode
+			dirtyLocals[user] = struct{}{}
+			if e.hasLocalSideEffects(dirtyLocals, user) {
+				return true
+			}
+		}
+	}
+
+	// No side effects found.
+	return false
+}
+
+// updateSeverity sets r.severity to the max of r.severity and severity,
+// conservatively assuming the worst severity.
+func (r *sideEffectResult) updateSeverity(severity sideEffectSeverity) {
+	if severity > r.severity {
+		r.severity = severity
+	}
+}
+
+// updateSeverity updates the severity with the severity of the child severity,
+// like in a function call. This means it also copies the mentioned globals.
+func (r *sideEffectResult) update(child *sideEffectResult) {
+	r.updateSeverity(child.severity)
+	for global := range child.mentionsGlobals {
+		r.mentionsGlobals[global] = struct{}{}
+	}
+}
@@ -0,0 +1,95 @@
+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)
+		}
+	}
+}
@@ -4,10 +4,6 @@ target triple = "x86_64--linux"
@main.v1 = internal global i64 0
@main.nonConst1 = global [4 x i64] zeroinitializer
@main.nonConst2 = global i64 0
-@main.someArray = global [8 x {i16, i32}] zeroinitializer
-@main.exportedValue = global [1 x i16*] [i16* @main.exposedValue1]
-@main.exposedValue1 = global i16 0
-@main.exposedValue2 = global i16 0

 declare void @runtime.printint64(i64) unnamed_addr

@@ -51,20 +47,6 @@ entry:
  %value2 = load i64, i64* %gep2
  store i64 %value2, i64* @main.nonConst2

-  ; Test that the following GEP works:
-  ;     var someArray
-  ;     modifyExternal(&someArray[3].field1)
-  %gep3 = getelementptr [8 x {i16, i32}], [8 x {i16, i32}]* @main.someArray, i32 0, i32 3, i32 1
-  call void @modifyExternal(i32* %gep3)
-
-  ; Test that marking a value as external also marks all referenced values.
-  call void @modifyExternal(i32* bitcast ([1 x i16*]* @main.exportedValue to i32*))
-  store i16 5, i16* @main.exposedValue1
-
-  ; Test that this even propagates through functions.
-  call void @modifyExternal(i32* bitcast (void ()* @willModifyGlobal to i32*))
-  store i16 7, i16* @main.exposedValue2
-
  ret void
 }

@@ -76,14 +58,3 @@ entry:
 }

 declare i64 @someValue()
-
-declare void @modifyExternal(i32*)
-
-; This function will modify an external value. By passing this function as a
-; function pointer to an external function, @main.exposedValue2 should be
-; marked as external.
-define void @willModifyGlobal() {
-entry:
-  store i16 8, i16* @main.exposedValue2
-  ret void
-}
@@ -3,10 +3,6 @@ target triple = "x86_64--linux"

@main.nonConst1 = local_unnamed_addr global [4 x i64] zeroinitializer
@main.nonConst2 = local_unnamed_addr global i64 0
-@main.someArray = global [8 x { i16, i32 }] zeroinitializer
-@main.exportedValue = global [1 x i16*] [i16* @main.exposedValue1]
-@main.exposedValue1 = global i16 0
-@main.exposedValue2 = local_unnamed_addr global i16 0

 declare void @runtime.printint64(i64) unnamed_addr

@@ -20,11 +16,6 @@ entry:
  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
-  call void @modifyExternal(i32* getelementptr inbounds ([8 x { i16, i32 }], [8 x { i16, i32 }]* @main.someArray, i32 0, i32 3, i32 1))
-  call void @modifyExternal(i32* bitcast ([1 x i16*]* @main.exportedValue to i32*))
-  store i16 5, i16* @main.exposedValue1
-  call void @modifyExternal(i32* bitcast (void ()* @willModifyGlobal to i32*))
-  store i16 7, i16* @main.exposedValue2
  ret void
 }

@@ -36,11 +27,3 @@ entry:
 }

 declare i64 @someValue() local_unnamed_addr
-
-declare void @modifyExternal(i32*) local_unnamed_addr
-
-define void @willModifyGlobal() {
-entry:
-  store i16 8, i16* @main.exposedValue2
-  ret void
-}
@@ -48,7 +48,8 @@ entry:
 define internal void @main.testNonConstantBinarySet() {
  %hashmap.key = alloca i8
  %hashmap.value = alloca i8
-  ; Create hashmap from global.
+  ; Create hashmap from global. This breaks the normal hashmapBinarySet
+  ; optimization, to test the fallback.
  %map.new = call %runtime.hashmap* @runtime.hashmapMake(i8 1, i8 1, i32 1, i8* undef, i8* null)
  store %runtime.hashmap* %map.new, %runtime.hashmap** @main.binaryMap
  %map = load %runtime.hashmap*, %runtime.hashmap** @main.binaryMap
@@ -63,7 +64,8 @@ define internal void @main.testNonConstantBinarySet() {
 ; operations (with string keys).
 define internal void @main.testNonConstantStringSet() {
  %hashmap.value = alloca i8
-  ; Create hashmap from global.
+  ; Create hashmap from global. This breaks the normal hashmapStringSet
+  ; optimization, to test the fallback.
  %map.new = call %runtime.hashmap* @runtime.hashmapMake(i8 8, i8 1, i32 1, i8* undef, i8* null)
  store %runtime.hashmap* %map.new, %runtime.hashmap** @main.stringMap
  %map = load %runtime.hashmap*, %runtime.hashmap** @main.stringMap
@@ -2,19 +2,27 @@ target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "armv6m-none-eabi"

 %runtime.hashmap = type { %runtime.hashmap*, i8*, i32, i8, i8, i8 }
+%runtime._string = type { i8*, i32 }

@main.m = local_unnamed_addr global %runtime.hashmap* @"main$map"
-@main.binaryMap = local_unnamed_addr global %runtime.hashmap* @"main$map.1"
-@main.stringMap = local_unnamed_addr global %runtime.hashmap* @"main$map.3"
+@main.binaryMap = local_unnamed_addr global %runtime.hashmap* @"main$map.4"
+@main.stringMap = local_unnamed_addr global %runtime.hashmap* @"main$map.6"
@main.init.string = internal unnamed_addr constant [7 x i8] c"CONNECT"
-@"main$map" = internal global %runtime.hashmap { %runtime.hashmap* null, i8* getelementptr inbounds ({ [8 x i8], i8*, { i8, [7 x i8] }, { { [7 x i8]*, [4 x i8] }, [56 x i8] } }, { [8 x i8], i8*, { i8, [7 x i8] }, { { [7 x i8]*, [4 x i8] }, [56 x i8] } }* @"main$mapbucket", i32 0, i32 0, i32 0), i32 1, i8 1, i8 8, i8 0 }
-@"main$mapbucket" = internal unnamed_addr global { [8 x i8], i8*, { i8, [7 x i8] }, { { [7 x i8]*, [4 x i8] }, [56 x i8] } } { [8 x i8] c"\04\00\00\00\00\00\00\00", i8* null, { i8, [7 x i8] } { i8 1, [7 x i8] zeroinitializer }, { { [7 x i8]*, [4 x i8] }, [56 x i8] } { { [7 x i8]*, [4 x i8] } { [7 x i8]* @main.init.string, [4 x i8] c"\07\00\00\00" }, [56 x i8] zeroinitializer } }
-@"main$map.1" = internal global %runtime.hashmap { %runtime.hashmap* null, i8* getelementptr inbounds ({ [8 x i8], i8*, { i8, [7 x i8] }, { i8, [7 x i8] } }, { [8 x i8], i8*, { i8, [7 x i8] }, { i8, [7 x i8] } }* @"main$mapbucket.2", i32 0, i32 0, i32 0), i32 1, i8 1, i8 1, i8 0 }
-@"main$mapbucket.2" = internal unnamed_addr global { [8 x i8], i8*, { i8, [7 x i8] }, { i8, [7 x i8] } } { [8 x i8] c"\04\00\00\00\00\00\00\00", i8* null, { i8, [7 x i8] } { i8 1, [7 x i8] zeroinitializer }, { i8, [7 x i8] } { i8 2, [7 x i8] zeroinitializer } }
-@"main$map.3" = internal global %runtime.hashmap { %runtime.hashmap* null, i8* getelementptr inbounds ({ [8 x i8], i8*, { { [7 x i8]*, [4 x i8] }, [56 x i8] }, { i8, [7 x i8] } }, { [8 x i8], i8*, { { [7 x i8]*, [4 x i8] }, [56 x i8] }, { i8, [7 x i8] } }* @"main$mapbucket.4", i32 0, i32 0, i32 0), i32 1, i8 8, i8 1, i8 0 }
-@"main$mapbucket.4" = internal unnamed_addr global { [8 x i8], i8*, { { [7 x i8]*, [4 x i8] }, [56 x i8] }, { i8, [7 x i8] } } { [8 x i8] c"x\00\00\00\00\00\00\00", i8* null, { { [7 x i8]*, [4 x i8] }, [56 x i8] } { { [7 x i8]*, [4 x i8] } { [7 x i8]* @main.init.string, [4 x i8] c"\07\00\00\00" }, [56 x i8] zeroinitializer }, { i8, [7 x i8] } { i8 2, [7 x i8] zeroinitializer } }
+@"main$mapbucket" = internal unnamed_addr global { [8 x i8], i8*, [8 x i8], [8 x %runtime._string] } { [8 x i8] c"\04\00\00\00\00\00\00\00", i8* null, [8 x i8] c"\01\00\00\00\00\00\00\00", [8 x %runtime._string] [%runtime._string { i8* getelementptr inbounds ([7 x i8], [7 x i8]* @main.init.string, i32 0, i32 0), i32 7 }, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer] }
+@"main$map" = internal unnamed_addr global %runtime.hashmap { %runtime.hashmap* null, i8* getelementptr inbounds ({ [8 x i8], i8*, [8 x i8], [8 x %runtime._string] }, { [8 x i8], i8*, [8 x i8], [8 x %runtime._string] }* @"main$mapbucket", i32 0, i32 0, i32 0), i32 1, i8 1, i8 8, i8 0 }
+@"main$alloca.2" = internal global i8 1
+@"main$alloca.3" = internal global i8 2
+@"main$map.4" = internal unnamed_addr global %runtime.hashmap { %runtime.hashmap* null, i8* null, i32 0, i8 1, i8 1, i8 0 }
+@"main$alloca.5" = internal global i8 2
+@"main$map.6" = internal unnamed_addr global %runtime.hashmap { %runtime.hashmap* null, i8* null, i32 0, i8 8, i8 1, i8 0 }
+
+declare void @runtime.hashmapBinarySet(%runtime.hashmap*, i8*, i8*, i8*, i8*) local_unnamed_addr
+
+declare void @runtime.hashmapStringSet(%runtime.hashmap*, i8*, i32, i8*, i8*, i8*) local_unnamed_addr

