targets/gba: implement interrupt handler

targets/gba: make linker script cleaner
Make it clearer where the stack is located.
2026-07-30 00:28:41 +00:00 · 2020-01-06 14:45:32 +01:00 · 2020-01-06 11:48:09 +01:00 · 2020-01-05 08:05:38 +01:00 · 2020-01-04 23:40:45 +01:00 · 2020-01-04 23:40:44 +01:00
304 changed files with 5938 additions and 12955 deletions
@@ -14,16 +14,18 @@ commands:
      - run:
          name: "Install apt dependencies"
          command: |
-            echo 'deb https://apt.llvm.org/buster/ llvm-toolchain-buster-<<parameters.llvm>> main' | sudo tee /etc/apt/sources.list.d/llvm.list
+            echo 'deb http://apt.llvm.org/stretch/ llvm-toolchain-stretch<<parameters.llvm>> main' | sudo tee /etc/apt/sources.list.d/llvm.list
            wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
            sudo apt-get update
            sudo apt-get install \
-                llvm-<<parameters.llvm>>-dev \
-                clang-<<parameters.llvm>> \
-                libclang-<<parameters.llvm>>-dev \
-                lld-<<parameters.llvm>> \
+                llvm<<parameters.llvm>>-dev \
+                clang<<parameters.llvm>> \
+                libclang<<parameters.llvm>>-dev \
+                lld<<parameters.llvm>> \
                gcc-arm-linux-gnueabihf \
+                libc6-dev-armel-cross \
                gcc-aarch64-linux-gnu \
+                libc6-dev-arm64-cross \
                qemu-system-arm \
                qemu-user \
                gcc-avr \
@@ -41,51 +43,28 @@ commands:
    steps:
      - restore_cache:
          keys:
-            - llvm-source-10-v0
+            - llvm-source-9-v0
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-10-v0
+          key: llvm-source-9-v0
          paths:
            - llvm-project
-  build-wasi-libc:
-    steps:
-      - restore_cache:
-          keys:
-            - wasi-libc-sysroot-v2
-      - run:
-          name: "Build wasi-libc"
-          command: make wasi-libc
-      - save_cache:
-          key: wasi-libc-sysroot-v2
-          paths:
-            - lib/wasi-libc/sysroot
  test-linux:
-    parameters:
-      llvm:
-        type: string
    steps:
      - checkout
      - submodules
      - apt-dependencies:
-          llvm: "<<parameters.llvm>>"
+          llvm: "-9"
      - install-node
      - restore_cache:
          keys:
            - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
            - go-cache-v2-{{ checksum "go.mod" }}
      - llvm-source-linux
-      - run: go install -tags=llvm<<parameters.llvm>> .
-      - restore_cache:
-          keys:
-            - wasi-libc-sysroot-systemclang-v1
-      - run: make wasi-libc
-      - save_cache:
-          key: wasi-libc-sysroot-systemclang-v1
-          paths:
-            - lib/wasi-libc/sysroot
-      - run: go test -v -tags=llvm<<parameters.llvm>> ./cgo ./compileopts ./interp ./transform .
+      - run: go install .
+      - run: go test -v ./cgo ./compileopts ./interp ./transform .
      - run: make gen-device -j4
      - run: make smoketest
      - save_cache:
@@ -120,7 +99,7 @@ commands:
      - llvm-source-linux
      - restore_cache:
          keys:
-            - llvm-build-10-linux-v0-assert
+            - llvm-build-9-linux-v0-assert
      - run:
          name: "Build LLVM"
          command: |
@@ -138,11 +117,10 @@ commands:
              make ASSERT=1 llvm-build
            fi
      - save_cache:
-          key: llvm-build-10-linux-v0-assert
+          key: llvm-build-9-linux-v0-assert
          paths:
            llvm-build
      - run: make ASSERT=1
-      - build-wasi-libc
      - run:
          name: "Test TinyGo"
          command: make ASSERT=1 test
@@ -179,7 +157,7 @@ commands:
      - llvm-source-linux
      - restore_cache:
          keys:
-            - llvm-build-10-linux-v0
+            - llvm-build-9-linux-v0
      - run:
          name: "Build LLVM"
          command: |
@@ -197,10 +175,9 @@ commands:
              make llvm-build
            fi
      - save_cache:
-          key: llvm-build-10-linux-v0
+          key: llvm-build-9-linux-v0
          paths:
            llvm-build
-      - build-wasi-libc
      - run:
          name: "Test TinyGo"
          command: make test
@@ -232,8 +209,8 @@ commands:
      - run:
          name: "Install dependencies"
          command: |
-            curl https://dl.google.com/go/go1.14.darwin-amd64.tar.gz -o go1.14.darwin-amd64.tar.gz
-            sudo tar -C /usr/local -xzf go1.14.darwin-amd64.tar.gz
+            curl https://dl.google.com/go/go1.13.darwin-amd64.tar.gz -o go1.13.darwin-amd64.tar.gz
+            sudo tar -C /usr/local -xzf go1.13.darwin-amd64.tar.gz
            ln -s /usr/local/go/bin/go /usr/local/bin/go
            HOMEBREW_NO_AUTO_UPDATE=1 brew install qemu
      - restore_cache:
@@ -242,17 +219,17 @@ commands:
            - go-cache-macos-v2-{{ checksum "go.mod" }}
      - restore_cache:
          keys:
-            - llvm-source-10-macos-v0
+            - llvm-source-9-macos-v0
      - run:
          name: "Fetch LLVM source"
          command: make llvm-source
      - save_cache:
-          key: llvm-source-10-macos-v0
+          key: llvm-source-9-macos-v0
          paths:
            - llvm-project
      - restore_cache:
          keys:
-            - llvm-build-10-macos-v0
+            - llvm-build-9-macos-v0
      - run:
          name: "Build LLVM"
          command: |
@@ -264,19 +241,9 @@ commands:
              make llvm-build
            fi
      - save_cache:
-          key: llvm-build-10-macos-v0
+          key: llvm-build-9-macos-v0
          paths:
            llvm-build
-      - restore_cache:
-          keys:
-            - wasi-libc-sysroot-macos-v1
-      - run:
-          name: "Build wasi-libc"
-          command: make wasi-libc
-      - save_cache:
-          key: wasi-libc-sysroot-macos-v1
-          paths:
-            - lib/wasi-libc/sysroot
      - run:
          name: "Test TinyGo"
          command: make test
@@ -311,36 +278,27 @@ commands:
 jobs:
  test-llvm9-go111:
    docker:
-      - image: circleci/golang:1.11-buster
+      - image: circleci/golang:1.11-stretch
    steps:
-      - test-linux:
-          llvm: "9"
-  test-llvm10-go112:
+      - test-linux
+  test-llvm9-go112:
    docker:
-      - image: circleci/golang:1.12-buster
+      - image: circleci/golang:1.12-stretch
    steps:
-      - test-linux:
-          llvm: "10"
-  test-llvm10-go113:
+      - test-linux
+  test-llvm9-go113:
    docker:
-      - image: circleci/golang:1.13-buster
+      - image: circleci/golang:1.13-stretch
    steps:
-      - test-linux:
-          llvm: "10"
-  test-llvm10-go114:
-    docker:
-      - image: circleci/golang:1.14-buster
-    steps:
-      - test-linux:
-          llvm: "10"
+      - test-linux
  assert-test-linux:
    docker:
-      - image: circleci/golang:1.14-stretch
+      - image: circleci/golang:1.13-stretch
    steps:
      - assert-test-linux
  build-linux:
    docker:
-      - image: circleci/golang:1.14-stretch
+      - image: circleci/golang:1.13-stretch
    steps:
      - build-linux
  build-macos:
@@ -356,9 +314,8 @@ workflows:
  test-all:
    jobs:
      - test-llvm9-go111
-      - test-llvm10-go112
-      - test-llvm10-go113
-      - test-llvm10-go114
+      - test-llvm9-go112
+      - test-llvm9-go113
      - build-linux
      - build-macos
      - assert-test-linux
@@ -9,14 +9,8 @@
 	url = https://github.com/avr-rust/avr-mcu.git
 [submodule "lib/cmsis-svd"]
 	path = lib/cmsis-svd
-	url = https://github.com/posborne/cmsis-svd
+	url = https://github.com/tinygo-org/cmsis-svd
 [submodule "lib/compiler-rt"]
 	path = lib/compiler-rt
 	url = https://github.com/llvm-mirror/compiler-rt.git
 	branch = release_80
-[submodule "lib/wasi-libc"]
-	path = lib/wasi-libc
-	url = https://github.com/CraneStation/wasi-libc
-[submodule "lib/picolibc"]
-	path = lib/picolibc
-	url = https://github.com/keith-packard/picolibc.git
@@ -1,152 +1,3 @@
-0.13.0
---
-* **command line**
-  - use `gdb-multiarch` for debugging Cortex-M chips
-  - support `tinygo run` with simavr
-  - support LLVM 10
-  - support Go 1.14
-  - retry 3 times when attempting to do a 1200-baud reset
-* **compiler**
-  - mark the `abort` function as noreturn
-  - fix deferred calls to exported functions
-  - add debug info for local variables
-  - check for channel size limit
-  - refactor coroutine lowering
-  - add `dereferenceable_or_null` attribute to pointer parameters
-  - do not perform nil checking when indexing slices and on `unsafe.Pointer`
-  - remove `runtime.isnil` hack
-  - use LLVM builtins for runtime `memcpy`/`memmove`/`memzero` functions
-  - implement spec-compliant shifts on negative/overflow
-  - support anonymous type asserts
-  - track pointer result of string concatenation for GC
-  - track PHI nodes for GC
-  - add debug info to goroutine start wrappers
-  - optimize comparing interface values against nil
-  - fix miscompilation when deferring an interface call
-  - builder: include picolibc for most baremetal targets
-  - builder: run tools (clang, lld) as separate processes
-  - builder: use `-fshort-enums` consistently
-  - interp: add support for constant type asserts
-  - interp: better support for interface operations
-  - interp: include backtrace with error
-  - transform: do not track const globals for GC
-  - transform: replace panics with source locations
-  - transform: fix error in interface lowering pass
-  - transform: make coroutine lowering deterministic
-  - transform: fix miscompilation in func lowering
-* **cgo**
-  - make `-I` and `-L` paths absolute
-* **standard library**
-  - `machine`: set the USB VID and PID to the manufacturer values
-  - `machine`: correct USB CDC composite descriptors
-  - `machine`: move `errors.New` calls to globals
-  - `runtime`: support operations on nil maps
-  - `runtime`: fix copy builtin return value on AVR
-  - `runtime`: refactor goroutines
-  - `runtime`: support `-scheduler=none` on most platforms
-  - `runtime`: run package initialization in the main goroutine
-  - `runtime`: export `malloc` / `free` for use from C
-  - `runtime`: add garbage collector that uses an external allocator
-  - `runtime`: scan callee-saved registers while marking the stack
-  - `runtime`: remove recursion from conservative GC
-  - `runtime`: fix blocking select on nil channel
-  - `runtime/volatile`: include `ReplaceBits` method
-  - `sync`: implement trivial `sync.Map`
-* **targets**
-  - `arm`: use `-fomit-frame-pointer`
-  - `atmega1284`: support this chip for testing purposes
-  - `atsamd51`: make QSPI available on all boards
-  - `atsamd51`: add support for ADC1
-  - `atsamd51`: use new interrupt registration in UART code
-  - `attiny`: clean up pin definitions
-  - `avr`: use the correct RAM start address
-  - `avr`: pass the correct `-mmcu` flag to the linker
-  - `avr`: add support for tasks scheduler (disabled by default)
-  - `avr`: fix linker problem with overlapping program/data areas
-  - `nrf`: fix typo in pin configuration options
-  - `nrf`: add lib/nrfx/mdk to include dirs
-  - `nrf52840`: implement USB-CDC
-  - `riscv`: implement VirtIO target and add RISC-V integration test
-  - `riscv`: add I2C support for the HiFive1 rev B board
-  - `stm32`: refactor GPIO pin handling
-  - `stm32`: refactor UART code
-  - `stm32f4`: add SPI
-  - `wasm`: support Go 1.14 (breaking previous versions)
-  - `wasm`: support `syscall/js.CopyBytesToJS`
-  - `wasm`: sync polyfills from Go 1.14.
-* **boards**
-  - `arduino-mega2560`: add the Arduino Mega 2560
-  - `clue-alpha`: add the Adafruit CLUE Alpha
-  - `gameboy-advance`: enable debugging with GDB
-  - `particle-argon`: add the Particle Argon board
-  - `particle-boron`: add the Particle Boron board
-  - `particle-xenon`: add the Particle Xenon board
-  - `reelboard`: add `reelboard-s140v7` SoftDevice target
-
-0.12.0
---
-* **command line**
-  - add initial FreeBSD support
-  - remove getting a serial port in gdb subcommand
-  - add support for debugging through JLinkGDBServer
-  - fix CGo when cross compiling
-  - remove default port check for Digispark as micronucleus communicates directly using HID
-  - differentiate between various serial/USB error messages
-* **builder**
-  - improve detection of Clang headers
-* **compiler**
-  - fix assertion on empty interface
-  - don't crash when encountering `types.Invalid`
-  - revise defer to use heap allocations when running a variable number of times
-  - improve error messages for failed imports
-  - improve "function redeclared" error
-  - add globaldce pass to start of optimization pipeline
-  - add support for debugging globals
-  - implement RISC-V CSR operations as intrinsics
-  - add support for CGO_ENABLED environment variable
-  - do not emit debug info for extern globals (bugfix)
-  - add support for interrupts
-  - implement maps for arbitrary keys
-  - interp: error location for "unknown GEP" error
-  - wasm-abi: create temporary allocas in the entry block
-* **cgo**
-  - add support for symbols in `#define`
-  - fix a bug in number tokenization
-* **standard library**
-  - `machine`: avoid bytes package in USB logic
-  - `runtime`: fix external address declarations
-  - `runtime`: provide implementation for `internal/bytealg.IndexByte`
-* **targets**
-  - `atsamd51`: fix volatile usage
-  - `atsamd51`: fix ADC, updating to 12-bits precision
-  - `atsamd51`: refactor SPI pin configuration to only look at pin numbers
-  - `atsamd51`: switch UART to use new pin configuration
-  - `atsamd51`: fix obvious bug in I2C code
-  - `atsamd51`: use only the necessary UART interrupts
-  - `atsamd51`: refactor I2C pin handling to auto-detect pin mode
-  - `avr`: use a garbage collector
-  - `fe310`: use CLINT peripheral for timekeeping
-  - `fe310`: add support for PLIC interrupts
-  - `fe310`: implement UART receive interrupts
-  - `riscv`: support sleeping in QEMU
-  - `riscv`: add bare-bones interrupt support
-  - `riscv`: print exception PC and code
-  - `wasm`: implement memcpy and memset
-  - `wasm`: include wasi-libc
-  - `wasm`: use wasi ABI for basic startup/stdout
-* **boards**
-  - `arduino`: make avrdude command line compatible with Windows
-  - `arduino-nano`: add this board
-  - `arduino-nano33`: fix UART1 and UART2
-  - `circuitplay-bluefruit`: add this board
-  - `digispark`: add clock speed and pin mappings
-  - `gameboy-advance`: include compiler-rt in build
-  - `gameboy-advance`: implement interrupt handler
-  - `hifive1b`: add support for gdb subcommand
-  - `pyportal`: add this board
-  - `pyportal`: remove manual SPI pin mapping as now handled by default
-
-
 0.11.0
 ---
 * **command line**
@@ -15,4 +15,3 @@ Ayke van Laethem <aykevanlaethem@gmail.com>
 Daniel Esteban <conejo@conejo.me>
 Loon, LLC.
 Ron Evans <ron@hybridgroup.com>
-Jaden Weiss <jaden@jadendw.dev>
@@ -1,10 +1,10 @@
-# TinyGo base stage installs Go 1.14, LLVM 10 and the TinyGo compiler itself.
-FROM golang:1.14 AS tinygo-base
+# TinyGo base stage installs Go 1.13, LLVM 9 and the TinyGo compiler itself.
+FROM golang:1.13 AS tinygo-base

 RUN wget -O- https://apt.llvm.org/llvm-snapshot.gpg.key| apt-key add - && \
-    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main" >> /etc/apt/sources.list && \
+    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-9 main" >> /etc/apt/sources.list && \
    apt-get update && \
-    apt-get install -y llvm-10-dev libclang-10-dev git
+    apt-get install -y llvm-9-dev libclang-9-dev git

 COPY . /tinygo

@@ -12,11 +12,8 @@ COPY . /tinygo
 # after copying the tinygo directory in the previous step.
 RUN cd /tinygo/ && \
    rm -rf ./lib/* && \
-    git submodule sync && \
    git submodule update --init --recursive --force

-COPY ./lib/picolibc-include/* /tinygo/lib/picolibc-include/
-
 RUN cd /tinygo/ && \
    go install /tinygo/

@@ -28,9 +25,9 @@ COPY --from=tinygo-base /tinygo/src /tinygo/src
 COPY --from=tinygo-base /tinygo/targets /tinygo/targets

 RUN wget -O- https://apt.llvm.org/llvm-snapshot.gpg.key| apt-key add - && \
-    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main" >> /etc/apt/sources.list && \
+    echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-9 main" >> /etc/apt/sources.list && \
    apt-get update && \
-    apt-get install -y libllvm10 lld-10
+    apt-get install -y libllvm9 lld-9

 # tinygo-avr stage installs the needed dependencies to compile TinyGo programs for AVR microcontrollers.
 FROM tinygo-base AS tinygo-avr
@@ -61,7 +58,7 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

 RUN cd /tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make clang-10 && \
+    apt-get install -y apt-utils make clang-9 && \
    make gen-device-nrf && make gen-device-stm32

 # tinygo-all stage installs the needed dependencies to compile TinyGo programs for all platforms.
@@ -73,7 +70,7 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

 RUN cd /tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils make clang-10 binutils-avr gcc-avr avr-libc && \
+    apt-get install -y apt-utils make clang-9 binutils-avr gcc-avr avr-libc && \
    make gen-device

 CMD ["tinygo"]
@@ -1,7 +1,7 @@
-Copyright (c) 2018-2020 TinyGo Authors. All rights reserved.
+Copyright (c) 2018-2019 TinyGo Authors. All rights reserved.

 TinyGo includes portions of the Go standard library.
-Copyright (c) 2009-2020 The Go Authors. All rights reserved.
+Copyright (c) 2009-2019 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.
@@ -4,30 +4,8 @@ all: tinygo

 # Default build and source directories, as created by `make llvm-build`.
 LLVM_BUILDDIR ?= llvm-build
-LLVM_PROJECTDIR ?= llvm-project
-CLANG_SRC ?= $(LLVM_PROJECTDIR)/clang
-LLD_SRC ?= $(LLVM_PROJECTDIR)/lld
-
-# Try to autodetect LLVM build tools.
-ifneq (, $(shell command -v llvm-build/bin/clang 2> /dev/null))
-    CLANG ?= $(abspath llvm-build/bin/clang)
-else
-    CLANG ?= clang-10
-endif
-ifneq (, $(shell command -v llvm-build/bin/llvm-ar 2> /dev/null))
-    LLVM_AR ?= $(abspath llvm-build/bin/llvm-ar)
-else ifneq (, $(shell command -v llvm-ar-10 2> /dev/null))
-    LLVM_AR ?= llvm-ar-10
-else
-    LLVM_AR ?= llvm-ar
-endif
-ifneq (, $(shell command -v llvm-build/bin/llvm-nm 2> /dev/null))
-    LLVM_NM ?= $(abspath llvm-build/bin/llvm-nm)
-else ifneq (, $(shell command -v llvm-nm-10 2> /dev/null))
-    LLVM_NM ?= llvm-nm-10
-else
-    LLVM_NM ?= llvm-nm
-endif
+CLANG_SRC ?= llvm-project/clang
+LLD_SRC ?= llvm-project/lld

 # Go binary and GOROOT to select
 GO ?= go
@@ -40,7 +18,7 @@ MD5SUM = md5sum
 TINYGO ?= tinygo

 # Use CCACHE for LLVM if possible
-ifneq (, $(shell command -v ccache 2> /dev/null))
+ifneq (, $(shell which ccache))
    LLVM_OPTION += '-DLLVM_CCACHE_BUILD=ON'
 endif

@@ -53,7 +31,7 @@ endif

 .PHONY: all tinygo test $(LLVM_BUILDDIR) llvm-source clean fmt gen-device gen-device-nrf gen-device-avr

-LLVM_COMPONENTS = all-targets analysis asmparser asmprinter bitreader bitwriter codegen core coroutines coverage debuginfodwarf executionengine frontendopenmp instrumentation interpreter ipo irreader linker lto mc mcjit objcarcopts option profiledata scalaropts support target
+LLVM_COMPONENTS = all-targets analysis asmparser asmprinter bitreader bitwriter codegen core coroutines coverage debuginfodwarf executionengine instrumentation interpreter ipo irreader linker lto mc mcjit objcarcopts option profiledata scalaropts support target

 ifeq ($(OS),Windows_NT)
    EXE = .exe
@@ -103,8 +81,8 @@ LLD_LIBS = $(START_GROUP) -llldCOFF -llldCommon -llldCore -llldDriver -llldELF -
 # For static linking.
 ifneq ("$(wildcard $(LLVM_BUILDDIR)/bin/llvm-config*)","")
    CGO_CPPFLAGS=$(shell $(LLVM_BUILDDIR)/bin/llvm-config --cppflags) -I$(abspath $(LLVM_BUILDDIR))/tools/clang/include -I$(abspath $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
-    CGO_CXXFLAGS=-std=c++14
-    CGO_LDFLAGS+=$(LIBCLANG_PATH) -std=c++14 -L$(abspath $(LLVM_BUILDDIR)/lib) $(CLANG_LIBS) $(LLD_LIBS) $(shell $(LLVM_BUILDDIR)/bin/llvm-config --ldflags --libs --system-libs $(LLVM_COMPONENTS)) -lstdc++ $(CGO_LDFLAGS_EXTRA)
+    CGO_CXXFLAGS=-std=c++11
+    CGO_LDFLAGS+=$(LIBCLANG_PATH) -std=c++11 -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


@@ -138,7 +116,7 @@ gen-device-sam: build/gen-device-svd
 	GO111MODULE=off $(GO) fmt ./src/device/sam

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

 gen-device-stm32: build/gen-device-svd
@@ -147,33 +125,26 @@ gen-device-stm32: build/gen-device-svd


 # Get LLVM sources.
-$(LLVM_PROJECTDIR)/README.md:
-	git clone -b release/10.x https://github.com/llvm/llvm-project $(LLVM_PROJECTDIR)
-llvm-source: $(LLVM_PROJECTDIR)/README.md
+llvm-project/README.md:
+	git clone -b release/9.x https://github.com/llvm/llvm-project
+llvm-source: llvm-project/README.md

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


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

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

 tinygo-test:
@@ -214,8 +185,6 @@ 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
 	$(TINYGO) build             -o test.wasm -tags=reelboard            examples/blinky1
@@ -257,12 +226,8 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=stm32f4disco        examples/blinky2
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=circuitplay-bluefruit examples/blinky1
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/i2s
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=clue_alpha          examples/blinky1
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.gba -target=gameboy-advance     examples/gba-display
 	@$(MD5SUM) test.gba
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m4        examples/blinky1
@@ -273,14 +238,6 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=metro-m4-airlift    examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pyportal            examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=particle-argon      examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=particle-boron      examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=particle-xenon      examples/blinky1
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nucleo-f103rb       examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pinetime-devkit0    examples/blinky1
@@ -289,35 +246,23 @@ smoketest:
 	@$(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
 ifneq ($(AVR), 0)
-	$(TINYGO) build -size short -o test.hex -target=atmega1284p         examples/serial
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino             examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=arduino -scheduler=tasks  examples/blinky1
-	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=arduino-nano        examples/blinky1
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=digispark           examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=digispark -gc=leaking examples/blinky1
-	@$(MD5SUM) test.hex
 endif
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/export
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/main

-release: tinygo gen-device wasi-libc
+release: tinygo gen-device
 	@mkdir -p build/release/tinygo/bin
 	@mkdir -p build/release/tinygo/lib/clang/include
 	@mkdir -p build/release/tinygo/lib/CMSIS/CMSIS
 	@mkdir -p build/release/tinygo/lib/compiler-rt/lib
 	@mkdir -p build/release/tinygo/lib/nrfx
-	@mkdir -p build/release/tinygo/lib/picolibc/newlib/libc
-	@mkdir -p build/release/tinygo/lib/wasi-libc
 	@mkdir -p build/release/tinygo/pkg/armv6m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7em-none-eabi
@@ -330,19 +275,9 @@ release: tinygo gen-device wasi-libc
 	@cp -rp lib/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt
 	@cp -rp lib/compiler-rt/README.txt   build/release/tinygo/lib/compiler-rt
 	@cp -rp lib/nrfx/*                   build/release/tinygo/lib/nrfx
-	@cp -rp lib/picolibc/newlib/libc/ctype       build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/include     build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/locale      build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/string      build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc/newlib/libc/tinystdio   build/release/tinygo/lib/picolibc/newlib/libc
-	@cp -rp lib/picolibc-include         build/release/tinygo/lib
-	@cp -rp lib/wasi-libc/sysroot        build/release/tinygo/lib/wasi-libc/sysroot
 	@cp -rp src                          build/release/tinygo/src
 	@cp -rp targets                      build/release/tinygo/targets
-	./build/tinygo build-library -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/compiler-rt.a compiler-rt
-	./build/tinygo build-library -target=armv7m-none-eabi  -o build/release/tinygo/pkg/armv7m-none-eabi/compiler-rt.a compiler-rt
-	./build/tinygo build-library -target=armv7em-none-eabi -o build/release/tinygo/pkg/armv7em-none-eabi/compiler-rt.a compiler-rt
-	./build/tinygo build-library -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/picolibc.a picolibc
-	./build/tinygo build-library -target=armv7m-none-eabi  -o build/release/tinygo/pkg/armv7m-none-eabi/picolibc.a picolibc
-	./build/tinygo build-library -target=armv7em-none-eabi -o build/release/tinygo/pkg/armv7em-none-eabi/picolibc.a picolibc
+	./build/tinygo build-builtins -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/compiler-rt.a
+	./build/tinygo build-builtins -target=armv7m-none-eabi  -o build/release/tinygo/pkg/armv7m-none-eabi/compiler-rt.a
+	./build/tinygo build-builtins -target=armv7em-none-eabi -o build/release/tinygo/pkg/armv7em-none-eabi/compiler-rt.a
 	tar -czf build/release.tar.gz -C build/release tinygo
@@ -43,21 +43,16 @@ See the [getting started instructions](https://tinygo.org/getting-started/) for

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

-The following 32 microcontroller boards are currently supported:
+The following 22 microcontroller boards are currently supported:

-* [Adafruit Circuit Playground Bluefruit](https://www.adafruit.com/product/4333)
 * [Adafruit Circuit Playground Express](https://www.adafruit.com/product/3333)
-* [Adafruit CLUE Alpha](https://www.adafruit.com/product/4500)
 * [Adafruit Feather M0](https://www.adafruit.com/product/2772)
 * [Adafruit Feather M4](https://www.adafruit.com/product/3857)
 * [Adafruit ItsyBitsy M0](https://www.adafruit.com/product/3727)
 * [Adafruit ItsyBitsy M4](https://www.adafruit.com/product/3800)
 * [Adafruit Metro M4 Express Airlift](https://www.adafruit.com/product/4000)
 * [Adafruit PyBadge](https://www.adafruit.com/product/4200)
-* [Adafruit PyPortal](https://www.adafruit.com/product/4116)
 * [Adafruit Trinket M0](https://www.adafruit.com/product/3500)
-* [Arduino Mega 2560](https://store.arduino.cc/arduino-mega-2560-rev3)
-* [Arduino Nano](https://store.arduino.cc/arduino-nano)
 * [Arduino Nano33 IoT](https://store.arduino.cc/nano-33-iot)
 * [Arduino Uno](https://store.arduino.cc/arduino-uno-rev3)
 * [BBC micro:bit](https://microbit.org/)
@@ -67,9 +62,6 @@ The following 32 microcontroller boards are currently supported:
 * [Nordic Semiconductor PCA10031](https://www.nordicsemi.com/eng/Products/nRF51-Dongle)
 * [Nordic Semiconductor PCA10040](https://www.nordicsemi.com/eng/Products/Bluetooth-low-energy/nRF52-DK)
 * [Nordic Semiconductor PCA10056](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-DK)
-* [Particle Argon](https://docs.particle.io/datasheets/wi-fi/argon-datasheet/)
-* [Particle Boron](https://docs.particle.io/datasheets/cellular/boron-datasheet/)
-* [Particle Xenon](https://docs.particle.io/datasheets/discontinued/xenon-datasheet/)
 * [Phytec reel board](https://www.phytec.eu/product-eu/internet-of-things/reelboard/)
 * [PineTime DevKit](https://www.pine64.org/pinetime/)
 * [SiFIve HiFive1](https://www.sifive.com/boards/hifive1)
@@ -136,4 +128,4 @@ 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/10.0.0/LICENSE.TXT). 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/9.0.0/LICENSE.TXT). This has been clearly indicated in the header of these files.
@@ -10,14 +10,11 @@ jobs:
  pool:
    vmImage: 'VS2017-Win2016'
  steps:
-    - task: GoTool@0
-      inputs:
-        version: '1.14.1'
    - checkout: self
    - task: CacheBeta@0
      displayName: Cache LLVM source
      inputs:
-        key: llvm-source-10-windows-v0
+        key: llvm-source-9-windows-v0
        path: llvm-project
    - task: Bash@3
      displayName: Download LLVM source
@@ -27,7 +24,7 @@ jobs:
    - task: CacheBeta@0
      displayName: Cache LLVM build
      inputs:
-        key: llvm-build-10-windows-v0
+        key: llvm-build-9-windows-v0
        path: llvm-build
    - task: Bash@3
      displayName: Build LLVM
@@ -37,6 +34,10 @@ jobs:
          if [ ! -f llvm-build/lib/liblldELF.a ]
          then
            choco install ninja
+            # LLVM 9 cannot be built with MinGW 8.
+            # For details: https://reviews.llvm.org/D70266
+            choco uninstall mingw
+            choco install mingw --version=7.3.0
            make llvm-build
          fi
    - task: Bash@3
@@ -44,22 +45,12 @@ jobs:
      inputs:
        targetType: inline
        script: choco install qemu
-    - task: CacheBeta@0
-      displayName: Cache wasi-libc sysroot
-      inputs:
-        key: wasi-libc-sysroot-v2
-        path: lib/wasi-libc/sysroot
-    - task: Bash@3
-      displayName: Build wasi-libc
-      inputs:
-        targetType: inline
-        script: PATH=/usr/bin:$PATH make wasi-libc
    - task: Bash@3
      displayName: Test TinyGo
      inputs:
        targetType: inline
        script: |
-          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
+          export PATH="/c/Go1.13/bin:$PATH:./llvm-build/bin:/c/Program Files/qemu"
          unset GOROOT
          make test
    - task: Bash@3
@@ -67,17 +58,17 @@ jobs:
      inputs:
        targetType: inline
        script: |
-          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
+          export PATH="/c/Go1.13/bin:$PATH:./llvm-build/bin:/c/Program Files/qemu"
          unset GOROOT
          make release -j4
-    - publish: $(System.DefaultWorkingDirectory)/build/release/tinygo
-      displayName: Publish zip as artifact
-      artifact: tinygo
+    - publish: $(System.DefaultWorkingDirectory)/build/release.tar.gz
+      displayName: Publish tarball as artifact
+      artifact: tinygo.windows-amd64.tar.gz
    - task: Bash@3
      displayName: Smoke tests
      inputs:
        targetType: inline
        script: |
-          export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
+          export PATH="/c/Go1.13/bin:$PATH:./llvm-build/bin:/c/Program Files/qemu"
          unset GOROOT
          make smoketest TINYGO=build/tinygo AVR=0
@@ -16,8 +16,6 @@ import (
 	"github.com/tinygo-org/tinygo/compiler"
 	"github.com/tinygo-org/tinygo/goenv"
 	"github.com/tinygo-org/tinygo/interp"
-	"github.com/tinygo-org/tinygo/transform"
-	"tinygo.org/x/go-llvm"
 )

 // Build performs a single package to executable Go build. It takes in a package
@@ -27,34 +25,34 @@ import (
 // The error value may be of type *MultiError. Callers will likely want to check
 // for this case and print such errors individually.
 func Build(pkgName, outpath string, config *compileopts.Config, action func(string) error) error {
-	// Compile Go code to IR.
-	machine, err := compiler.NewTargetMachine(config)
+	c, err := compiler.NewCompiler(pkgName, config)
 	if err != nil {
 		return err
 	}
-	mod, extraFiles, errs := compiler.Compile(pkgName, machine, config)
-	if errs != nil {
+
+	// Compile Go code to IR.
+	errs := c.Compile(pkgName)
+	if len(errs) != 0 {
 		return newMultiError(errs)
 	}
-
 	if config.Options.PrintIR {
 		fmt.Println("; Generated LLVM IR:")
-		fmt.Println(mod.String())
+		fmt.Println(c.IR())
 	}
-	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
+	if err := c.Verify(); err != nil {
 		return errors.New("verification error after IR construction")
 	}

-	err = interp.Run(mod, config.DumpSSA())
+	err = interp.Run(c.Module(), config.DumpSSA())
 	if err != nil {
 		return err
 	}
-	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
+	if err := c.Verify(); err != nil {
 		return errors.New("verification error after interpreting runtime.initAll")
 	}

 	if config.GOOS() != "darwin" {
-		transform.ApplyFunctionSections(mod) // -ffunction-sections
+		c.ApplyFunctionSections() // -ffunction-sections
 	}

 	// Browsers cannot handle external functions that have type i64 because it
@@ -63,7 +61,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 	// stack-allocated values.
 	// Use -wasm-abi=generic to disable this behaviour.
 	if config.Options.WasmAbi == "js" && strings.HasPrefix(config.Triple(), "wasm") {
-		err := transform.ExternalInt64AsPtr(mod)
+		err := c.ExternalInt64AsPtr()
 		if err != nil {
 			return err
 		}
@@ -73,23 +71,23 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 	// exactly.
 	errs = nil
 	switch config.Options.Opt {
-	case "none", "0":
-		errs = transform.Optimize(mod, config, 0, 0, 0) // -O0
+	case "none:", "0":
+		errs = c.Optimize(0, 0, 0) // -O0
 	case "1":
-		errs = transform.Optimize(mod, config, 1, 0, 0) // -O1
+		errs = c.Optimize(1, 0, 0) // -O1
 	case "2":
-		errs = transform.Optimize(mod, config, 2, 0, 225) // -O2
+		errs = c.Optimize(2, 0, 225) // -O2
 	case "s":
-		errs = transform.Optimize(mod, config, 2, 1, 225) // -Os
+		errs = c.Optimize(2, 1, 225) // -Os
 	case "z":
-		errs = transform.Optimize(mod, config, 2, 2, 5) // -Oz, default
+		errs = c.Optimize(2, 2, 5) // -Oz, default
 	default:
 		errs = []error{errors.New("unknown optimization level: -opt=" + config.Options.Opt)}
 	}
 	if len(errs) > 0 {
 		return newMultiError(errs)
 	}
-	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
+	if err := c.Verify(); err != nil {
 		return errors.New("verification failure after LLVM optimization passes")
 	}

@@ -99,8 +97,8 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 	// 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 {
+		c.NonConstGlobals()
+		if err := c.Verify(); err != nil {
 			return errors.New("verification error after making all globals non-constant on AVR")
 		}
 	}
@@ -109,17 +107,11 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 	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)
+		return c.EmitObject(outpath)
 	case ".bc":
-		data := llvm.WriteBitcodeToMemoryBuffer(mod).Bytes()
-		return ioutil.WriteFile(outpath, data, 0666)
+		return c.EmitBitcode(outpath)
 	case ".ll":
-		data := []byte(mod.String())
-		return ioutil.WriteFile(outpath, data, 0666)
+		return c.EmitText(outpath)
 	default:
 		// Act as a compiler driver.