 define void @runtime.initAll() unnamed_addr {
 entry:
+  call void @runtime.hashmapBinarySet(%runtime.hashmap* @"main$map.4", i8* @"main$alloca.2", i8* @"main$alloca.3", i8* undef, i8* null)
+  call void @runtime.hashmapStringSet(%runtime.hashmap* @"main$map.6", i8* getelementptr inbounds ([7 x i8], [7 x i8]* @main.init.string, i32 0, i32 0), i32 7, i8* @"main$alloca.5", i8* undef, i8* null)
  ret void
 }
@@ -0,0 +1,78 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+%runtime.typecodeID = type { %runtime.typecodeID*, i64 }
+
+declare i1 @runtime.typeAssert(i64, %runtime.typecodeID*, i8*, i8*)
+declare i1 @runtime.interfaceImplements(i64, i8**)
+
+define i64 @returnsConst() {
+  ret i64 0
+}
+
+define i64 @returnsArg(i64 %arg) {
+  ret i64 %arg
+}
+
+declare i64 @externalCall()
+
+define i64 @externalCallOnly() {
+  %result = call i64 @externalCall()
+  ret i64 0
+}
+
+define i64 @externalCallAndReturn() {
+  %result = call i64 @externalCall()
+  ret i64 %result
+}
+
+define i64 @externalCallBranch() {
+  %result = call i64 @externalCall()
+  %zero = icmp eq i64 %result, 0
+  br i1 %zero, label %if.then, label %if.done
+
+if.then:
+  ret i64 2
+
+if.done:
+  ret i64 4
+}
+
+@cleanGlobalInt = global i64 5
+define i64 @readCleanGlobal() {
+  %global = load i64, i64* @cleanGlobalInt
+  ret i64 %global
+}
+
+@dirtyGlobalInt = global i64 5
+define i64 @readDirtyGlobal() {
+  %global = load i64, i64* @dirtyGlobalInt
+  ret i64 %global
+}
+
+declare i64* @getDirtyPointer()
+
+define void @storeToPointer() {
+  %ptr = call i64* @getDirtyPointer()
+  store i64 3, i64* %ptr
+  ret void
+}
+
+@functionPointer = global i64()* null
+define i64 @callFunctionPointer() {
+  %fp = load i64()*, i64()** @functionPointer
+  %result = call i64 %fp()
+  ret i64 %result
+}
+
+define i1 @callTypeAssert() {
+  ; Note: parameters are not realistic.
+  %ok = call i1 @runtime.typeAssert(i64 0, %runtime.typecodeID* null, i8* undef, i8* null)
+  ret i1 %ok
+}
+
+define i1 @callInterfaceImplements() {
+  ; Note: parameters are not realistic.
+  %ok = call i1 @runtime.interfaceImplements(i64 0, i8** null)
+  ret i1 %ok
+}
@@ -1,8 +1,6 @@
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64--linux"

-@"main$alloc.1" = internal unnamed_addr constant [6 x i8] c"\05\00{\00\00\04"
-
 declare void @runtime.printuint8(i8) local_unnamed_addr

 declare void @runtime.printint16(i16) local_unnamed_addr
@@ -17,7 +15,6 @@ entry:
  call void @runtime.printuint8(i8 3)
  call void @runtime.printuint8(i8 3)
  call void @runtime.printint16(i16 5)
-  %int16SliceDst.val = load i16, i16* bitcast ([6 x i8]* @"main$alloc.1" to i16*)
-  call void @runtime.printint16(i16 %int16SliceDst.val)
+  call void @runtime.printint16(i16 5)
  ret void
 }
@@ -0,0 +1,121 @@
+package interp
+
+import (
+	"tinygo.org/x/go-llvm"
+)
+
+// Return a list of values (actually, instructions) where this value is used as
+// an operand.
+func getUses(value llvm.Value) []llvm.Value {
+	var uses []llvm.Value
+	use := value.FirstUse()
+	for !use.IsNil() {
+		uses = append(uses, use.User())
+		use = use.NextUse()
+	}
+	return uses
+}
+
+// getStringBytes loads the byte slice of a Go string represented as a
+// {ptr, len} pair.
+func getStringBytes(strPtr Value, strLen llvm.Value) []byte {
+	if !strLen.IsConstant() {
+		panic("getStringBytes with a non-constant length")
+	}
+	buf := make([]byte, strLen.ZExtValue())
+	for i := range buf {
+		gep, err := strPtr.GetElementPtr([]uint32{uint32(i)})
+		if err != nil {
+			panic(err) // TODO
+		}
+		c := gep.Load()
+		buf[i] = byte(c.ZExtValue())
+	}
+	return buf
+}
+
+// getLLVMIndices converts an []uint32 into an []llvm.Value, for use in
+// llvm.ConstGEP.
+func getLLVMIndices(int32Type llvm.Type, indices []uint32) []llvm.Value {
+	llvmIndices := make([]llvm.Value, len(indices))
+	for i, index := range indices {
+		llvmIndices[i] = llvm.ConstInt(int32Type, uint64(index), false)
+	}
+	return llvmIndices
+}
+
+// Return true if this type is a scalar value (integer or floating point), false
+// otherwise.
+func isScalar(t llvm.Type) bool {
+	switch t.TypeKind() {
+	case llvm.IntegerTypeKind, llvm.FloatTypeKind, llvm.DoubleTypeKind:
+		return true
+	default:
+		return false
+	}
+}
+
+// isPointerNil returns whether this is a nil pointer or not. The ok value
+// indicates whether the result is certain: if it is false the result boolean is
+// not valid.
+func isPointerNil(v llvm.Value) (result bool, ok bool) {
+	if !v.IsAConstantExpr().IsNil() {
+		switch v.Opcode() {
+		case llvm.IntToPtr:
+			// Whether a constant inttoptr is nil is easy to
+			// determine.
+			result, ok = isZero(v.Operand(0))
+			if ok {
+				return
+			}
+		case llvm.BitCast, llvm.GetElementPtr:
+			// These const instructions are just a kind of wrappers for the
+			// underlying pointer.
+			return isPointerNil(v.Operand(0))
+		}
+	}
+	if !v.IsAConstantPointerNull().IsNil() {
+		// A constant pointer null is always null, of course.
+		return true, true
+	}
+	if !v.IsAGlobalValue().IsNil() {
+		// A global value is never null.
+		return false, true
+	}
+	return false, false // not valid
+}
+
+// isZero returns whether the value in v is the integer zero, and whether that
+// can be known right now.
+func isZero(v llvm.Value) (result bool, ok bool) {
+	if !v.IsAConstantExpr().IsNil() {
+		switch v.Opcode() {
+		case llvm.PtrToInt:
+			return isPointerNil(v.Operand(0))
+		}
+	}
+	if !v.IsAConstantInt().IsNil() {
+		val := v.ZExtValue()
+		return val == 0, true
+	}
+	return false, false // not valid
+}
+
+// unwrap returns the underlying value, with GEPs removed. This can be useful to
+// get the underlying global of a GEP pointer.
+func unwrap(value llvm.Value) llvm.Value {
+	for {
+		if !value.IsAConstantExpr().IsNil() {
+			switch value.Opcode() {
+			case llvm.GetElementPtr:
+				value = value.Operand(0)
+				continue
+			}
+		} else if !value.IsAGetElementPtrInst().IsNil() {
+			value = value.Operand(0)
+			continue
+		}
+		break
+	}
+	return value
+}
@@ -0,0 +1,419 @@
+package interp
+
+// This file provides a litte bit of abstraction around LLVM values.
+
+import (
+	"errors"
+	"strconv"
+
+	"tinygo.org/x/go-llvm"
+)
+
+// A Value is a LLVM value with some extra methods attached for easier
+// interpretation.
+type Value interface {
+	Value() llvm.Value                     // returns a LLVM value
+	Type() llvm.Type                       // equal to Value().Type()
+	IsConstant() bool                      // returns true if this value is a constant value
+	Load() llvm.Value                      // dereference a pointer
+	Store(llvm.Value)                      // store to a pointer
+	GetElementPtr([]uint32) (Value, error) // returns an interior pointer
+	String() string                        // string representation, for debugging
+}
+
+// A type that simply wraps a LLVM constant value.
+type LocalValue struct {
+	Eval       *Eval
+	Underlying llvm.Value
+}
+
+// Value implements Value by returning the constant value itself.
+func (v *LocalValue) Value() llvm.Value {
+	return v.Underlying
+}
+
+func (v *LocalValue) Type() llvm.Type {
+	return v.Underlying.Type()
+}
+
+func (v *LocalValue) IsConstant() bool {
+	if _, ok := v.Eval.dirtyGlobals[unwrap(v.Underlying)]; ok {
+		return false
+	}
+	return v.Underlying.IsConstant()
+}
+
+// Load loads a constant value if this is a constant pointer.
+func (v *LocalValue) Load() llvm.Value {
+	if !v.Underlying.IsAGlobalVariable().IsNil() {
+		return v.Underlying.Initializer()
+	}
+	switch v.Underlying.Opcode() {
+	case llvm.GetElementPtr:
+		indices := v.getConstGEPIndices()
+		if indices[0] != 0 {
+			panic("invalid GEP")
+		}
+		global := v.Eval.getValue(v.Underlying.Operand(0))
+		agg := global.Load()
+		return llvm.ConstExtractValue(agg, indices[1:])
+	case llvm.BitCast:
+		panic("interp: load from a bitcast")
+	default:
+		panic("interp: load from a constant")
+	}
+}
+
+// Store stores to the underlying value if the value type is a pointer type,
+// otherwise it panics.
+func (v *LocalValue) Store(value llvm.Value) {
+	if !v.Underlying.IsAGlobalVariable().IsNil() {
+		if !value.IsConstant() {
+			v.MarkDirty()
+			v.Eval.builder.CreateStore(value, v.Underlying)
+		} else {
+			v.Underlying.SetInitializer(value)
+		}
+		return
+	}
+	if !value.IsConstant() {
+		v.MarkDirty()
+		v.Eval.builder.CreateStore(value, v.Underlying)
+		return
+	}
+	switch v.Underlying.Opcode() {
+	case llvm.GetElementPtr:
+		indices := v.getConstGEPIndices()
+		if indices[0] != 0 {
+			panic("invalid GEP")
+		}
+		global := &LocalValue{v.Eval, v.Underlying.Operand(0)}
+		agg := global.Load()
+		agg = llvm.ConstInsertValue(agg, value, indices[1:])
+		global.Store(agg)
+		return
+	default:
+		panic("interp: store on a constant")
+	}
+}
+
+// GetElementPtr returns a GEP when the underlying value is of pointer type.
+func (v *LocalValue) GetElementPtr(indices []uint32) (Value, error) {
+	if !v.Underlying.IsAGlobalVariable().IsNil() {
+		int32Type := v.Underlying.Type().Context().Int32Type()
+		gep := llvm.ConstGEP(v.Underlying, getLLVMIndices(int32Type, indices))
+		return &LocalValue{v.Eval, gep}, nil
+	}
+	if !v.Underlying.IsAConstantExpr().IsNil() {
+		switch v.Underlying.Opcode() {
+		case llvm.GetElementPtr, llvm.IntToPtr, llvm.BitCast:
+			int32Type := v.Underlying.Type().Context().Int32Type()
+			llvmIndices := getLLVMIndices(int32Type, indices)
+			return &LocalValue{v.Eval, llvm.ConstGEP(v.Underlying, llvmIndices)}, nil
+		}
+	}
+	return nil, errors.New("interp: unknown GEP")
+}
+
+// stripPointerCasts removes all const bitcasts from pointer values, if there
+// are any.
+func (v *LocalValue) stripPointerCasts() *LocalValue {
+	value := v.Underlying
+	for {
+		if !value.IsAConstantExpr().IsNil() {
+			switch value.Opcode() {
+			case llvm.BitCast:
+				value = value.Operand(0)
+				continue
+			}
+		}
+		return &LocalValue{
+			Eval:       v.Eval,
+			Underlying: value,
+		}
+	}
+}
+
+func (v *LocalValue) String() string {
+	isConstant := "false"
+	if v.IsConstant() {
+		isConstant = "true"
+	}
+	return "&LocalValue{Type: " + v.Type().String() + ", IsConstant: " + isConstant + "}"
+}
+
+// getConstGEPIndices returns indices of this constant GEP, if this is a GEP
+// instruction. If it is not, the behavior is undefined.
+func (v *LocalValue) getConstGEPIndices() []uint32 {
+	indices := make([]uint32, v.Underlying.OperandsCount()-1)
+	for i := range indices {
+		operand := v.Underlying.Operand(i + 1)
+		indices[i] = uint32(operand.ZExtValue())
+	}
+	return indices
+}
+
+// MarkDirty marks this global as dirty, meaning that every load from and store
+// to this global (from now on) must be performed at runtime.
+func (v *LocalValue) MarkDirty() {
+	underlying := unwrap(v.Underlying)
+	if underlying.IsAGlobalVariable().IsNil() {
+		panic("trying to mark a non-global as dirty")
+	}
+	if !v.IsConstant() {
+		return // already dirty
+	}
+	v.Eval.dirtyGlobals[underlying] = struct{}{}
+}
+
+// MapValue implements a Go map which is created at compile time and stored as a
+// global variable.
+type MapValue struct {
+	Eval       *Eval
+	PkgName    string
+	Underlying llvm.Value
+	Keys       []Value
+	Values     []Value
+	KeySize    int
+	ValueSize  int
+	KeyType    llvm.Type
+	ValueType  llvm.Type
+}
+
+func (v *MapValue) newBucket() llvm.Value {
+	ctx := v.Eval.Mod.Context()
+	i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
+	bucketType := ctx.StructType([]llvm.Type{
+		llvm.ArrayType(ctx.Int8Type(), 8), // tophash
+		i8ptrType,                         // next bucket
+		llvm.ArrayType(v.KeyType, 8),      // key type
+		llvm.ArrayType(v.ValueType, 8),    // value type
+	}, false)
+	bucketValue := llvm.ConstNull(bucketType)
+	bucket := llvm.AddGlobal(v.Eval.Mod, bucketType, v.PkgName+"$mapbucket")
+	bucket.SetInitializer(bucketValue)
+	bucket.SetLinkage(llvm.InternalLinkage)
+	bucket.SetUnnamedAddr(true)
+	return bucket
+}
+
+// Value returns a global variable which is a pointer to the actual hashmap.
+func (v *MapValue) Value() llvm.Value {
+	if !v.Underlying.IsNil() {
+		return v.Underlying
+	}
+
+	ctx := v.Eval.Mod.Context()
+	i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
+
+	var firstBucketGlobal llvm.Value
+	if len(v.Keys) == 0 {
+		// there are no buckets
+		firstBucketGlobal = llvm.ConstPointerNull(i8ptrType)
+	} else {
+		// create initial bucket
+		firstBucketGlobal = v.newBucket()
+	}
+
+	// Insert each key/value pair in the hashmap.
+	bucketGlobal := firstBucketGlobal
+	for i, key := range v.Keys {
+		var keyBuf []byte
+		llvmKey := key.Value()
+		llvmValue := v.Values[i].Value()
+		if key.Type().TypeKind() == llvm.StructTypeKind && key.Type().StructName() == "runtime._string" {
+			keyPtr := llvm.ConstExtractValue(llvmKey, []uint32{0})
+			keyLen := llvm.ConstExtractValue(llvmKey, []uint32{1})
+			keyPtrVal := v.Eval.getValue(keyPtr)
+			keyBuf = getStringBytes(keyPtrVal, keyLen)
+		} else if key.Type().TypeKind() == llvm.IntegerTypeKind {
+			keyBuf = make([]byte, v.Eval.TargetData.TypeAllocSize(key.Type()))
+			n := key.Value().ZExtValue()
+			for i := range keyBuf {
+				keyBuf[i] = byte(n)
+				n >>= 8
+			}
+		} else if key.Type().TypeKind() == llvm.ArrayTypeKind &&
+			key.Type().ElementType().TypeKind() == llvm.IntegerTypeKind &&
+			key.Type().ElementType().IntTypeWidth() == 8 {
+			keyBuf = make([]byte, v.Eval.TargetData.TypeAllocSize(key.Type()))
+			for i := range keyBuf {
+				keyBuf[i] = byte(llvm.ConstExtractValue(llvmKey, []uint32{uint32(i)}).ZExtValue())
+			}
+		} else {
+			panic("interp: map key type not implemented: " + key.Type().String())
+		}
+		hash := v.hash(keyBuf)
+
+		if i%8 == 0 && i != 0 {
+			// Bucket is full, create a new one.
+			newBucketGlobal := v.newBucket()
+			zero := llvm.ConstInt(ctx.Int32Type(), 0, false)
+			newBucketPtr := llvm.ConstInBoundsGEP(newBucketGlobal, []llvm.Value{zero})
+			newBucketPtrCast := llvm.ConstBitCast(newBucketPtr, i8ptrType)
+			// insert pointer into old bucket
+			bucket := bucketGlobal.Initializer()
+			bucket = llvm.ConstInsertValue(bucket, newBucketPtrCast, []uint32{1})
+			bucketGlobal.SetInitializer(bucket)
+			// switch to next bucket
+			bucketGlobal = newBucketGlobal
+		}
+
+		tophashValue := llvm.ConstInt(ctx.Int8Type(), uint64(v.topHash(hash)), false)
+		bucket := bucketGlobal.Initializer()
+		bucket = llvm.ConstInsertValue(bucket, tophashValue, []uint32{0, uint32(i % 8)})
+		bucket = llvm.ConstInsertValue(bucket, llvmKey, []uint32{2, uint32(i % 8)})
+		bucket = llvm.ConstInsertValue(bucket, llvmValue, []uint32{3, uint32(i % 8)})
+		bucketGlobal.SetInitializer(bucket)
+	}
+
+	// Create the hashmap itself.
+	zero := llvm.ConstInt(ctx.Int32Type(), 0, false)
+	bucketPtr := llvm.ConstInBoundsGEP(firstBucketGlobal, []llvm.Value{zero})
+	hashmapType := v.Type()
+	hashmap := llvm.ConstNamedStruct(hashmapType, []llvm.Value{
+		llvm.ConstPointerNull(llvm.PointerType(hashmapType, 0)),                        // next
+		llvm.ConstBitCast(bucketPtr, i8ptrType),                                        // buckets
+		llvm.ConstInt(hashmapType.StructElementTypes()[2], uint64(len(v.Keys)), false), // count
+		llvm.ConstInt(ctx.Int8Type(), uint64(v.KeySize), false),                        // keySize
+		llvm.ConstInt(ctx.Int8Type(), uint64(v.ValueSize), false),                      // valueSize
+		llvm.ConstInt(ctx.Int8Type(), 0, false),                                        // bucketBits
+	})
+
+	// Create a pointer to this hashmap.
+	hashmapPtr := llvm.AddGlobal(v.Eval.Mod, hashmap.Type(), v.PkgName+"$map")
+	hashmapPtr.SetInitializer(hashmap)
+	hashmapPtr.SetLinkage(llvm.InternalLinkage)
+	hashmapPtr.SetUnnamedAddr(true)
+	v.Underlying = llvm.ConstInBoundsGEP(hashmapPtr, []llvm.Value{zero})
+	return v.Underlying
+}
+
+// Type returns type runtime.hashmap, which is the actual hashmap type.
+func (v *MapValue) Type() llvm.Type {
+	return v.Eval.Mod.GetTypeByName("runtime.hashmap")
+}
+
+func (v *MapValue) IsConstant() bool {
+	return true // TODO: dirty maps
+}
+
+// Load panics: maps are of reference type so cannot be dereferenced.
+func (v *MapValue) Load() llvm.Value {
+	panic("interp: load from a map")
+}
+
+// Store panics: maps are of reference type so cannot be stored to.
+func (v *MapValue) Store(value llvm.Value) {
+	panic("interp: store on a map")
+}
+
+// GetElementPtr panics: maps are of reference type so their (interior)
+// addresses cannot be calculated.
+func (v *MapValue) GetElementPtr(indices []uint32) (Value, error) {
+	return nil, errors.New("interp: GEP on a map")
+}
+
+// PutString does a map assign operation, assuming that the map is of type
+// map[string]T.
+func (v *MapValue) PutString(keyBuf, keyLen, valPtr *LocalValue) {
+	if !v.Underlying.IsNil() {
+		panic("map already created")
+	}
+
+	if valPtr.Underlying.Opcode() == llvm.BitCast {
+		valPtr = &LocalValue{v.Eval, valPtr.Underlying.Operand(0)}
+	}
+	value := valPtr.Load()
+	if v.ValueType.IsNil() {
+		v.ValueType = value.Type()
+		if int(v.Eval.TargetData.TypeAllocSize(v.ValueType)) != v.ValueSize {