@@ -132,39 +124,29 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri

 		// Write the object file.
 		objfile := filepath.Join(dir, "main.o")
-		llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
+		err = c.EmitObject(objfile)
 		if err != nil {
 			return err
 		}
-		err = ioutil.WriteFile(objfile, llvmBuf.Bytes(), 0666)
-		if err != nil {
-			return err
+
+		// Load builtins library from the cache, possibly compiling it on the
+		// fly.
+		var librt string
+		if config.Target.RTLib == "compiler-rt" {
+			librt, err = loadBuiltins(config.Triple())
+			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() {
@@ -178,13 +160,16 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 		}

 		// 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}
+		for i, pkg := range c.Packages() {
+			for _, file := range pkg.CFiles {
+				path := filepath.Join(pkg.Package.Dir, file)
+				outpath := filepath.Join(dir, "pkg"+strconv.Itoa(i)+"-"+file+".o")
+				err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, path)...)
+				if err != nil {
+					return &commandError{"failed to build", path, err}
+				}
+				ldflags = append(ldflags, outpath)
 			}
-			ldflags = append(ldflags, outpath)
 		}

 		// Link the object files together.
@@ -222,7 +207,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 		} else if outext == ".uf2" {
 			// Get UF2 from the .elf file.
 			tmppath = filepath.Join(dir, "main"+outext)
-			err := convertELFFileToUF2File(executable, tmppath, config.Target.UF2FamilyID)
+			err := convertELFFileToUF2File(executable, tmppath)
 			if err != nil {
 				return err
 			}
@@ -1,7 +1,12 @@
 package builder

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

 // These are the GENERIC_SOURCES according to CMakeList.txt.
@@ -151,20 +156,105 @@ var aeabiBuiltins = []string{
 	"arm/aeabi_uldivmod.S",
 }

-// CompilerRT is a library with symbols required by programs compiled with LLVM.
-// These symbols are for operations that cannot be emitted with a single
-// instruction or a short sequence of instructions for that target.
-//
-// For more information, see: https://compiler-rt.llvm.org/
-var CompilerRT = Library{
-	name:      "compiler-rt",
-	cflags:    func() []string { return []string{"-Werror", "-Wall", "-std=c11", "-nostdlibinc"} },
-	sourceDir: "lib/compiler-rt/lib/builtins",
-	sources: func(target string) []string {
-		builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
-		if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
-			builtins = append(builtins, aeabiBuiltins...)
-		}
-		return builtins
-	},
+func builtinFiles(target string) []string {
+	builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
+	if strings.HasPrefix(target, "arm") {
+		builtins = append(builtins, aeabiBuiltins...)
+	}
+	return builtins
+}
+
+// builtinsDir returns the directory where the sources for compiler-rt are kept.
+func builtinsDir() string {
+	return filepath.Join(goenv.Get("TINYGOROOT"), "lib", "compiler-rt", "lib", "builtins")
+}
+
+// Get the builtins archive, possibly generating it as needed.
+func loadBuiltins(target string) (path string, err error) {
+	// Try to load a precompiled compiler-rt library.
+	precompiledPath := filepath.Join(goenv.Get("TINYGOROOT"), "pkg", target, "compiler-rt.a")
+	if _, err := os.Stat(precompiledPath); err == nil {
+		// Found a precompiled compiler-rt for this OS/architecture. Return the
+		// path directly.
+		return precompiledPath, nil
+	}
+
+	outfile := "librt-" + target + ".a"
+	builtinsDir := builtinsDir()
+
+	builtins := builtinFiles(target)
+	srcs := make([]string, len(builtins))
+	for i, name := range builtins {
+		srcs[i] = filepath.Join(builtinsDir, name)
+	}
+
+	if path, err := cacheLoad(outfile, commands["clang"][0], srcs); path != "" || err != nil {
+		return path, err
+	}
+
+	var cachepath string
+	err = CompileBuiltins(target, func(path string) error {
+		path, err := cacheStore(path, outfile, commands["clang"][0], srcs)
+		cachepath = path
+		return err
+	})
+	return cachepath, err
+}
+
+// CompileBuiltins compiles builtins from compiler-rt into a static library.
+// When it succeeds, it will call the callback with the resulting path. The path
+// will be removed after callback returns. If callback returns an error, this is
+// passed through to the return value of this function.
+func CompileBuiltins(target string, callback func(path string) error) error {
+	builtinsDir := builtinsDir()
+
+	builtins := builtinFiles(target)
+	srcs := make([]string, len(builtins))
+	for i, name := range builtins {
+		srcs[i] = filepath.Join(builtinsDir, name)
+	}
+
+	dirPrefix := "tinygo-builtins"
+	remapDir := filepath.Join(os.TempDir(), dirPrefix)
+	dir, err := ioutil.TempDir(os.TempDir(), dirPrefix)
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(dir)
+
+	// Compile all builtins.
+	// TODO: use builtins optimized for a given target if available.
+	objs := make([]string, 0, len(builtins))
+	for _, name := range builtins {
+		objname := name
+		if strings.LastIndexByte(objname, '/') >= 0 {
+			objname = objname[strings.LastIndexByte(objname, '/'):]
+		}
+		objpath := filepath.Join(dir, objname+".o")
+		objs = append(objs, objpath)
+		srcpath := filepath.Join(builtinsDir, name)
+		// Note: -fdebug-prefix-map is necessary to make the output archive
+		// reproducible. Otherwise the temporary directory is stored in the
+		// archive itself, which varies each run.
+		args := []string{"-c", "-Oz", "-g", "-Werror", "-Wall", "-std=c11", "-fshort-enums", "-nostdlibinc", "-ffunction-sections", "-fdata-sections", "-Wno-macro-redefined", "--target=" + target, "-fdebug-prefix-map=" + dir + "=" + remapDir}
+		if strings.HasPrefix(target, "riscv32-") {
+			args = append(args, "-march=rv32imac", "-mabi=ilp32", "-fforce-enable-int128")
+		}
+		err := runCCompiler("clang", append(args, "-o", objpath, srcpath)...)
+		if err != nil {
+			return &commandError{"failed to build", srcpath, err}
+		}
+	}
+
+	// Put all the object files in a single archive. This archive file will be
+	// used to statically link compiler-rt.
+	arpath := filepath.Join(dir, "librt.a")
+	err = makeArchive(arpath, objs)
+	if err != nil {
+		return err
+	}
+
+	// Give the caller the resulting file. The callback must copy the file,
+	// because after it returns the temporary directory will be removed.
+	return callback(arpath)
 }
@@ -48,7 +48,6 @@
 #include "llvm/Support/Host.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetRegistry.h"
@@ -71,12 +70,12 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
  bool Success = true;

  // Parse the arguments.
-  const OptTable &OptTbl = getDriverOptTable();
+  std::unique_ptr<OptTable> OptTbl(createDriverOptTable());

  const unsigned IncludedFlagsBitmask = options::CC1AsOption;
  unsigned MissingArgIndex, MissingArgCount;
-  InputArgList Args = OptTbl.ParseArgs(Argv, MissingArgIndex, MissingArgCount,
-                                       IncludedFlagsBitmask);
+  InputArgList Args = OptTbl->ParseArgs(Argv, MissingArgIndex, MissingArgCount,
+                                        IncludedFlagsBitmask);

  // Check for missing argument error.
  if (MissingArgCount) {
@@ -89,7 +88,7 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
  for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
    auto ArgString = A->getAsString(Args);
    std::string Nearest;
-    if (OptTbl.findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
+    if (OptTbl->findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
      Diags.Report(diag::err_drv_unknown_argument) << ArgString;
    else
      Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
@@ -182,7 +181,6 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
  Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
  Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
  Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
-  Opts.NoWarn = Args.hasArg(OPT_massembler_no_warn);
  Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
  Opts.TargetABI = Args.getLastArgValue(OPT_target_abi);
  Opts.IncrementalLinkerCompatible =
@@ -210,8 +208,8 @@ getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
    sys::RemoveFileOnSignal(Path);

  std::error_code EC;
-  auto Out = std::make_unique<raw_fd_ostream>(
-      Path, EC, (Binary ? sys::fs::OF_None : sys::fs::OF_Text));
+  auto Out = llvm::make_unique<raw_fd_ostream>(
+      Path, EC, (Binary ? sys::fs::F_None : sys::fs::F_Text));
  if (EC) {
    Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
    return nullptr;
@@ -247,9 +245,7 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
  std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
  assert(MRI && "Unable to create target register info!");

-  MCTargetOptions MCOptions;
-  std::unique_ptr<MCAsmInfo> MAI(
-      TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
+  std::unique_ptr<MCAsmInfo> MAI(TheTarget->createMCAsmInfo(*MRI, Opts.Triple));
  assert(MAI && "Unable to create target asm info!");

  // Ensure MCAsmInfo initialization occurs before any use, otherwise sections
@@ -273,7 +269,7 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
  // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
  std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());

-  MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr, &MCOptions);
+  MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr);

  bool PIC = false;
  if (Opts.RelocationModel == "static") {
@@ -330,8 +326,7 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
  raw_pwrite_stream *Out = FDOS.get();
  std::unique_ptr<buffer_ostream> BOS;

-  MCOptions.MCNoWarn = Opts.NoWarn;
-  MCOptions.MCFatalWarnings = Opts.FatalWarnings;
+  MCTargetOptions MCOptions;
  MCOptions.ABIName = Opts.TargetABI;

  // FIXME: There is a bit of code duplication with addPassesToEmitFile.
@@ -345,7 +340,7 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
    std::unique_ptr<MCAsmBackend> MAB(
        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));

-    auto FOut = std::make_unique<formatted_raw_ostream>(*Out);
+    auto FOut = llvm::make_unique<formatted_raw_ostream>(*Out);
    Str.reset(TheTarget->createAsmStreamer(
        Ctx, std::move(FOut), /*asmverbose*/ true,
        /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
@@ -356,7 +351,7 @@ bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
    assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
           "Invalid file type!");
    if (!FDOS->supportsSeeking()) {
-      BOS = std::make_unique<buffer_ostream>(*FDOS);
+      BOS = make_unique<buffer_ostream>(*FDOS);
      Out = BOS.get();
    }

@@ -441,7 +436,7 @@ static void LLVMErrorHandler(void *UserData, const std::string &Message,
  Diags.Report(diag::err_fe_error_backend) << Message;

  // We cannot recover from llvm errors.
-  sys::Process::Exit(1);
+  exit(1);
 }

 int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
@@ -469,11 +464,11 @@ int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
    return 1;

  if (Asm.ShowHelp) {
-    getDriverOptTable().PrintHelp(
-        llvm::outs(), "clang -cc1as [options] file...",
-        "Clang Integrated Assembler",
-        /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
-        /*ShowAllAliases=*/false);
+    std::unique_ptr<OptTable> Opts(driver::createDriverOptTable());
+    Opts->PrintHelp(llvm::outs(), "clang -cc1as [options] file...",
+                    "Clang Integrated Assembler",
+                    /*Include=*/driver::options::CC1AsOption, /*Exclude=*/0,
+                    /*ShowAllAliases=*/false);
    return 0;
  }

@@ -490,7 +485,7 @@ int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
  // FIXME: Remove this, one day.
  if (!Asm.LLVMArgs.empty()) {
    unsigned NumArgs = Asm.LLVMArgs.size();
-    auto Args = std::make_unique<const char*[]>(NumArgs + 2);
+    auto Args = llvm::make_unique<const char*[]>(NumArgs + 2);
    Args[0] = "clang (LLVM option parsing)";
    for (unsigned i = 0; i != NumArgs; ++i)
      Args[i + 1] = Asm.LLVMArgs[i].c_str();
@@ -504,7 +499,6 @@ int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
  // If any timers were active but haven't been destroyed yet, print their
  // results now.
  TimerGroup::printAll(errs());
-  TimerGroup::clearAll();

  return !!Failed;
 }
@@ -11,6 +11,8 @@
 //
 //===----------------------------------------------------------------------===//

+#include "llvm/ADT/ArrayRef.h"
+
 /// Helper class for representing a single invocation of the assembler.
 struct AssemblerInvocation {
  /// @name Target Options
@@ -80,7 +82,6 @@ struct AssemblerInvocation {
  unsigned RelaxAll : 1;
  unsigned NoExecStack : 1;
  unsigned FatalWarnings : 1;
-  unsigned NoWarn : 1;
  unsigned IncrementalLinkerCompatible : 1;
  unsigned EmbedBitcode : 1;

@@ -106,7 +107,6 @@ public:
    RelaxAll = 0;
    NoExecStack = 0;
    FatalWarnings = 0;
-    NoWarn = 0;
    IncrementalLinkerCompatible = 0;
    DwarfVersion = 0;
    EmbedBitcode = 0;
@@ -52,7 +52,8 @@ bool tinygo_clang_driver(int argc, char **argv) {
 			std::unique_ptr<clang::CompilerInstance> Clang(new clang::CompilerInstance());
 			bool success = clang::CompilerInvocation::CreateFromArgs(
 					Clang->getInvocation(),
-					CCArgs,
+					const_cast<const char **>(CCArgs.data()),
+					const_cast<const char **>(CCArgs.data()) + CCArgs.size(),
 					Diags);
 			if (!success) {
 				return false;
@@ -73,8 +74,7 @@ bool tinygo_clang_driver(int argc, char **argv) {
 		} else if (strcmp(*CCArgs.data(), "-cc1as") == 0) {
 			// This is the assembler frontend. Parse the arguments.
 			AssemblerInvocation Asm;
-			ArrayRef<const char *> Argv = llvm::ArrayRef<const char*>(CCArgs);
-			if (!AssemblerInvocation::CreateFromArgs(Asm, Argv.slice(1), Diags))
+			if (!AssemblerInvocation::CreateFromArgs(Asm, llvm::ArrayRef<const char*>(CCArgs).slice(1), Diags))
 				return false;

 			// Execute the invocation, unless there were parsing errors.
@@ -6,28 +6,25 @@ import (
 	"os/exec"
 	"runtime"
 	"strings"
-
-	"tinygo.org/x/go-llvm"
 )

 // Commands lists command alternatives for various operating systems. These
 // commands may have a slightly different name across operating systems and
 // distributions or may not even exist in $PATH, in which case absolute paths
 // may be used.
-var commands = map[string][]string{}
+var commands = map[string][]string{
+	"clang":   {"clang-9"},
+	"ld.lld":  {"ld.lld-9", "ld.lld"},
+	"wasm-ld": {"wasm-ld-9", "wasm-ld"},
+}

 func init() {
-	llvmMajor := strings.Split(llvm.Version, ".")[0]
-	commands["clang"] = []string{"clang-" + llvmMajor}
-	commands["ld.lld"] = []string{"ld.lld-" + llvmMajor, "ld.lld"}
-	commands["wasm-ld"] = []string{"wasm-ld-" + llvmMajor, "wasm-ld"}
-	// Add the path to a Homebrew-installed LLVM for ease of use (no need to
+	// Add the path to a Homebrew-installed LLVM 9 for ease of use (no need to
 	// manually set $PATH).
 	if runtime.GOOS == "darwin" {
-		prefix := "/usr/local/opt/llvm@" + llvmMajor + "/bin/"
-		commands["clang"] = append(commands["clang"], prefix+"clang-"+llvmMajor)
-		commands["ld.lld"] = append(commands["ld.lld"], prefix+"ld.lld")
-		commands["wasm-ld"] = append(commands["wasm-ld"], prefix+"wasm-ld")
+		commands["clang"] = append(commands["clang"], "/usr/local/opt/llvm@9/bin/clang-9")
+		commands["ld.lld"] = append(commands["ld.lld"], "/usr/local/opt/llvm@9/bin/ld.lld")
+		commands["wasm-ld"] = append(commands["wasm-ld"], "/usr/local/opt/llvm@9/bin/wasm-ld")
 	}
 	// Add the path for when LLVM was installed with the installer from
 	// llvm.org, which by default doesn't add LLVM to the $PATH environment
@@ -37,12 +34,11 @@ func init() {
 		commands["ld.lld"] = append(commands["ld.lld"], "lld", "C:\\Program Files\\LLVM\\bin\\lld.exe")
 		commands["wasm-ld"] = append(commands["wasm-ld"], "C:\\Program Files\\LLVM\\bin\\wasm-ld.exe")
 	}
-	// Add the path to LLVM installed from ports.
+	// Add the path to the llvm90 installed from ports
 	if runtime.GOOS == "freebsd" {
-		prefix := "/usr/local/llvm" + llvmMajor + "/bin/"
-		commands["clang"] = append(commands["clang"], prefix+"clang-"+llvmMajor)
-		commands["ld.lld"] = append(commands["ld.lld"], prefix+"ld.lld")
-		commands["wasm-ld"] = append(commands["wasm-ld"], prefix+"wasm-ld")
+		commands["clang"] = append(commands["clang"], "/usr/local/llvm90/bin/clang-9")
+		commands["ld.lld"] = append(commands["ld.lld"], "/usr/local/llvm90/bin/ld.lld")
+		commands["wasm-ld"] = append(commands["wasm-ld"], "/usr/local/llvm90/bin/wasm-ld")
 	}
 }

@@ -0,0 +1,60 @@
+// +build byollvm
+
+package builder
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"unsafe"
+
+	"github.com/tinygo-org/tinygo/goenv"
+)
+
+/*
+#cgo CXXFLAGS: -fno-rtti
+#include <stdbool.h>
+#include <stdlib.h>
+bool tinygo_clang_driver(int argc, char **argv);
+*/
+import "C"
+
+// runCCompiler invokes a C compiler with the given arguments.
+//
+// This version invokes the built-in Clang when trying to run the Clang compiler.
+func runCCompiler(command string, flags ...string) error {
+	switch command {
+	case "clang":
+		// Compile this with the internal Clang compiler.
+		headerPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))
+		if headerPath == "" {
+			return errors.New("could not locate Clang headers")
+		}
+		flags = append(flags, "-I"+headerPath)
+		flags = append([]string{"tinygo:" + command}, flags...)
+		var cflag *C.char
+		buf := C.calloc(C.size_t(len(flags)), C.size_t(unsafe.Sizeof(cflag)))
+		cflags := (*[1 << 10]*C.char)(unsafe.Pointer(buf))[:len(flags):len(flags)]
+		for i, flag := range flags {
+			cflag := C.CString(flag)
+			cflags[i] = cflag
+			defer C.free(unsafe.Pointer(cflag))
+		}
+		ok := C.tinygo_clang_driver(C.int(len(flags)), (**C.char)(buf))
+		if !ok {
+			return errors.New("failed to compile using built-in clang")
+		}
+		return nil
+	default:
+		// Running some other compiler. Maybe it has been defined in the
+		// commands map (unlikely).
+		if cmdNames, ok := commands[command]; ok {
+			return execCommand(cmdNames, flags...)
+		}
+		// Alternatively, run the compiler directly.
+		cmd := exec.Command(command, flags...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		return cmd.Run()
+	}
+}
@@ -0,0 +1,24 @@
+// +build !byollvm
+
+package builder
+
+// This file provides a way to a C compiler as an external command. See also:
+// clang-external.go
+
+import (
+	"os"
+	"os/exec"
+)
+
+// runCCompiler invokes a C compiler with the given arguments.
+//
+// This version always runs the compiler as an external command.
+func runCCompiler(command string, flags ...string) error {
+	if cmdNames, ok := commands[command]; ok {
+		return execCommand(cmdNames, flags...)
+	}
+	cmd := exec.Command(command, flags...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
@@ -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 < 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)
+	if major != 1 || (minor != 11 && minor != 12 && minor != 13) {
+		return nil, fmt.Errorf("requires go version 1.11, 1.12, or 1.13, got go%d.%d", major, minor)
 	}
 	clangHeaderPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))
 	return &compileopts.Config{
@@ -1,102 +0,0 @@
-package builder
-
-import (
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"strings"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// Library is a container for information about a single C library, such as a
-// compiler runtime or libc.
-type Library struct {
-	// The library name, such as compiler-rt or picolibc.
-	name string
-
-	cflags func() []string
-
-	// The source directory, relative to TINYGOROOT.
-	sourceDir string
-
-	// The source files, relative to sourceDir.
-	sources func(target string) []string
-}
-
-// fullPath returns the full path to the source directory.
-func (l *Library) fullPath() string {
-	return filepath.Join(goenv.Get("TINYGOROOT"), l.sourceDir)
-}
-
-// sourcePaths returns a slice with the full paths to the source files.
-func (l *Library) sourcePaths(target string) []string {
-	sources := l.sources(target)
-	paths := make([]string, len(sources))
-	for i, name := range sources {
-		paths[i] = filepath.Join(l.fullPath(), name)
-	}
-	return paths
-}
-
-// Load the library archive, possibly generating and caching it if needed.
-func (l *Library) Load(target string) (path string, err error) {
-	// Try to load a precompiled library.
-	precompiledPath := filepath.Join(goenv.Get("TINYGOROOT"), "pkg", target, l.name+".a")
-	if _, err := os.Stat(precompiledPath); err == nil {
-		// Found a precompiled library for this OS/architecture. Return the path
-		// directly.
-		return precompiledPath, nil
-	}
-
-	outfile := l.name + "-" + target + ".a"
-
-	// Try to fetch this library from the cache.
-	if path, err := cacheLoad(outfile, commands["clang"][0], l.sourcePaths(target)); path != "" || err != nil {
-		// Cache hit.
-		return path, err
-	}
-	// Cache miss, build it now.
-
-	dirPrefix := "tinygo-" + l.name
-	remapDir := filepath.Join(os.TempDir(), dirPrefix)
-	dir, err := ioutil.TempDir(os.TempDir(), dirPrefix)
-	if err != nil {
-		return "", err
-	}
-	defer os.RemoveAll(dir)
-
-	// Precalculate the flags to the compiler invocation.
-	args := append(l.cflags(), "-c", "-Oz", "-g", "-ffunction-sections", "-fdata-sections", "-Wno-macro-redefined", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir)
-	if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
-		args = append(args, "-fshort-enums", "-fomit-frame-pointer")
-	}
-	if strings.HasPrefix(target, "riscv32-") {
-		args = append(args, "-march=rv32imac", "-mabi=ilp32", "-fforce-enable-int128")
-	}
-
-	// Compile all sources.
-	var objs []string
-	for _, srcpath := range l.sourcePaths(target) {
-		objpath := filepath.Join(dir, filepath.Base(srcpath)+".o")
-		objs = append(objs, objpath)
-		// Note: -fdebug-prefix-map is necessary to make the output archive
-		// reproducible. Otherwise the temporary directory is stored in the
-		// archive itself, which varies each run.
-		err := runCCompiler("clang", append(args, "-o", objpath, srcpath)...)
-		if err != nil {
-			return "", &commandError{"failed to build", srcpath, err}
-		}
-	}
-
-	// Put all the object files in a single archive. This archive file will be
-	// used to statically link this library.
-	arpath := filepath.Join(dir, l.name+".a")
-	err = makeArchive(arpath, objs)
-	if err != nil {
-		return "", err
-	}
-
-	// Store this archive in the cache.
-	return cacheStore(arpath, outfile, commands["clang"][0], l.sourcePaths(target))
-}
@@ -0,0 +1,71 @@
+// +build byollvm
+
+package builder
+
+// This file provides a Link() function that uses the bundled lld if possible.
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"unsafe"
+
+	"github.com/tinygo-org/tinygo/goenv"
+)
+
+/*
+#include <stdbool.h>
+#include <stdlib.h>
+bool tinygo_link_elf(int argc, char **argv);
+bool tinygo_link_wasm(int argc, char **argv);
+*/
+import "C"
+
+// link invokes a linker with the given name and flags.
+//
+// This version uses the built-in linker when trying to use lld.
+func link(linker string, flags ...string) error {
+	switch linker {
+	case "ld.lld":
+		flags = append([]string{"tinygo:" + linker}, flags...)
+		var cflag *C.char
+		buf := C.calloc(C.size_t(len(flags)), C.size_t(unsafe.Sizeof(cflag)))
+		cflags := (*[1 << 10]*C.char)(unsafe.Pointer(buf))[:len(flags):len(flags)]
+		for i, flag := range flags {
+			cflag := C.CString(flag)
+			cflags[i] = cflag
+			defer C.free(unsafe.Pointer(cflag))
+		}
+		ok := C.tinygo_link_elf(C.int(len(flags)), (**C.char)(buf))
+		if !ok {
+			return errors.New("failed to link using built-in ld.lld")
+		}
+		return nil
+	case "wasm-ld":
+		flags = append([]string{"tinygo:" + linker}, flags...)
+		var cflag *C.char
+		buf := C.calloc(C.size_t(len(flags)), C.size_t(unsafe.Sizeof(cflag)))
+		defer C.free(buf)
+		cflags := (*[1 << 10]*C.char)(unsafe.Pointer(buf))[:len(flags):len(flags)]
+		for i, flag := range flags {
+			cflag := C.CString(flag)
+			cflags[i] = cflag
+			defer C.free(unsafe.Pointer(cflag))
+		}
+		ok := C.tinygo_link_wasm(C.int(len(flags)), (**C.char)(buf))
+		if !ok {
+			return errors.New("failed to link using built-in wasm-ld")
+		}
+		return nil
+	default:
+		// Fall back to external command.
+		if cmdNames, ok := commands[linker]; ok {
+			return execCommand(cmdNames, flags...)
+		}
+		cmd := exec.Command(linker, flags...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		cmd.Dir = goenv.Get("TINYGOROOT")
+		return cmd.Run()
+	}
+}
@@ -0,0 +1,27 @@
+// +build !byollvm
+
+package builder
+
+// This file provides a Link() function that always runs an external command. It
+// is provided for when tinygo is built without linking to liblld.
+
+import (
+	"os"
+	"os/exec"
+
+	"github.com/tinygo-org/tinygo/goenv"
+)
+
+// link invokes a linker with the given name and arguments.
+//
+// This version always runs the linker as an external command.
+func link(linker string, flags ...string) error {
+	if cmdNames, ok := commands[linker]; ok {
+		return execCommand(cmdNames, flags...)
+	}
+	cmd := exec.Command(linker, flags...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.Dir = goenv.Get("TINYGOROOT")
+	return cmd.Run()
+}
@@ -8,12 +8,12 @@ extern "C" {

 bool tinygo_link_elf(int argc, char **argv) {
 	std::vector<const char*> args(argv, argv + argc);
-	return lld::elf::link(args, false, llvm::outs(), llvm::errs());
+	return lld::elf::link(args, false);
 }

 bool tinygo_link_wasm(int argc, char **argv) {
 	std::vector<const char*> args(argv, argv + argc);
-	return lld::wasm::link(args, false, llvm::outs(), llvm::errs());
+	return lld::wasm::link(args, false);
 }