+			panic("interp: map store value type has the wrong size")
+		}
+	} else {
+		if value.Type() != v.ValueType {
+			panic("interp: map store value type is inconsistent")
+		}
+	}
+
+	keyType := v.Eval.Mod.GetTypeByName("runtime._string")
+	v.KeyType = keyType
+	key := llvm.ConstNull(keyType)
+	key = llvm.ConstInsertValue(key, keyBuf.Value(), []uint32{0})
+	key = llvm.ConstInsertValue(key, keyLen.Value(), []uint32{1})
+
+	// TODO: avoid duplicate keys
+	v.Keys = append(v.Keys, &LocalValue{v.Eval, key})
+	v.Values = append(v.Values, &LocalValue{v.Eval, value})
+}
+
+// PutBinary does a map assign operation.
+func (v *MapValue) PutBinary(keyPtr, valPtr *LocalValue) {
+	if !v.Underlying.IsNil() {
+		panic("map already created")
+	}
+
+	if valPtr.Underlying.Opcode() == llvm.BitCast {
+		valPtr = &LocalValue{v.Eval, valPtr.Underlying.Operand(0)}
+	}
+	value := valPtr.Load()
+	if v.ValueType.IsNil() {
+		v.ValueType = value.Type()
+		if int(v.Eval.TargetData.TypeAllocSize(v.ValueType)) != v.ValueSize {
+			panic("interp: map store value type has the wrong size")
+		}
+	} else {
+		if value.Type() != v.ValueType {
+			panic("interp: map store value type is inconsistent")
+		}
+	}
+
+	if !keyPtr.Underlying.IsAConstantExpr().IsNil() {
+		if keyPtr.Underlying.Opcode() == llvm.BitCast {
+			keyPtr = &LocalValue{v.Eval, keyPtr.Underlying.Operand(0)}
+		} else if keyPtr.Underlying.Opcode() == llvm.GetElementPtr {
+			keyPtr = &LocalValue{v.Eval, keyPtr.Underlying.Operand(0)}
+		}
+	}
+	key := keyPtr.Load()
+	if v.KeyType.IsNil() {
+		v.KeyType = key.Type()
+		if int(v.Eval.TargetData.TypeAllocSize(v.KeyType)) != v.KeySize {
+			panic("interp: map store key type has the wrong size")
+		}
+	} else {
+		if key.Type() != v.KeyType {
+			panic("interp: map store key type is inconsistent")
+		}
+	}
+
+	// TODO: avoid duplicate keys
+	v.Keys = append(v.Keys, &LocalValue{v.Eval, key})
+	v.Values = append(v.Values, &LocalValue{v.Eval, value})
+}
+
+// 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 (v *MapValue) hash(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 (v *MapValue) topHash(hash uint32) uint8 {
+	tophash := uint8(hash >> 24)
+	if tophash < 1 {
+		// 0 means empty slot, so make it bigger.
+		tophash += 1
+	}
+	return tophash
+}
+
+func (v *MapValue) String() string {
+	return "&MapValue{KeySize: " + strconv.Itoa(v.KeySize) + ", ValueSize: " + strconv.Itoa(v.ValueSize) + "}"
+}
@@ -0,0 +1,309 @@
+package ir
+
+import (
+	"go/ast"
+	"go/types"
+	"sort"
+	"strings"
+
+	"github.com/tinygo-org/tinygo/loader"
+	"golang.org/x/tools/go/ssa"
+	"tinygo.org/x/go-llvm"
+)
+
+// This file provides a wrapper around go/ssa values and adds extra
+// functionality to them.
+
+// View on all functions, types, and globals in a program, with analysis
+// results.
+type Program struct {
+	Program       *ssa.Program
+	LoaderProgram *loader.Program
+	mainPkg       *ssa.Package
+	Functions     []*Function
+	functionMap   map[*ssa.Function]*Function
+}
+
+// Function or method.
+type Function struct {
+	*ssa.Function
+	LLVMFn   llvm.Value
+	module   string     // go:wasm-module
+	linkName string     // go:linkname, go:export
+	exported bool       // go:export
+	nobounds bool       // go:nobounds
+	flag     bool       // used by dead code elimination
+	inline   InlineType // go:inline
+}
+
+// Interface type that is at some point used in a type assert (to check whether
+// it implements another interface).
+type Interface struct {
+	Num  int
+	Type *types.Interface
+}
+
+type InlineType int
+
+// How much to inline.
+const (
+	// Default behavior. The compiler decides for itself whether any given
+	// function will be inlined. Whether any function is inlined depends on the
+	// optimization level.
+	InlineDefault InlineType = iota
+
+	// Inline hint, just like the C inline keyword (signalled using
+	// //go:inline). The compiler will be more likely to inline this function,
+	// but it is not a guarantee.
+	InlineHint
+
+	// Don't inline, just like the GCC noinline attribute. Signalled using
+	// //go:noinline.
+	InlineNone
+)
+
+// Create and initialize a new *Program from a *ssa.Program.
+func NewProgram(lprogram *loader.Program) *Program {
+	program := lprogram.LoadSSA()
+	program.Build()
+
+	// Find the main package, which is a bit difficult when running a .go file
+	// directly.
+	mainPkg := program.ImportedPackage(lprogram.MainPkg.PkgPath)
+	if mainPkg == nil {
+		panic("could not find main package")
+	}
+
+	// Make a list of packages in import order.
+	packageList := []*ssa.Package{}
+	packageSet := map[string]struct{}{}
+	worklist := []string{"runtime", lprogram.MainPkg.PkgPath}
+	for len(worklist) != 0 {
+		pkgPath := worklist[0]
+		pkg := program.ImportedPackage(pkgPath)
+		if _, ok := packageSet[pkgPath]; ok {
+			// Package already in the final package list.
+			worklist = worklist[1:]
+			continue
+		}
+
+		unsatisfiedImports := make([]string, 0)
+		imports := pkg.Pkg.Imports()
+		for _, pkg := range imports {
+			if _, ok := packageSet[pkg.Path()]; ok {
+				continue
+			}
+			unsatisfiedImports = append(unsatisfiedImports, pkg.Path())
+		}
+		if len(unsatisfiedImports) == 0 {
+			// All dependencies of this package are satisfied, so add this
+			// package to the list.
+			packageList = append(packageList, pkg)
+			packageSet[pkgPath] = struct{}{}
+			worklist = worklist[1:]
+		} else {
+			// Prepend all dependencies to the worklist and reconsider this
+			// package (by not removing it from the worklist). At that point, it
+			// must be possible to add it to packageList.
+			worklist = append(unsatisfiedImports, worklist...)
+		}
+	}
+
+	p := &Program{
+		Program:       program,
+		LoaderProgram: lprogram,
+		mainPkg:       mainPkg,
+		functionMap:   make(map[*ssa.Function]*Function),
+	}
+
+	for _, pkg := range packageList {
+		p.AddPackage(pkg)
+	}
+
+	return p
+}
+
+// Add a package to this Program. All packages need to be added first before any
+// analysis is done for correct results.
+func (p *Program) AddPackage(pkg *ssa.Package) {
+	memberNames := make([]string, 0)
+	for name := range pkg.Members {
+		memberNames = append(memberNames, name)
+	}
+	sort.Strings(memberNames)
+
+	for _, name := range memberNames {
+		member := pkg.Members[name]
+		switch member := member.(type) {
+		case *ssa.Function:
+			p.addFunction(member)
+		case *ssa.Type:
+			methods := getAllMethods(pkg.Prog, member.Type())
+			if !types.IsInterface(member.Type()) {
+				// named type
+				for _, method := range methods {
+					p.addFunction(pkg.Prog.MethodValue(method))
+				}
+			}
+		case *ssa.Global:
+			// Ignore. Globals are not handled here.
+		case *ssa.NamedConst:
+			// Ignore: these are already resolved.
+		default:
+			panic("unknown member type: " + member.String())
+		}
+	}
+}
+
+func (p *Program) addFunction(ssaFn *ssa.Function) {
+	if _, ok := p.functionMap[ssaFn]; ok {
+		return
+	}
+	f := &Function{Function: ssaFn}
+	f.parsePragmas()
+	p.Functions = append(p.Functions, f)
+	p.functionMap[ssaFn] = f
+
+	for _, anon := range ssaFn.AnonFuncs {
+		p.addFunction(anon)
+	}
+}
+
+// Return true if this package imports "unsafe", false otherwise.
+func hasUnsafeImport(pkg *types.Package) bool {
+	for _, imp := range pkg.Imports() {
+		if imp == types.Unsafe {
+			return true
+		}
+	}
+	return false
+}
+
+func (p *Program) GetFunction(ssaFn *ssa.Function) *Function {
+	return p.functionMap[ssaFn]
+}
+
+func (p *Program) MainPkg() *ssa.Package {
+	return p.mainPkg
+}
+
+// Parse compiler directives in the preceding comments.
+func (f *Function) parsePragmas() {
+	if f.Syntax() == nil {
+		return
+	}
+	if decl, ok := f.Syntax().(*ast.FuncDecl); ok && decl.Doc != nil {
+		for _, comment := range decl.Doc.List {
+			text := comment.Text
+			if strings.HasPrefix(text, "//export ") {
+				// Rewrite '//export' to '//go:export' for compatibility with
+				// gc.
+				text = "//go:" + text[2:]
+			}
+			if !strings.HasPrefix(text, "//go:") {
+				continue
+			}
+			parts := strings.Fields(text)
+			switch parts[0] {
+			case "//go:export":
+				if len(parts) != 2 {
+					continue
+				}
+				f.linkName = parts[1]
+				f.exported = true
+			case "//go:wasm-module":
+				// Alternative comment for setting the import module.
+				if len(parts) != 2 {
+					continue
+				}
+				f.module = parts[1]
+			case "//go:inline":
+				f.inline = InlineHint
+			case "//go:noinline":
+				f.inline = InlineNone
+			case "//go:linkname":
+				if len(parts) != 3 || parts[1] != f.Name() {
+					continue
+				}
+				// Only enable go:linkname when the package imports "unsafe".
+				// This is a slightly looser requirement than what gc uses: gc
+				// requires the file to import "unsafe", not the package as a
+				// whole.
+				if hasUnsafeImport(f.Pkg.Pkg) {
+					f.linkName = parts[2]
+				}
+			case "//go:nobounds":
+				// Skip bounds checking in this function. Useful for some
+				// runtime functions.
+				// This is somewhat dangerous and thus only imported in packages
+				// that import unsafe.
+				if hasUnsafeImport(f.Pkg.Pkg) {
+					f.nobounds = true
+				}
+			}
+		}
+	}
+}
+
+func (f *Function) IsNoBounds() bool {
+	return f.nobounds
+}
+
+// Return true iff this function is externally visible.
+func (f *Function) IsExported() bool {
+	return f.exported || f.CName() != ""
+}
+
+// Return the inline directive of this function.
+func (f *Function) Inline() InlineType {
+	return f.inline
+}
+
+// Return the module name if not the default.
+func (f *Function) Module() string {
+	return f.module
+}
+
+// Return the link name for this function.
+func (f *Function) LinkName() string {
+	if f.linkName != "" {
+		return f.linkName
+	}
+	if f.Signature.Recv() != nil {
+		// Method on a defined type (which may be a pointer).
+		return f.RelString(nil)
+	} else {
+		// Bare function.
+		if name := f.CName(); name != "" {
+			// Name CGo functions directly.
+			return name
+		} else {
+			return f.RelString(nil)
+		}
+	}
+}
+
+// Return the name of the C function if this is a CGo wrapper. Otherwise, return
+// a zero-length string.
+func (f *Function) CName() string {
+	name := f.Name()
+	if strings.HasPrefix(name, "_Cfunc_") {
+		// emitted by `go tool cgo`
+		return name[len("_Cfunc_"):]
+	}
+	if strings.HasPrefix(name, "C.") {
+		// created by ../loader/cgo.go
+		return name[2:]
+	}
+	return ""
+}
+
+// Get all methods of a type.
+func getAllMethods(prog *ssa.Program, typ types.Type) []*types.Selection {
+	ms := prog.MethodSets.MethodSet(typ)
+	methods := make([]*types.Selection, ms.Len())
+	for i := 0; i < ms.Len(); i++ {
+		methods[i] = ms.At(i)
+	}
+	return methods
+}
@@ -0,0 +1,149 @@
+package ir
+
+import (
+	"errors"
+	"go/types"
+
+	"golang.org/x/tools/go/ssa"
+)
+
+// This file implements several optimization passes (analysis + transform) to
+// optimize code in SSA form before it is compiled to LLVM IR. It is based on
+// the IR defined in ir.go.
+
+// Make a readable version of a method signature (including the function name,
+// excluding the receiver name). This string is used internally to match
+// interfaces and to call the correct method on an interface. Examples:
+//
+//     String() string
+//     Read([]byte) (int, error)
+func MethodSignature(method *types.Func) string {
+	return method.Name() + signature(method.Type().(*types.Signature))
+}
+
+// Make a readable version of a function (pointer) signature.
+// Examples:
+//
+//     () string
+//     (string, int) (int, error)
+func signature(sig *types.Signature) string {
+	s := ""
+	if sig.Params().Len() == 0 {
+		s += "()"
+	} else {
+		s += "("
+		for i := 0; i < sig.Params().Len(); i++ {
+			if i > 0 {
+				s += ", "
+			}
+			s += sig.Params().At(i).Type().String()
+		}
+		s += ")"
+	}
+	if sig.Results().Len() == 0 {
+		// keep as-is
+	} else if sig.Results().Len() == 1 {
+		s += " " + sig.Results().At(0).Type().String()
+	} else {
+		s += " ("
+		for i := 0; i < sig.Results().Len(); i++ {
+			if i > 0 {
+				s += ", "
+			}
+			s += sig.Results().At(i).Type().String()
+		}
+		s += ")"
+	}
+	return s
+}
+
+// Simple pass that removes dead code. This pass makes later analysis passes
+// more useful.
+func (p *Program) SimpleDCE() error {
+	// Unmark all functions.
+	for _, f := range p.Functions {
+		f.flag = false
+	}
+
+	// Initial set of live functions. Include main.main, *.init and runtime.*
+	// functions.
+	main, ok := p.mainPkg.Members["main"].(*ssa.Function)
+	if !ok {
+		if p.mainPkg.Members["main"] == nil {
+			return errors.New("function main is undeclared in the main package")
+		} else {
+			return errors.New("cannot declare main - must be func")
+		}
+	}
+	runtimePkg := p.Program.ImportedPackage("runtime")
+	mathPkg := p.Program.ImportedPackage("math")
+	taskPkg := p.Program.ImportedPackage("internal/task")
+	p.GetFunction(main).flag = true
+	worklist := []*ssa.Function{main}
+	for _, f := range p.Functions {
+		if f.exported || f.Synthetic == "package initializer" || f.Pkg == runtimePkg || f.Pkg == taskPkg || (f.Pkg == mathPkg && f.Pkg != nil) {
+			if f.flag {
+				continue
+			}
+			f.flag = true
+			worklist = append(worklist, f.Function)
+		}
+	}
+
+	// Mark all called functions recursively.
+	for len(worklist) != 0 {
+		f := worklist[len(worklist)-1]
+		worklist = worklist[:len(worklist)-1]
+		for _, block := range f.Blocks {
+			for _, instr := range block.Instrs {
+				if instr, ok := instr.(*ssa.MakeInterface); ok {
+					for _, sel := range getAllMethods(p.Program, instr.X.Type()) {
+						fn := p.Program.MethodValue(sel)
+						callee := p.GetFunction(fn)
+						if callee == nil {
+							// TODO: why is this necessary?
+							p.addFunction(fn)
+							callee = p.GetFunction(fn)
+						}
+						if !callee.flag {
+							callee.flag = true
+							worklist = append(worklist, callee.Function)
+						}
+					}
+				}
+				for _, operand := range instr.Operands(nil) {
+					if operand == nil || *operand == nil {
+						continue
+					}
+					switch operand := (*operand).(type) {
+					case *ssa.Function:
+						f := p.GetFunction(operand)
+						if f == nil {
+							// FIXME HACK: this function should have been
+							// discovered already. It is not for bound methods.
+							p.addFunction(operand)
+							f = p.GetFunction(operand)
+						}
+						if !f.flag {
+							f.flag = true
+							worklist = append(worklist, operand)
+						}
+					}
+				}
+			}
+		}
+	}
+
+	// Remove unmarked functions.
+	livefunctions := []*Function{}
+	for _, f := range p.Functions {
+		if f.flag {
+			livefunctions = append(livefunctions, f)
+		} else {
+			delete(p.functionMap, f.Function)
+		}
+	}
+	p.Functions = livefunctions
+
+	return nil
+}
@@ -1,7 +1,5 @@
 package loader