 } // external "C"
@@ -1,127 +0,0 @@
-package builder
-
-import (
-	"path/filepath"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// Picolibc is a C library for bare metal embedded devices. It was originally
-// based on newlib.
-var Picolibc = Library{
-	name: "picolibc",
-	cflags: func() []string {
-		picolibcDir := filepath.Join(goenv.Get("TINYGOROOT"), "lib/picolibc/newlib/libc")
-		return []string{"-Werror", "-Wall", "-std=gnu11", "-D_COMPILING_NEWLIB", "--sysroot=" + picolibcDir, "-I" + picolibcDir + "/tinystdio", "-I" + goenv.Get("TINYGOROOT") + "/lib/picolibc-include"}
-	},
-	sourceDir: "lib/picolibc/newlib/libc",
-	sources: func(target string) []string {
-		return picolibcSources
-	},
-}
-
-var picolibcSources = []string{
-	"string/bcmp.c",
-	"string/bcopy.c",
-	"string/bzero.c",
-	"string/explicit_bzero.c",
-	"string/ffsl.c",
-	"string/ffsll.c",
-	"string/fls.c",
-	"string/flsl.c",
-	"string/flsll.c",
-	"string/gnu_basename.c",
-	"string/index.c",
-	"string/memccpy.c",
-	"string/memchr.c",
-	"string/memcmp.c",
-	"string/memcpy.c",
-	"string/memmem.c",
-	"string/memmove.c",
-	"string/mempcpy.c",
-	"string/memrchr.c",
-	"string/memset.c",
-	"string/rawmemchr.c",
-	"string/rindex.c",
-	"string/stpcpy.c",
-	"string/stpncpy.c",
-	"string/strcasecmp.c",
-	"string/strcasecmp_l.c",
-	"string/strcasestr.c",
-	"string/strcat.c",
-	"string/strchr.c",
-	"string/strchrnul.c",
-	"string/strcmp.c",
-	"string/strcoll.c",
-	"string/strcoll_l.c",
-	"string/strcpy.c",
-	"string/strcspn.c",
-	"string/strdup.c",
-	"string/strerror.c",
-	"string/strerror_r.c",
-	"string/strlcat.c",
-	"string/strlcpy.c",
-	"string/strlen.c",
-	"string/strlwr.c",
-	"string/strncasecmp.c",
-	"string/strncasecmp_l.c",
-	"string/strncat.c",
-	"string/strncmp.c",
-	"string/strncpy.c",
-	"string/strndup.c",
-	"string/strnlen.c",
-	"string/strnstr.c",
-	"string/strpbrk.c",
-	"string/strrchr.c",
-	"string/strsep.c",
-	"string/strsignal.c",
-	"string/strspn.c",
-	"string/strstr.c",
-	"string/strtok.c",
-	"string/strtok_r.c",
-	"string/strupr.c",
-	"string/strverscmp.c",
-	"string/strxfrm.c",
-	"string/strxfrm_l.c",
-	"string/swab.c",
-	"string/timingsafe_bcmp.c",
-	"string/timingsafe_memcmp.c",
-	"string/u_strerr.c",
-	"string/wcpcpy.c",
-	"string/wcpncpy.c",
-	"string/wcscasecmp.c",
-	"string/wcscasecmp_l.c",
-	"string/wcscat.c",
-	"string/wcschr.c",
-	"string/wcscmp.c",
-	"string/wcscoll.c",
-	"string/wcscoll_l.c",
-	"string/wcscpy.c",
-	"string/wcscspn.c",
-	"string/wcsdup.c",
-	"string/wcslcat.c",
-	"string/wcslcpy.c",
-	"string/wcslen.c",
-	"string/wcsncasecmp.c",
-	"string/wcsncasecmp_l.c",
-	"string/wcsncat.c",
-	"string/wcsncmp.c",
-	"string/wcsncpy.c",
-	"string/wcsnlen.c",
-	"string/wcspbrk.c",
-	"string/wcsrchr.c",
-	"string/wcsspn.c",
-	"string/wcsstr.c",
-	"string/wcstok.c",
-	"string/wcswidth.c",
-	"string/wcsxfrm.c",
-	"string/wcsxfrm_l.c",
-	"string/wcwidth.c",
-	"string/wmemchr.c",
-	"string/wmemcmp.c",
-	"string/wmemcpy.c",
-	"string/wmemmove.c",
-	"string/wmempcpy.c",
-	"string/wmemset.c",
-	"string/xpg_strerror_r.c",
-}
@@ -84,18 +84,7 @@ func loadProgramSize(path string) (*programSize, error) {
 		if section.Type != elf.SHT_PROGBITS && section.Type != elf.SHT_NOBITS {
 			continue
 		}
-		if section.Name == ".stack" {
-			// HACK: this works around a bug in ld.lld from LLVM 10. The linker
-			// marks sections with no input symbols (such as is the case for the
-			// .stack section) as SHT_PROGBITS instead of SHT_NOBITS. While it
-			// doesn't affect the generated binaries (.hex and .bin), it does
-			// affect the reported size.
-			// https://bugs.llvm.org/show_bug.cgi?id=45336
-			// https://reviews.llvm.org/D76981
-			// It has been merged in master, but it has not (yet) been
-			// backported to the LLVM 10 release branch.
-			sumBSS += section.Size
-		} else if section.Type == elf.SHT_NOBITS {
+		if section.Type == elf.SHT_NOBITS {
 			sumBSS += section.Size
 		} else if section.Flags&elf.SHF_EXECINSTR != 0 {
 			sumCode += section.Size
@@ -1,54 +0,0 @@
-// +build byollvm
-
-package builder
-
-import (
-	"errors"
-	"unsafe"
-)
-
-/*
-#cgo CXXFLAGS: -fno-rtti
-#include <stdbool.h>
-#include <stdlib.h>
-bool tinygo_clang_driver(int argc, char **argv);
-bool tinygo_link_elf(int argc, char **argv);
-bool tinygo_link_wasm(int argc, char **argv);
-*/
-import "C"
-
-const hasBuiltinTools = true
-
-// RunTool runs the given tool (such as clang).
-//
-// This version actually runs the tools because TinyGo was compiled while
-// linking statically with LLVM (with the byollvm build tag).
-func RunTool(tool string, args ...string) error {
-	args = append([]string{"tinygo:" + tool}, args...)
-
-	var cflag *C.char
-	buf := C.calloc(C.size_t(len(args)), C.size_t(unsafe.Sizeof(cflag)))
-	defer C.free(buf)
-	cflags := (*[1 << 10]*C.char)(unsafe.Pointer(buf))[:len(args):len(args)]
-	for i, flag := range args {
-		cflag := C.CString(flag)
-		cflags[i] = cflag
-		defer C.free(unsafe.Pointer(cflag))
-	}
-
-	var ok C.bool
-	switch tool {
-	case "clang":
-		ok = C.tinygo_clang_driver(C.int(len(args)), (**C.char)(buf))
-	case "ld.lld":
-		ok = C.tinygo_link_elf(C.int(len(args)), (**C.char)(buf))
-	case "wasm-ld":
-		ok = C.tinygo_link_wasm(C.int(len(args)), (**C.char)(buf))
-	default:
-		return errors.New("unknown tool: " + tool)
-	}
-	if !ok {
-		return errors.New("failed to run tool: " + tool)
-	}
-	return nil
-}
@@ -1,15 +0,0 @@
-// +build !byollvm
-
-package builder
-
-import "errors"
-
-const hasBuiltinTools = false
-
-// RunTool runs the given tool (such as clang).
-//
-// This version doesn't actually run the tool: TinyGo has not been compiled by
-// statically linking to LLVM.
-func RunTool(tool string, args ...string) error {
-	return errors.New("cannot run tool: " + tool)
-}
@@ -1,59 +0,0 @@
-package builder
-
-import (
-	"errors"
-	"os"
-	"os/exec"
-
-	"github.com/tinygo-org/tinygo/goenv"
-)
-
-// runCCompiler invokes a C compiler with the given arguments.
-func runCCompiler(command string, flags ...string) error {
-	if hasBuiltinTools && command == "clang" {
-		// Compile this with the internal Clang compiler.
-		headerPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))
-		if headerPath == "" {
-			return errors.New("could not locate Clang headers")
-		}
-		flags = append(flags, "-I"+headerPath)
-		cmd := exec.Command(os.Args[0], append([]string{"clang"}, flags...)...)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		return cmd.Run()
-	}
-
-	// Running some other compiler. Maybe it has been defined in the
-	// commands map (unlikely).
-	if cmdNames, ok := commands[command]; ok {
-		return execCommand(cmdNames, flags...)
-	}
-
-	// Alternatively, run the compiler directly.
-	cmd := exec.Command(command, flags...)
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	return cmd.Run()
-}
-
-// link invokes a linker with the given name and flags.
-func link(linker string, flags ...string) error {
-	if hasBuiltinTools && (linker == "ld.lld" || linker == "wasm-ld") {
-		// Run command with internal linker.
-		cmd := exec.Command(os.Args[0], append([]string{linker}, flags...)...)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		return cmd.Run()
-	}
-
-	// Fall back to external command.
-	if cmdNames, ok := commands[linker]; ok {
-		return execCommand(cmdNames, flags...)
-	}
-
-	cmd := exec.Command(linker, flags...)
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	cmd.Dir = goenv.Get("TINYGOROOT")
-	return cmd.Run()
-}
@@ -11,33 +11,26 @@ import (
 	"bytes"
 	"encoding/binary"
 	"io/ioutil"
-	"strconv"
 )

 // convertELFFileToUF2File converts an ELF file to a UF2 file.
-func convertELFFileToUF2File(infile, outfile string, uf2FamilyID string) error {
+func convertELFFileToUF2File(infile, outfile string) error {
 	// Read the .text segment.
 	targetAddress, data, err := extractROM(infile)
 	if err != nil {
 		return err
 	}

-	output, _, err := convertBinToUF2(data, uint32(targetAddress), uf2FamilyID)
-	if err != nil {
-		return err
-	}
+	output, _ := convertBinToUF2(data, uint32(targetAddress))
 	return ioutil.WriteFile(outfile, output, 0644)
 }

 // convertBinToUF2 converts the binary bytes in input to UF2 formatted data.
-func convertBinToUF2(input []byte, targetAddr uint32, uf2FamilyID string) ([]byte, int, error) {
+func convertBinToUF2(input []byte, targetAddr uint32) ([]byte, int) {
 	blocks := split(input, 256)
 	output := make([]byte, 0)

-	bl, err := newUF2Block(targetAddr, uf2FamilyID)
-	if err != nil {
-		return nil, 0, err
-	}
+	bl := newUF2Block(targetAddr)
 	bl.SetNumBlocks(len(blocks))

 	for i := 0; i < len(blocks); i++ {
@@ -48,7 +41,7 @@ func convertBinToUF2(input []byte, targetAddr uint32, uf2FamilyID string) ([]byt
 		bl.IncrementAddress(bl.payloadSize)
 	}

-	return output, len(blocks), nil
+	return output, len(blocks)
 }

 const (
@@ -72,32 +65,18 @@ type uf2Block struct {
 }

 // newUF2Block returns a new uf2Block struct that has been correctly populated
-func newUF2Block(targetAddr uint32, uf2FamilyID string) (*uf2Block, error) {
-	var flags uint32
-	var familyID uint32
-	if uf2FamilyID != "" {
-		flags |= flagFamilyIDPresent
-		v, err := strconv.ParseUint(uf2FamilyID, 0, 32)
-		if err != nil {
-			return nil, err
-		}
-		familyID = uint32(v)
-	}
+func newUF2Block(targetAddr uint32) *uf2Block {
 	return &uf2Block{magicStart0: uf2MagicStart0,
 		magicStart1: uf2MagicStart1,
 		magicEnd:    uf2MagicEnd,
 		targetAddr:  targetAddr,
-		flags:       flags,
-		familyID:    familyID,
+		flags:       0x0,
+		familyID:    0x0,
 		payloadSize: 256,
 		data:        make([]byte, 476),
-	}, nil
+	}
 }

-const (
-	flagFamilyIDPresent = 0x00002000
-)
-
 // Bytes converts the uf2Block to a slice of bytes that can be written to file.
 func (b *uf2Block) Bytes() []byte {
 	buf := bytes.NewBuffer(make([]byte, 0, 512))
@@ -14,9 +14,7 @@ package cgo
 import (
 	"fmt"
 	"go/ast"
-	"go/scanner"
 	"go/token"
-	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
@@ -170,28 +168,11 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		enums:           map[string]enumInfo{},
 	}

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

-	// Find the absolute path for this package.
-	packagePath, err := filepath.Abs(fset.File(files[0].Pos()).Name())
-	if err != nil {
-		return nil, []error{
-			scanner.Error{
-				Pos: fset.Position(files[0].Pos()),
-				Msg: "cgo: cannot find absolute path: " + err.Error(), // TODO: wrap this error
-			},
-		}
-	}
-	packagePath = filepath.Dir(packagePath)
-
 	// Construct a new in-memory AST for CGo declarations of this package.
 	unsafeImport := &ast.ImportSpec{
 		Path: &ast.BasicLit{
@@ -357,7 +338,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 						p.addErrorAfter(comment.Slash, comment.Text[:lineStart+colon+1], err.Error())
 						continue
 					}
-					makePathsAbsolute(flags, packagePath)
 					cflags = append(cflags, flags...)
 				default:
 					startPos := strings.LastIndex(line[4:colon], name) + 4
@@ -415,30 +395,6 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	return p.generated, p.errors
 }

-// makePathsAbsolute converts some common path compiler flags (-I, -L) from
-// relative flags into absolute flags, if they are relative. This is necessary
-// because the C compiler is usually not invoked from the package path.
-func makePathsAbsolute(args []string, packagePath string) {
-	nextIsPath := false
-	for i, arg := range args {
-		if nextIsPath {
-			if !filepath.IsAbs(arg) {
-				args[i] = filepath.Join(packagePath, arg)
-			}
-		}
-		if arg == "-I" || arg == "-L" {
-			nextIsPath = true
-			continue
-		}
-		if strings.HasPrefix(arg, "-I") || strings.HasPrefix(arg, "-L") {
-			path := arg[2:]
-			if !filepath.IsAbs(path) {
-				args[i] = arg[:2] + filepath.Join(packagePath, path)
-			}
-		}
-	}
-}
-
 // addFuncDecls adds the C function declarations found by libclang in the
 // comment above the `import "C"` statement.
 func (p *cgoPackage) addFuncDecls() {
@@ -11,7 +11,6 @@ import (
 	"go/types"
 	"io/ioutil"
 	"path/filepath"
-	"regexp"
 	"runtime"
 	"strings"
 	"testing"
@@ -20,21 +19,6 @@ import (
 // Pass -update to go test to update the output of the test files.
 var flagUpdate = flag.Bool("update", false, "Update images based on test output.")

-// normalizeResult normalizes Go source code that comes out of tests across
-// platforms and Go versions.
-func normalizeResult(result string) string {
-	actual := strings.Replace(result, "\r\n", "\n", -1)
-
-	// Make sure all functions are wrapped, even those that would otherwise be
-	// single-line functions. This is necessary because Go 1.14 changed the way
-	// such functions are wrapped and it's important to have consistent test
-	// results.
-	re := regexp.MustCompile(`func \((.+)\)( .*?) +{ (.+) }`)
-	actual = re.ReplaceAllString(actual, "func ($1)$2 {\n\t$3\n}")
-
-	return actual
-}
-
 func TestCGo(t *testing.T) {
 	var cflags = []string{"--target=armv6m-none-eabi"}

@@ -90,7 +74,7 @@ func TestCGo(t *testing.T) {
 			if err != nil {
 				t.Errorf("could not write out CGo AST: %v", err)
 			}
-			actual := normalizeResult(string(buf.Bytes()))
+			actual := strings.Replace(string(buf.Bytes()), "\r\n", "\n", -1)

 			// Read the file with the expected output, to compare against.
 			outfile := filepath.Join("testdata", name+".out.go")
@@ -15,7 +15,7 @@ import (
 )

 /*
-#include <clang-c/Index.h> // if this fails, install libclang-10-dev
+#include <clang-c/Index.h> // if this fails, install libclang-9-dev
 #include <stdlib.h>
 #include <stdint.h>

@@ -1,14 +1,13 @@
 // +build !byollvm
-// +build !llvm9

 package cgo

 /*
-#cgo linux  CFLAGS: -I/usr/lib/llvm-10/include
-#cgo darwin CFLAGS: -I/usr/local/opt/llvm@10/include
-#cgo freebsd CFLAGS: -I/usr/local/llvm10/include
-#cgo linux  LDFLAGS: -L/usr/lib/llvm-10/lib -lclang
-#cgo darwin LDFLAGS: -L/usr/local/opt/llvm@10/lib -lclang -lffi
-#cgo freebsd LDFLAGS: -L/usr/local/llvm10/lib -lclang
+#cgo linux  CFLAGS: -I/usr/lib/llvm-9/include
+#cgo darwin CFLAGS: -I/usr/local/opt/llvm@9/include
+#cgo freebsd CFLAGS: -I/usr/local/llvm90/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/llvm90/lib -lclang
 */
 import "C"
@@ -1,14 +0,0 @@
-// +build !byollvm
-// +build llvm9
-
-package cgo
-
-/*
-#cgo linux  CFLAGS: -I/usr/lib/llvm-9/include
-#cgo darwin CFLAGS: -I/usr/local/opt/llvm@9/include
-#cgo freebsd CFLAGS: -I/usr/local/llvm9/include
-#cgo linux  LDFLAGS: -L/usr/lib/llvm-9/lib -lclang
-#cgo darwin LDFLAGS: -L/usr/local/opt/llvm@9/lib -lclang -lffi
-#cgo freebsd LDFLAGS: -L/usr/local/llvm9/lib -lclang
-*/
-import "C"
@@ -3,7 +3,7 @@
 // are slightly different from the ones defined in libclang.go, but they
 // should be ABI compatible.

-#include <clang-c/Index.h> // if this fails, install libclang-10-dev
+#include <clang-c/Index.h> // if this fails, install libclang-9-dev

 CXCursor tinygo_clang_getTranslationUnitCursor(CXTranslationUnit tu) {
 	return clang_getTranslationUnitCursor(tu);
@@ -9,9 +9,6 @@ package main

 #cgo CFLAGS: -DFOO

-#cgo CFLAGS: -Iinclude
-#include "foo.h"
-
 #if defined(FOO)
 #define BAR 3
 #else
@@ -26,5 +23,4 @@ import "C"

 var (
 	_ = C.BAR
-	_ = C.FOO_H
 )
@@ -9,7 +9,6 @@ import "unsafe"
 var _ unsafe.Pointer

 const C.BAR = 3
-const C.FOO_H = 1

 type C.int16_t = int16
 type C.int32_t = int32
@@ -1 +0,0 @@
-#define FOO_H 1
@@ -62,18 +62,12 @@ type C.union3_t = C.union_1
 type C.union_nested_t = C.union_3
 type C.unionarray_t = struct{ arr [10]C.uchar }

-func (s *C.struct_4) bitfield_a() C.uchar {
-	return s.__bitfield_1 & 0x1f
-}
-func (s *C.struct_4) set_bitfield_a(value C.uchar) {
-	s.__bitfield_1 = s.__bitfield_1&^0x1f | value&0x1f<<0
-}
+func (s *C.struct_4) bitfield_a() C.uchar          { return s.__bitfield_1 & 0x1f }
+func (s *C.struct_4) set_bitfield_a(value C.uchar) { s.__bitfield_1 = s.__bitfield_1&^0x1f | value&0x1f<<0 }
 func (s *C.struct_4) bitfield_b() C.uchar {
 	return s.__bitfield_1 >> 5 & 0x1
 }
-func (s *C.struct_4) set_bitfield_b(value C.uchar) {
-	s.__bitfield_1 = s.__bitfield_1&^0x20 | value&0x1<<5
-}
+func (s *C.struct_4) set_bitfield_b(value C.uchar) { s.__bitfield_1 = s.__bitfield_1&^0x20 | value&0x1<<5 }
 func (s *C.struct_4) bitfield_c() C.uchar {
 	return s.__bitfield_1 >> 6
 }
@@ -100,45 +94,25 @@ type C.struct_type1 struct {
 }
 type C.struct_type2 struct{ _type C.int }

-func (union *C.union_1) unionfield_i() *C.int {
-	return (*C.int)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_1) unionfield_d() *float64 {
-	return (*float64)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_1) unionfield_s() *C.short {
-	return (*C.short)(unsafe.Pointer(&union.$union))
-}
+func (union *C.union_1) unionfield_i() *C.int   { return (*C.int)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_1) unionfield_d() *float64 { return (*float64)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_1) unionfield_s() *C.short { return (*C.short)(unsafe.Pointer(&union.$union)) }

 type C.union_1 struct{ $union uint64 }

-func (union *C.union_2) unionfield_area() *C.point2d_t {
-	return (*C.point2d_t)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_2) unionfield_solid() *C.point3d_t {
-	return (*C.point3d_t)(unsafe.Pointer(&union.$union))
-}
+func (union *C.union_2) unionfield_area() *C.point2d_t  { return (*C.point2d_t)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_2) unionfield_solid() *C.point3d_t { return (*C.point3d_t)(unsafe.Pointer(&union.$union)) }

 type C.union_2 struct{ $union [3]uint32 }

-func (union *C.union_3) unionfield_point() *C.point3d_t {
-	return (*C.point3d_t)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_3) unionfield_array() *C.unionarray_t {
-	return (*C.unionarray_t)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_3) unionfield_thing() *C.union3_t {
-	return (*C.union3_t)(unsafe.Pointer(&union.$union))
-}
+func (union *C.union_3) unionfield_point() *C.point3d_t    { return (*C.point3d_t)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_3) unionfield_array() *C.unionarray_t { return (*C.unionarray_t)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_3) unionfield_thing() *C.union3_t     { return (*C.union3_t)(unsafe.Pointer(&union.$union)) }

 type C.union_3 struct{ $union [2]uint64 }

-func (union *C.union_union2d) unionfield_i() *C.int {
-	return (*C.int)(unsafe.Pointer(&union.$union))
-}
-func (union *C.union_union2d) unionfield_d() *[2]float64 {
-	return (*[2]float64)(unsafe.Pointer(&union.$union))
-}
+func (union *C.union_union2d) unionfield_i() *C.int      { return (*C.int)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_union2d) unionfield_d() *[2]float64 { return (*[2]float64)(unsafe.Pointer(&union.$union)) }

 type C.union_union2d struct{ $union [2]uint64 }
 type C.enum_option C.int
@@ -5,7 +5,6 @@ package compileopts
 import (
 	"errors"
 	"fmt"
-	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"
@@ -22,29 +21,6 @@ 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
@@ -89,14 +65,8 @@ func (c *Config) BuildTags() []string {
 	return tags
 }

-// CgoEnabled returns true if (and only if) CGo is enabled. It is true by
-// default and false if CGO_ENABLED is set to "0".
-func (c *Config) CgoEnabled() bool {
-	return goenv.Get("CGO_ENABLED") == "1"
-}
-
 // GC returns the garbage collection strategy in use on this platform. Valid
-// values are "none", "leaking", "extalloc", and "conservative".
+// values are "none", "leaking", and "conservative".
 func (c *Config) GC() string {
 	if c.Options.GC != "" {
 		return c.Options.GC
@@ -104,29 +74,22 @@ func (c *Config) GC() string {
 	if c.Target.GC != "" {
 		return c.Target.GC
 	}
-	for _, tag := range c.Target.BuildTags {
-		if tag == "baremetal" || tag == "wasm" {
-			return "conservative"
-		}
-	}
-	return "extalloc"
+	return "conservative"
 }

 // NeedsStackObjects returns true if the compiler should insert stack objects
 // that can be traced by the garbage collector.
 func (c *Config) NeedsStackObjects() bool {
-	switch c.GC() {
-	case "conservative", "extalloc":
-		for _, tag := range c.BuildTags() {
-			if tag == "baremetal" {
-				return false
-			}
-		}
-
-		return true
-	default:
+	if c.GC() != "conservative" {
 		return false
 	}
+	for _, tag := range c.BuildTags() {
+		if tag == "baremetal" {
+			return false
+		}
+	}
+
+	return true
 }

 // Scheduler returns the scheduler implementation. Valid values are "coroutines"
@@ -142,21 +105,6 @@ func (c *Config) Scheduler() string {
 	return "coroutines"
 }

-// FuncImplementation picks an appropriate func value implementation for the
-// target.
-func (c *Config) FuncImplementation() FuncValueImplementation {
-	// Always pick the switch implementation, as it allows the use of blocking
-	// inside a function that is used as a func value.
-	switch c.Scheduler() {
-	case "none", "coroutines":
-		return FuncValueSwitch
-	case "tasks":
-		return FuncValueDoubleword
-	default:
-		panic("unknown scheduler type")
-	}
-}
-
 // PanicStrategy returns the panic strategy selected for this target. Valid
 // values are "print" (print the panic value, then exit) or "trap" (issue a trap
 // instruction).
@@ -171,11 +119,6 @@ func (c *Config) CFlags() []string {
 	for _, flag := range c.Target.CFlags {
 		cflags = append(cflags, strings.Replace(flag, "{root}", goenv.Get("TINYGOROOT"), -1))
 	}
-	if c.Target.Libc == "picolibc" {
-		root := goenv.Get("TINYGOROOT")
-		cflags = append(cflags, "--sysroot="+filepath.Join(root, "lib", "picolibc", "newlib", "libc"))
-		cflags = append(cflags, "-I"+filepath.Join(root, "lib/picolibc-include"))
-	}
 	return cflags
 }

@@ -32,7 +32,6 @@ type TargetSpec struct {
 	Compiler         string   `json:"compiler"`
 	Linker           string   `json:"linker"`
 	RTLib            string   `json:"rtlib"` // compiler runtime library (libgcc, compiler-rt)
-	Libc             string   `json:"libc"`
 	CFlags           []string `json:"cflags"`
 	LDFlags          []string `json:"ldflags"`
 	LinkerScript     string   `json:"linkerscript"`
@@ -44,11 +43,9 @@ type TargetSpec struct {
 	FlashMethod      string   `json:"flash-method"`
 	FlashVolume      string   `json:"msd-volume-name"`
 	FlashFilename    string   `json:"msd-firmware-name"`
-	UF2FamilyID      string   `json:"uf2-family-id"`
 	OpenOCDInterface string   `json:"openocd-interface"`
 	OpenOCDTarget    string   `json:"openocd-target"`
 	OpenOCDTransport string   `json:"openocd-transport"`
-	JLinkDevice      string   `json:"jlink-device"`
 }

 // copyProperties copies all properties that are set in spec2 into itself.
@@ -85,9 +82,6 @@ func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
 	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 != "" {
@@ -115,9 +109,6 @@ func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
 	if spec2.FlashFilename != "" {
 		spec.FlashFilename = spec2.FlashFilename
 	}
-	if spec2.UF2FamilyID != "" {
-		spec.UF2FamilyID = spec2.UF2FamilyID
-	}
 	if spec2.OpenOCDInterface != "" {
 		spec.OpenOCDInterface = spec2.OpenOCDInterface
 	}
@@ -127,9 +118,6 @@ func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
 	if spec2.OpenOCDTransport != "" {
 		spec.OpenOCDTransport = spec2.OpenOCDTransport
 	}
-	if spec2.JLinkDevice != "" {
-		spec.JLinkDevice = spec2.JLinkDevice
-	}
 }

 // load reads a target specification from the JSON in the given io.Reader. It
@@ -233,14 +221,6 @@ func LoadTarget(target string) (*TargetSpec, error) {
 		if len(tripleSplit) < 3 {
 			return nil, errors.New("expected a full LLVM target or a custom target in -target flag")
 		}
-		if tripleSplit[0] == "arm" {
-			// LLVM and Clang have a different idea of what "arm" means, so
-			// upgrade to a slightly more modern ARM. In fact, when you pass
-			// --target=arm--linux-gnueabihf to Clang, it will convert that
-			// internally to armv7-unknown-linux-gnueabihf. Changing the
-			// architecture to armv7 will keep things consistent.
-			tripleSplit[0] = "armv7"
-		}
 		goos := tripleSplit[2]
 		if strings.HasPrefix(goos, "darwin") {
 			goos = "darwin"
@@ -249,12 +229,11 @@ func LoadTarget(target string) (*TargetSpec, error) {
 			"i386":    "386",
 			"x86_64":  "amd64",
 			"aarch64": "arm64",
-			"armv7":   "arm",
 		}[tripleSplit[0]]
 		if goarch == "" {
 			goarch = tripleSplit[0]
 		}
-		return defaultTarget(goos, goarch, strings.Join(tripleSplit, "-"))
+		return defaultTarget(goos, goarch, target)
 	}
 }

@@ -268,7 +247,6 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		BuildTags:   []string{goos, goarch},
 		Compiler:    "clang",
 		Linker:      "cc",
-		CFlags:      []string{"--target=" + triple},
 		GDB:         "gdb",
 		PortReset:   "false",
 		FlashMethod: "native",
@@ -281,13 +259,11 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	if goarch != runtime.GOARCH {
 		// Some educated guesses as to how to invoke helper programs.
 		if goarch == "arm" && goos == "linux" {
-			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/arm-linux-gnueabihf")
 			spec.Linker = "arm-linux-gnueabihf-gcc"
 			spec.GDB = "arm-linux-gnueabihf-gdb"
 			spec.Emulator = []string{"qemu-arm", "-L", "/usr/arm-linux-gnueabihf"}
 		}
 		if goarch == "arm64" && goos == "linux" {
-			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/aarch64-linux-gnu")
 			spec.Linker = "aarch64-linux-gnu-gcc"
 			spec.GDB = "aarch64-linux-gnu-gdb"
 			spec.Emulator = []string{"qemu-aarch64", "-L", "/usr/aarch64-linux-gnu"}
@@ -4,19 +4,16 @@ package compiler
 // required by the Go programming language.

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

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

-// createLookupBoundsCheck emits a bounds check before doing a lookup into a
+// emitLookupBoundsCheck emits a bounds check before doing a lookup into a
 // slice. This is required by the Go language spec: an index out of bounds must
 // cause a panic.
-func (b *builder) createLookupBoundsCheck(arrayLen, index llvm.Value, indexType types.Type) {
-	if b.fn.IsNoBounds() {
+func (c *Compiler) emitLookupBoundsCheck(frame *Frame, arrayLen, index llvm.Value, indexType types.Type) {
+	if frame.fn.IsNoBounds() {
 		// The //go:nobounds pragma was added to the function to avoid bounds
 		// checking.
 		return
@@ -26,29 +23,41 @@ func (b *builder) createLookupBoundsCheck(arrayLen, index llvm.Value, indexType
 		// Sometimes, the index can be e.g. an uint8 or int8, and we have to
 		// correctly extend that type.
 		if indexType.Underlying().(*types.Basic).Info()&types.IsUnsigned == 0 {
-			index = b.CreateZExt(index, arrayLen.Type(), "")
+			index = c.builder.CreateZExt(index, arrayLen.Type(), "")
 		} else {
-			index = b.CreateSExt(index, arrayLen.Type(), "")
+			index = c.builder.CreateSExt(index, arrayLen.Type(), "")
 		}
 	} else if index.Type().IntTypeWidth() > arrayLen.Type().IntTypeWidth() {
 		// The index is bigger than the array length type, so extend it.
-		arrayLen = b.CreateZExt(arrayLen, index.Type(), "")
+		arrayLen = c.builder.CreateZExt(arrayLen, index.Type(), "")
 	}

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

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

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

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

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

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

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

-	// isNegative = shift < 0
-	isNegative := b.CreateICmp(llvm.IntSLT, shift, llvm.ConstInt(shift.Type(), 0, false), "")
-	b.createRuntimeAssert(isNegative, "shift", "negativeShiftPanic")
-}
-
-// createRuntimeAssert is a common function to create a new branch on an assert
-// bool, calling an assert func if the assert value is true (1).
-func (b *builder) createRuntimeAssert(assert llvm.Value, blockPrefix, assertFunc string) {
-	// Check whether we can resolve this check at compile time.
-	if !assert.IsAConstantInt().IsNil() {
-		val := assert.ZExtValue()
-		if val == 0 {
-			// Everything is constant so the check does not have to be emitted
-			// in IR. This avoids emitting some redundant IR.
-			return
-		}
-	}
-
-	faultBlock := b.ctx.AddBasicBlock(b.fn.LLVMFn, blockPrefix+".throw")
-	nextBlock := b.ctx.AddBasicBlock(b.fn.LLVMFn, blockPrefix+".next")
-	b.blockExits[b.currentBlock] = nextBlock // adjust outgoing block for phi nodes
-
-	// Now branch to the out-of-bounds or the regular block.
-	b.CreateCondBr(assert, faultBlock, nextBlock)
-
-	// Fail: the assert triggered so panic.
-	b.SetInsertPointAtEnd(faultBlock)
-	b.createRuntimeCall(assertFunc, nil, "")
-	b.CreateUnreachable()
-
-	// Ok: assert didn't trigger so continue normally.
-	b.SetInsertPointAtEnd(nextBlock)
+	// Fail: this is a nil pointer, exit with a panic.
+	c.builder.SetInsertPointAtEnd(faultBlock)
+	c.createRuntimeCall("nilPanic", nil, "")
+	c.builder.CreateUnreachable()
+
+	// Ok: this is a valid pointer.
+	c.builder.SetInsertPointAtEnd(nextBlock)
 }
@@ -1,8 +1,8 @@
 package compiler

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

@@ -11,68 +11,62 @@ import (

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

-// paramFlags identifies parameter attributes for flags. Most importantly, it
-// determines which parameters are dereferenceable_or_null and which aren't.
-type paramFlags uint8
-
-const (
-	// Parameter may have the deferenceable_or_null attribute. This attribute
-	// cannot be applied to unsafe.Pointer and to the data pointer of slices.
-	paramIsDeferenceableOrNull = 1 << iota
-)
-
-// createCall creates a new call to runtime.<fnName> with the given arguments.
-func (b *builder) createRuntimeCall(fnName string, args []llvm.Value, name string) llvm.Value {
-	fullName := "runtime." + fnName
-	fn := b.mod.NamedFunction(fullName)
-	if fn.IsNil() {
-		panic("trying to call non-existent function: " + fullName)
+// Shortcut: create a call to runtime.<fnName> with the given arguments.
+func (c *Compiler) createRuntimeCall(fnName string, args []llvm.Value, name string) llvm.Value {
+	runtimePkg := c.ir.Program.ImportedPackage("runtime")
+	member := runtimePkg.Members[fnName]
+	if member == nil {
+		panic("trying to call runtime." + fnName)
 	}
-	args = append(args, llvm.Undef(b.i8ptrType))            // unused context parameter
-	args = append(args, llvm.ConstPointerNull(b.i8ptrType)) // coroutine handle
-	return b.createCall(fn, args, name)
+	fn := c.ir.GetFunction(member.(*ssa.Function))
+	if fn.LLVMFn.IsNil() {
+		panic(fmt.Errorf("function %s does not appear in LLVM IR", fnName))
+	}
+	if !fn.IsExported() {
+		args = append(args, llvm.Undef(c.i8ptrType))            // unused context parameter
+		args = append(args, llvm.ConstPointerNull(c.i8ptrType)) // coroutine handle
+	}
+	return c.createCall(fn.LLVMFn, args, name)
 }

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

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

-// expandFormalParamOffsets returns a list of offsets from the start of an
-// object of type t after it would have been split up by expandFormalParam. This
-// is useful for debug information, where it is necessary to know the offset
-// from the start of the combined object.
-func (b *builder) expandFormalParamOffsets(t llvm.Type) []uint64 {
+// Expand an argument type to a list of offsets from the start of the object.
+// Used together with expandFormalParam to get the offset of each value from the
+// start of the non-expanded value.
+func (c *Compiler) expandFormalParamOffsets(t llvm.Type) []uint64 {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
-		fields := b.flattenAggregateTypeOffsets(t)
-		if len(fields) <= maxFieldsPerParam {
+		fields := c.flattenAggregateTypeOffsets(t)
+		if len(fields) <= MaxFieldsPerParam {
 			return fields
 		} else {
 			// failed to lower
@@ -84,16 +78,13 @@ func (b *builder) expandFormalParamOffsets(t llvm.Type) []uint64 {
 	}
 }

-// expandFormalParam splits a formal param value into pieces, so it can be
-// passed directly as part of a function call. For example, it splits up small
-// structs into individual fields. It is the equivalent of expandFormalParamType
-// for parameter values.
-func (b *builder) expandFormalParam(v llvm.Value) []llvm.Value {
+// Equivalent of expandFormalParamType for parameter values.
+func (c *Compiler) expandFormalParam(v llvm.Value) []llvm.Value {
 	switch v.Type().TypeKind() {
 	case llvm.StructTypeKind:
-		fieldTypes, _ := flattenAggregateType(v.Type(), nil)
-		if len(fieldTypes) <= maxFieldsPerParam {
-			fields := b.flattenAggregate(v)
+		fieldTypes := c.flattenAggregateType(v.Type())
+		if len(fieldTypes) <= MaxFieldsPerParam {
+			fields := c.flattenAggregate(v)
 			if len(fields) != len(fieldTypes) {
 				panic("type and value param lowering don't match")
 			}
@@ -110,72 +101,24 @@ func (b *builder) expandFormalParam(v llvm.Value) []llvm.Value {

 // Try to flatten a struct type to a list of types. Returns a 1-element slice
 // with the passed in type if this is not possible.
-func flattenAggregateType(t llvm.Type, goType types.Type) ([]llvm.Type, []paramFlags) {
-	typeFlags := getTypeFlags(goType)
+func (c *Compiler) flattenAggregateType(t llvm.Type) []llvm.Type {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
 		fields := make([]llvm.Type, 0, t.StructElementTypesCount())
-		fieldFlags := make([]paramFlags, 0, cap(fields))
-		for i, subfield := range t.StructElementTypes() {
-			subfields, subfieldFlags := flattenAggregateType(subfield, extractSubfield(goType, i))
-			for i := range subfieldFlags {
-				subfieldFlags[i] |= typeFlags
-			}
+		for _, subfield := range t.StructElementTypes() {
+			subfields := c.flattenAggregateType(subfield)
 			fields = append(fields, subfields...)
-			fieldFlags = append(fieldFlags, subfieldFlags...)
 		}
-		return fields, fieldFlags
+		return fields
 	default:
-		return []llvm.Type{t}, []paramFlags{typeFlags}
+		return []llvm.Type{t}
 	}
 }

-// getTypeFlags returns the type flags for a given type. It will not recurse
-// into sub-types (such as in structs).
-func getTypeFlags(t types.Type) paramFlags {
-	if t == nil {
-		return 0
-	}
-	switch t.Underlying().(type) {
-	case *types.Pointer:
-		// Pointers in Go must either point to an object or be nil.
-		return paramIsDeferenceableOrNull
-	case *types.Chan, *types.Map:
-		// Channels and maps are implemented as pointers pointing to some
-		// object, and follow the same rules as *types.Pointer.
-		return paramIsDeferenceableOrNull
-	default:
-		return 0
-	}
-}
-
-// extractSubfield extracts a field from a struct, or returns null if this is
-// not a struct and thus no subfield can be obtained.
-func extractSubfield(t types.Type, field int) types.Type {
-	if t == nil {
-		return nil
-	}
-	switch t := t.Underlying().(type) {
-	case *types.Struct:
-		return t.Field(field).Type()
-	case *types.Interface, *types.Slice, *types.Basic, *types.Signature:
-		// These Go types are (sometimes) implemented as LLVM structs but can't
-		// really be split further up in Go (with the possible exception of
-		// complex numbers).
-		return nil
-	default:
-		// This should be unreachable.
-		panic("cannot split subfield: " + t.String())
-	}
-}
-
-// flattenAggregateTypeOffset returns the offsets from the start of an object of
-// type t if this object were flattened like in flattenAggregate. Used together
-// with flattenAggregate to know the start indices of each value in the
-// non-flattened object.
-//
-// Note: this is an implementation detail, use expandFormalParamOffsets instead.
-func (c *compilerContext) flattenAggregateTypeOffsets(t llvm.Type) []uint64 {
+// Return the offsets from the start of the object if this object type were
+// flattened like in flattenAggregate. Used together with flattenAggregate to
+// know the start indices of each value in the non-flattened object.
+func (c *Compiler) flattenAggregateTypeOffsets(t llvm.Type) []uint64 {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
 		fields := make([]uint64, 0, t.StructElementTypesCount())
@@ -193,15 +136,15 @@ func (c *compilerContext) flattenAggregateTypeOffsets(t llvm.Type) []uint64 {
 	}
 }

-// flattenAggregate breaks down a struct into its elementary values for argument
-// passing. It is the value equivalent of flattenAggregateType
-func (b *builder) flattenAggregate(v llvm.Value) []llvm.Value {
+// Break down a struct into its elementary types for argument passing. The value
+// equivalent of flattenAggregateType
+func (c *Compiler) flattenAggregate(v llvm.Value) []llvm.Value {
 	switch v.Type().TypeKind() {
 	case llvm.StructTypeKind:
 		fields := make([]llvm.Value, 0, v.Type().StructElementTypesCount())
 		for i := range v.Type().StructElementTypes() {
-			subfield := b.CreateExtractValue(v, i, "")
-			subfields := b.flattenAggregate(subfield)
+			subfield := c.builder.CreateExtractValue(v, i, "")
+			subfields := c.flattenAggregate(subfield)
 			fields = append(fields, subfields...)
 		}
 		return fields
@@ -210,29 +153,25 @@ func (b *builder) flattenAggregate(v llvm.Value) []llvm.Value {
 	}
 }

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

-// collapseFormalParamInternal is an implementation detail of
-// collapseFormalParam: it works by recursing until there are no fields left.
-func (b *builder) collapseFormalParamInternal(t llvm.Type, fields []llvm.Value) (llvm.Value, []llvm.Value) {
+// Returns (value, remainingFields). Used by collapseFormalParam.
+func (c *Compiler) collapseFormalParamInternal(t llvm.Type, fields []llvm.Value) (llvm.Value, []llvm.Value) {
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
-		flattened, _ := flattenAggregateType(t, nil)
-		if len(flattened) <= maxFieldsPerParam {
+		if len(c.flattenAggregateType(t)) <= MaxFieldsPerParam {
 			value := llvm.ConstNull(t)
 			for i, subtyp := range t.StructElementTypes() {
-				structField, remaining := b.collapseFormalParamInternal(subtyp, fields)
+				structField, remaining := c.collapseFormalParamInternal(subtyp, fields)
 				fields = remaining
-				value = b.CreateInsertValue(value, structField, i, "")
+				value = c.builder.CreateInsertValue(value, structField, i, "")
 			}
 			return value, fields
 		} else {
@@ -11,79 +11,73 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-func (b *builder) createMakeChan(expr *ssa.MakeChan) llvm.Value {
-	elementSize := b.targetData.TypeAllocSize(b.getLLVMType(expr.Type().(*types.Chan).Elem()))
-	elementSizeValue := llvm.ConstInt(b.uintptrType, elementSize, false)
-	bufSize := b.getValue(expr.Size)
-	b.createChanBoundsCheck(elementSize, bufSize, expr.Size.Type().Underlying().(*types.Basic), expr.Pos())
-	if bufSize.Type().IntTypeWidth() < b.uintptrType.IntTypeWidth() {
-		bufSize = b.CreateZExt(bufSize, b.uintptrType, "")
-	} else if bufSize.Type().IntTypeWidth() > b.uintptrType.IntTypeWidth() {
-		bufSize = b.CreateTrunc(bufSize, b.uintptrType, "")
-	}
-	return b.createRuntimeCall("chanMake", []llvm.Value{elementSizeValue, bufSize}, "")
+func (c *Compiler) emitMakeChan(frame *Frame, expr *ssa.MakeChan) llvm.Value {
+	elementSize := c.targetData.TypeAllocSize(c.getLLVMType(expr.Type().(*types.Chan).Elem()))
+	elementSizeValue := llvm.ConstInt(c.uintptrType, elementSize, false)
+	bufSize := c.getValue(frame, expr.Size)
+	return c.createRuntimeCall("chanMake", []llvm.Value{elementSizeValue, bufSize}, "")
 }

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

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

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

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

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

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

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

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

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

-// createSelect emits all IR necessary for a select statements. That's a
+// emitSelect emits all IR necessary for a select statements. That's a
 // non-trivial amount of code because select is very complex to implement.
-func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
+func (c *Compiler) emitSelect(frame *Frame, expr *ssa.Select) llvm.Value {
 	if len(expr.States) == 0 {
 		// Shortcuts for some simple selects.
-		llvmType := b.getLLVMType(expr.Type())
+		llvmType := c.getLLVMType(expr.Type())
 		if expr.Blocking {
 			// Blocks forever:
 			//     select {}
-			b.createRuntimeCall("deadlock", nil, "")
+			c.createRuntimeCall("deadlock", nil, "")
 			return llvm.Undef(llvmType)
 		} else {
 			// No-op:
@@ -91,7 +85,7 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 			//     default:
 			//     }
 			retval := llvm.Undef(llvmType)
-			retval = b.CreateInsertValue(retval, llvm.ConstInt(b.intType, 0xffffffffffffffff, true), 0, "")
+			retval = c.builder.CreateInsertValue(retval, llvm.ConstInt(c.intType, 0xffffffffffffffff, true), 0, "")
 			return retval // {-1, false}
 		}
 	}
@@ -109,30 +103,30 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 	recvbufAlign := 0
 	hasReceives := false
 	var selectStates []llvm.Value
-	chanSelectStateType := b.getLLVMRuntimeType("chanSelectState")
+	chanSelectStateType := c.getLLVMRuntimeType("chanSelectState")
 	for _, state := range expr.States {
-		ch := b.getValue(state.Chan)
+		ch := c.getValue(frame, state.Chan)
 		selectState := llvm.ConstNull(chanSelectStateType)
-		selectState = b.CreateInsertValue(selectState, ch, 0, "")
+		selectState = c.builder.CreateInsertValue(selectState, ch, 0, "")
 		switch state.Dir {
 		case types.RecvOnly:
 			// Make sure the receive buffer is big enough and has the correct alignment.
-			llvmType := b.getLLVMType(state.Chan.Type().(*types.Chan).Elem())
-			if size := b.targetData.TypeAllocSize(llvmType); size > recvbufSize {
+			llvmType := c.getLLVMType(state.Chan.Type().(*types.Chan).Elem())
+			if size := c.targetData.TypeAllocSize(llvmType); size > recvbufSize {
 				recvbufSize = size
 			}
-			if align := b.targetData.ABITypeAlignment(llvmType); align > recvbufAlign {
+			if align := c.targetData.ABITypeAlignment(llvmType); align > recvbufAlign {
 				recvbufAlign = align
 			}
 			hasReceives = true
 		case types.SendOnly:
 			// Store this value in an alloca and put a pointer to this alloca
 			// in the send state.
-			sendValue := b.getValue(state.Send)
-			alloca := llvmutil.CreateEntryBlockAlloca(b.Builder, sendValue.Type(), "select.send.value")
-			b.CreateStore(sendValue, alloca)
-			ptr := b.CreateBitCast(alloca, b.i8ptrType, "")
-			selectState = b.CreateInsertValue(selectState, ptr, 1, "")
+			sendValue := c.getValue(frame, state.Send)
+			alloca := llvmutil.CreateEntryBlockAlloca(c.builder, sendValue.Type(), "select.send.value")
+			c.builder.CreateStore(sendValue, alloca)
+			ptr := c.builder.CreateBitCast(alloca, c.i8ptrType, "")
+			selectState = c.builder.CreateInsertValue(selectState, ptr, 1, "")
 		default:
 			panic("unreachable")
 		}
@@ -140,74 +134,74 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 	}

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

 	// Create the states slice (allocated on the stack).
 	statesAllocaType := llvm.ArrayType(chanSelectStateType, len(selectStates))
-	statesAlloca, statesI8, statesSize := b.createTemporaryAlloca(statesAllocaType, "select.states.alloca")
+	statesAlloca, statesI8, statesSize := c.createTemporaryAlloca(statesAllocaType, "select.states.alloca")
 	for i, state := range selectStates {
 		// Set each slice element to the appropriate channel.
-		gep := b.CreateGEP(statesAlloca, []llvm.Value{
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(b.ctx.Int32Type(), uint64(i), false),
+		gep := c.builder.CreateGEP(statesAlloca, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
 		}, "")
-		b.CreateStore(state, gep)
+		c.builder.CreateStore(state, gep)
 	}
-	statesPtr := b.CreateGEP(statesAlloca, []llvm.Value{
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-		llvm.ConstInt(b.ctx.Int32Type(), 0, false),
+	statesPtr := c.builder.CreateGEP(statesAlloca, []llvm.Value{
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
 	}, "select.states")
-	statesLen := llvm.ConstInt(b.uintptrType, uint64(len(selectStates)), false)
+	statesLen := llvm.ConstInt(c.uintptrType, uint64(len(selectStates)), false)

 	// Do the select in the runtime.
 	var results llvm.Value
 	if expr.Blocking {
 		// Stack-allocate operation structures.
 		// If these were simply created as a slice, they would heap-allocate.
-		chBlockAllocaType := llvm.ArrayType(b.getLLVMRuntimeType("channelBlockedList"), len(selectStates))
-		chBlockAlloca, chBlockAllocaPtr, chBlockSize := b.createTemporaryAlloca(chBlockAllocaType, "select.block.alloca")
-		chBlockLen := llvm.ConstInt(b.uintptrType, uint64(len(selectStates)), false)
-		chBlockPtr := b.CreateGEP(chBlockAlloca, []llvm.Value{
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
+		chBlockAllocaType := llvm.ArrayType(c.getLLVMRuntimeType("channelBlockedList"), len(selectStates))
+		chBlockAlloca, chBlockAllocaPtr, chBlockSize := c.createTemporaryAlloca(chBlockAllocaType, "select.block.alloca")
+		chBlockLen := llvm.ConstInt(c.uintptrType, uint64(len(selectStates)), false)
+		chBlockPtr := c.builder.CreateGEP(chBlockAlloca, []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
 		}, "select.block")

-		results = b.createRuntimeCall("chanSelect", []llvm.Value{
+		results = c.createRuntimeCall("chanSelect", []llvm.Value{
 			recvbuf,
 			statesPtr, statesLen, statesLen, // []chanSelectState
 			chBlockPtr, chBlockLen, chBlockLen, // []channelBlockList
 		}, "select.result")

 		// Terminate the lifetime of the operation structures.
-		b.emitLifetimeEnd(chBlockAllocaPtr, chBlockSize)
+		c.emitLifetimeEnd(chBlockAllocaPtr, chBlockSize)
 	} else {
-		results = b.createRuntimeCall("tryChanSelect", []llvm.Value{
+		results = c.createRuntimeCall("tryChanSelect", []llvm.Value{
 			recvbuf,
 			statesPtr, statesLen, statesLen, // []chanSelectState
 		}, "select.result")
 	}

 	// Terminate the lifetime of the states alloca.
-	b.emitLifetimeEnd(statesI8, statesSize)
+	c.emitLifetimeEnd(statesI8, statesSize)

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

 	return results
 }
@@ -216,28 +210,28 @@ func (b *builder) createSelect(expr *ssa.Select) llvm.Value {
 // when extracting a value from a select statement (*ssa.Select). Because
 // *ssa.Select cannot load all values in advance, it does this later in the
 // *ssa.Extract expression.
-func (b *builder) getChanSelectResult(expr *ssa.Extract) llvm.Value {
+func (c *Compiler) getChanSelectResult(frame *Frame, expr *ssa.Extract) llvm.Value {
 	if expr.Index == 0 {
 		// index
-		value := b.getValue(expr.Tuple)
-		index := b.CreateExtractValue(value, expr.Index, "")
-		if index.Type().IntTypeWidth() < b.intType.IntTypeWidth() {
-			index = b.CreateSExt(index, b.intType, "")
+		value := c.getValue(frame, expr.Tuple)
+		index := c.builder.CreateExtractValue(value, expr.Index, "")
+		if index.Type().IntTypeWidth() < c.intType.IntTypeWidth() {
+			index = c.builder.CreateSExt(index, c.intType, "")
 		}
 		return index
 	} else if expr.Index == 1 {
 		// comma-ok
-		value := b.getValue(expr.Tuple)
-		return b.CreateExtractValue(value, expr.Index, "")
+		value := c.getValue(frame, expr.Tuple)
+		return c.builder.CreateExtractValue(value, expr.Index, "")
 	} else {
 		// Select statements are (index, ok, ...) where ... is a number of
 		// received values, depending on how many receive statements there
 		// are. They are all combined into one alloca (because only one
 		// receive can proceed at a time) so we'll get that alloca, bitcast
 		// it to the correct type, and dereference it.
-		recvbuf := b.selectRecvBuf[expr.Tuple.(*ssa.Select)]
-		typ := llvm.PointerType(b.getLLVMType(expr.Type()), 0)
-		ptr := b.CreateBitCast(recvbuf, typ, "")
-		return b.CreateLoad(ptr, "")
+		recvbuf := frame.selectRecvBuf[expr.Tuple.(*ssa.Select)]
+		typ := llvm.PointerType(c.getLLVMType(expr.Type()), 0)
+		ptr := c.builder.CreateBitCast(recvbuf, typ, "")
+		return c.builder.CreateLoad(ptr, "")
 	}
 }
@@ -1,8 +1,7 @@
-// Package ircheck implements a checker for LLVM IR, that goes a bit further
-// than the regular LLVM IR verifier. Note that it checks different things, so
-// this is not a replacement for the LLVM verifier but does catch things that
-// the LLVM verifier doesn't catch.
-package ircheck
+package compiler
+
+// This file implements a set of sanity checks for the IR that is generated.
+// It can catch some mistakes that LLVM's verifier cannot.

 import (
 	"errors"
@@ -11,11 +10,7 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-type checker struct {
-	ctx llvm.Context
-}
-
-func (c *checker) checkType(t llvm.Type, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
+func (c *Compiler) checkType(t llvm.Type, checked map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
 	// prevent infinite recursion for self-referential types
 	if _, ok := checked[t]; ok {
 		return nil
@@ -86,7 +81,7 @@ func (c *checker) checkType(t llvm.Type, checked map[llvm.Type]struct{}, special
 	return nil
 }

-func (c *checker) checkValue(v llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
+func (c *Compiler) checkValue(v llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
 	// check type
 	if err := c.checkType(v.Type(), types, specials); err != nil {
 		return fmt.Errorf("failed to verify type of value: %s", err.Error())
@@ -100,30 +95,12 @@ func (c *checker) checkValue(v llvm.Value, types map[llvm.Type]struct{}, special
 	return nil
 }

-func (c *checker) checkInstruction(inst llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
+func (c *Compiler) checkInstruction(inst llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) error {
 	// check value properties
 	if err := c.checkValue(inst, types, specials); err != nil {
 		return errorAt(inst, err.Error())
 	}

-	// The alloca instruction can be present in every basic block. However,
-	// allocas in basic blocks other than the entry basic block have a number of
-	// problems:
-	//   * They are hard to optimize, leading to potential missed optimizations.
-	//   * They may cause stack overflows in loops that would otherwise be
-	//     innocent.
-	//   * They cause extra code to be generated, because it requires the use of
-	//     a frame pointer.
-	//   * Perhaps most importantly, the coroutine lowering pass of LLVM (as of
-	//     LLVM 9) cannot deal with these allocas:
-	//     https://llvm.org/docs/Coroutines.html
-	// Therefore, alloca instructions should be limited to the entry block.
-	if !inst.IsAAllocaInst().IsNil() {
-		if inst.InstructionParent() != inst.InstructionParent().Parent().EntryBasicBlock() {
-			return errorAt(inst, "internal error: non-static alloca")
-		}
-	}
-
 	// check operands
 	for i := 0; i < inst.OperandsCount(); i++ {
 		if err := c.checkValue(inst.Operand(i), types, specials); err != nil {
@@ -134,7 +111,7 @@ func (c *checker) checkInstruction(inst llvm.Value, types map[llvm.Type]struct{}
 	return nil
 }

-func (c *checker) checkBasicBlock(bb llvm.BasicBlock, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) []error {
+func (c *Compiler) checkBasicBlock(bb llvm.BasicBlock, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) []error {
 	// check basic block value and type
 	var errs []error
 	if err := c.checkValue(bb.AsValue(), types, specials); err != nil {
@@ -151,7 +128,7 @@ func (c *checker) checkBasicBlock(bb llvm.BasicBlock, types map[llvm.Type]struct
 	return errs
 }

-func (c *checker) checkFunction(fn llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) []error {
+func (c *Compiler) checkFunction(fn llvm.Value, types map[llvm.Type]struct{}, specials map[llvm.TypeKind]llvm.Type) []error {
 	// check function value and type
 	var errs []error
 	if err := c.checkValue(fn, types, specials); err != nil {
@@ -166,25 +143,26 @@ func (c *checker) checkFunction(fn llvm.Value, types map[llvm.Type]struct{}, spe
 	return errs
 }

-// Module checks the given module and returns a slice of error, if there are
-// any.
-func Module(mod llvm.Module) []error {
+func (c *Compiler) checkModule() []error {
 	// check for any context mismatches
 	var errs []error
-	c := checker{
-		ctx: mod.Context(),
-	}
-	if c.ctx == llvm.GlobalContext() {
+	switch {
+	case c.mod.Context() == c.ctx:
+		// this is correct
+	case c.mod.Context() == llvm.GlobalContext():
 		// somewhere we accidentally used the global context instead of a real context
 		errs = append(errs, errors.New("module uses global context"))
+	default:
+		// we used some other context by accident
+		errs = append(errs, fmt.Errorf("module uses context %v instead of the main context %v", c.mod.Context(), c.ctx))
 	}

 	types := map[llvm.Type]struct{}{}
 	specials := map[llvm.TypeKind]llvm.Type{}
-	for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
 		errs = append(errs, c.checkFunction(fn, types, specials)...)
 	}
-	for g := mod.FirstGlobal(); !g.IsNil(); g = llvm.NextGlobal(g) {
+	for g := c.mod.FirstGlobal(); !g.IsNil(); g = llvm.NextGlobal(g) {
 		if err := c.checkValue(g, types, specials); err != nil {
 			errs = append(errs, fmt.Errorf("failed to verify global %s of module: %s", g.Name(), err.Error()))
 		}
@@ -23,16 +23,16 @@ import (
 // deferInitFunc sets up this function for future deferred calls. It must be
 // called from within the entry block when this function contains deferred
 // calls.
-func (b *builder) deferInitFunc() {
+func (c *Compiler) deferInitFunc(frame *Frame) {
 	// Some setup.
-	b.deferFuncs = make(map[*ir.Function]int)
-	b.deferInvokeFuncs = make(map[string]int)
-	b.deferClosureFuncs = make(map[*ir.Function]int)
+	frame.deferFuncs = make(map[*ir.Function]int)
+	frame.deferInvokeFuncs = make(map[string]int)
+	frame.deferClosureFuncs = make(map[*ir.Function]int)

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

 // isInLoop checks if there is a path from a basic block to itself.
@@ -69,54 +69,53 @@ func isInLoop(start *ssa.BasicBlock) bool {
 	return false
 }

-// createDefer emits a single defer instruction, to be run when this function
+// emitDefer emits a single defer instruction, to be run when this function
 // returns.
-func (b *builder) createDefer(instr *ssa.Defer) {
+func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) {
 	// The pointer to the previous defer struct, which we will replace to
 	// make a linked list.
-	next := b.CreateLoad(b.deferPtr, "defer.next")
+	next := c.builder.CreateLoad(frame.deferPtr, "defer.next")

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

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

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

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

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

 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields).
 		values = []llvm.Value{callback, next}
 		for _, param := range instr.Call.Args {
-			llvmParam := b.getValue(param)
+			llvmParam := c.getValue(frame, param)
 			values = append(values, llvmParam)
 			valueTypes = append(valueTypes, llvmParam.Type())
 		}
@@ -128,23 +127,23 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		// pointer.
 		// TODO: ignore this closure entirely and put pointers to the free
 		// variables directly in the defer struct, avoiding a memory allocation.
-		closure := b.getValue(instr.Call.Value)
-		context := b.CreateExtractValue(closure, 0, "")
+		closure := c.getValue(frame, instr.Call.Value)
+		context := c.builder.CreateExtractValue(closure, 0, "")

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

 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields, followed by all parameters including the
 		// context pointer).
 		values = []llvm.Value{callback, next}
 		for _, param := range instr.Call.Args {
-			llvmParam := b.getValue(param)
+			llvmParam := c.getValue(frame, param)
 			values = append(values, llvmParam)
 			valueTypes = append(valueTypes, llvmParam.Type())
 		}
@@ -152,41 +151,41 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		valueTypes = append(valueTypes, context.Type())

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

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

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

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

-// createRunDefers emits code to run all deferred functions.
-func (b *builder) createRunDefers() {
+// emitRunDefers emits code to run all deferred functions.
+func (c *Compiler) emitRunDefers(frame *Frame) {
 	// Add a loop like the following:
 	//     for stack != nil {
 	//         _stack := stack
@@ -203,44 +202,44 @@ func (b *builder) createRunDefers() {
 	//     }

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

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

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

-	for i, callback := range b.allDeferFuncs {
+	for i, callback := range frame.allDeferFuncs {
 		// Create switch case, for example:
 		//     case 0:
 		//         // run first deferred call
-		block := b.ctx.AddBasicBlock(b.fn.LLVMFn, "rundefers.callback")
-		sw.AddCase(llvm.ConstInt(b.uintptrType, uint64(i), false), block)
-		b.SetInsertPointAtEnd(block)
+		block := c.ctx.AddBasicBlock(frame.fn.LLVMFn, "rundefers.callback")
+		sw.AddCase(llvm.ConstInt(c.uintptrType, uint64(i), false), block)
+		c.builder.SetInsertPointAtEnd(block)
 		switch callback := callback.(type) {
 		case *ssa.CallCommon:
 			// Call on an interface value.
@@ -249,112 +248,105 @@ func (b *builder) createRunDefers() {
 			}

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

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

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

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

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

 		case *ir.Function:
 			// Direct call.