-import "go/scanner"
-
 // Errors contains a list of parser errors or a list of typechecker errors for
 // the given package.
 type Errors struct {
@@ -12,14 +10,3 @@ type Errors struct {
 func (e Errors) Error() string {
 	return "could not compile: " + e.Errs[0].Error()
 }
-
-// Error is a regular error but with an added import stack. This is especially
-// useful for debugging import cycle errors.
-type Error struct {
-	ImportStack []string
-	Err         scanner.Error
-}
-
-func (e Error) Error() string {
-	return e.Err.Error()
-}
@@ -7,22 +7,19 @@ import (
 	"crypto/sha512"
 	"encoding/hex"
 	"errors"
-	"fmt"
-	"io"
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"os/exec"
 	"path"
 	"path/filepath"
 	"runtime"
-	"sync"
+	"strconv"

 	"github.com/tinygo-org/tinygo/compileopts"
 	"github.com/tinygo-org/tinygo/goenv"
 )

-var gorootCreateMutex sync.Mutex
-
 // GetCachedGoroot creates a new GOROOT by merging both the standard GOROOT and
 // the GOROOT from TinyGo using lots of symbolic links.
 func GetCachedGoroot(config *compileopts.Config) (string, error) {
@@ -35,45 +32,30 @@ func GetCachedGoroot(config *compileopts.Config) (string, error) {
 		return "", errors.New("could not determine TINYGOROOT")
 	}

+	needsSyscallPackage := false
+	for _, tag := range config.BuildTags() {
+		if tag == "baremetal" || tag == "darwin" {
+			needsSyscallPackage = true
+		}
+	}
+
 	// Determine the location of the cached GOROOT.
 	version, err := goenv.GorootVersionString(goroot)
 	if err != nil {
 		return "", err
 	}
-	// This hash is really a cache key, that contains (hopefully) enough
-	// information to make collisions unlikely during development.
-	// By including the Go version and TinyGo version, cache collisions should
-	// not happen outside of development.
-	hash := sha512.New512_256()
-	fmt.Fprintln(hash, goroot)
-	fmt.Fprintln(hash, version)
-	fmt.Fprintln(hash, goenv.Version)
-	fmt.Fprintln(hash, tinygoroot)
-	gorootsHash := hash.Sum(nil)
+	gorootsHash := sha512.Sum512_256([]byte(goroot + "\x00" + tinygoroot))
 	gorootsHashHex := hex.EncodeToString(gorootsHash[:])
-	cachedgorootName := "goroot-" + version + "-" + gorootsHashHex
-	cachedgoroot := filepath.Join(goenv.Get("GOCACHE"), cachedgorootName)
-	if needsSyscallPackage(config.BuildTags()) {
+	cachedgoroot := filepath.Join(goenv.Get("GOCACHE"), "goroot-"+version+"-"+gorootsHashHex)
+	if needsSyscallPackage {
 		cachedgoroot += "-syscall"
 	}

-	// Do not try to create the cached GOROOT in parallel, that's only a waste
-	// of I/O bandwidth and thus speed. Instead, use a mutex to make sure only
-	// one goroutine does it at a time.
-	// This is not a way to ensure atomicity (a different TinyGo invocation
-	// could be creating the same directory), but instead a way to avoid
-	// creating it many times in parallel when running tests in parallel.
-	gorootCreateMutex.Lock()
-	defer gorootCreateMutex.Unlock()
-
 	if _, err := os.Stat(cachedgoroot); err == nil {
 		return cachedgoroot, nil
 	}
-	err = os.MkdirAll(goenv.Get("GOCACHE"), 0777)
-	if err != nil {
-		return "", err
-	}
-	tmpgoroot, err := ioutil.TempDir(goenv.Get("GOCACHE"), cachedgorootName+".tmp")
+	tmpgoroot := cachedgoroot + ".tmp" + strconv.Itoa(rand.Int())
+	err = os.MkdirAll(tmpgoroot, 0777)
 	if err != nil {
 		return "", err
 	}
@@ -88,7 +70,7 @@ func GetCachedGoroot(config *compileopts.Config) (string, error) {
 			return "", err
 		}
 	}
-	err = mergeDirectory(goroot, tinygoroot, tmpgoroot, "", pathsToOverride(needsSyscallPackage(config.BuildTags())))
+	err = mergeDirectory(goroot, tinygoroot, tmpgoroot, "", pathsToOverride(needsSyscallPackage))
 	if err != nil {
 		return "", err
 	}
@@ -100,15 +82,6 @@ func GetCachedGoroot(config *compileopts.Config) (string, error) {
 			// deleted by the defer above.
 			return cachedgoroot, nil
 		}
-		if runtime.GOOS == "windows" && os.IsPermission(err) {
-			// On Windows, a rename with a destination directory that already
-			// exists does not result in an IsExist error, but rather in an
-			// access denied error. To be sure, check for this case by checking
-			// whether the target directory exists.
-			if _, err := os.Stat(cachedgoroot); err == nil {
-				return cachedgoroot, nil
-			}
-		}
 		return "", err
 	}
 	return cachedgoroot, nil
@@ -185,17 +158,6 @@ func mergeDirectory(goroot, tinygoroot, tmpgoroot, importPath string, overrides
 	return nil
 }