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

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

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

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

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

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

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

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

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

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

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

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

 	// End of loop.
-	b.SetInsertPointAtEnd(end)
+	c.builder.SetInsertPointAtEnd(end)
 }
@@ -1,7 +1,5 @@
 package compiler

-// This file contains some utility functions related to error handling.
-
 import (
 	"go/scanner"
 	"go/token"
@@ -11,8 +9,7 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// makeError makes it easy to create an error from a token.Pos with a message.
-func (c *compilerContext) makeError(pos token.Pos, msg string) types.Error {
+func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
 	return types.Error{
 		Fset: c.ir.Program.Fset,
 		Pos:  pos,
@@ -20,7 +17,7 @@ func (c *compilerContext) makeError(pos token.Pos, msg string) types.Error {
 	}
 }

-func (c *compilerContext) addError(pos token.Pos, msg string) {
+func (c *Compiler) addError(pos token.Pos, msg string) {
 	c.diagnostics = append(c.diagnostics, c.makeError(pos, msg))
 }

@@ -6,26 +6,53 @@ package compiler
 import (
 	"go/types"

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

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

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

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

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

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

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

 // getRawFuncType returns a LLVM function pointer type for a given signature.
-func (c *compilerContext) getRawFuncType(typ *types.Signature) llvm.Type {
+func (c *Compiler) getRawFuncType(typ *types.Signature) llvm.Type {
 	// Get the return type.
 	var returnType llvm.Type
 	switch typ.Results().Len() {
@@ -125,13 +152,11 @@ func (c *compilerContext) getRawFuncType(typ *types.Signature) llvm.Type {
 			// The receiver is not an interface, but a i8* type.
 			recv = c.i8ptrType
 		}
-		recvFragments, _ := expandFormalParamType(recv, nil)
-		paramTypes = append(paramTypes, recvFragments...)
+		paramTypes = append(paramTypes, c.expandFormalParamType(recv)...)
 	}
 	for i := 0; i < typ.Params().Len(); i++ {
 		subType := c.getLLVMType(typ.Params().At(i).Type())
-		paramTypeFragments, _ := expandFormalParamType(subType, nil)
-		paramTypes = append(paramTypes, paramTypeFragments...)
+		paramTypes = append(paramTypes, c.expandFormalParamType(subType)...)
 	}
 	// All functions take these parameters at the end.
 	paramTypes = append(paramTypes, c.i8ptrType) // context
@@ -143,24 +168,24 @@ func (c *compilerContext) getRawFuncType(typ *types.Signature) llvm.Type {

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

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

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

 	// Create the closure.
-	return b.createFuncValue(f.LLVMFn, context, f.Signature), nil
+	return c.createFuncValue(f.LLVMFn, context, f.Signature), nil
 }
@@ -12,59 +12,53 @@ import (

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

 // trackValue locates pointers in a value (possibly an aggregate) and tracks the
 // individual pointers
-func (b *builder) trackValue(value llvm.Value) {
+func (c *Compiler) trackValue(value llvm.Value) {
 	typ := value.Type()
 	switch typ.TypeKind() {
 	case llvm.PointerTypeKind:
-		b.trackPointer(value)
+		c.trackPointer(value)
 	case llvm.StructTypeKind:
 		if !typeHasPointers(typ) {
 			return
 		}
 		numElements := typ.StructElementTypesCount()
 		for i := 0; i < numElements; i++ {
-			subValue := b.CreateExtractValue(value, i, "")
-			b.trackValue(subValue)
+			subValue := c.builder.CreateExtractValue(value, i, "")
+			c.trackValue(subValue)
 		}
 	case llvm.ArrayTypeKind:
 		if !typeHasPointers(typ) {
@@ -72,19 +66,19 @@ func (b *builder) trackValue(value llvm.Value) {
 		}
 		numElements := typ.ArrayLength()
 		for i := 0; i < numElements; i++ {
-			subValue := b.CreateExtractValue(value, i, "")
-			b.trackValue(subValue)
+			subValue := c.builder.CreateExtractValue(value, i, "")
+			c.trackValue(subValue)
 		}
 	}
 }

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

 // typeHasPointers returns whether this type is a pointer or contains pointers.
@@ -3,32 +3,34 @@ package compiler
 // This file implements the 'go' keyword to start a new goroutine. See
 // goroutine-lowering.go for more details.

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

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

@@ -50,57 +52,36 @@ func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, p
 // allows a single (pointer) argument to the newly started goroutine. Also, it
 // ignores the return value because newly started goroutines do not have a
 // return value.
-func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix string, pos token.Pos) llvm.Value {
+func (c *Compiler) createGoroutineStartWrapper(fn llvm.Value) llvm.Value {
 	var wrapper llvm.Value

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

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

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

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

 	} else {
 		// For a function pointer like this:
@@ -120,40 +101,22 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		// With a bit of luck, identical wrapper functions like these can be
 		// merged into one.

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

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

 		// Get the function pointer.
 		fnPtr := params[len(params)-1]
@@ -163,13 +126,13 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		params[len(params)-1] = llvm.Undef(c.i8ptrType)

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

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

 	// Return a ptrtoint of the wrapper, not the function itself.
-	return builder.CreatePtrToInt(wrapper, c.uintptrType, "")
+	return c.builder.CreatePtrToInt(wrapper, c.uintptrType, "")
 }
@@ -18,8 +18,8 @@ import (
 //     func ReadRegister(name string) uintptr
 //
 // The register name must be a constant, for example "sp".
-func (b *builder) createReadRegister(name string, args []ssa.Value) (llvm.Value, error) {
-	fnType := llvm.FunctionType(b.uintptrType, []llvm.Type{}, false)
+func (c *Compiler) emitReadRegister(name string, args []ssa.Value) (llvm.Value, error) {
+	fnType := llvm.FunctionType(c.uintptrType, []llvm.Type{}, false)
 	regname := constant.StringVal(args[0].(*ssa.Const).Value)
 	var asm string
 	switch name {
@@ -31,7 +31,7 @@ func (b *builder) createReadRegister(name string, args []ssa.Value) (llvm.Value,
 		panic("unknown architecture")
 	}
 	target := llvm.InlineAsm(fnType, asm, "=r", false, false, 0)
-	return b.CreateCall(target, nil, ""), nil
+	return c.builder.CreateCall(target, nil, ""), nil
 }

 // This is a compiler builtin, which emits a piece of inline assembly with no
@@ -41,12 +41,12 @@ func (b *builder) createReadRegister(name string, args []ssa.Value) (llvm.Value,
 //     func Asm(asm string)
 //
 // The provided assembly must be a constant.
-func (b *builder) createInlineAsm(args []ssa.Value) (llvm.Value, error) {
+func (c *Compiler) emitAsm(args []ssa.Value) (llvm.Value, error) {
 	// Magic function: insert inline assembly instead of calling it.
-	fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{}, false)
+	fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{}, false)
 	asm := constant.StringVal(args[0].(*ssa.Const).Value)
 	target := llvm.InlineAsm(fnType, asm, "", true, false, 0)
-	return b.CreateCall(target, nil, ""), nil
+	return c.builder.CreateCall(target, nil, ""), nil
 }

 // This is a compiler builtin, which allows assembly to be called in a flexible
@@ -63,7 +63,7 @@ func (b *builder) createInlineAsm(args []ssa.Value) (llvm.Value, error) {
 //             "value":  1
 //             "result": &dest,
 //         })
-func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error) {
+func (c *Compiler) emitAsmFull(frame *Frame, instr *ssa.CallCommon) (llvm.Value, error) {
 	asmString := constant.StringVal(instr.Args[0].(*ssa.Const).Value)
 	registers := map[string]llvm.Value{}
 	registerMap := instr.Args[1].(*ssa.MakeMap)
@@ -73,17 +73,17 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 			// ignore
 		case *ssa.MapUpdate:
 			if r.Block() != registerMap.Block() {
-				return llvm.Value{}, b.makeError(instr.Pos(), "register value map must be created in the same basic block")
+				return llvm.Value{}, c.makeError(instr.Pos(), "register value map must be created in the same basic block")
 			}
 			key := constant.StringVal(r.Key.(*ssa.Const).Value)
 			//println("value:", r.Value.(*ssa.MakeInterface).X.String())
-			registers[key] = b.getValue(r.Value.(*ssa.MakeInterface).X)
+			registers[key] = c.getValue(frame, r.Value.(*ssa.MakeInterface).X)
 		case *ssa.Call:
 			if r.Common() == instr {
 				break
 			}
 		default:
-			return llvm.Value{}, b.makeError(instr.Pos(), "don't know how to handle argument to inline assembly: "+r.String())
+			return llvm.Value{}, c.makeError(instr.Pos(), "don't know how to handle argument to inline assembly: "+r.String())
 		}
 	}
 	// TODO: handle dollar signs in asm string
@@ -98,7 +98,7 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 		name := s[1 : len(s)-1]
 		if _, ok := registers[name]; !ok {
 			if err == nil {
-				err = b.makeError(instr.Pos(), "unknown register name: "+name)
+				err = c.makeError(instr.Pos(), "unknown register name: "+name)
 			}
 			return s
 		}
@@ -112,7 +112,7 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 			case llvm.PointerTypeKind:
 				constraints = append(constraints, "*m")
 			default:
-				err = b.makeError(instr.Pos(), "unknown type in inline assembly for value: "+name)
+				err = c.makeError(instr.Pos(), "unknown type in inline assembly for value: "+name)
 				return s
 			}
 		}
@@ -121,9 +121,9 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 	if err != nil {
 		return llvm.Value{}, err
 	}
-	fnType := llvm.FunctionType(b.ctx.VoidType(), argTypes, false)
+	fnType := llvm.FunctionType(c.ctx.VoidType(), argTypes, false)
 	target := llvm.InlineAsm(fnType, asmString, strings.Join(constraints, ","), true, false, 0)
-	return b.CreateCall(target, args, ""), nil
+	return c.builder.CreateCall(target, args, ""), nil
 }

 // This is a compiler builtin which emits an inline SVCall instruction. It can
@@ -137,7 +137,7 @@ func (b *builder) createInlineAsmFull(instr *ssa.CallCommon) (llvm.Value, error)
 //
 // The num parameter must be a constant. All other parameters may be any scalar
 // value supported by LLVM inline assembly.
-func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
+func (c *Compiler) emitSVCall(frame *Frame, args []ssa.Value) (llvm.Value, error) {
 	num, _ := constant.Uint64Val(args[0].(*ssa.Const).Value)
 	llvmArgs := []llvm.Value{}
 	argTypes := []llvm.Type{}
@@ -150,7 +150,7 @@ func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
 		} else {
 			constraints += ",{r" + strconv.Itoa(i) + "}"
 		}
-		llvmValue := b.getValue(arg)
+		llvmValue := c.getValue(frame, arg)
 		llvmArgs = append(llvmArgs, llvmValue)
 		argTypes = append(argTypes, llvmValue.Type())
 	}
@@ -158,52 +158,7 @@ func (b *builder) emitSVCall(args []ssa.Value) (llvm.Value, error) {
 	// clobbered. r0 is used as an output register so doesn't have to be
 	// marked as clobbered.
 	constraints += ",~{r1},~{r2},~{r3}"
-	fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
+	fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 	target := llvm.InlineAsm(fnType, asm, constraints, true, false, 0)
-	return b.CreateCall(target, llvmArgs, ""), nil
-}
-
-// This is a compiler builtin which emits CSR instructions. It can be one of:
-//
-//     func (csr CSR) Get() uintptr
-//     func (csr CSR) Set(uintptr)
-//     func (csr CSR) SetBits(uintptr) uintptr
-//     func (csr CSR) ClearBits(uintptr) uintptr
-//
-// The csr parameter (method receiver) must be a constant. Other parameter can
-// be any value.
-func (b *builder) emitCSROperation(call *ssa.CallCommon) (llvm.Value, error) {
-	csrConst, ok := call.Args[0].(*ssa.Const)
-	if !ok {
-		return llvm.Value{}, b.makeError(call.Pos(), "CSR must be constant")
-	}
-	csr := csrConst.Uint64()
-	switch name := call.StaticCallee().Name(); name {
-	case "Get":
-		// Note that this instruction may have side effects, and thus must be
-		// marked as such.
-		fnType := llvm.FunctionType(b.uintptrType, nil, false)
-		asm := fmt.Sprintf("csrr $0, %d", csr)
-		target := llvm.InlineAsm(fnType, asm, "=r", true, false, 0)
-		return b.CreateCall(target, nil, ""), nil
-	case "Set":
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.uintptrType}, false)
-		asm := fmt.Sprintf("csrw %d, $0", csr)
-		target := llvm.InlineAsm(fnType, asm, "r", true, false, 0)
-		return b.CreateCall(target, []llvm.Value{b.getValue(call.Args[1])}, ""), nil
-	case "SetBits":
-		// Note: it may be possible to optimize this to csrrsi in many cases.
-		fnType := llvm.FunctionType(b.uintptrType, []llvm.Type{b.uintptrType}, false)
-		asm := fmt.Sprintf("csrrs $0, %d, $1", csr)
-		target := llvm.InlineAsm(fnType, asm, "=r,r", true, false, 0)
-		return b.CreateCall(target, []llvm.Value{b.getValue(call.Args[1])}, ""), nil
-	case "ClearBits":
-		// Note: it may be possible to optimize this to csrrci in many cases.
-		fnType := llvm.FunctionType(b.uintptrType, []llvm.Type{b.uintptrType}, false)
-		asm := fmt.Sprintf("csrrc $0, %d, $1", csr)
-		target := llvm.InlineAsm(fnType, asm, "=r,r", true, false, 0)
-		return b.CreateCall(target, []llvm.Value{b.getValue(call.Args[1])}, ""), nil
-	default:
-		return llvm.Value{}, b.makeError(call.Pos(), "unknown CSR operation: "+name)
-	}
+	return c.builder.CreateCall(target, llvmArgs, ""), nil
 }
@@ -16,35 +16,35 @@ import (
 	"tinygo.org/x/go-llvm"
 )

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

 // getTypeCode returns a reference to a type code.
 // It returns a pointer to an external global which should be replaced with the
 // real type in the interface lowering pass.
-func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
+func (c *Compiler) getTypeCode(typ types.Type) llvm.Value {
 	globalName := "reflect/types.type:" + getTypeCodeName(typ)
 	global := c.mod.NamedGlobal(globalName)
 	if global.IsNil() {
@@ -91,7 +91,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 // makeStructTypeFields creates a new global that stores all type information
 // related to this struct type, and returns the resulting global. This global is
 // actually an array of all the fields in the structs.
-func (c *compilerContext) makeStructTypeFields(typ *types.Struct) llvm.Value {
+func (c *Compiler) makeStructTypeFields(typ *types.Struct) llvm.Value {
 	// The global is an array of runtime.structField structs.
 	runtimeStructField := c.getLLVMRuntimeType("structField")
 	structGlobalType := llvm.ArrayType(runtimeStructField, typ.NumFields())
@@ -228,7 +228,7 @@ func getTypeCodeName(t types.Type) string {

 // getTypeMethodSet returns a reference (GEP) to a global method set. This
 // method set should be unreferenced after the interface lowering pass.
-func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
+func (c *Compiler) getTypeMethodSet(typ types.Type) llvm.Value {
 	global := c.mod.NamedGlobal(typ.String() + "$methodset")
 	zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 	if !global.IsNil() {
@@ -271,13 +271,8 @@ func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
 // getInterfaceMethodSet returns a global variable with the method set of the
 // given named interface type. This method set is used by the interface lowering
 // pass.
-func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
-	name := typ.String()
-	if _, ok := typ.(*types.Named); !ok {
-		// Anonymous interface.
-		name = "reflect/types.interface:" + name
-	}
-	global := c.mod.NamedGlobal(name + "$interface")
+func (c *Compiler) getInterfaceMethodSet(typ *types.Named) llvm.Value {
+	global := c.mod.NamedGlobal(typ.String() + "$interface")
 	zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 	if !global.IsNil() {
 		// method set already exist, return it
@@ -292,7 +287,7 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 	}

 	value := llvm.ConstArray(c.i8ptrType, methods)
-	global = llvm.AddGlobal(c.mod, value.Type(), name+"$interface")
+	global = llvm.AddGlobal(c.mod, value.Type(), typ.String()+"$interface")
 	global.SetInitializer(value)
 	global.SetGlobalConstant(true)
 	global.SetLinkage(llvm.PrivateLinkage)
@@ -302,7 +297,7 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 // getMethodSignature returns a global variable which is a reference to an
 // external *i8 indicating the indicating the signature of this method. It is
 // used during the interface lowering pass.
-func (c *compilerContext) getMethodSignature(method *types.Func) llvm.Value {
+func (c *Compiler) getMethodSignature(method *types.Func) llvm.Value {
 	signature := ir.MethodSignature(method)
 	signatureGlobal := c.mod.NamedGlobal("func " + signature)
 	if signatureGlobal.IsNil() {
@@ -312,18 +307,18 @@ func (c *compilerContext) getMethodSignature(method *types.Func) llvm.Value {
 	return signatureGlobal
 }

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

-	actualTypeNum := b.CreateExtractValue(itf, 0, "interface.type")
+	actualTypeNum := c.builder.CreateExtractValue(itf, 0, "interface.type")
 	commaOk := llvm.Value{}
 	if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
 		// Type assert on interface type.
@@ -334,15 +329,15 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 		// the main Go compiler, where the runtime checks whether the type
 		// implements each method of the interface. See:
 		// https://research.swtch.com/interfaces
-		methodSet := b.getInterfaceMethodSet(expr.AssertedType)
-		commaOk = b.createRuntimeCall("interfaceImplements", []llvm.Value{actualTypeNum, methodSet}, "")
+		methodSet := c.getInterfaceMethodSet(expr.AssertedType.(*types.Named))
+		commaOk = c.createRuntimeCall("interfaceImplements", []llvm.Value{actualTypeNum, methodSet}, "")

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

 	// Add 2 new basic blocks (that should get optimized away): one for the
@@ -356,15 +351,15 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 	// typeassert should return a zero value, not an incorrectly casted
 	// value.

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

 	// Retrieve the value from the interface if the type assert was
 	// successful.
-	b.SetInsertPointAtEnd(okBlock)
+	c.builder.SetInsertPointAtEnd(okBlock)
 	var valueOk llvm.Value
 	if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
 		// Type assert on interface type. Easy: just return the same
@@ -373,70 +368,74 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 	} else {
 		// Type assert on concrete type. Extract the underlying type from
 		// the interface (but only after checking it matches).
-		valuePtr := b.CreateExtractValue(itf, 1, "typeassert.value.ptr")
-		valueOk = b.emitPointerUnpack(valuePtr, []llvm.Type{assertedType})[0]
+		valuePtr := c.builder.CreateExtractValue(itf, 1, "typeassert.value.ptr")
+		valueOk = c.emitPointerUnpack(valuePtr, []llvm.Type{assertedType})[0]
 	}
-	b.CreateBr(nextBlock)
+	c.builder.CreateBr(nextBlock)

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

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

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

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

 	return fnCast, args
 }

-// getInterfaceInvokeWrapper returns a wrapper for the given method so it can be
-// invoked from an interface. The wrapper takes in a pointer to the underlying
-// value, dereferences or unpacks it if necessary, and calls the real method.
-// If the method to wrap has a pointer receiver, no wrapping is necessary and
-// the function is returned directly.
-func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
+// interfaceInvokeWrapper keeps some state between getInterfaceInvokeWrapper and
+// createInterfaceInvokeWrapper. The former is called during IR construction
+// itself and the latter is called when finishing up the IR.
+type interfaceInvokeWrapper struct {
+	fn           *ir.Function
+	wrapper      llvm.Value
+	receiverType llvm.Type
+}
+
+// Wrap an interface method function pointer. The wrapper takes in a pointer to
+// the underlying value, dereferences it, and calls the real method. This
+// wrapper is only needed when the interface value actually doesn't fit in a
+// pointer and a pointer to the value must be created.
+func (c *Compiler) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
 	wrapperName := f.LinkName() + "$invoke"
 	wrapper := c.mod.NamedFunction(wrapperName)
 	if !wrapper.IsNil() {
@@ -446,7 +445,7 @@ func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {

 	// Get the expanded receiver type.
 	receiverType := c.getLLVMType(f.Params[0].Type())
-	expandedReceiverType, _ := expandFormalParamType(receiverType, nil)
+	expandedReceiverType := c.expandFormalParamType(receiverType)

 	// Does this method even need any wrapping?
 	if len(expandedReceiverType) == 1 && receiverType.TypeKind() == llvm.PointerTypeKind {
@@ -465,37 +464,41 @@ func (c *compilerContext) getInterfaceInvokeWrapper(f *ir.Function) llvm.Value {
 	if f.LLVMFn.LastParam().Name() == "parentHandle" {
 		wrapper.LastParam().SetName("parentHandle")
 	}
+	c.interfaceInvokeWrappers = append(c.interfaceInvokeWrappers, interfaceInvokeWrapper{
+		fn:           f,
+		wrapper:      wrapper,
+		receiverType: receiverType,
+	})
+	return wrapper
+}

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

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

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

-	receiverValue := b.emitPointerUnpack(wrapper.Param(0), []llvm.Type{receiverType})[0]
-	params := append(b.expandFormalParam(receiverValue), wrapper.Params()[1:]...)
-	if f.LLVMFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
-		b.CreateCall(f.LLVMFn, params, "")
-		b.CreateRetVoid()
+	receiverValue := c.emitPointerUnpack(wrapper.Param(0), []llvm.Type{receiverType})[0]
+	params := append(c.expandFormalParam(receiverValue), wrapper.Params()[1:]...)
+	if fn.LLVMFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
+		c.builder.CreateCall(fn.LLVMFn, params, "")
+		c.builder.CreateRetVoid()
 	} else {
-		ret := b.CreateCall(f.LLVMFn, params, "ret")
-		b.CreateRet(ret)
+		ret := c.builder.CreateCall(fn.LLVMFn, params, "ret")
+		c.builder.CreateRet(ret)
 	}
-
-	return wrapper
 }
@@ -8,62 +8,61 @@ import (
 	"tinygo.org/x/go-llvm"
 )

-// createInterruptGlobal creates a new runtime/interrupt.Interrupt struct that
+// emitInterruptGlobal creates a new runtime/interrupt.Interrupt struct that
 // will be lowered to a real interrupt during interrupt lowering.
 //
 // This two-stage approach allows unused interrupts to be optimized away if
 // necessary.
-func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, error) {
+func (c *Compiler) emitInterruptGlobal(frame *Frame, instr *ssa.CallCommon) (llvm.Value, error) {
 	// Get the interrupt number, which must be a compile-time constant.
 	id, ok := instr.Args[0].(*ssa.Const)
 	if !ok {
-		return llvm.Value{}, b.makeError(instr.Pos(), "interrupt ID is not a constant")
+		return llvm.Value{}, c.makeError(instr.Pos(), "interrupt ID is not a constant")
 	}

 	// Get the func value, which also must be a compile time constant.
 	// Note that bound functions are allowed if the function has a pointer
 	// receiver and is a global. This is rather strict but still allows for
 	// idiomatic Go code.
-	funcValue := b.getValue(instr.Args[1])
+	funcValue := c.getValue(frame, instr.Args[1])
 	if funcValue.IsAConstant().IsNil() {
 		// Try to determine the cause of the non-constantness for a nice error
 		// message.
 		switch instr.Args[1].(type) {
 		case *ssa.MakeClosure:
 			// This may also be a bound method.
-			return llvm.Value{}, b.makeError(instr.Pos(), "closures are not supported in interrupt.New")
+			return llvm.Value{}, c.makeError(instr.Pos(), "closures are not supported in interrupt.New")
 		}
 		// Fall back to a generic error.
-		return llvm.Value{}, b.makeError(instr.Pos(), "interrupt function must be constant")
+		return llvm.Value{}, c.makeError(instr.Pos(), "interrupt function must be constant")
 	}

 	// Create a new global of type runtime/interrupt.handle. Globals of this
 	// type are lowered in the interrupt lowering pass.
-	globalType := b.ir.Program.ImportedPackage("runtime/interrupt").Type("handle").Type()
-	globalLLVMType := b.getLLVMType(globalType)
+	globalType := c.ir.Program.ImportedPackage("runtime/interrupt").Type("handle").Type()
+	globalLLVMType := c.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")
+	if global := c.mod.NamedGlobal(globalName); !global.IsNil() {
+		return llvm.Value{}, c.makeError(instr.Pos(), "interrupt redeclared in this program")
 	}
-	global := llvm.AddGlobal(b.mod, globalLLVMType, globalName)
+	global := llvm.AddGlobal(c.mod, globalLLVMType, globalName)
 	global.SetLinkage(llvm.PrivateLinkage)
 	global.SetGlobalConstant(true)
-	global.SetUnnamedAddr(true)
 	initializer := llvm.ConstNull(globalLLVMType)
 	initializer = llvm.ConstInsertValue(initializer, funcValue, []uint32{0})
-	initializer = llvm.ConstInsertValue(initializer, llvm.ConstInt(b.intType, uint64(id.Int64()), true), []uint32{1, 0})
+	initializer = llvm.ConstInsertValue(initializer, llvm.ConstInt(c.intType, uint64(id.Int64()), true), []uint32{1, 0})
 	global.SetInitializer(initializer)

 	// Add debug info to the interrupt global.
-	if b.Debug() {
-		pos := b.ir.Program.Fset.Position(instr.Pos())
-		diglobal := b.dibuilder.CreateGlobalVariableExpression(b.getDIFile(pos.Filename), llvm.DIGlobalVariableExpression{
+	if c.Debug() {
+		pos := c.ir.Program.Fset.Position(instr.Pos())
+		diglobal := c.dibuilder.CreateGlobalVariableExpression(c.difiles[pos.Filename], llvm.DIGlobalVariableExpression{
 			Name:        "interrupt" + strconv.FormatInt(id.Int64(), 10),
 			LinkageName: globalName,
-			File:        b.getDIFile(pos.Filename),
+			File:        c.getDIFile(pos.Filename),
 			Line:        pos.Line,
-			Type:        b.getDIType(globalType),
-			Expr:        b.dibuilder.CreateExpression(nil),
+			Type:        c.getDIType(globalType),
+			Expr:        c.dibuilder.CreateExpression(nil),
 			LocalToUnit: false,
 		})
 		global.AddMetadata(0, diglobal)
@@ -71,21 +70,21 @@ func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, erro

 	// Create the runtime/interrupt.Interrupt type. It is a struct with a single
 	// member of type int.
-	num := llvm.ConstPtrToInt(global, b.intType)
-	interrupt := llvm.ConstNamedStruct(b.mod.GetTypeByName("runtime/interrupt.Interrupt"), []llvm.Value{num})
+	num := llvm.ConstPtrToInt(global, c.intType)
+	interrupt := llvm.ConstNamedStruct(c.mod.GetTypeByName("runtime/interrupt.Interrupt"), []llvm.Value{num})

 	// Add dummy "use" call for AVR, because interrupts may be used even though
 	// they are never referenced again. This is unlike Cortex-M or the RISC-V
 	// PLIC where each interrupt must be enabled using the interrupt number, and
 	// thus keeps the Interrupt object alive.
 	// This call is removed during interrupt lowering.
-	if strings.HasPrefix(b.Triple(), "avr") {
-		useFn := b.mod.NamedFunction("runtime/interrupt.use")
+	if strings.HasPrefix(c.Triple(), "avr") {
+		useFn := c.mod.NamedFunction("runtime/interrupt.use")
 		if useFn.IsNil() {
-			useFnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{interrupt.Type()}, false)
-			useFn = llvm.AddFunction(b.mod, "runtime/interrupt.use", useFnType)
+			useFnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{interrupt.Type()}, false)
+			useFn = llvm.AddFunction(c.mod, "runtime/interrupt.use", useFnType)
 		}
-		b.CreateCall(useFn, []llvm.Value{interrupt}, "")
+		c.builder.CreateCall(useFn, []llvm.Value{interrupt}, "")
 	}

 	return interrupt, nil
@@ -1,50 +0,0 @@
-package compiler
-
-// This file contains helper functions to create calls to LLVM intrinsics.
-
-import (
-	"strconv"
-
-	"golang.org/x/tools/go/ssa"
-	"tinygo.org/x/go-llvm"
-)
-
-// createMemoryCopyCall creates a call to a builtin LLVM memcpy or memmove
-// function, declaring this function if needed. These calls are treated
-// specially by optimization passes possibly resulting in better generated code,
-// and will otherwise be lowered to regular libc memcpy/memmove calls.
-func (b *builder) createMemoryCopyCall(fn *ssa.Function, args []ssa.Value) (llvm.Value, error) {
-	fnName := "llvm." + fn.Name() + ".p0i8.p0i8.i" + strconv.Itoa(b.uintptrType.IntTypeWidth())
-	llvmFn := b.mod.NamedFunction(fnName)
-	if llvmFn.IsNil() {
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.i8ptrType, b.i8ptrType, b.uintptrType, b.ctx.Int1Type()}, false)
-		llvmFn = llvm.AddFunction(b.mod, fnName, fnType)
-	}
-	var params []llvm.Value
-	for _, param := range args {
-		params = append(params, b.getValue(param))
-	}
-	params = append(params, llvm.ConstInt(b.ctx.Int1Type(), 0, false))
-	b.CreateCall(llvmFn, params, "")
-	return llvm.Value{}, nil
-}
-
-// createMemoryZeroCall creates calls to llvm.memset.* to zero a block of
-// memory, declaring the function if needed. These calls will be lowered to
-// regular libc memset calls if they aren't optimized out in a different way.
-func (b *builder) createMemoryZeroCall(args []ssa.Value) (llvm.Value, error) {
-	fnName := "llvm.memset.p0i8.i" + strconv.Itoa(b.uintptrType.IntTypeWidth())
-	llvmFn := b.mod.NamedFunction(fnName)
-	if llvmFn.IsNil() {
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.i8ptrType, b.ctx.Int8Type(), b.uintptrType, b.ctx.Int1Type()}, false)
-		llvmFn = llvm.AddFunction(b.mod, fnName, fnType)
-	}
-	params := []llvm.Value{
-		b.getValue(args[0]),
-		llvm.ConstInt(b.ctx.Int8Type(), 0, false),
-		b.getValue(args[1]),
-		llvm.ConstInt(b.ctx.Int1Type(), 0, false),
-	}
-	b.CreateCall(llvmFn, params, "")
-	return llvm.Value{}, nil
-}
@@ -1,48 +0,0 @@
-package ircheck
-
-import (
-	"go/scanner"
-	"go/token"
-	"path/filepath"
-
-	"tinygo.org/x/go-llvm"
-)
-
-// errorAt returns an error value at the location of the instruction.
-// The location information may not be complete as it depends on debug
-// information in the IR.
-func errorAt(inst llvm.Value, msg string) scanner.Error {
-	return scanner.Error{
-		Pos: getPosition(inst),
-		Msg: msg,
-	}
-}
-
-// getPosition returns the position information for the given value, as far as
-// it is available.
-func getPosition(val llvm.Value) token.Position {
-	if !val.IsAInstruction().IsNil() {
-		loc := val.InstructionDebugLoc()
-		if loc.IsNil() {
-			return token.Position{}
-		}
-		file := loc.LocationScope().ScopeFile()
-		return token.Position{
-			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-			Line:     int(loc.LocationLine()),
-			Column:   int(loc.LocationColumn()),
-		}
-	} else if !val.IsAFunction().IsNil() {
-		loc := val.Subprogram()
-		if loc.IsNil() {
-			return token.Position{}
-		}
-		file := loc.ScopeFile()
-		return token.Position{
-			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
-			Line:     int(loc.SubprogramLine()),
-		}
-	} else {
-		return token.Position{}
-	}
-}
@@ -24,39 +24,39 @@ func getUses(value llvm.Value) []llvm.Value {
 }

 // createTemporaryAlloca creates a new alloca in the entry block and adds
-// lifetime start information in the IR signalling that the alloca won't be used
+// lifetime start infromation in the IR signalling that the alloca won't be used
 // before this point.
 //
 // This is useful for creating temporary allocas for intrinsics. Don't forget to
 // end the lifetime using emitLifetimeEnd after you're done with it.
-func (b *builder) createTemporaryAlloca(t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
-	return llvmutil.CreateTemporaryAlloca(b.Builder, b.mod, t, name)
+func (c *Compiler) createTemporaryAlloca(t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
+	return llvmutil.CreateTemporaryAlloca(c.builder, c.mod, t, name)
 }

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

 // emitPointerPack packs the list of values into a single pointer value using
 // bitcasts, or else allocates a value on the heap if it cannot be packed in the
 // pointer value directly. It returns the pointer with the packed data.
-func (b *builder) emitPointerPack(values []llvm.Value) llvm.Value {
-	return llvmutil.EmitPointerPack(b.Builder, b.mod, b.Config, values)
+func (c *Compiler) emitPointerPack(values []llvm.Value) llvm.Value {
+	return llvmutil.EmitPointerPack(c.builder, c.mod, c.Config, values)
 }

 // emitPointerUnpack extracts a list of values packed using emitPointerPack.
-func (b *builder) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
-	return llvmutil.EmitPointerUnpack(b.Builder, b.mod, ptr, valueTypes)
+func (c *Compiler) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
+	return llvmutil.EmitPointerUnpack(c.builder, c.mod, ptr, valueTypes)
 }