-// needsSyscallPackage returns whether the syscall package should be overriden
-// with the TinyGo version. This is the case on some targets.
-func needsSyscallPackage(buildTags []string) bool {
-	for _, tag := range buildTags {
-		if tag == "baremetal" || tag == "darwin" || tag == "nintendoswitch" || tag == "wasi" {
-			return true
-		}
-	}
-	return false
-}
-
 // The boolean indicates whether to merge the subdirs. True means merge, false
 // means use the TinyGo version.
 func pathsToOverride(needsSyscallPackage bool) map[string]bool {
@@ -204,7 +166,6 @@ func pathsToOverride(needsSyscallPackage bool) map[string]bool {
 		"device/":               false,
 		"examples/":             false,
 		"internal/":             true,
-		"internal/bytealg/":     false,
 		"internal/reflectlite/": false,
 		"internal/task/":        false,
 		"machine/":              false,
@@ -212,7 +173,7 @@ func pathsToOverride(needsSyscallPackage bool) map[string]bool {
 		"reflect/":              false,
 		"runtime/":              false,
 		"sync/":                 true,
-		"testing/":              true,
+		"testing/":              false,
 	}
 	if needsSyscallPackage {
 		paths["syscall/"] = true // include syscall/js
@@ -252,27 +213,10 @@ func symlink(oldname, newname string) error {
 				return symlinkErr
 			}
 		} else {
-			// Try making a hard link.
+			// Make a hard link.
 			err := os.Link(oldname, newname)
 			if err != nil {
-				// Making a hardlink failed. Try copying the file as a last
-				// fallback.
-				inf, err := os.Open(oldname)
-				if err != nil {
-					return err
-				}
-				defer inf.Close()
-				outf, err := os.Create(newname)
-				if err != nil {
-					return err
-				}
-				defer outf.Close()
-				_, err = io.Copy(outf, inf)
-				if err != nil {
-					os.Remove(newname)
-					return err
-				}
-				// File was copied.
+				return symlinkErr
 			}
 		}
 		return nil // success
@@ -1,30 +0,0 @@
-package loader
-
-import (
-	"os"
-	"os/exec"
-	"strings"
-
-	"github.com/tinygo-org/tinygo/compileopts"
-)
-
-// List returns a ready-to-run *exec.Cmd for running the `go list` command with
-// the configuration used for TinyGo.
-func List(config *compileopts.Config, extraArgs, pkgs []string) (*exec.Cmd, error) {
-	goroot, err := GetCachedGoroot(config)
-	if err != nil {
-		return nil, err
-	}
-	args := append([]string{"list"}, extraArgs...)
-	if len(config.BuildTags()) != 0 {
-		args = append(args, "-tags", strings.Join(config.BuildTags(), " "))
-	}
-	args = append(args, pkgs...)
-	cgoEnabled := "0"
-	if config.CgoEnabled() {
-		cgoEnabled = "1"
-	}
-	cmd := exec.Command("go", args...)
-	cmd.Env = append(os.Environ(), "GOROOT="+goroot, "GOOS="+config.GOOS(), "GOARCH="+config.GOARCH(), "CGO_ENABLED="+cgoEnabled)
-	return cmd, nil
-}
@@ -2,245 +2,159 @@ package loader

 import (
 	"bytes"
-	"crypto/sha512"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"go/ast"
+	"go/build"
 	"go/parser"
-	"go/scanner"
 	"go/token"
 	"go/types"
-	"io"
-	"io/ioutil"
 	"os"
-	"os/exec"
 	"path/filepath"
-	"strconv"
+	"sort"
 	"strings"
+	"text/template"

 	"github.com/tinygo-org/tinygo/cgo"
-	"github.com/tinygo-org/tinygo/compileopts"
 	"github.com/tinygo-org/tinygo/goenv"
+	"golang.org/x/tools/go/packages"
 )

 // Program holds all packages and some metadata about the program as a whole.
 type Program struct {
-	config       *compileopts.Config
-	clangHeaders string
-	typeChecker  types.Config
-	goroot       string // synthetic GOROOT
-	workingDir   string
-
-	Packages map[string]*Package
-	sorted   []*Package
-	fset     *token.FileSet
-
-	// Information obtained during parsing.
-	LDFlags []string
-}
-
-// PackageJSON is a subset of the JSON struct returned from `go list`.
-type PackageJSON struct {
-	Dir        string
-	ImportPath string
-	Name       string
-	ForTest    string
-
-	// Source files
-	GoFiles  []string
-	CgoFiles []string
-	CFiles   []string
-
-	// Dependency information
-	Imports   []string
-	ImportMap map[string]string
-
-	// Error information
-	Error *struct {
-		ImportStack []string
-		Pos         string
-		Err         string
-	}
+	Build        *build.Context
+	Tests        bool
+	Packages     map[string]*Package
+	MainPkg      *Package
+	sorted       []*Package
+	fset         *token.FileSet
+	TypeChecker  types.Config
+	Dir          string // current working directory (for error reporting)
+	TINYGOROOT   string // root of the TinyGo installation or root of the source code
+	CFlags       []string
+	ClangHeaders string
 }

 // Package holds a loaded package, its imports, and its parsed files.
 type Package struct {
-	PackageJSON
-
-	program    *Program
-	Files      []*ast.File
-	FileHashes map[string][]byte
-	CFlags     []string // CFlags used during CGo preprocessing (only set if CGo is used)
-	Pkg        *types.Package
-	info       types.Info
+	*Program
+	*packages.Package
+	Files []*ast.File
+	Pkg   *types.Package
+	types.Info
 }

 // Load loads the given package with all dependencies (including the runtime
 // package). Call .Parse() afterwards to parse all Go files (including CGo
 // processing, if necessary).
-func Load(config *compileopts.Config, inputPkgs []string, clangHeaders string, typeChecker types.Config) (*Program, error) {
-	goroot, err := GetCachedGoroot(config)
-	if err != nil {
-		return nil, err
-	}
-	wd, err := os.Getwd()
-	if err != nil {
-		return nil, err
-	}
-	p := &Program{
-		config:       config,
-		clangHeaders: clangHeaders,
-		typeChecker:  typeChecker,
-		goroot:       goroot,
-		workingDir:   wd,
-		Packages:     make(map[string]*Package),
-		fset:         token.NewFileSet(),
+func (p *Program) Load(importPath string) error {
+	if p.Packages == nil {
+		p.Packages = make(map[string]*Package)
 	}

-	// List the dependencies of this package, in raw JSON format.
-	extraArgs := []string{"-json", "-deps"}
-	if config.TestConfig.CompileTestBinary {
-		extraArgs = append(extraArgs, "-test")
-	}
-	cmd, err := List(config, extraArgs, inputPkgs)
+	err := p.loadPackage(importPath)
 	if err != nil {
-		return nil, err
+		return err
 	}
-	buf := &bytes.Buffer{}
-	cmd.Stdout = buf
-	cmd.Stderr = os.Stderr
-	err = cmd.Run()
-	if err != nil {
-		if exitErr, ok := err.(*exec.ExitError); ok {
-			os.Exit(exitErr.ExitCode())
-		}
-		return nil, fmt.Errorf("failed to run `go list`: %s", err)
+	p.MainPkg = p.sorted[len(p.sorted)-1]
+	if _, ok := p.Packages["runtime"]; !ok {
+		// The runtime package wasn't loaded. Although `go list -deps` seems to
+		// return the full dependency list, there is no way to get those
+		// packages from the go/packages package. Therefore load the runtime
+		// manually and add it to the list of to-be-compiled packages
+		// (duplicates are already filtered).
+		return p.loadPackage("runtime")
 	}
-
-	// Parse the returned json from `go list`.
-	decoder := json.NewDecoder(buf)
-	for {
-		pkg := &Package{
-			program:    p,
-			FileHashes: make(map[string][]byte),
-			info: types.Info{
-				Types:      make(map[ast.Expr]types.TypeAndValue),
-				Defs:       make(map[*ast.Ident]types.Object),
-				Uses:       make(map[*ast.Ident]types.Object),
-				Implicits:  make(map[ast.Node]types.Object),
-				Scopes:     make(map[ast.Node]*types.Scope),
-				Selections: make(map[*ast.SelectorExpr]*types.Selection),
-			},
-		}
-		err := decoder.Decode(&pkg.PackageJSON)
-		if err != nil {
-			if err == io.EOF {
-				break
-			}
-			return nil, err
-		}
-		if pkg.Error != nil {
-			// There was an error while importing (for example, a circular
-			// dependency).
-			pos := token.Position{}
-			fields := strings.Split(pkg.Error.Pos, ":")
-			if len(fields) >= 2 {
-				// There is some file/line/column information.
-				if n, err := strconv.Atoi(fields[len(fields)-2]); err == nil {
-					// Format: filename.go:line:colum
-					pos.Filename = strings.Join(fields[:len(fields)-2], ":")
-					pos.Line = n
-					pos.Column, _ = strconv.Atoi(fields[len(fields)-1])
-				} else {
-					// Format: filename.go:line
-					pos.Filename = strings.Join(fields[:len(fields)-1], ":")
-					pos.Line, _ = strconv.Atoi(fields[len(fields)-1])
-				}
-				pos.Filename = p.getOriginalPath(pos.Filename)
-			}
-			err := scanner.Error{
-				Pos: pos,
-				Msg: pkg.Error.Err,
-			}
-			if len(pkg.Error.ImportStack) != 0 {
-				return nil, Error{
-					ImportStack: pkg.Error.ImportStack,
-					Err:         err,
-				}
-			}
-			return nil, err
-		}
-		if config.TestConfig.CompileTestBinary {
-			// When creating a test binary, `go list` will list two or three
-			// packages used for testing the package. The first is the original
-			// package as if it were built normally, the second is the same
-			// package but with the *_test.go files included. A possible third
-			// may be included for _test packages (such as math_test), used to
-			// test the external API with no access to internal functions.
-			// All packages that are necessary for testing (including the to be
-			// tested package with *_test.go files, but excluding the original
-			// unmodified package) have a suffix added to the import path, for
-			// example the math package has import path "math [math.test]" and
-			// test dependencies such as fmt will have an import path of the
-			// form "fmt [math.test]".
-			// The code below removes this suffix, and if this results in a
-			// duplicate (which happens with the to-be-tested package without
-			// *.test.go files) the previous package is removed from the list of
-			// packages included in this build.
-			// This is necessary because the change in import paths results in
-			// breakage to //go:linkname. Additionally, the duplicated package
-			// slows down the build and so is best removed.
-			if pkg.ForTest != "" && strings.HasSuffix(pkg.ImportPath, " ["+pkg.ForTest+".test]") {
-				newImportPath := pkg.ImportPath[:len(pkg.ImportPath)-len(" ["+pkg.ForTest+".test]")]
-				if _, ok := p.Packages[newImportPath]; ok {
-					// Delete the previous package (that this package overrides).
-					delete(p.Packages, newImportPath)
-					for i, pkg := range p.sorted {
-						if pkg.ImportPath == newImportPath {
-							p.sorted = append(p.sorted[:i], p.sorted[i+1:]...) // remove element from slice
-							break
-						}
-					}
-				}
-				pkg.ImportPath = newImportPath
-			}
-		}
-		p.sorted = append(p.sorted, pkg)
-		p.Packages[pkg.ImportPath] = pkg
-	}
-
-	return p, nil
+	return nil
 }