 // makeGlobalArray creates a new LLVM global with the given name and integers as
 // contents, and returns the global.
 // Note that it is left with the default linkage etc., you should set
 // linkage/constant/etc properties yourself.
-func (c *compilerContext) makeGlobalArray(buf []byte, name string, elementType llvm.Type) llvm.Value {
+func (c *Compiler) makeGlobalArray(buf []byte, name string, elementType llvm.Type) llvm.Value {
 	globalType := llvm.ArrayType(elementType, len(buf))
 	global := llvm.AddGlobal(c.mod, globalType, name)
 	value := llvm.Undef(globalType)
@@ -12,7 +12,6 @@ import (
 // EmitPointerPack packs the list of values into a single pointer value using
 // bitcasts, or else allocates a value on the heap if it cannot be packed in the
 // pointer value directly. It returns the pointer with the packed data.
-// If the values are all constants, they are be stored in a constant global and deduplicated.
 func EmitPointerPack(builder llvm.Builder, mod llvm.Module, config *compileopts.Config, values []llvm.Value) llvm.Value {
 	ctx := mod.Context()
 	targetData := llvm.NewTargetData(mod.DataLayout())
@@ -43,27 +42,6 @@ func EmitPointerPack(builder llvm.Builder, mod llvm.Module, config *compileopts.
 		// it in an alloca first for bitcasting (store+bitcast+load).
 		packedAlloc, _, _ = CreateTemporaryAlloca(builder, mod, packedType, "")
 	} else {
-		// Check if the values are all constants.
-		constant := true
-		for _, v := range values {
-			if !v.IsConstant() {
-				constant = false
-				break
-			}
-		}
-
-		if constant {
-			// The data is known at compile time, so store it in a constant global.
-			// The global address is marked as unnamed, which allows LLVM to merge duplicates.
-			funcName := builder.GetInsertBlock().Parent().Name()
-			global := llvm.AddGlobal(mod, packedType, funcName+"$pack")
-			global.SetInitializer(ctx.ConstStruct(values, false))
-			global.SetGlobalConstant(true)
-			global.SetUnnamedAddr(true)
-			global.SetLinkage(llvm.PrivateLinkage)
-			return llvm.ConstBitCast(global, i8ptrType)
-		}
-
 		// Packed data is bigger than a pointer, so allocate it on the heap.
 		sizeValue := llvm.ConstInt(uintptrType, size, false)
 		alloc := mod.NamedFunction("runtime.alloc")
@@ -6,167 +6,115 @@ import (
 	"go/token"
 	"go/types"

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

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

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

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

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

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

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

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

+// Get FNV-1a hash of this string.
+//
+// https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
+func hashmapHash(data []byte) uint32 {
+	var result uint32 = 2166136261 // FNV offset basis
+	for _, c := range data {
+		result ^= uint32(c)
+		result *= 16777619 // FNV prime
+	}
+	return result
+}
+
+// Get the topmost 8 bits of the hash, without using a special value (like 0).
+func hashmapTopHash(hash uint32) uint8 {
+	tophash := uint8(hash >> 24)
+	if tophash < 1 {
+		// 0 means empty slot, so make it bigger.
+		tophash += 1
+	}
+	return tophash
+}
+
 // Returns true if this key type does not contain strings, interfaces etc., so
 // can be compared with runtime.memequal.
 func hashmapIsBinaryKey(keyType types.Type) bool {
@@ -0,0 +1,164 @@
+package compiler
+
+import (
+	"errors"
+
+	"github.com/tinygo-org/tinygo/transform"
+	"tinygo.org/x/go-llvm"
+)
+
+// Run the LLVM optimizer over the module.
+// The inliner can be disabled (if necessary) by passing 0 to the inlinerThreshold.
+func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) []error {
+	builder := llvm.NewPassManagerBuilder()
+	defer builder.Dispose()
+	builder.SetOptLevel(optLevel)
+	builder.SetSizeLevel(sizeLevel)
+	if inlinerThreshold != 0 {
+		builder.UseInlinerWithThreshold(inlinerThreshold)
+	}
+	builder.AddCoroutinePassesToExtensionPoints()
+
+	if c.PanicStrategy() == "trap" {
+		transform.ReplacePanicsWithTrap(c.mod) // -panic=trap
+	}
+
+	// run a check of all of our code
+	if c.VerifyIR() {
+		errs := c.checkModule()
+		if errs != nil {
+			return errs
+		}
+	}
+
+	// Run function passes for each function.
+	funcPasses := llvm.NewFunctionPassManagerForModule(c.mod)
+	defer funcPasses.Dispose()
+	builder.PopulateFunc(funcPasses)
+	funcPasses.InitializeFunc()
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+		funcPasses.RunFunc(fn)
+	}
+	funcPasses.FinalizeFunc()
+
+	if optLevel > 0 {
+		// Run some preparatory passes for the Go optimizer.
+		goPasses := llvm.NewPassManager()
+		defer goPasses.Dispose()
+		goPasses.AddGlobalDCEPass()
+		goPasses.AddGlobalOptimizerPass()
+		goPasses.AddConstantPropagationPass()
+		goPasses.AddAggressiveDCEPass()
+		goPasses.AddFunctionAttrsPass()
+		goPasses.Run(c.mod)
+
+		// Run Go-specific optimization passes.
+		transform.OptimizeMaps(c.mod)
+		transform.OptimizeStringToBytes(c.mod)
+		transform.OptimizeAllocs(c.mod)
+		transform.LowerInterfaces(c.mod)
+
+		errs := transform.LowerInterruptRegistrations(c.mod)
+		if len(errs) > 0 {
+			return errs
+		}
+
+		if c.funcImplementation() == funcValueSwitch {
+			transform.LowerFuncValues(c.mod)
+		}
+
+		// After interfaces are lowered, there are many more opportunities for
+		// interprocedural optimizations. To get them to work, function
+		// attributes have to be updated first.
+		goPasses.Run(c.mod)
+
+		// Run TinyGo-specific interprocedural optimizations.
+		transform.OptimizeAllocs(c.mod)
+		transform.OptimizeStringToBytes(c.mod)
+
+		// Lower runtime.isnil calls to regular nil comparisons.
+		isnil := c.mod.NamedFunction("runtime.isnil")
+		if !isnil.IsNil() {
+			for _, use := range getUses(isnil) {
+				c.builder.SetInsertPointBefore(use)
+				ptr := use.Operand(0)
+				if !ptr.IsABitCastInst().IsNil() {
+					ptr = ptr.Operand(0)
+				}
+				nilptr := llvm.ConstPointerNull(ptr.Type())
+				icmp := c.builder.CreateICmp(llvm.IntEQ, ptr, nilptr, "")
+				use.ReplaceAllUsesWith(icmp)
+				use.EraseFromParentAsInstruction()
+			}
+		}
+
+		err := c.LowerGoroutines()
+		if err != nil {
+			return []error{err}
+		}
+	} else {
+		// Must be run at any optimization level.
+		transform.LowerInterfaces(c.mod)
+		if c.funcImplementation() == funcValueSwitch {
+			transform.LowerFuncValues(c.mod)
+		}
+		err := c.LowerGoroutines()
+		if err != nil {
+			return []error{err}
+		}
+		errs := transform.LowerInterruptRegistrations(c.mod)
+		if len(errs) > 0 {
+			return errs
+		}
+	}
+	if c.VerifyIR() {
+		if errs := c.checkModule(); errs != nil {
+			return errs
+		}
+	}
+	if err := c.Verify(); err != nil {
+		return []error{errors.New("optimizations caused a verification failure")}
+	}
+
+	if sizeLevel >= 2 {
+		// Set the "optsize" attribute to make slightly smaller binaries at the
+		// cost of some performance.
+		kind := llvm.AttributeKindID("optsize")
+		attr := c.ctx.CreateEnumAttribute(kind, 0)
+		for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+			fn.AddFunctionAttr(attr)
+		}
+	}
+
+	// After TinyGo-specific transforms have finished, undo exporting these functions.
+	for _, name := range c.getFunctionsUsedInTransforms() {
+		fn := c.mod.NamedFunction(name)
+		if fn.IsNil() {
+			continue
+		}
+		fn.SetLinkage(llvm.InternalLinkage)
+	}
+
+	// Run function passes again, because without it, llvm.coro.size.i32()
+	// doesn't get lowered.
+	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
+		funcPasses.RunFunc(fn)
+	}
+	funcPasses.FinalizeFunc()
+
+	// Run module passes.
+	modPasses := llvm.NewPassManager()
+	defer modPasses.Dispose()
+	builder.Populate(modPasses)
+	modPasses.Run(c.mod)
+
+	hasGCPass := transform.AddGlobalsBitmap(c.mod)
+	hasGCPass = transform.MakeGCStackSlots(c.mod) || hasGCPass
+	if hasGCPass {
+		if err := c.Verify(); err != nil {
+			return []error{errors.New("GC pass caused a verification failure")}
+		}
+	}
+
+	return nil
+}
@@ -10,13 +10,13 @@ import (
 // The original license can be found here:
 //     https://golang.org/LICENSE

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

-func (s *stdSizes) Alignof(T types.Type) int64 {
+func (s *StdSizes) Alignof(T types.Type) int64 {
 	// For arrays and structs, alignment is defined in terms
 	// of alignment of the elements and fields, respectively.
 	switch t := T.Underlying().(type) {
@@ -61,7 +61,7 @@ func (s *stdSizes) Alignof(T types.Type) int64 {
 	return a
 }

-func (s *stdSizes) Offsetsof(fields []*types.Var) []int64 {
+func (s *StdSizes) Offsetsof(fields []*types.Var) []int64 {
 	offsets := make([]int64, len(fields))
 	var o int64
 	for i, f := range fields {
@@ -89,7 +89,7 @@ var basicSizes = [...]byte{
 	types.Complex128: 16,
 }

-func (s *stdSizes) Sizeof(T types.Type) int64 {
+func (s *StdSizes) Sizeof(T types.Type) int64 {
 	switch t := T.Underlying().(type) {
 	case *types.Basic:
 		k := t.Kind()
@@ -26,7 +26,7 @@ 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(lprogram *loader.Program) {
+func (c *Compiler) loadASTComments(lprogram *loader.Program) {
 	c.astComments = map[string]*ast.CommentGroup{}
 	for _, pkgInfo := range lprogram.Sorted() {
 		for _, file := range pkgInfo.Files {
@@ -56,7 +56,7 @@ func (c *compilerContext) loadASTComments(lprogram *loader.Program) {

 // getGlobal returns a LLVM IR global value for a Go SSA global. It is added to
 // the LLVM IR if it has not been added already.
-func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
+func (c *Compiler) getGlobal(g *ssa.Global) llvm.Value {
 	info := c.getGlobalInfo(g)
 	llvmGlobal := c.mod.NamedGlobal(info.linkName)
 	if llvmGlobal.IsNil() {
@@ -82,7 +82,7 @@ func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
 			}
 		}

-		if c.Debug() && !info.extern {
+		if c.Debug() {
 			// Add debug info.
 			// TODO: this should be done for every global in the program, not just
 			// the ones that are referenced from some code.
@@ -104,7 +104,7 @@ func (c *compilerContext) getGlobal(g *ssa.Global) llvm.Value {
 }

 // getGlobalInfo returns some information about a specific global.
-func (c *compilerContext) getGlobalInfo(g *ssa.Global) globalInfo {
+func (c *Compiler) getGlobalInfo(g *ssa.Global) globalInfo {
 	info := globalInfo{}
 	if strings.HasPrefix(g.Name(), "C.") {
 		// Created by CGo: such a name cannot be created by regular C code.
@@ -10,14 +10,14 @@ import (
 	"tinygo.org/x/go-llvm"
 )

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

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

-// createVolatileStore is the implementation of the intrinsic function
-// runtime/volatile.StoreT().
-func (b *builder) createVolatileStore(instr *ssa.CallCommon) (llvm.Value, error) {
-	addr := b.getValue(instr.Args[0])
-	val := b.getValue(instr.Args[1])
-	b.createNilCheck(instr.Args[0], addr, "deref")
-	store := b.CreateStore(val, addr)
+func (c *Compiler) emitVolatileStore(frame *Frame, instr *ssa.CallCommon) (llvm.Value, error) {
+	addr := c.getValue(frame, instr.Args[0])
+	val := c.getValue(frame, instr.Args[1])
+	c.emitNilCheck(frame, addr, "deref")
+	store := c.builder.CreateStore(val, addr)
 	store.SetVolatile(true)
 	return llvm.Value{}, nil
 }
@@ -4,10 +4,11 @@ go 1.11

 require (
 	github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2
+	github.com/creack/goselect v0.1.0 // indirect
 	github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf
 	github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46
-	go.bug.st/serial v1.0.0
-	golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2
-	google.golang.org/appengine v1.4.0 // indirect
-	tinygo.org/x/go-llvm v0.0.0-20200401165421-8d120882fc7a
+	go.bug.st/serial.v1 v0.0.0-20180827123349-5f7892a7bb45
+	golang.org/x/sys v0.0.0-20191010194322-b09406accb47 // indirect
+	golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef
+	tinygo.org/x/go-llvm v0.0.0-20200104190746-1ff21df33566
 )
@@ -1,42 +1,23 @@
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2 h1:oMCHnXa6CCCafdPDbMh/lWRhRByN0VFLvv+g+ayx1SI=
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2/go.mod h1:PkYb9DJNAwrSvRx5DYA+gUcOIgTGVMNkfSCbZM8cWpI=
-github.com/creack/goselect v0.1.1 h1:tiSSgKE1eJtxs1h/VgGQWuXUP0YS4CDIFMp6vaI1ls0=
-github.com/creack/goselect v0.1.1/go.mod h1:a/NhLweNvqIYMuxcMOuWY516Cimucms3DglDzQP3hKY=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/creack/goselect v0.1.0 h1:4QiXIhcpSQF50XGaBsFzesjwX/1qOY5bOveQPmN9CXY=
+github.com/creack/goselect v0.1.0/go.mod h1:gHrIcH/9UZDn2qgeTUeW5K9eZsVYCH6/60J/FHysWyE=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf h1:7+FW5aGwISbqUtkfmIpZJGRgNFg2ioYPvFaUxdqpDsg=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE=
 github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46 h1:wXG2bA8fO7Vv7lLk2PihFMTqmbT173Tje39oKzQ50Mo=
 github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46/go.mod h1:Pb6XcsXyropB9LNHhnqaknG/vEwYztLkQzVCHv8sQ3M=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-go.bug.st/serial v1.0.0 h1:ogEPzrllCsnG00EqKRjeYvPRsO7NJW6DqykzkdD6E/k=
-go.bug.st/serial v1.0.0/go.mod h1:rpXPISGjuNjPTRTcMlxi9lN6LoIPxd1ixVjBd8aSk/Q=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee h1:WG0RUwxtNT4qqaXX3DPA8zHFNm/D9xaBpxzHt1WcA/E=
-golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+go.bug.st/serial.v1 v0.0.0-20180827123349-5f7892a7bb45 h1:mACY1anK6HNCZtm/DK2Rf2ZPHggVqeB0+7rY9Gl6wyI=
+go.bug.st/serial.v1 v0.0.0-20180827123349-5f7892a7bb45/go.mod h1:dRSl/CVCTf56CkXgJMDOdSwNfo2g1orOGE/gBGdvjZw=
 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 v0.0.0-20191010194322-b09406accb47 h1:/XfQ9z7ib8eEJX2hdgFTZJ/ntt0swNk5oYBziWeTCvY=
+golang.org/x/sys v0.0.0-20191010194322-b09406accb47/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef h1:ymc9FeDom3RIEA3coKokSllBB1hRcMT0tZ1W3Jf9Ids=
 golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
-golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2 h1:0sfSpGSa544Fwnbot3Oxq/U6SXqjty6Jy/3wRhVS7ig=
-golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbOeHJjicWYPqR9bpxqxYG2pA=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 tinygo.org/x/go-llvm v0.0.0-20190224120431-7707ae5d1261 h1:rJS2Hga39YAnm7DE4qrPm6Dr/67EOojL0XPzvbEeBiw=
 tinygo.org/x/go-llvm v0.0.0-20190224120431-7707ae5d1261/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
 tinygo.org/x/go-llvm v0.0.0-20190818154551-95bc4ffe1add h1:dFjMH1sLhYADg8UQm7DB56B7e+TfvAmWmEZLhyv3r/w=
@@ -53,7 +34,3 @@ tinygo.org/x/go-llvm v0.0.0-20191215173731-ad71f3d24aae h1:s8J5EyxCkHxXB08UI3gk9
 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=
@@ -18,7 +18,6 @@ var Keys = []string{
 	"GOROOT",
 	"GOPATH",
 	"GOCACHE",
-	"CGO_ENABLED",
 	"TINYGOROOT",
 }

@@ -58,13 +57,6 @@ func Get(name string) string {
 			panic("could not find cache dir: " + err.Error())
 		}
 		return filepath.Join(dir, "tinygo")
-	case "CGO_ENABLED":
-		val := os.Getenv("CGO_ENABLED")
-		if val == "1" || val == "0" {
-			return val
-		}
-		// Default to enabling CGo.
-		return "1"
 	case "TINYGOROOT":
 		return sourceDir()
 	default:
@@ -13,44 +13,55 @@ import (

 // 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")}
+var errUnreachable = errors.New("interp: unreachable executed")
+
+// Unsupported is the specific error that is returned when an unsupported
+// instruction is hit while trying to interpret all initializers.
+type Unsupported struct {
+	ImportPath string
+	Inst       llvm.Value
+	Pos        token.Position
+}
+
+func (e Unsupported) Error() string {
+	// TODO: how to return the actual instruction string?
+	// It looks like LLVM provides no function for that...
+	return scanner.Error{
+		Pos: e.Pos,
+		Msg: "interp: unsupported instruction",
+	}.Error()
+}

 // unsupportedInstructionError returns a new "unsupported instruction" error for
 // the given instruction. It includes source location information, when
 // available.
-func (e *evalPackage) unsupportedInstructionError(inst llvm.Value) *Error {
-	return e.errorAt(inst, errors.New("interp: unsupported instruction"))
-}
-
-// ErrorLine is one line in a traceback. The position may be missing.
-type ErrorLine struct {
-	Pos  token.Position
-	Inst llvm.Value
+func (e *evalPackage) unsupportedInstructionError(inst llvm.Value) *Unsupported {
+	return &Unsupported{
+		ImportPath: e.packagePath,
+		Inst:       inst,
+		Pos:        getPosition(inst),
+	}
 }

 // Error encapsulates compile-time interpretation errors with an associated
 // import path. The errors may not have a precise location attached.
 type Error struct {
 	ImportPath string
-	Inst       llvm.Value
-	Pos        token.Position
-	Err        error
-	Traceback  []ErrorLine
+	Errs       []scanner.Error
 }

 // Error returns the string of the first error in the list of errors.
-func (e *Error) Error() string {
-	return e.Pos.String() + ": " + e.Err.Error()
+func (e Error) Error() string {
+	return e.Errs[0].Error()
 }

 // errorAt returns an error value for the currently interpreted package at the
 // location of the instruction. The location information may not be complete as
 // it depends on debug information in the IR.
-func (e *evalPackage) errorAt(inst llvm.Value, err error) *Error {
-	return &Error{
+func (e *evalPackage) errorAt(inst llvm.Value, msg string) Error {
+	return Error{
 		ImportPath: e.packagePath,
-		Pos:        getPosition(inst),
-		Err:        err,
+		Errs:       []scanner.Error{errorAt(inst, msg)},
 	}
 }

@@ -4,7 +4,6 @@ package interp
 // functions.

 import (
-	"errors"
 	"strings"

 	"tinygo.org/x/go-llvm"
@@ -22,7 +21,7 @@ type frame struct {
 // Most of it works at compile time. Some calls get translated into calls to be
 // executed at runtime: calls to functions with side effects, external calls,
 // and operations on the result of such instructions.
-func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (retval Value, outgoing []llvm.Value, err *Error) {
+func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (retval Value, outgoing []llvm.Value, err error) {
 	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
 		if fr.Debug {
 			print(indent)
@@ -98,7 +97,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				value = operand.Load()
 			}
 			if value.Type() != inst.Type() {
-				return nil, nil, fr.errorAt(inst, errors.New("interp: load: type does not match"))
+				return nil, nil, fr.errorAt(inst, "interp: load: type does not match")
 			}
 			fr.locals[inst] = fr.getValue(value)
 		case !inst.IsAStoreInst().IsNil():
@@ -122,16 +121,13 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					// Not a constant operation.
 					// This should be detected by the scanner, but isn't at the
 					// moment.
-					return nil, nil, fr.errorAt(inst, errors.New("todo: non-const gep"))
+					return nil, nil, fr.errorAt(inst, "todo: non-const gep")
 				}
 				indices[i] = uint32(operand.Value().ZExtValue())
 			}
-			result, err := value.GetElementPtr(indices)
-			if err != nil {
-				return nil, nil, fr.errorAt(inst, err)
-			}
+			result := value.GetElementPtr(indices)
 			if result.Type() != inst.Type() {
-				return nil, nil, fr.errorAt(inst, errors.New("interp: gep: type does not match"))
+				return nil, nil, fr.errorAt(inst, "interp: gep: type does not match")
 			}
 			fr.locals[inst] = result

@@ -186,7 +182,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					}
 				}
 				// It is not possible in Go to bitcast a map value to a pointer.
-				return nil, nil, fr.errorAt(inst, errors.New("unimplemented: bitcast of map"))
+				return nil, nil, fr.errorAt(inst, "unimplemented: bitcast of map")
 			}
 			value := fr.getLocal(operand).(*LocalValue)
 			fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateBitCast(value.Value(), inst.Type(), "")}
@@ -268,11 +264,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				if elementCount == 1 {
 					fr.locals[resultInst] = result
 				} else {
-					result, err := result.GetElementPtr([]uint32{0, 0})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					fr.locals[resultInst] = result
+					fr.locals[resultInst] = result.GetElementPtr([]uint32{0, 0})
 				}
 			case callee.Name() == "runtime.hashmapMake":
 				// create a map
@@ -373,49 +365,32 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					// 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)
+					dstArray = dstArray.GetElementPtr([]uint32{0, 0}).(*LocalValue)
+					srcArray = srcArray.GetElementPtr([]uint32{0, 0}).(*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"))
+					return nil, nil, fr.errorAt(inst, "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"))
+					return nil, nil, fr.errorAt(inst, "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"))
+					return nil, nil, fr.errorAt(inst, "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?"))
+					return nil, nil, fr.errorAt(inst, "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)
+					dstArray = dstArray.GetElementPtr([]uint32{1}).(*LocalValue)
 					// src++
-					srcArrayValue, err := srcArray.GetElementPtr([]uint32{1})
-					if err != nil {
-						return nil, nil, fr.errorAt(inst, err)
-					}
-					srcArray = srcArrayValue.(*LocalValue)
+					srcArray = srcArray.GetElementPtr([]uint32{1}).(*LocalValue)
 				}
 			case callee.Name() == "runtime.stringToBytes":
 				// convert a string to a []byte
@@ -441,35 +416,20 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				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"))
+					return nil, nil, fr.errorAt(inst, "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"))
+					return nil, nil, fr.errorAt(inst, "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"))
+					return nil, nil, fr.errorAt(inst, "interp: expected method set to be a constant gep")
 				}
 				methodSet = methodSet.Operand(0).Initializer()

@@ -569,11 +529,6 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					//     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
 					}
 				}
@@ -592,7 +547,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = fr.getValue(newValue)
 			} else {
 				if len(indices) != 1 {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: cannot handle extractvalue with not exactly 1 index"))
+					return nil, nil, fr.errorAt(inst, "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())}
 			}
@@ -605,22 +560,10 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = &LocalValue{fr.Eval, newValue}
 			} else {
 				if len(indices) != 1 {
-					return nil, nil, fr.errorAt(inst, errors.New("interp: cannot handle insertvalue with not exactly 1 index"))
+					return nil, nil, fr.errorAt(inst, "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
@@ -630,17 +573,17 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 			// conditional branch (if/then/else)
 			cond := fr.getLocal(inst.Operand(0)).Value()
 			if cond.Type() != fr.Mod.Context().Int1Type() {
-				return nil, nil, fr.errorAt(inst, errors.New("expected an i1 in a branch instruction"))
+				return nil, nil, fr.errorAt(inst, "expected an i1 in a branch instruction")
 			}
 			thenBB := inst.Operand(1)
 			elseBB := inst.Operand(2)
 			if !cond.IsAInstruction().IsNil() {
-				return nil, nil, fr.errorAt(inst, errors.New("interp: branch on a non-constant"))
+				return nil, nil, fr.errorAt(inst, "interp: branch on a non-constant")
 			}
 			if !cond.IsAConstantExpr().IsNil() {
 				// This may happen when the instruction builder could not
 				// const-fold some instructions.
-				return nil, nil, fr.errorAt(inst, errors.New("interp: branch on a non-const-propagated constant expression"))
+				return nil, nil, fr.errorAt(inst, "interp: branch on a non-const-propagated constant expression")
 			}
 			switch cond {
 			case llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false): // false
@@ -648,7 +591,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 			case llvm.ConstInt(fr.Mod.Context().Int1Type(), 1, false): // true
 				return nil, []llvm.Value{elseBB}, nil // else
 			default:
-				return nil, nil, fr.errorAt(inst, errors.New("branch was not true or false"))
+				return nil, nil, fr.errorAt(inst, "branch was not true or false")
 			}
 		case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 1:
 			// unconditional branch (goto)
@@ -97,7 +97,7 @@ func Run(mod llvm.Module, debug bool) error {
 // function interprets the given function. The params are the function params
 // and the indent is the string indentation to use when dumping all interpreted
 // instructions.
-func (e *evalPackage) function(fn llvm.Value, params []Value, indent string) (Value, *Error) {
+func (e *evalPackage) function(fn llvm.Value, params []Value, indent string) (Value, error) {
 	fr := frame{
 		evalPackage: e,
 		fn:          fn,
@@ -15,7 +15,6 @@ func TestInterp(t *testing.T) {
 		"slice-copy",
 		"consteval",
 		"map",
-		"interface",
 	} {
 		name := name // make tc local to this closure
 		t.Run(name, func(t *testing.T) {
@@ -1,7 +1,6 @@
 package interp

 import (
-	"errors"
 	"strings"

 	"tinygo.org/x/go-llvm"
@@ -41,7 +40,7 @@ type sideEffectResult struct {
 // hasSideEffects scans this function and all descendants, recursively. It
 // returns whether this function has side effects and if it does, which globals
 // it mentions anywhere in this function or any called functions.
-func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error) {
+func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, error) {
 	name := fn.Name()
 	switch {
 	case name == "runtime.alloc":
@@ -52,8 +51,6 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 		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":
@@ -100,7 +97,7 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 			switch inst.InstructionOpcode() {
 			case llvm.IndirectBr, llvm.Invoke:
 				// Not emitted by the compiler.
-				return nil, e.errorAt(inst, errors.New("unknown instructions"))
+				return nil, e.errorAt(inst, "unknown instructions")
 			case llvm.Call:
 				child := inst.CalledValue()
 				if !child.IsAInlineAsm().IsNil() {
@@ -121,12 +118,6 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error)
 				if child.IsDeclaration() {
 					// External function call. Assume only limited side effects
 					// (no affected globals, etc.).
-					switch child.Name() {
-					case "runtime.typeAssert":
-						continue // implemented in interp
-					case "runtime.interfaceImplements":
-						continue // implemented in interp
-					}
 					if e.hasLocalSideEffects(dirtyLocals, inst) {
 						result.updateSeverity(sideEffectLimited)
 					}
@@ -23,8 +23,6 @@ var scanTestTable = []struct {
 	{"callFunctionPointer", sideEffectAll, []string{"functionPointer"}},
 	{"getDirtyPointer", sideEffectLimited, nil},
 	{"storeToPointer", sideEffectLimited, nil},
-	{"callTypeAssert", sideEffectNone, nil},
-	{"callInterfaceImplements", sideEffectNone, nil},
 }

 func TestScan(t *testing.T) {
@@ -1,28 +0,0 @@
-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 }
-%runtime.interfaceMethodInfo = type { i8*, i64 }
-%runtime.typeInInterface = type { %runtime.typecodeID*, %runtime.interfaceMethodInfo* }
-
-@main.v1 = global i1 0
-@"reflect/types.type:named:main.foo" = private constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:basic:int", i64 0 }
-@"reflect/types.type:basic:int" = external constant %runtime.typecodeID
-@"typeInInterface:reflect/types.type:named:main.foo" = private constant %runtime.typeInInterface { %runtime.typecodeID* @"reflect/types.type:named:main.foo", %runtime.interfaceMethodInfo* null }
-
-
-declare i1 @runtime.typeAssert(i64, %runtime.typecodeID*, i8*, i8*)
-
-define void @runtime.initAll() unnamed_addr {
-entry:
-  call void @main.init()
-  ret void
-}
-
-define internal void @main.init() unnamed_addr {
-entry:
-  ; Test type asserts.
-  %typecode = call i1 @runtime.typeAssert(i64 ptrtoint (%runtime.typeInInterface* @"typeInInterface:reflect/types.type:named:main.foo" to i64), %runtime.typecodeID* @"reflect/types.type:named:main.foo", i8* undef, i8* null)
-  store i1 %typecode, i1* @main.v1
-  ret void
-}
@@ -1,9 +0,0 @@
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64--linux"
-
-@main.v1 = local_unnamed_addr global i1 true
-
-define void @runtime.initAll() unnamed_addr {
-entry:
-  ret void
-}
@@ -1,11 +1,6 @@
 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
 }
@@ -64,15 +59,3 @@ define i64 @callFunctionPointer() {
  %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
-}
@@ -24,11 +24,7 @@ func getStringBytes(strPtr Value, strLen llvm.Value) []byte {
 	}
 	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()
+		c := strPtr.GetElementPtr([]uint32{uint32(i)}).Load()
 		buf[i] = byte(c.ZExtValue())
 	}
 	return buf
@@ -3,7 +3,6 @@ package interp
 // This file provides a litte bit of abstraction around LLVM values.

 import (
-	"errors"
 	"strconv"

 	"tinygo.org/x/go-llvm"
@@ -12,13 +11,13 @@ import (
 // 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
+	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 // returns an interior pointer
+	String() string               // string representation, for debugging
 }

 // A type that simply wraps a LLVM constant value.
@@ -98,21 +97,21 @@ func (v *LocalValue) Store(value llvm.Value) {
 }

 // GetElementPtr returns a GEP when the underlying value is of pointer type.
-func (v *LocalValue) GetElementPtr(indices []uint32) (Value, error) {
+func (v *LocalValue) GetElementPtr(indices []uint32) Value {
 	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
+		return &LocalValue{v.Eval, gep}
 	}
 	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 &LocalValue{v.Eval, llvm.ConstGEP(v.Underlying, llvmIndices)}
 		}
 	}
-	return nil, errors.New("interp: unknown GEP")
+	panic("interp: unknown GEP")
 }

 // stripPointerCasts removes all const bitcasts from pointer values, if there
@@ -310,8 +309,8 @@ func (v *MapValue) Store(value llvm.Value) {

 // 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")
+func (v *MapValue) GetElementPtr(indices []uint32) Value {
+	panic("interp: GEP on a map")
 }

 // PutString does a map assign operation, assuming that the map is of type
@@ -1,7 +1,6 @@
 package ir

 import (
-	"errors"
 	"go/types"

 	"golang.org/x/tools/go/ssa"
@@ -59,7 +58,7 @@ func signature(sig *types.Signature) string {

 // Simple pass that removes dead code. This pass makes later analysis passes
 // more useful.
-func (p *Program) SimpleDCE() error {
+func (p *Program) SimpleDCE() {
 	// Unmark all functions.
 	for _, f := range p.Functions {
 		f.flag = false
@@ -67,21 +66,13 @@ func (p *Program) SimpleDCE() error {