-// getOriginalPath looks whether this path is in the generated GOROOT and if so,
-// replaces the path with the original path (in GOROOT or TINYGOROOT). Otherwise
-// the input path is returned.
-func (p *Program) getOriginalPath(path string) string {
-	originalPath := path
-	if strings.HasPrefix(path, p.goroot+string(filepath.Separator)) {
-		// If this file is part of the synthetic GOROOT, try to infer the
-		// original path.
-		relpath := path[len(filepath.Join(p.goroot, "src"))+1:]
-		realgorootPath := filepath.Join(goenv.Get("GOROOT"), "src", relpath)
-		if _, err := os.Stat(realgorootPath); err == nil {
-			originalPath = realgorootPath
-		}
-		maybeInTinyGoRoot := false
-		for prefix := range pathsToOverride(needsSyscallPackage(p.config.BuildTags())) {
-			if !strings.HasPrefix(relpath, prefix) {
-				continue
-			}
-			maybeInTinyGoRoot = true
-		}
-		if maybeInTinyGoRoot {
-			tinygoPath := filepath.Join(goenv.Get("TINYGOROOT"), "src", relpath)
-			if _, err := os.Stat(tinygoPath); err == nil {
-				originalPath = tinygoPath
-			}
-		}
+func (p *Program) loadPackage(importPath string) error {
+	cgoEnabled := "0"
+	if p.Build.CgoEnabled {
+		cgoEnabled = "1"
+	}
+	pkgs, err := packages.Load(&packages.Config{
+		Mode:       packages.NeedName | packages.NeedFiles | packages.NeedImports | packages.NeedDeps,
+		Env:        append(os.Environ(), "GOROOT="+p.Build.GOROOT, "GOOS="+p.Build.GOOS, "GOARCH="+p.Build.GOARCH, "CGO_ENABLED="+cgoEnabled),
+		BuildFlags: []string{"-tags", strings.Join(p.Build.BuildTags, " ")},
+		Tests:      p.Tests,
+	}, importPath)
+	if err != nil {
+		return err
+	}
+	var pkg *packages.Package
+	if p.Tests {
+		// We need the second package. Quoting from the docs:
+		// > For example, when using the go command, loading "fmt" with Tests=true
+		// > returns four packages, with IDs "fmt" (the standard package),
+		// > "fmt [fmt.test]" (the package as compiled for the test),
+		// > "fmt_test" (the test functions from source files in package fmt_test),
+		// > and "fmt.test" (the test binary).
+		pkg = pkgs[1]
+	} else {
+		if len(pkgs) != 1 {
+			return fmt.Errorf("expected exactly one package while importing %s, got %d", importPath, len(pkgs))
+		}
+		pkg = pkgs[0]
+	}
+	var importError *Errors
+	var addPackages func(pkg *packages.Package)
+	addPackages = func(pkg *packages.Package) {
+		if _, ok := p.Packages[pkg.PkgPath]; ok {
+			return
+		}
+		pkg2 := p.newPackage(pkg)
+		p.Packages[pkg.PkgPath] = pkg2
+		if len(pkg.Errors) != 0 {
+			if importError != nil {
+				// There was another error reported already. Do not report
+				// errors from multiple packages at once.
+				return
+			}
+			importError = &Errors{
+				Pkg: pkg2,
+			}
+			for _, err := range pkg.Errors {
+				importError.Errs = append(importError.Errs, err)
+			}
+			return
+		}
+
+		// Get the list of imports (sorted alphabetically).
+		names := make([]string, 0, len(pkg.Imports))
+		for name := range pkg.Imports {
+			names = append(names, name)
+		}
+		sort.Strings(names)
+
+		// Add all the imports.
+		for _, name := range names {
+			addPackages(pkg.Imports[name])
+		}
+
+		p.sorted = append(p.sorted, pkg2)
+	}
+	addPackages(pkg)
+	if importError != nil {
+		return importError
+	}
+	return nil
+}
+
+// newPackage instantiates a new *Package object with initialized members.
+func (p *Program) newPackage(pkg *packages.Package) *Package {
+	return &Package{
+		Program: p,
+		Package: pkg,
+		Info: types.Info{
+			Types:      make(map[ast.Expr]types.TypeAndValue),
+			Defs:       make(map[*ast.Ident]types.Object),
+			Uses:       make(map[*ast.Ident]types.Object),
+			Implicits:  make(map[ast.Node]types.Object),
+			Scopes:     make(map[ast.Node]*types.Scope),
+			Selections: make(map[*ast.SelectorExpr]*types.Selection),
+		},
 	}
-	return originalPath
 }

 // Sorted returns a list of all packages, sorted in a way that no packages come
@@ -249,12 +163,6 @@ func (p *Program) Sorted() []*Package {
 	return p.sorted
 }

-// MainPkg returns the last package in the Sorted() slice. This is the main
-// package of the program.
-func (p *Program) MainPkg() *Package {
-	return p.sorted[len(p.sorted)-1]
-}
-
 // Parse parses all packages and typechecks them.
 //
 // The returned error may be an Errors error, which contains a list of errors.
@@ -262,16 +170,22 @@ func (p *Program) MainPkg() *Package {
 // Idempotent.
 func (p *Program) Parse() error {
 	// Parse all packages.
-	// TODO: do this in parallel.
-	for _, pkg := range p.sorted {
+	for _, pkg := range p.Sorted() {
 		err := pkg.Parse()
 		if err != nil {
 			return err
 		}
 	}

+	if p.Tests {
+		err := p.swapTestMain()
+		if err != nil {
+			return err
+		}
+	}
+
 	// Typecheck all packages.
-	for _, pkg := range p.sorted {
+	for _, pkg := range p.Sorted() {
 		err := pkg.Check()
 		if err != nil {
 			return err
@@ -281,16 +195,108 @@ func (p *Program) Parse() error {
 	return nil
 }

+func (p *Program) swapTestMain() error {
+	var tests []string
+
+	isTestFunc := func(f *ast.FuncDecl) bool {
+		// TODO: improve signature check
+		if strings.HasPrefix(f.Name.Name, "Test") && f.Name.Name != "TestMain" {
+			return true
+		}
+		return false
+	}
+	for _, f := range p.MainPkg.Files {
+		for i, d := range f.Decls {
+			switch v := d.(type) {
+			case *ast.FuncDecl:
+				if isTestFunc(v) {
+					tests = append(tests, v.Name.Name)
+				}
+				if v.Name.Name == "main" {
+					// Remove main
+					if len(f.Decls) == 1 {
+						f.Decls = make([]ast.Decl, 0)
+					} else {
+						f.Decls[i] = f.Decls[len(f.Decls)-1]
+						f.Decls = f.Decls[:len(f.Decls)-1]
+					}
+				}
+			}
+		}
+	}
+
+	// TODO: Check if they defined a TestMain and call it instead of testing.TestMain
+	const mainBody = `package main
+
+import (
+	"testing"
+)
+
+func main () {
+	m := &testing.M{
+		Tests: []testing.TestToCall{
+{{range .TestFunctions}}
+			{Name: "{{.}}", Func: {{.}}},
+{{end}}
+		},
+	}
+
+	testing.TestMain(m)
+}
+`
+	tmpl := template.Must(template.New("testmain").Parse(mainBody))
+	b := bytes.Buffer{}
+	tmplData := struct {
+		TestFunctions []string
+	}{
+		TestFunctions: tests,
+	}
+
+	err := tmpl.Execute(&b, tmplData)
+	if err != nil {
+		return err
+	}
+	path := filepath.Join(p.MainPkg.Dir, "$testmain.go")
+
+	if p.fset == nil {
+		p.fset = token.NewFileSet()
+	}
+
+	newMain, err := parser.ParseFile(p.fset, path, b.Bytes(), parser.AllErrors)
+	if err != nil {
+		return err
+	}
+	p.MainPkg.Files = append(p.MainPkg.Files, newMain)
+
+	return nil
+}
+
 // parseFile is a wrapper around parser.ParseFile.
-func (p *Package) parseFile(path string, mode parser.Mode) (*ast.File, error) {
-	originalPath := p.program.getOriginalPath(path)
-	data, err := ioutil.ReadFile(path)
+func (p *Program) parseFile(path string, mode parser.Mode) (*ast.File, error) {
+	if p.fset == nil {
+		p.fset = token.NewFileSet()
+	}
+
+	rd, err := os.Open(path)
 	if err != nil {
 		return nil, err
 	}
-	sum := sha512.Sum512_224(data)
-	p.FileHashes[originalPath] = sum[:]
-	return parser.ParseFile(p.program.fset, originalPath, data, mode)
+	defer rd.Close()
+	diagnosticPath := path
+	if strings.HasPrefix(path, p.Build.GOROOT+string(filepath.Separator)) {
+		// If this file is part of the synthetic GOROOT, try to infer the
+		// original path.
+		relpath := path[len(p.Build.GOROOT)+1:]
+		tinygoPath := filepath.Join(p.TINYGOROOT, relpath)
+		if _, err := os.Stat(tinygoPath); err == nil {
+			diagnosticPath = tinygoPath
+		}
+		realgorootPath := filepath.Join(goenv.Get("GOROOT"), relpath)
+		if _, err := os.Stat(realgorootPath); err == nil {
+			diagnosticPath = realgorootPath
+		}
+	}
+	return parser.ParseFile(p.fset, diagnosticPath, rd, mode)
 }

 // Parse parses and typechecks this package.
@@ -298,13 +304,14 @@ func (p *Package) parseFile(path string, mode parser.Mode) (*ast.File, error) {
 // Idempotent.
 func (p *Package) Parse() error {
 	if len(p.Files) != 0 {
-		return nil // nothing to do (?)
+		return nil
 	}

 	// Load the AST.
-	if p.ImportPath == "unsafe" {
-		// Special case for the unsafe package, which is defined internally by
-		// the types package.
+	// TODO: do this in parallel.
+	if p.PkgPath == "unsafe" {
+		// Special case for the unsafe package. Don't even bother loading
+		// the files.
 		p.Pkg = types.Unsafe
 		return nil
 	}
@@ -324,11 +331,11 @@ func (p *Package) Parse() error {
 // Idempotent.
 func (p *Package) Check() error {
 	if p.Pkg != nil {
-		return nil // already typechecked
+		return nil
 	}

 	var typeErrors []error
-	checker := p.program.typeChecker // make a copy, because it will be modified
+	checker := p.TypeChecker
 	checker.Error = func(err error) {
 		typeErrors = append(typeErrors, err)
 	}
@@ -336,16 +343,7 @@ func (p *Package) Check() error {
 	// Do typechecking of the package.
 	checker.Importer = p

-	packageName := p.ImportPath
-	if p.Name == "main" {
-		// The main package normally has a different import path, such as
-		// "command-line-arguments" or "./testdata/cgo". Therefore, use the name
-		// "main" in such a case: this package isn't imported from anywhere.
-		// This is safe as it isn't possible to import a package with the name
-		// "main".
-		packageName = "main"
-	}
-	typesPkg, err := checker.Check(packageName, p.program.fset, p.Files, &p.info)
+	typesPkg, err := checker.Check(p.PkgPath, p.fset, p.Files, &p.Info)
 	if err != nil {
 		if err, ok := err.(Errors); ok {
 			return err
@@ -358,50 +356,39 @@ func (p *Package) Check() error {

 // parseFiles parses the loaded list of files and returns this list.
 func (p *Package) parseFiles() ([]*ast.File, error) {
+	// TODO: do this concurrently.
 	var files []*ast.File
 	var fileErrs []error

-	// Parse all files (incuding CgoFiles).
-	parseFile := func(file string) {
-		if !filepath.IsAbs(file) {
-			file = filepath.Join(p.Dir, file)
-		}
+	var cgoFiles []*ast.File
+	for _, file := range p.GoFiles {
 		f, err := p.parseFile(file, parser.ParseComments)
 		if err != nil {
 			fileErrs = append(fileErrs, err)
-			return
+			continue
+		}
+		if err != nil {
+			fileErrs = append(fileErrs, err)
+			continue
+		}
+		for _, importSpec := range f.Imports {
+			if importSpec.Path.Value == `"C"` {
+				cgoFiles = append(cgoFiles, f)
+			}
 		}
 		files = append(files, f)
 	}
-	for _, file := range p.GoFiles {
-		parseFile(file)
-	}
-	for _, file := range p.CgoFiles {
-		parseFile(file)
-	}
-
-	// Do CGo processing.
-	if len(p.CgoFiles) != 0 {
-		var cflags []string
-		cflags = append(cflags, p.program.config.CFlags()...)
-		cflags = append(cflags, "-I"+p.Dir)
-		if p.program.clangHeaders != "" {
-			cflags = append(cflags, "-Xclang", "-internal-isystem", "-Xclang", p.program.clangHeaders)
-		}
-		p.CFlags = cflags
-		generated, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.program.fset, cflags)
-		for path, hash := range accessedFiles {
-			p.FileHashes[path] = hash
+	if len(cgoFiles) != 0 {
+		cflags := append(p.CFlags, "-I"+filepath.Dir(p.GoFiles[0]))
+		if p.ClangHeaders != "" {
+			cflags = append(cflags, "-Xclang", "-internal-isystem", "-Xclang", p.ClangHeaders)
 		}
+		generated, errs := cgo.Process(files, p.Program.Dir, p.fset, cflags)
 		if errs != nil {
 			fileErrs = append(fileErrs, errs...)
 		}
 		files = append(files, generated)
-		p.program.LDFlags = append(p.program.LDFlags, ldflags...)
 	}
-
-	// Only return an error after CGo processing, so that errors in parsing and
-	// CGo can be reported together.
 	if len(fileErrs) != 0 {
 		return nil, Errors{p, fileErrs}
 	}
@@ -415,11 +402,8 @@ func (p *Package) Import(to string) (*types.Package, error) {
 	if to == "unsafe" {
 		return types.Unsafe, nil
 	}
-	if newTo, ok := p.ImportMap[to]; ok && !strings.HasSuffix(newTo, ".test]") {
-		to = newTo
-	}
-	if imported, ok := p.program.Packages[to]; ok {
-		return imported.Pkg, nil
+	if _, ok := p.Imports[to]; ok {
+		return p.Packages[p.Imports[to].PkgPath].Pkg, nil
 	} else {
 		return nil, errors.New("package not imported: " + to)
 	}
@@ -10,17 +10,9 @@ import (
 func (p *Program) LoadSSA() *ssa.Program {
 	prog := ssa.NewProgram(p.fset, ssa.SanityCheckFunctions|ssa.BareInits|ssa.GlobalDebug)

-	for _, pkg := range p.sorted {
-		prog.CreatePackage(pkg.Pkg, pkg.Files, &pkg.info, true)
+	for _, pkg := range p.Sorted() {
+		prog.CreatePackage(pkg.Pkg, pkg.Files, &pkg.Info, true)
 	}

 	return prog
 }
-
-// LoadSSA constructs the SSA form of this package.
-//
-// The program must already be parsed and type-checked with the .Parse() method.
-func (p *Package) LoadSSA() *ssa.Package {
-	prog := ssa.NewProgram(p.program.fset, ssa.SanityCheckFunctions|ssa.BareInits|ssa.GlobalDebug)
-	return prog.CreatePackage(p.Pkg, p.Files, &p.info, true)
-}
@@ -6,7 +6,6 @@ package main
 import (
 	"bufio"
 	"bytes"
-	"flag"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -26,8 +25,6 @@ import (

 const TESTDATA = "testdata"

-var testTarget = flag.String("target", "", "override test target")
-
 func TestCompiler(t *testing.T) {
 	matches, err := filepath.Glob(filepath.Join(TESTDATA, "*.go"))
 	if err != nil {
@@ -47,20 +44,9 @@ func TestCompiler(t *testing.T) {

 	sort.Strings(matches)

-	if *testTarget != "" {
-		// This makes it possible to run one specific test (instead of all),
-		// which is especially useful to quickly check whether some changes
-		// affect a particular target architecture.
-		runPlatTests(*testTarget, matches, t)
-		return
-	}
-
 	if runtime.GOOS != "windows" {
 		t.Run("Host", func(t *testing.T) {
 			runPlatTests("", matches, t)
-			if runtime.GOOS == "darwin" {
-				runTest("testdata/libc/env.go", "", t, []string{"ENV1=VALUE1", "ENV2=VALUE2"}...)
-			}
 		})
 	}

@@ -81,9 +67,6 @@ func TestCompiler(t *testing.T) {
 	}

 	if runtime.GOOS == "linux" {
-		t.Run("X86Linux", func(t *testing.T) {
-			runPlatTests("i386--linux-gnu", matches, t)
-		})
 		t.Run("ARMLinux", func(t *testing.T) {
 			runPlatTests("arm--linux-gnueabihf", matches, t)
 		})
@@ -104,11 +87,6 @@ func TestCompiler(t *testing.T) {
 				runPlatTests("wasm", matches, t)
 			})
 		}
-
-		t.Run("WASI", func(t *testing.T) {
-			runPlatTests("wasi", matches, t)
-			runTest("testdata/libc/env.go", "wasi", t, []string{"ENV1=VALUE1", "ENV2=VALUE2"}...)
-		})
 	}
 }

@@ -117,8 +95,10 @@ func runPlatTests(target string, matches []string, t *testing.T) {

 	for _, path := range matches {
 		path := path // redefine to avoid race condition
+
 		t.Run(filepath.Base(path), func(t *testing.T) {
 			t.Parallel()
+
 			runTest(path, target, t)
 		})
 	}
@@ -136,7 +116,7 @@ func runBuild(src, out string, opts *compileopts.Options) error {
 	return Build(src, out, opts)
 }

-func runTest(path, target string, t *testing.T, environmentVars ...string) {
+func runTest(path, target string, t *testing.T) {
 	// Get the expected output for this test.
 	txtpath := path[:len(path)-3] + ".txt"
 	if path[len(path)-1] == os.PathSeparator {
@@ -166,11 +146,10 @@ func runTest(path, target string, t *testing.T, environmentVars ...string) {
 		PrintIR:    false,
 		DumpSSA:    false,
 		VerifyIR:   true,
-		Debug:      true,
+		Debug:      false,
 		PrintSizes: "",
-		WasmAbi:    "",
+		WasmAbi:    "js",
 	}
-
 	binary := filepath.Join(tmpdir, "test")
 	err = runBuild("./"+path, binary, config)
 	if err != nil {
@@ -185,26 +164,16 @@ func runTest(path, target string, t *testing.T, environmentVars ...string) {
 	ranTooLong := false
 	if target == "" {
 		cmd = exec.Command(binary)
-		cmd.Env = append(cmd.Env, environmentVars...)
 	} else {
 		spec, err := compileopts.LoadTarget(target)
 		if err != nil {
 			t.Fatal("failed to load target spec:", err)
 		}
 		if len(spec.Emulator) == 0 {
-			cmd = exec.Command(binary)
-		} else {
-			args := append(spec.Emulator[1:], binary)
-			cmd = exec.Command(spec.Emulator[0], args...)
-		}
-
-		if len(spec.Emulator) != 0 && spec.Emulator[0] == "wasmtime" {
-			for _, v := range environmentVars {
-				cmd.Args = append(cmd.Args, "--env", v)
-			}
-		} else {
-			cmd.Env = append(cmd.Env, environmentVars...)
+			t.Fatal("no emulator available for target:", target)
 		}
+		args := append(spec.Emulator[1:], binary)
+		cmd = exec.Command(spec.Emulator[0], args...)
 	}
 	stdout := &bytes.Buffer{}
 	cmd.Stdout = stdout
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Ayke van Laethem	4e07fc569c	main: add -json flag support to go env This is needed for VS Code support.	2020-05-08 14:50:37 +02:00
Ayke van Laethem	25e13d887f	loader: load packages using Go modules This commit replaces the existing ad-hoc package loader with a package loader that uses the x/tools/go/packages package to find all to-be-loaded packages.	2020-05-08 14:50:26 +02:00
Ayke van Laethem	51daa2a044	main: fix test subcommand It was broken for quite some time without anybody noticing...	2020-05-08 14:50:26 +02:00
Ayke van Laethem	f70dc70247	loader: merge roots from both Go and TinyGo in a cached directory This commit changes the way that packages are looked up. Instead of working around the loader package by modifying the GOROOT variable for specific packages, create a new GOROOT using symlinks. This GOROOT is cached for the specified configuration (Go version, underlying GOROOT path, TinyGo path, whether to override the syscall package). This will also enable go module support in the future.	2020-05-05 00:06:53 +02:00
Ayke van Laethem	f24bb1ceda	builder: move Go version code to goenv package This is necessary to avoid a circular dependency in the loader (which soon will need to read the Go version) and because it seems like a better place anyway.	2020-05-04 21:58:27 +02:00