 	// 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")
-		}
-	}
+	main := p.mainPkg.Members["main"].(*ssa.Function)
 	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.exported || f.Synthetic == "package initializer" || f.Pkg == runtimePkg || (f.Pkg == mathPkg && f.Pkg != nil) {
 			if f.flag {
 				continue
 			}
@@ -144,6 +135,4 @@ func (p *Program) SimpleDCE() error {
 		}
 	}
 	p.Functions = livefunctions
-
-	return nil
 }
@@ -423,7 +423,7 @@ func (p *Package) parseFiles(includeTests bool) ([]*ast.File, error) {
 	if len(p.CgoFiles) != 0 {
 		cflags := append(p.CFlags, "-I"+p.Package.Dir)
 		if p.ClangHeaders != "" {
-			cflags = append(cflags, "-Xclang", "-internal-isystem", "-Xclang", p.ClangHeaders)
+			cflags = append(cflags, "-I"+p.ClangHeaders)
 		}
 		generated, errs := cgo.Process(files, p.Program.Dir, p.fset, cflags)
 		if errs != nil {
@@ -23,9 +23,8 @@ import (
 	"github.com/tinygo-org/tinygo/goenv"
 	"github.com/tinygo-org/tinygo/interp"
 	"github.com/tinygo-org/tinygo/loader"
-	"tinygo.org/x/go-llvm"

-	"go.bug.st/serial"
+	serial "go.bug.st/serial.v1"
 )

 // commandError is an error type to wrap os/exec.Command errors. This provides
@@ -51,17 +50,6 @@ func moveFile(src, dst string) error {
 	}
 	// Failed to move, probably a different filesystem.
 	// Do a copy + remove.
-	err = copyFile(src, dst)
-	if err != nil {
-		return err
-	}
-	return os.Remove(src)
-}
-
-// copyFile copies the given file from src to dst. It copies first to a .tmp
-// file which is then moved over a possibly already existing file at the
-// destination.
-func copyFile(src, dst string) error {
 	inf, err := os.Open(src)
 	if err != nil {
 		return err
@@ -157,6 +145,14 @@ func Test(pkgName string, options *compileopts.Options) error {

 // Flash builds and flashes the built binary to the given serial port.
 func Flash(pkgName, port string, options *compileopts.Options) error {
+	if port == "" {
+		var err error
+		port, err = getDefaultPort()
+		if err != nil {
+			return err
+		}
+	}
+
 	config, err := builder.NewConfig(options)
 	if err != nil {
 		return err
@@ -196,14 +192,6 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 	return builder.Build(pkgName, fileExt, config, func(tmppath string) error {
 		// do we need port reset to put MCU into bootloader mode?
 		if config.Target.PortReset == "true" {
-			if port == "" {
-				var err error
-				port, err = getDefaultPort()
-				if err != nil {
-					return err
-				}
-			}
-
 			err := touchSerialPortAt1200bps(port)
 			if err != nil {
 				return &commandError{"failed to reset port", tmppath, err}
@@ -219,15 +207,6 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			flashCmd := config.Target.FlashCommand
 			fileToken := "{" + fileExt[1:] + "}"
 			flashCmd = strings.Replace(flashCmd, fileToken, tmppath, -1)
-
-			if port == "" && strings.Contains(flashCmd, "{port}") {
-				var err error
-				port, err = getDefaultPort()
-				if err != nil {
-					return err
-				}
-			}
-
 			flashCmd = strings.Replace(flashCmd, "{port}", port, -1)

 			// Execute the command.
@@ -309,23 +288,17 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 		gdbInterface, openocdInterface := config.Programmer()
 		switch gdbInterface {
 		case "msd", "command", "":
+			if openocdInterface != "" && config.Target.OpenOCDTarget != "" {
+				gdbInterface = "openocd"
+			}
 			if len(config.Target.Emulator) != 0 {
 				// Assume QEMU as an emulator.
-				if config.Target.Emulator[0] == "mgba" {
-					gdbInterface = "mgba"
-				} else {
-					gdbInterface = "qemu"
-				}
-			} else if openocdInterface != "" && config.Target.OpenOCDTarget != "" {
-				gdbInterface = "openocd"
-			} else if config.Target.JLinkDevice != "" {
-				gdbInterface = "jlink"
+				gdbInterface = "qemu"
 			}
 		}

 		// Run the GDB server, if necessary.
 		var gdbCommands []string
-		var daemon *exec.Cmd
 		switch gdbInterface {
 		case "native":
 			// Run GDB directly.
@@ -337,7 +310,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 			if err != nil {
 				return err
 			}
-			daemon = exec.Command("openocd", args...)
+			daemon := exec.Command("openocd", args...)
 			if ocdOutput {
 				// Make it clear which output is from the daemon.
 				w := &ColorWriter{
@@ -348,58 +321,40 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 				daemon.Stdout = w
 				daemon.Stderr = w
 			}
-		case "jlink":
-			gdbCommands = append(gdbCommands, "target remote :2331", "load", "monitor reset halt")
-
-			// We need a separate debugging daemon for on-chip debugging.
-			daemon = exec.Command("JLinkGDBServer", "-device", config.Target.JLinkDevice)
-			if ocdOutput {
-				// Make it clear which output is from the daemon.
-				w := &ColorWriter{
-					Out:    os.Stderr,
-					Prefix: "jlink: ",
-					Color:  TermColorYellow,
-				}
-				daemon.Stdout = w
-				daemon.Stderr = w
-			}
-		case "qemu":
-			gdbCommands = append(gdbCommands, "target remote :1234")
-
-			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], tmppath, "-s", "-S")
-			daemon = exec.Command(config.Target.Emulator[0], args...)
-			daemon.Stdout = os.Stdout
-			daemon.Stderr = os.Stderr
-		case "mgba":
-			gdbCommands = append(gdbCommands, "target remote :2345")
-
-			// Run in an emulator.
-			args := append(config.Target.Emulator[1:], tmppath, "-g")
-			daemon = exec.Command(config.Target.Emulator[0], args...)
-			daemon.Stdout = os.Stdout
-			daemon.Stderr = os.Stderr
-		case "msd":
-			return errors.New("gdb is not supported for drag-and-drop programmable devices")
-		default:
-			return fmt.Errorf("gdb is not supported with interface %#v", gdbInterface)
-		}
-
-		if daemon != nil {
 			// Make sure the daemon doesn't receive Ctrl-C that is intended for
 			// GDB (to break the currently executing program).
 			setCommandAsDaemon(daemon)
-
 			// Start now, and kill it on exit.
-			err = daemon.Start()
-			if err != nil {
-				return &commandError{"failed to run", daemon.Path, err}
-			}
+			daemon.Start()
 			defer func() {
 				daemon.Process.Signal(os.Interrupt)
 				// Maybe we should send a .Kill() after x seconds?
 				daemon.Wait()
 			}()
+		case "qemu":
+			gdbCommands = append(gdbCommands, "target remote :1234")
+
+			// Run in an emulator.
+			args := append(config.Target.Emulator[1:], tmppath, "-s", "-S")
+			daemon := exec.Command(config.Target.Emulator[0], args...)
+			daemon.Stdout = os.Stdout
+			daemon.Stderr = os.Stderr
+
+			// Make sure the daemon doesn't receive Ctrl-C that is intended for
+			// GDB (to break the currently executing program).
+			setCommandAsDaemon(daemon)
+
+			// Start now, and kill it on exit.
+			daemon.Start()
+			defer func() {
+				daemon.Process.Signal(os.Interrupt)
+				// Maybe we should send a .Kill() after x seconds?
+				daemon.Wait()
+			}()
+		case "msd":
+			return errors.New("gdb is not supported for drag-and-drop programmable devices")
+		default:
+			return fmt.Errorf("gdb is not supported with interface %#v", gdbInterface)
 		}

 		// Ignore Ctrl-C, it must be passed on to GDB.
@@ -473,22 +428,16 @@ func Run(pkgName string, options *compileopts.Options) error {
 	})
 }

-func touchSerialPortAt1200bps(port string) (err error) {
-	retryCount := 3
-	for i := 0; i < retryCount; i++ {
-		// Open port
-		p, e := serial.Open(port, &serial.Mode{BaudRate: 1200})
-		if e != nil {
-			time.Sleep(1 * time.Second)
-			err = e
-			continue
-		}
-		defer p.Close()
-
-		p.SetDTR(false)
-		return nil
+func touchSerialPortAt1200bps(port string) error {
+	// Open port
+	p, err := serial.Open(port, &serial.Mode{BaudRate: 1200})
+	if err != nil {
+		return fmt.Errorf("opening port: %s", err)
 	}
-	return fmt.Errorf("opening port: %s", err)
+	defer p.Close()
+
+	p.SetDTR(false)
+	return nil
 }

 func flashUF2UsingMSD(volume, tmppath string) error {
@@ -593,6 +542,7 @@ func parseSize(s string) (int64, error) {
 }

 // getDefaultPort returns the default serial port depending on the operating system.
+// Currently only supports macOS and Linux.
 func getDefaultPort() (port string, err error) {
 	var portPath string
 	switch runtime.GOOS {
@@ -614,7 +564,7 @@ func getDefaultPort() (port string, err error) {
 		}

 		if out.String() == "No Instance(s) Available." {
-			return "", errors.New("no serial ports available")
+			return "", errors.New("unable to locate a USB device to be flashed")
 		}

 		for _, line := range strings.Split(out.String(), "\n") {
@@ -625,7 +575,7 @@ func getDefaultPort() (port string, err error) {
 				}
 			}
 		}
-		return "", errors.New("unable to locate a serial port")
+		return "", errors.New("unable to locate a USB device to be flashed")
 	default:
 		return "", errors.New("unable to search for a default USB device to be flashed on this OS")
 	}
@@ -635,7 +585,7 @@ func getDefaultPort() (port string, err error) {
 		return "", err
 	}
 	if d == nil {
-		return "", errors.New("unable to locate a serial port")
+		return "", errors.New("unable to locate a USB device to be flashed")
 	}

 	return d[0], nil
@@ -658,49 +608,38 @@ func usage() {
 	flag.PrintDefaults()
 }

-// printCompilerError prints compiler errors using the provided logger function
-// (similar to fmt.Println).
-//
-// There is one exception: interp errors may print to stderr unconditionally due
-// to limitations in the LLVM bindings.
-func printCompilerError(logln func(...interface{}), err error) {
-	switch err := err.(type) {
-	case types.Error, scanner.Error:
-		logln(err)
-	case *interp.Error:
-		logln("#", err.ImportPath)
-		logln(err.Error())
-		if !err.Inst.IsNil() {
-			err.Inst.Dump()
-			logln()
-		}
-		if len(err.Traceback) > 0 {
-			logln("\ntraceback:")
-			for _, line := range err.Traceback {
-				logln(line.Pos.String() + ":")
-				line.Inst.Dump()
-				logln()
-			}
-		}
-	case loader.Errors:
-		logln("#", err.Pkg.ImportPath)
-		for _, err := range err.Errs {
-			logln(err)
-		}
-	case *builder.MultiError:
-		for _, err := range err.Errs {
-			logln(err)
-		}
-	default:
-		logln("error:", err)
-	}
-}
-
 func handleCompilerError(err error) {
 	if err != nil {
-		printCompilerError(func(args ...interface{}) {
-			fmt.Fprintln(os.Stderr, args...)
-		}, err)
+		switch err := err.(type) {
+		case *interp.Unsupported:
+			// hit an unknown/unsupported instruction
+			fmt.Fprintln(os.Stderr, "#", err.ImportPath)
+			msg := "unsupported instruction during init evaluation:"
+			if err.Pos.String() != "" {
+				msg = err.Pos.String() + " " + msg
+			}
+			fmt.Fprintln(os.Stderr, msg)
+			err.Inst.Dump()
+			fmt.Fprintln(os.Stderr)
+		case types.Error, scanner.Error:
+			fmt.Fprintln(os.Stderr, err)
+		case interp.Error:
+			fmt.Fprintln(os.Stderr, "#", err.ImportPath)
+			for _, err := range err.Errs {
+				fmt.Fprintln(os.Stderr, err)
+			}
+		case loader.Errors:
+			fmt.Fprintln(os.Stderr, "#", err.Pkg.ImportPath)
+			for _, err := range err.Errs {
+				fmt.Fprintln(os.Stderr, err)
+			}
+		case *builder.MultiError:
+			for _, err := range err.Errs {
+				fmt.Fprintln(os.Stderr, err)
+			}
+		default:
+			fmt.Fprintln(os.Stderr, "error:", err)
+		}
 		os.Exit(1)
 	}
 }
@@ -708,7 +647,7 @@ func handleCompilerError(err error) {
 func main() {
 	outpath := flag.String("o", "", "output filename")
 	opt := flag.String("opt", "z", "optimization level: 0, 1, 2, s, z")
-	gc := flag.String("gc", "", "garbage collector to use (none, leaking, extalloc, conservative)")
+	gc := flag.String("gc", "", "garbage collector to use (none, leaking, conservative)")
 	panicStrategy := flag.String("panic", "print", "panic strategy (print, trap)")
 	scheduler := flag.String("scheduler", "", "which scheduler to use (coroutines, tasks)")
 	printIR := flag.Bool("printir", false, "print LLVM IR")
@@ -733,18 +672,6 @@ func main() {
 	}
 	command := os.Args[1]

-	// Early command processing, before commands are interpreted by the Go flag
-	// library.
-	switch command {
-	case "clang", "ld.lld", "wasm-ld":
-		err := builder.RunTool(command, os.Args[2:]...)
-		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
-		}
-		os.Exit(0)
-	}
-
 	flag.CommandLine.Parse(os.Args[2:])
 	options := &compileopts.Options{
 		Target:        *target,
@@ -805,7 +732,7 @@ func main() {
 		}
 		err := Build(pkgName, *outpath, options)
 		handleCompilerError(err)
-	case "build-library":
+	case "build-builtins":
 		// Note: this command is only meant to be used while making a release!
 		if *outpath == "" {
 			fmt.Fprintln(os.Stderr, "No output filename supplied (-o).")
@@ -815,24 +742,10 @@ func main() {
 		if *target == "" {
 			fmt.Fprintln(os.Stderr, "No target (-target).")
 		}
-		if flag.NArg() != 1 {
-			fmt.Fprintf(os.Stderr, "Build-library only accepts exactly one library name as argument, %d given\n", flag.NArg())
-			usage()
-			os.Exit(1)
-		}
-		var lib *builder.Library
-		switch name := flag.Arg(0); name {
-		case "compiler-rt":
-			lib = &builder.CompilerRT
-		case "picolibc":
-			lib = &builder.Picolibc
-		default:
-			fmt.Fprintf(os.Stderr, "Unknown library: %s\n", name)
-			os.Exit(1)
-		}
-		path, err := lib.Load(*target)
+		err := builder.CompileBuiltins(*target, func(path string) error {
+			return moveFile(path, *outpath)
+		})
 		handleCompilerError(err)
-		copyFile(path, *outpath)
 	case "flash", "gdb":
 		if *outpath != "" {
 			fmt.Fprintln(os.Stderr, "Output cannot be specified with the flash command.")
@@ -909,7 +822,7 @@ func main() {
 		if s, err := builder.GorootVersionString(goenv.Get("GOROOT")); err == nil {
 			goversion = s
 		}
-		fmt.Printf("tinygo version %s %s/%s (using go version %s and LLVM version %s)\n", version, runtime.GOOS, runtime.GOARCH, goversion, llvm.Version)
+		fmt.Printf("tinygo version %s %s/%s (using go version %s)\n", version, runtime.GOOS, runtime.GOARCH, goversion)
 	case "env":
 		if flag.NArg() == 0 {
 			// Show all environment variables.
@@ -6,21 +6,18 @@ package main
 import (
 	"bufio"
 	"bytes"
-	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
 	"sort"
-	"strings"
 	"sync"
 	"testing"
 	"time"

-	"github.com/tinygo-org/tinygo/builder"
 	"github.com/tinygo-org/tinygo/compileopts"
-	"github.com/tinygo-org/tinygo/goenv"
+	"github.com/tinygo-org/tinygo/loader"
 )

 const TESTDATA = "testdata"
@@ -58,14 +55,6 @@ func TestCompiler(t *testing.T) {
 		runPlatTests("cortex-m-qemu", matches, t)
 	})

-	if runtime.GOOS == "windows" || runtime.GOOS == "darwin" {
-		// Note: running only on Windows and macOS because Linux (as of 2020)
-		// usually has an outdated QEMU version that doesn't support RISC-V yet.
-		t.Run("EmulatedRISCV", func(t *testing.T) {
-			runPlatTests("riscv-qemu", matches, t)
-		})
-	}
-
 	if runtime.GOOS == "linux" {
 		t.Run("ARMLinux", func(t *testing.T) {
 			runPlatTests("arm--linux-gnueabihf", matches, t)
@@ -73,20 +62,9 @@ func TestCompiler(t *testing.T) {
 		t.Run("ARM64Linux", func(t *testing.T) {
 			runPlatTests("aarch64--linux-gnu", matches, t)
 		})
-		goVersion, err := builder.GorootVersionString(goenv.Get("GOROOT"))
-		if err != nil {
-			t.Error("could not get Go version:", err)
-			return
-		}
-		minorVersion := strings.Split(goVersion, ".")[1]
-		if minorVersion != "13" {
-			// WebAssembly tests fail on Go 1.13, so skip them there. Versions
-			// below that are also not supported but still seem to pass, so
-			// include them in the tests for now.
-			t.Run("WebAssembly", func(t *testing.T) {
-				runPlatTests("wasm", matches, t)
-			})
-		}
+		t.Run("WebAssembly", func(t *testing.T) {
+			runPlatTests("wasm", matches, t)
+		})
 	}
 }

@@ -94,7 +72,22 @@ func runPlatTests(target string, matches []string, t *testing.T) {
 	t.Parallel()

 	for _, path := range matches {
-		path := path // redefine to avoid race condition
+		switch {
+		case target == "wasm":
+			// testdata/gc.go is known not to work on WebAssembly
+			if path == filepath.Join("testdata", "gc.go") {
+				continue
+			}
+		case target == "":
+			// run all tests on host
+		case target == "cortex-m-qemu":
+			// all tests are supported
+		default:
+			// cross-compilation of cgo is not yet supported
+			if path == filepath.Join("testdata", "cgo")+string(filepath.Separator) {
+				continue
+			}
+		}

 		t.Run(filepath.Base(path), func(t *testing.T) {
 			t.Parallel()
@@ -153,7 +146,13 @@ func runTest(path, target string, t *testing.T) {
 	binary := filepath.Join(tmpdir, "test")
 	err = runBuild("./"+path, binary, config)
 	if err != nil {
-		printCompilerError(t.Log, err)
+		if errLoader, ok := err.(loader.Errors); ok {
+			for _, err := range errLoader.Errs {
+				t.Log("failed to build:", err)
+			}
+		} else {
+			t.Log("failed to build:", err)
+		}
 		t.Fail()
 		return
 	}
@@ -184,7 +183,7 @@ func runTest(path, target string, t *testing.T) {
 	}
 	go func() {
 		// Terminate the process if it runs too long.
-		timer := time.NewTimer(10 * time.Second)
+		timer := time.NewTimer(1 * time.Second)
 		select {
 		case <-runComplete:
 			timer.Stop()
@@ -233,24 +232,3 @@ func runTest(path, target string, t *testing.T) {
 		t.Fail()
 	}
 }
-
-// This TestMain is necessary because TinyGo may also be invoked to run certain
-// LLVM tools in a separate process. Not capturing these invocations would lead
-// to recursive tests.
-func TestMain(m *testing.M) {
-	if len(os.Args) >= 2 {
-		switch os.Args[1] {
-		case "clang", "ld.lld", "wasm-ld":
-			// Invoke a specific tool.
-			err := builder.RunTool(os.Args[1], os.Args[2:]...)
-			if err != nil {
-				fmt.Fprintln(os.Stderr, err)
-				os.Exit(1)
-			}
-			os.Exit(0)
-		}
-	}
-
-	// Run normal tests.
-	os.Exit(m.Run())
-}
@@ -35,8 +35,6 @@ import (
 	"unsafe"
 )

-var errCycleCountTooLarge = errors.New("requested cycle count is too large, overflows 24 bit counter")
-
 // Run the given assembly code. The code will be marked as having side effects,
 // as it doesn't produce output and thus would normally be eliminated by the
 // optimizer.
@@ -234,7 +232,7 @@ func SetupSystemTimer(cyclecount uint32) error {
 	}
 	if cyclecount&SYST_RVR_RELOAD_Msk != cyclecount {
 		// The cycle refresh register is only 24 bits wide.  The user-specified value will overflow.
-		return errCycleCountTooLarge
+		return errors.New("requested cycle count is too large, overflows 24 bit counter")
 	}

 	// set refresh count
@@ -1,277 +0,0 @@
-package riscv
-
-// This file lists constants for CSR operations and defines methods on CSRs that
-// are implemented as compiler intrinsics.
-
-// CSR constants are used for use in CSR (Control and Status Register) compiler
-// intrinsics.
-type CSR int16
-
-// Get returns the value of the given CSR.
-func (csr CSR) Get() uintptr
-
-// Set stores a new value in the given CSR.
-func (csr CSR) Set(uintptr)
-
-// SetBits atomically sets the given bits in this ISR and returns the old value.
-func (csr CSR) SetBits(uintptr) uintptr
-
-// ClearBits atomically clears the given bits in this ISR and returns the old
-// value.
-func (csr CSR) ClearBits(uintptr) uintptr
-
-// CSR values defined in the RISC-V privileged specification. Not all values may
-// be available on any given chip.
-//
-// Source: https://github.com/riscv/riscv-isa-manual/blob/riscv-priv-1.10/src/priv-csrs.tex
-const (
-	// User Trap Setup
-	USTATUS CSR = 0x000 // User status register.
-	UIE     CSR = 0x004 // User interrupt-enable register.
-	UTVEC   CSR = 0x005 // User trap handler base address.
-
-	// User Trap Handling
-	USCRATCH CSR = 0x040 // Scratch register for user trap handlers.
-	UEPC     CSR = 0x041 // User exception program counter.
-	UCAUSE   CSR = 0x042 // User trap cause.
-	UTVAL    CSR = 0x043 // User bad address or instruction.
-	UIP      CSR = 0x044 // User interrupt pending.
-
-	// User Floating-Point CSRs
-	FFLAGS CSR = 0x001 // Floating-Point Accrued Exceptions.
-	FRM    CSR = 0x002 // Floating-Point Dynamic Rounding Mode.
-	FCSR   CSR = 0x003 // Floating-Point Control and Status
-
-	// User Counter/Timers
-	CYCLE         CSR = 0xC00 // Cycle counter for RDCYCLE instruction.
-	TIME          CSR = 0xC01 // Timer for RDTIME instruction.
-	INSTRET       CSR = 0xC02 // Instructions-retired counter for RDINSTRET instruction.
-	HPMCOUNTER3   CSR = 0xC03 // Performance-monitoring counter 3.
-	HPMCOUNTER4   CSR = 0xC04 // Performance-monitoring counter 4.
-	HPMCOUNTER5   CSR = 0xC05 // Performance-monitoring counter 5.
-	HPMCOUNTER6   CSR = 0xC06 // Performance-monitoring counter 6.
-	HPMCOUNTER7   CSR = 0xC07 // Performance-monitoring counter 7.
-	HPMCOUNTER8   CSR = 0xC08 // Performance-monitoring counter 8.
-	HPMCOUNTER9   CSR = 0xC09 // Performance-monitoring counter 9.
-	HPMCOUNTER10  CSR = 0xC0A // Performance-monitoring counter 10.
-	HPMCOUNTER11  CSR = 0xC0B // Performance-monitoring counter 11.
-	HPMCOUNTER12  CSR = 0xC0C // Performance-monitoring counter 12.
-	HPMCOUNTER13  CSR = 0xC0D // Performance-monitoring counter 13.
-	HPMCOUNTER14  CSR = 0xC0E // Performance-monitoring counter 14.
-	HPMCOUNTER15  CSR = 0xC0F // Performance-monitoring counter 15.
-	HPMCOUNTER16  CSR = 0xC10 // Performance-monitoring counter 16.
-	HPMCOUNTER17  CSR = 0xC11 // Performance-monitoring counter 17.
-	HPMCOUNTER18  CSR = 0xC12 // Performance-monitoring counter 18.
-	HPMCOUNTER19  CSR = 0xC13 // Performance-monitoring counter 19.
-	HPMCOUNTER20  CSR = 0xC14 // Performance-monitoring counter 20.
-	HPMCOUNTER21  CSR = 0xC15 // Performance-monitoring counter 21.
-	HPMCOUNTER22  CSR = 0xC16 // Performance-monitoring counter 22.
-	HPMCOUNTER23  CSR = 0xC17 // Performance-monitoring counter 23.
-	HPMCOUNTER24  CSR = 0xC18 // Performance-monitoring counter 24.
-	HPMCOUNTER25  CSR = 0xC19 // Performance-monitoring counter 25.
-	HPMCOUNTER26  CSR = 0xC1A // Performance-monitoring counter 26.
-	HPMCOUNTER27  CSR = 0xC1B // Performance-monitoring counter 27.
-	HPMCOUNTER28  CSR = 0xC1C // Performance-monitoring counter 28.
-	HPMCOUNTER29  CSR = 0xC1D // Performance-monitoring counter 29.
-	HPMCOUNTER30  CSR = 0xC1E // Performance-monitoring counter 30.
-	HPMCOUNTER31  CSR = 0xC1F // Performance-monitoring counter 31.
-	CYCLEH        CSR = 0xC80 // Upper 32 bits of CYCLE, RV32I only.
-	TIMEH         CSR = 0xC81 // Upper 32 bits of TIME, RV32I only.
-	INSTRETH      CSR = 0xC82 // Upper 32 bits of INSTRET, RV32I only.
-	HPMCOUNTER3H  CSR = 0xC83 // Upper 32 bits of HPMCOUNTER3, RV32I only.
-	HPMCOUNTER4H  CSR = 0xC84 // Upper 32 bits of HPMCOUNTER4, RV32I only.
-	HPMCOUNTER5H  CSR = 0xC85 // Upper 32 bits of HPMCOUNTER5, RV32I only.
-	HPMCOUNTER6H  CSR = 0xC86 // Upper 32 bits of HPMCOUNTER6, RV32I only.
-	HPMCOUNTER7H  CSR = 0xC87 // Upper 32 bits of HPMCOUNTER7, RV32I only.
-	HPMCOUNTER8H  CSR = 0xC88 // Upper 32 bits of HPMCOUNTER8, RV32I only.
-	HPMCOUNTER9H  CSR = 0xC89 // Upper 32 bits of HPMCOUNTER9, RV32I only.
-	HPMCOUNTER10H CSR = 0xC8A // Upper 32 bits of HPMCOUNTER10, RV32I only.
-	HPMCOUNTER11H CSR = 0xC8B // Upper 32 bits of HPMCOUNTER11, RV32I only.
-	HPMCOUNTER12H CSR = 0xC8C // Upper 32 bits of HPMCOUNTER12, RV32I only.
-	HPMCOUNTER13H CSR = 0xC8D // Upper 32 bits of HPMCOUNTER13, RV32I only.
-	HPMCOUNTER14H CSR = 0xC8E // Upper 32 bits of HPMCOUNTER14, RV32I only.
-	HPMCOUNTER15H CSR = 0xC8F // Upper 32 bits of HPMCOUNTER15, RV32I only.
-	HPMCOUNTER16H CSR = 0xC90 // Upper 32 bits of HPMCOUNTER16, RV32I only.
-	HPMCOUNTER17H CSR = 0xC91 // Upper 32 bits of HPMCOUNTER17, RV32I only.
-	HPMCOUNTER18H CSR = 0xC92 // Upper 32 bits of HPMCOUNTER18, RV32I only.
-	HPMCOUNTER19H CSR = 0xC93 // Upper 32 bits of HPMCOUNTER19, RV32I only.
-	HPMCOUNTER20H CSR = 0xC94 // Upper 32 bits of HPMCOUNTER20, RV32I only.
-	HPMCOUNTER21H CSR = 0xC95 // Upper 32 bits of HPMCOUNTER21, RV32I only.
-	HPMCOUNTER22H CSR = 0xC96 // Upper 32 bits of HPMCOUNTER22, RV32I only.
-	HPMCOUNTER23H CSR = 0xC97 // Upper 32 bits of HPMCOUNTER23, RV32I only.
-	HPMCOUNTER24H CSR = 0xC98 // Upper 32 bits of HPMCOUNTER24, RV32I only.
-	HPMCOUNTER25H CSR = 0xC99 // Upper 32 bits of HPMCOUNTER25, RV32I only.
-	HPMCOUNTER26H CSR = 0xC9A // Upper 32 bits of HPMCOUNTER26, RV32I only.
-	HPMCOUNTER27H CSR = 0xC9B // Upper 32 bits of HPMCOUNTER27, RV32I only.
-	HPMCOUNTER28H CSR = 0xC9C // Upper 32 bits of HPMCOUNTER28, RV32I only.
-	HPMCOUNTER29H CSR = 0xC9D // Upper 32 bits of HPMCOUNTER29, RV32I only.
-	HPMCOUNTER30H CSR = 0xC9E // Upper 32 bits of HPMCOUNTER30, RV32I only.
-	HPMCOUNTER31H CSR = 0xC9F // Upper 32 bits of HPMCOUNTER31, RV32I only.
-
-	// Supervisor Trap Setup
-	SSTATUS    CSR = 0x100 // Supervisor status register.
-	SEDELEG    CSR = 0x102 // Supervisor exception delegation register.
-	SIDELEG    CSR = 0x103 // Supervisor interrupt delegation register.
-	SIE        CSR = 0x104 // Supervisor interrupt-enable register.
-	STVEC      CSR = 0x105 // Supervisor trap handler base address.
-	SCOUNTEREN CSR = 0x106 // Supervisor counter enable.
-
-	// Supervisor Trap Handling
-	SSCRATCH CSR = 0x140 // Scratch register for supervisor trap handlers.
-	SEPC     CSR = 0x141 // Supervisor exception program counter.
-	SCAUSE   CSR = 0x142 // Supervisor trap cause.
-	STVAL    CSR = 0x143 // Supervisor bad address or instruction.
-	SIP      CSR = 0x144 // Supervisor interrupt pending.
-
-	// Supervisor Protection and Translation
-	SATP CSR = 0x180 // Supervisor address translation and protection.
-
-	// Machine Information Registers
-	MVENDORID CSR = 0xF11 // Vendor ID.
-	MARCHID   CSR = 0xF12 // Architecture ID.
-	MIMPID    CSR = 0xF13 // Implementation ID.
-	MHARTID   CSR = 0xF14 // Hardware thread ID.
-
-	// Machine Trap Setup
-	MSTATUS    CSR = 0x300 // Machine status register.
-	MISA       CSR = 0x301 // ISA and extensions
-	MEDELEG    CSR = 0x302 // Machine exception delegation register.
-	MIDELEG    CSR = 0x303 // Machine interrupt delegation register.
-	MIE        CSR = 0x304 // Machine interrupt-enable register.
-	MTVEC      CSR = 0x305 // Machine trap-handler base address.
-	MCOUNTEREN CSR = 0x306 // Machine counter enable.
-
-	// Machine Trap Handling
-	MSCRATCH CSR = 0x340 // Scratch register for machine trap handlers.
-	MEPC     CSR = 0x341 // Machine exception program counter.
-	MCAUSE   CSR = 0x342 // Machine trap cause.
-	MTVAL    CSR = 0x343 // Machine bad address or instruction.
-	MIP      CSR = 0x344 // Machine interrupt pending.
-
-	// Machine Protection and Translation
-	PMPCFG0   CSR = 0x3A0 // Physical memory protection configuration.
-	PMPCFG1   CSR = 0x3A1 // Physical memory protection configuration, RV32 only.
-	PMPCFG2   CSR = 0x3A2 // Physical memory protection configuration.
-	PMPCFG3   CSR = 0x3A3 // Physical memory protection configuration, RV32 only.
-	PMPADDR0  CSR = 0x3B0 // Physical memory protection address register 0.
-	PMPADDR1  CSR = 0x3B1 // Physical memory protection address register 1.
-	PMPADDR2  CSR = 0x3B2 // Physical memory protection address register 2.
-	PMPADDR3  CSR = 0x3B3 // Physical memory protection address register 3.
-	PMPADDR4  CSR = 0x3B4 // Physical memory protection address register 4.
-	PMPADDR5  CSR = 0x3B5 // Physical memory protection address register 5.
-	PMPADDR6  CSR = 0x3B6 // Physical memory protection address register 6.
-	PMPADDR7  CSR = 0x3B7 // Physical memory protection address register 7.
-	PMPADDR8  CSR = 0x3B8 // Physical memory protection address register 8.
-	PMPADDR9  CSR = 0x3B9 // Physical memory protection address register 9.
-	PMPADDR10 CSR = 0x3BA // Physical memory protection address register 10.
-	PMPADDR11 CSR = 0x3BB // Physical memory protection address register 11.
-	PMPADDR12 CSR = 0x3BC // Physical memory protection address register 12.
-	PMPADDR13 CSR = 0x3BD // Physical memory protection address register 13.
-	PMPADDR14 CSR = 0x3BE // Physical memory protection address register 14.
-	PMPADDR15 CSR = 0x3BF // Physical memory protection address register 15.
-
-	// Machine Counter/Timers
-	mcycle         CSR = 0xB00 // Machine cycle counter.
-	minstret       CSR = 0xB02 // Machine instructions-retired counter.
-	MHPMCOUNTER3   CSR = 0xB03 // Machine performance-monitoring counter 3.
-	MHPMCOUNTER4   CSR = 0xB04 // Machine performance-monitoring counter 4.
-	MHPMCOUNTER5   CSR = 0xB05 // Machine performance-monitoring counter 5.
-	MHPMCOUNTER6   CSR = 0xB06 // Machine performance-monitoring counter 6.
-	MHPMCOUNTER7   CSR = 0xB07 // Machine performance-monitoring counter 7.
-	MHPMCOUNTER8   CSR = 0xB08 // Machine performance-monitoring counter 8.
-	MHPMCOUNTER9   CSR = 0xB09 // Machine performance-monitoring counter 9.
-	MHPMCOUNTER10  CSR = 0xB0A // Machine performance-monitoring counter 10.
-	MHPMCOUNTER11  CSR = 0xB0B // Machine performance-monitoring counter 11.
-	MHPMCOUNTER12  CSR = 0xB0C // Machine performance-monitoring counter 12.
-	MHPMCOUNTER13  CSR = 0xB0D // Machine performance-monitoring counter 13.
-	MHPMCOUNTER14  CSR = 0xB0E // Machine performance-monitoring counter 14.
-	MHPMCOUNTER15  CSR = 0xB0F // Machine performance-monitoring counter 15.
-	MHPMCOUNTER16  CSR = 0xB10 // Machine performance-monitoring counter 16.
-	MHPMCOUNTER17  CSR = 0xB11 // Machine performance-monitoring counter 17.
-	MHPMCOUNTER18  CSR = 0xB12 // Machine performance-monitoring counter 18.
-	MHPMCOUNTER19  CSR = 0xB13 // Machine performance-monitoring counter 19.
-	MHPMCOUNTER20  CSR = 0xB14 // Machine performance-monitoring counter 20.
-	MHPMCOUNTER21  CSR = 0xB15 // Machine performance-monitoring counter 21.
-	MHPMCOUNTER22  CSR = 0xB16 // Machine performance-monitoring counter 22.
-	MHPMCOUNTER23  CSR = 0xB17 // Machine performance-monitoring counter 23.
-	MHPMCOUNTER24  CSR = 0xB18 // Machine performance-monitoring counter 24.
-	MHPMCOUNTER25  CSR = 0xB19 // Machine performance-monitoring counter 25.
-	MHPMCOUNTER26  CSR = 0xB1A // Machine performance-monitoring counter 26.
-	MHPMCOUNTER27  CSR = 0xB1B // Machine performance-monitoring counter 27.
-	MHPMCOUNTER28  CSR = 0xB1C // Machine performance-monitoring counter 28.
-	MHPMCOUNTER29  CSR = 0xB1D // Machine performance-monitoring counter 29.
-	MHPMCOUNTER30  CSR = 0xB1E // Machine performance-monitoring counter 30.
-	MHPMCOUNTER31  CSR = 0xB1F // Machine performance-monitoring counter 31.
-	MCYCLEH        CSR = 0xB80 // Upper 32 bits of MCYCLE, RV32I only.
-	MINSTRETH      CSR = 0xB82 // Upper 32 bits of MINSTRET, RV32I only.
-	MHPMCOUNTER3H  CSR = 0xB83 // Upper 32 bits of MHPMCOUNTER3, RV32I only.
-	MHPMCOUNTER4H  CSR = 0xB84 // Upper 32 bits of MHPMCOUNTER4, RV32I only.
-	MHPMCOUNTER5H  CSR = 0xB85 // Upper 32 bits of MHPMCOUNTER5, RV32I only.
-	MHPMCOUNTER6H  CSR = 0xB86 // Upper 32 bits of MHPMCOUNTER6, RV32I only.
-	MHPMCOUNTER7H  CSR = 0xB87 // Upper 32 bits of MHPMCOUNTER7, RV32I only.
-	MHPMCOUNTER8H  CSR = 0xB88 // Upper 32 bits of MHPMCOUNTER8, RV32I only.
-	MHPMCOUNTER9H  CSR = 0xB89 // Upper 32 bits of MHPMCOUNTER9, RV32I only.
-	MHPMCOUNTER10H CSR = 0xB8A // Upper 32 bits of MHPMCOUNTER10, RV32I only.
-	MHPMCOUNTER11H CSR = 0xB8B // Upper 32 bits of MHPMCOUNTER11, RV32I only.
-	MHPMCOUNTER12H CSR = 0xB8C // Upper 32 bits of MHPMCOUNTER12, RV32I only.
-	MHPMCOUNTER13H CSR = 0xB8D // Upper 32 bits of MHPMCOUNTER13, RV32I only.
-	MHPMCOUNTER14H CSR = 0xB8E // Upper 32 bits of MHPMCOUNTER14, RV32I only.
-	MHPMCOUNTER15H CSR = 0xB8F // Upper 32 bits of MHPMCOUNTER15, RV32I only.
-	MHPMCOUNTER16H CSR = 0xB90 // Upper 32 bits of MHPMCOUNTER16, RV32I only.
-	MHPMCOUNTER17H CSR = 0xB91 // Upper 32 bits of MHPMCOUNTER17, RV32I only.
-	MHPMCOUNTER18H CSR = 0xB92 // Upper 32 bits of MHPMCOUNTER18, RV32I only.
-	MHPMCOUNTER19H CSR = 0xB93 // Upper 32 bits of MHPMCOUNTER19, RV32I only.
-	MHPMCOUNTER20H CSR = 0xB94 // Upper 32 bits of MHPMCOUNTER20, RV32I only.
-	MHPMCOUNTER21H CSR = 0xB95 // Upper 32 bits of MHPMCOUNTER21, RV32I only.
-	MHPMCOUNTER22H CSR = 0xB96 // Upper 32 bits of MHPMCOUNTER22, RV32I only.
-	MHPMCOUNTER23H CSR = 0xB97 // Upper 32 bits of MHPMCOUNTER23, RV32I only.
-	MHPMCOUNTER24H CSR = 0xB98 // Upper 32 bits of MHPMCOUNTER24, RV32I only.
-	MHPMCOUNTER25H CSR = 0xB99 // Upper 32 bits of MHPMCOUNTER25, RV32I only.
-	MHPMCOUNTER26H CSR = 0xB9A // Upper 32 bits of MHPMCOUNTER26, RV32I only.
-	MHPMCOUNTER27H CSR = 0xB9B // Upper 32 bits of MHPMCOUNTER27, RV32I only.
-	MHPMCOUNTER28H CSR = 0xB9C // Upper 32 bits of MHPMCOUNTER28, RV32I only.
-	MHPMCOUNTER29H CSR = 0xB9D // Upper 32 bits of MHPMCOUNTER29, RV32I only.
-	MHPMCOUNTER30H CSR = 0xB9E // Upper 32 bits of MHPMCOUNTER30, RV32I only.
-	MHPMCOUNTER31H CSR = 0xB9F // Upper 32 bits of MHPMCOUNTER31, RV32I only.
-
-	// Machine Counter Setup
-	MHPMEVENT4  CSR = 0x324 // Machine performance-monitoring event selector 4.
-	MHPMEVENT5  CSR = 0x325 // Machine performance-monitoring event selector 5.
-	MHPMEVENT6  CSR = 0x326 // Machine performance-monitoring event selector 6.
-	MHPMEVENT7  CSR = 0x327 // Machine performance-monitoring event selector 7.
-	MHPMEVENT8  CSR = 0x328 // Machine performance-monitoring event selector 8.
-	MHPMEVENT9  CSR = 0x329 // Machine performance-monitoring event selector 9.
-	MHPMEVENT10 CSR = 0x32A // Machine performance-monitoring event selector 10.
-	MHPMEVENT11 CSR = 0x32B // Machine performance-monitoring event selector 11.
-	MHPMEVENT12 CSR = 0x32C // Machine performance-monitoring event selector 12.
-	MHPMEVENT13 CSR = 0x32D // Machine performance-monitoring event selector 13.
-	MHPMEVENT14 CSR = 0x32E // Machine performance-monitoring event selector 14.
-	MHPMEVENT15 CSR = 0x32F // Machine performance-monitoring event selector 15.
-	MHPMEVENT16 CSR = 0x330 // Machine performance-monitoring event selector 16.
-	MHPMEVENT17 CSR = 0x331 // Machine performance-monitoring event selector 17.
-	MHPMEVENT18 CSR = 0x332 // Machine performance-monitoring event selector 18.
-	MHPMEVENT19 CSR = 0x333 // Machine performance-monitoring event selector 19.
-	MHPMEVENT20 CSR = 0x334 // Machine performance-monitoring event selector 20.
-	MHPMEVENT21 CSR = 0x335 // Machine performance-monitoring event selector 21.
-	MHPMEVENT22 CSR = 0x336 // Machine performance-monitoring event selector 22.
-	MHPMEVENT23 CSR = 0x337 // Machine performance-monitoring event selector 23.
-	MHPMEVENT24 CSR = 0x338 // Machine performance-monitoring event selector 24.
-	MHPMEVENT25 CSR = 0x339 // Machine performance-monitoring event selector 25.
-	MHPMEVENT26 CSR = 0x33A // Machine performance-monitoring event selector 26.
-	MHPMEVENT27 CSR = 0x33B // Machine performance-monitoring event selector 27.
-	MHPMEVENT28 CSR = 0x33C // Machine performance-monitoring event selector 28.
-	MHPMEVENT29 CSR = 0x33D // Machine performance-monitoring event selector 29.
-	MHPMEVENT30 CSR = 0x33E // Machine performance-monitoring event selector 30.
-	MHPMEVENT31 CSR = 0x33F // Machine performance-monitoring event selector 31.
-
-	// Debug/Trace Registers (shared with Debug Mode)
-	TSELECT CSR = 0x7A0 // Debug/Trace trigger register select.
-	TDATA1  CSR = 0x7A1 // First Debug/Trace trigger data register.
-	TDATA2  CSR = 0x7A2 // Second Debug/Trace trigger data register.
-	TDATA3  CSR = 0x7A3 // Third Debug/Trace trigger data register.
-
-	// Debug Mode Registers
-	DCSR     CSR = 0x7B0 // Debug control and status register.
-	DPC      CSR = 0x7B1 // Debug PC.
-	DSCRATCH CSR = 0x7B2 // Debug scratch register.
-)
@@ -5,56 +5,8 @@
 _start:
    // Load the stack pointer.
    la sp,      _stack_top
-
    // Load the globals pointer. The program will load pointers relative to this
    // register, so it must be set to the right value on startup.
    // See: https://gnu-mcu-eclipse.github.io/arch/riscv/programmer/#the-gp-global-pointer-register
    la gp,      __global_pointer$
-
-    // Jump to runtime.main
    call main
-
-.section .text.handleInterruptASM
-.global handleInterruptASM
-.type handleInterruptASM,@function
-handleInterruptASM:
-    // Save and restore all registers, because the hardware only saves/restores
-    // the pc.
-    // Note: we have to do this in assembly because the "interrupt"="machine"
-    // attribute is broken in LLVM: https://bugs.llvm.org/show_bug.cgi?id=42984
-    addi    sp, sp, -64
-    sw      ra, 60(sp)
-    sw      t0, 56(sp)
-    sw      t1, 52(sp)
-    sw      t2, 48(sp)
-    sw      a0, 44(sp)
-    sw      a1, 40(sp)
-    sw      a2, 36(sp)
-    sw      a3, 32(sp)
-    sw      a4, 28(sp)
-    sw      a5, 24(sp)
-    sw      a6, 20(sp)
-    sw      a7, 16(sp)
-    sw      t3, 12(sp)
-    sw      t4, 8(sp)
-    sw      t5, 4(sp)
-    sw      t6, 0(sp)
-    call    handleInterrupt
-    lw      t6, 0(sp)
-    lw      t5, 4(sp)
-    lw      t4, 8(sp)
-    lw      t3, 12(sp)
-    lw      a7, 16(sp)
-    lw      a6, 20(sp)
-    lw      a5, 24(sp)
-    lw      a4, 28(sp)
-    lw      a3, 32(sp)
-    lw      a2, 36(sp)
-    lw      a1, 40(sp)
-    lw      a0, 44(sp)
-    lw      t2, 48(sp)
-    lw      t1, 52(sp)
-    lw      t0, 56(sp)
-    lw      ra, 60(sp)
-    addi    sp, sp, 64
-    mret
@@ -1,57 +0,0 @@
-// Hand created file. DO NOT DELETE.
-// STM32FXXX (except stm32f1xx) bitfield definitions that are not
-//  auto-generated by gen-device-svd.go
-
-// These apply to the stm32 families that use the MODER, OTYPE amd PUPDR
-//  registers for managing GPIO functionality.
-
-// Add in other families that use the same settings, e.g. stm32f0xx, etc
-
-// +build stm32,!stm32f103xx
-
-package stm32
-
-// AltFunc represents the alternate function peripherals that can be mapped to
-// the GPIO ports. Since these differ by what is supported on the stm32 family
-// they are defined in the more specific files
-type AltFunc uint8
-
-// Family-wide common post-reset AltFunc. This represents
-//  normal GPIO operation of the pins
-const AF0_SYSTEM AltFunc = 0
-
-const (
-	// Register values for the chip
-	// GPIOx_MODER
-	GPIOModeInput         = 0
-	GPIOModeOutputGeneral = 1
-	GPIOModeOutputAltFunc = 2
-	GPIOModeAnalog        = 3
-
-	// GPIOx_OTYPER
-	GPIOOutputTypePushPull  = 0
-	GPIOOutputTypeOpenDrain = 1
-
-	// GPIOx_OSPEEDR
-	GPIOSpeedLow      = 0
-	GPIOSpeedMid      = 1
-	GPIOSpeedHigh     = 2 // Note: this is also low speed on stm32f0, see RM0091
-	GPIOSpeedVeryHigh = 3
-
-	// GPIOx_PUPDR
-	GPIOPUPDRFloating = 0
-	GPIOPUPDRPullUp   = 1
-	GPIOPUPDRPullDown = 2
-)
-
-// SPI prescaler values fPCLK / X
-const (
-	SPI_PCLK_2   = 0
-	SPI_PCLK_4   = 1
-	SPI_PCLK_8   = 2
-	SPI_PCLK_16  = 3
-	SPI_PCLK_32  = 4
-	SPI_PCLK_64  = 5
-	SPI_PCLK_128 = 6
-	SPI_PCLK_256 = 7
-)
@@ -1,26 +0,0 @@
-// These are the supported alternate function numberings on the stm32f407
-// +build stm32,stm32f407
-
-// Alternate function settings on the stm32f4xx series
-
-package stm32
-
-const (
-	// Alternative peripheral pin functions
-	// AF0_SYSTEM is defined im the common bitfields package
-	AF1_TIM1_2                AltFunc = 1
-	AF2_TIM3_4_5                      = 2
-	AF3_TIM8_9_10_11                  = 3
-	AF4_I2C1_2_3                      = 4
-	AF5_SPI1_SPI2                     = 5
-	AF6_SPI3                          = 6
-	AF7_USART1_2_3                    = 7
-	AF8_USART4_5_6                    = 8
-	AF9_CAN1_CAN2_TIM12_13_14         = 9
-	AF10_OTG_FS_OTG_HS                = 10
-	AF11_ETH                          = 11
-	AF12_FSMC_SDIO_OTG_HS_1           = 12
-	AF13_DCMI                         = 13
-	AF14                              = 14
-	AF15_EVENTOUT                     = 15
-)
@@ -17,7 +17,7 @@ func main() {

 var led_state bool

-//export SysTick_Handler
+//go:export SysTick_Handler
 func timer_isr() {
 	if led_state {
 		machine.LED.Low()
@@ -2,7 +2,7 @@

 The examples here show two different ways of using WebAssembly with TinyGo:

-1. Defining and exporting functions via the `//export <name>` directive. See
+1. Defining and exporting functions via the `//go:export <name>` directive. See
 [the export folder](./export) for an example of this.  Additionally, the Wasm
 module (which has a default value of `env`) can be specified using
 `//go:wasm-module <module>`.
@@ -8,12 +8,12 @@ import (
 func main() {
 }

-//export add
+//go:export add
 func add(a, b int) int {
 	return a + b
 }

-//export update
+//go:export update
 func update() {
 	document := js.Global().Get("document")
 	aStr := document.Call("getElementById", "a").Get("value").String()
@@ -1,98 +0,0 @@
-package task
-
-const asserts = false
-
-// Queue is a FIFO container of tasks.
-// The zero value is an empty queue.
-type Queue struct {
-	head, tail *Task
-}
-
-// Push a task onto the queue.
-func (q *Queue) Push(t *Task) {
-	if asserts && t.Next != nil {
-		panic("runtime: pushing a task to a queue with a non-nil Next pointer")
-	}
-	if q.tail != nil {
-		q.tail.Next = t
-	}
-	q.tail = t
-	t.Next = nil
-	if q.head == nil {
-		q.head = t
-	}
-}
-
-// Pop a task off of the queue.
-func (q *Queue) Pop() *Task {
-	t := q.head
-	if t == nil {
-		return nil
-	}
-	q.head = t.Next
-	if q.tail == t {
-		q.tail = nil
-	}
-	t.Next = nil
-	return t
-}
-
-// Append pops the contents of another queue and pushes them onto the end of this queue.
-func (q *Queue) Append(other *Queue) {
-	if q.head == nil {
-		q.head = other.head
-	} else {
-		q.tail.Next = other.head
-	}
-	q.tail = other.tail
-	other.head, other.tail = nil, nil
-}
-
-// Stack is a LIFO container of tasks.
-// The zero value is an empty stack.
-// This is slightly cheaper than a queue, so it can be preferable when strict ordering is not necessary.
-type Stack struct {
-	top *Task
-}
-
-// Push a task onto the stack.
-func (s *Stack) Push(t *Task) {
-	if asserts && t.Next != nil {
-		panic("runtime: pushing a task to a stack with a non-nil Next pointer")
-	}
-	s.top, t.Next = t, s.top
-}
-
-// Pop a task off of the stack.
-func (s *Stack) Pop() *Task {
-	t := s.top
-	if t != nil {
-		s.top = t.Next
-	}
-	t.Next = nil
-	return t
-}
-
-// tail follows the chain of tasks.
-// If t is nil, returns nil.
-// Otherwise, returns the task in the chain where the Next field is nil.
-func (t *Task) tail() *Task {
-	if t == nil {
-		return nil
-	}
-	for t.Next != nil {
-		t = t.Next
-	}
-	return t
-}
-
-// Queue moves the contents of the stack into a queue.
-// Elements can be popped from the queue in the same order that they would be popped from the stack.
-func (s *Stack) Queue() Queue {
-	head := s.top
-	s.top = nil
-	return Queue{
-		head: head,
-		tail: head.tail(),
-	}
-}
@@ -1,20 +0,0 @@
-package task
-
-import (
-	"unsafe"
-)
-
-// Task is a state of goroutine for scheduling purposes.
-type Task struct {
-	// Next is a field which can be used to make a linked list of tasks.
-	Next *Task
-
-	// Ptr is a field which can be used for storing a pointer.
-	Ptr unsafe.Pointer
-
-	// Data is a field which can be used for storing state information.
-	Data uint
-
-	// state is the underlying running state of the task.
-	state state
-}
@@ -1,103 +0,0 @@
-// +build scheduler.coroutines
-
-package task
-
-import (
-	"unsafe"
-)
-
-// rawState is an underlying coroutine state exposed by llvm.coro.
-// This matches *i8 in LLVM.
-type rawState uint8
-
-//export llvm.coro.resume
-func (s *rawState) resume()
-
-type state struct{ *rawState }
-
-//export llvm.coro.noop
-func noopState() *rawState
-
-// Resume the task until it pauses or completes.
-func (t *Task) Resume() {
-	t.state.resume()
-}
-
-// setState is used by the compiler to set the state of the function at the beginning of a function call.
-// Returns the state of the caller.
-func (t *Task) setState(s *rawState) *rawState {
-	caller := t.state
-	t.state = state{s}
-	return caller.rawState
-}
-
-// returnTo is used by the compiler to return to the state of the caller.
-func (t *Task) returnTo(parent *rawState) {
-	t.state = state{parent}
-	t.returnCurrent()
-}
-
-// returnCurrent is used by the compiler to return to the state of the caller in a case where the state is not replaced.
-func (t *Task) returnCurrent() {
-	scheduleTask(t)
-}
-
-//go:linkname scheduleTask runtime.runqueuePushBack
-func scheduleTask(*Task)
-
-// setReturnPtr is used by the compiler to store the return buffer into the task.
-// This buffer is where the return value of a function that is about to be called will be stored.
-func (t *Task) setReturnPtr(buf unsafe.Pointer) {
-	t.Ptr = buf
-}
-
-// getReturnPtr is used by the compiler to get the return buffer stored into the task.
-// This is called at the beginning of an async function, and the return is stored into this buffer immediately before resuming the caller.
-func (t *Task) getReturnPtr() unsafe.Pointer {
-	return t.Ptr
-}
-
-// createTask returns a new task struct initialized with a no-op state.
-func createTask() *Task {
-	return &Task{
-		state: state{noopState()},
-	}
-}
-
-// start invokes a function in a new goroutine. Calls to this are inserted by the compiler.
-// The created goroutine starts running immediately.
-// This is implemented inside the compiler.
-func start(fn uintptr, args unsafe.Pointer)
-
-// Current returns the current active task.
-// This is implemented inside the compiler.
-func Current() *Task
-
-// Pause suspends the current running task.
-// This is implemented inside the compiler.
-func Pause()
-
-type taskHolder interface {
-	setState(*rawState) *rawState
-	returnTo(*rawState)
-	returnCurrent()
-	setReturnPtr(unsafe.Pointer)
-	getReturnPtr() unsafe.Pointer
-}
-
-// If there are no direct references to the task methods, they will not be discovered by the compiler, and this will trigger a compiler error.
-// Instantiating this interface forces discovery of these methods.
-var _ = taskHolder((*Task)(nil))
-
-func fake() {
-	// Hack to ensure intrinsics are discovered.
-	Current()
-	go func() {}()
-	Pause()
-}
-
-// OnSystemStack returns whether the caller is running on the system stack.
-func OnSystemStack() bool {
-	// This scheduler does not do any stack switching.
-	return true
-}
@@ -1,35 +0,0 @@
-// +build scheduler.none
-
-package task
-
-import "unsafe"
-
-//go:linkname runtimePanic runtime.runtimePanic
-func runtimePanic(str string)
-
-func Pause() {
-	runtimePanic("scheduler is disabled")
-}
-
-func Current() *Task {
-	runtimePanic("scheduler is disabled")
-	return nil
-}
-
-//go:noinline
-func start(fn uintptr, args unsafe.Pointer) {
-	// The compiler will error if this is reachable.
-	runtimePanic("scheduler is disabled")
-}
-
-type state struct{}
-
-func (t *Task) Resume() {
-	runtimePanic("scheduler is disabled")
-}
-
-// OnSystemStack returns whether the caller is running on the system stack.
-func OnSystemStack() bool {
-	// This scheduler does not do any stack switching.
-	return true
-}
@@ -1,80 +0,0 @@
-// +build scheduler.tasks
-
-package task
-
-import "unsafe"
-
-//go:linkname runtimePanic runtime.runtimePanic
-func runtimePanic(str string)
-
-// Stack canary, to detect a stack overflow. The number is a random number
-// generated by random.org. The bit fiddling dance is necessary because
-// otherwise Go wouldn't allow the cast to a smaller integer size.
-const stackCanary = uintptr(uint64(0x670c1333b83bf575) & uint64(^uintptr(0)))
-
-// state is a structure which holds a reference to the state of the task.
-// When the task is suspended, the registers are stored onto the stack and the stack pointer is stored into sp.
-type state struct {
-	// sp is the stack pointer of the saved state.
-	// When the task is inactive, the saved registers are stored at the top of the stack.
-	sp uintptr
-
-	// canaryPtr points to the top word of the stack (the lowest address).
-	// This is used to detect stack overflows.
-	// When initializing the goroutine, the stackCanary constant is stored there.
-	// If the stack overflowed, the word will likely no longer equal stackCanary.
-	canaryPtr *uintptr
-}
-
-// currentTask is the current running task, or nil if currently in the scheduler.
-var currentTask *Task
-
-// Current returns the current active task.
-func Current() *Task {
-	return currentTask
-}
-
-// Pause suspends the current task and returns to the scheduler.
-// This function may only be called when running on a goroutine stack, not when running on the system stack or in an interrupt.
-func Pause() {
-	// Check whether the canary (the lowest address of the stack) is still
-	// valid. If it is not, a stack overflow has occured.
-	if *currentTask.state.canaryPtr != stackCanary {
-		runtimePanic("goroutine stack overflow")
-	}
-	currentTask.state.pause()
-}
-
-// Resume the task until it pauses or completes.
-// This may only be called from the scheduler.
-func (t *Task) Resume() {
-	currentTask = t
-	t.state.resume()
-	currentTask = nil
-}
-
-// initialize the state and prepare to call the specified function with the specified argument bundle.
-func (s *state) initialize(fn uintptr, args unsafe.Pointer) {
-	// Create a stack.
-	stack := make([]uintptr, stackSize/unsafe.Sizeof(uintptr(0)))
-
-	// Invoke architecture-specific initialization.
-	s.archInit(stack, fn, args)
-}
-
-//go:linkname runqueuePushBack runtime.runqueuePushBack
-func runqueuePushBack(*Task)
-
-// start creates and starts a new goroutine with the given function and arguments.
-// The new goroutine is scheduled to run later.
-func start(fn uintptr, args unsafe.Pointer) {
-	t := &Task{}
-	t.state.initialize(fn, args)
-	runqueuePushBack(t)
-}
-
-// OnSystemStack returns whether the caller is running on the system stack.
-func OnSystemStack() bool {
-	// If there is not an active goroutine, then this must be running on the system stack.
-	return Current() == nil
-}
@@ -1,88 +0,0 @@
-// +build scheduler.tasks,avr
-
-package task
-
-import "unsafe"
-
-const stackSize = 256
-
-// calleeSavedRegs is the list of registers that must be saved and restored when
-// switching between tasks. Also see scheduler_avr.S that relies on the
-// exact layout of this struct.
-//
-// https://gcc.gnu.org/wiki/avr-gcc#Call-Saved_Registers
-type calleeSavedRegs struct {
-	r2r3   uintptr
-	r4r5   uintptr
-	r6r7   uintptr
-	r8r9   uintptr
-	r10r11 uintptr
-	r12r13 uintptr
-	r14r15 uintptr
-	r16r17 uintptr
-	r28r29 uintptr // Y register
-
-	pc uintptr
-}
-
-// registers gets a pointer to the registers stored at the top of the stack.
-func (s *state) registers() *calleeSavedRegs {
-	return (*calleeSavedRegs)(unsafe.Pointer(s.sp + 1))
-}
-
-// startTask is a small wrapper function that sets up the first (and only)
-// argument to the new goroutine and makes sure it is exited when the goroutine
-// finishes.
-//go:extern tinygo_startTask
-var startTask [0]uint8
-
-// archInit runs architecture-specific setup for the goroutine startup.
-// Note: adding //go:noinline to work around an AVR backend bug.
-//go:noinline
-func (s *state) archInit(stack []uintptr, fn uintptr, args unsafe.Pointer) {
-	// Set up the stack canary, a random number that should be checked when
-	// switching from the task back to the scheduler. The stack canary pointer
-	// points to the first word of the stack. If it has changed between now and
-	// the next stack switch, there was a stack overflow.
-	s.canaryPtr = &stack[0]
-	*s.canaryPtr = stackCanary
-
-	// Store the initial sp for the startTask function (implemented in assembly).
-	s.sp = uintptr(unsafe.Pointer(&stack[uintptr(len(stack))-(unsafe.Sizeof(calleeSavedRegs{})/unsafe.Sizeof(uintptr(0)))])) - 1
-
-	// Initialize the registers.
-	// These will be popped off of the stack on the first resume of the goroutine.
-	r := s.registers()
-
-	// Start the function at tinygo_startTask.
-	startTask := uintptr(unsafe.Pointer(&startTask))
-	r.pc = startTask/2>>8 | startTask/2<<8
-
-	// Pass the function to call in r2:r3.
-	// This function is a compiler-generated wrapper which loads arguments out
-	// of a struct pointer. See createGoroutineStartWrapper (defined in
-	// compiler/goroutine.go) for more information.
-	r.r2r3 = fn
-
-	// Pass the pointer to the arguments struct in r4:45.
-	r.r4r5 = uintptr(args)
-}
-
-func (s *state) resume() {
-	switchToTask(s.sp)
-}
-
-//export tinygo_switchToTask
-func switchToTask(uintptr)
-
-//export tinygo_switchToScheduler
-func switchToScheduler(*uintptr)
-
-func (s *state) pause() {
-	switchToScheduler(&s.sp)
-}
-
-//export tinygo_pause
-func pause() {
-	Pause()
-}
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Ayke van Laethem	ebde8b5875	targets/gba: implement interrupt handler	2020-01-06 14:45:32 +01:00
Ayke van Laethem	9d50587d63	targets/gba: make linker script cleaner Make it clearer where the stack is located.	2020-01-06 11:48:09 +01:00
Ayke van Laethem	5e6f1725ac	WIP interrupts via ptrtoint handler	2020-01-05 08:05:38 +01:00
Ayke van Laethem	9cdc2fa768	WIP: interrupt API	2020-01-04 23:40:45 +01:00
Ayke van Laethem	084386262a	compiler: add support for debugging globals This makes most globals visible from GDB, using `info variables`.	2020-01-04 23:40:44 +01:00
Ayke van Laethem	674ddef219	compiler: add globaldce pass to start of optimization pipeline This reduces code size in a few cases when tested against the drivers smoketests (although there was one minor increase) without significantly increasing compile time. In fact, in my testing compile time appears to be going down a little bit (around 1%, within the noise).	2020-01-04 23:40:44 +01:00