targets/gba: implement interrupt handler

targets/gba: make linker script cleaner
Make it clearer where the stack is located.
2026-07-27 23:28:42 +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
117 changed files with 4606 additions and 1680 deletions
@@ -18,7 +18,6 @@ commands:
            wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
            sudo apt-get update
            sudo apt-get install \
-                python3 \
                llvm<<parameters.llvm>>-dev \
                clang<<parameters.llvm>> \
                libclang<<parameters.llvm>>-dev \
@@ -67,7 +66,7 @@ commands:
      - run: go install .
      - run: go test -v ./cgo ./compileopts ./interp ./transform .
      - run: make gen-device -j4
-      - run: make smoketest RISCV=0
+      - run: make smoketest
      - save_cache:
          key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
          paths:
@@ -83,7 +82,6 @@ commands:
          name: "Install apt dependencies"
          command: |
            sudo apt-get install \
-                python3 \
                gcc-arm-linux-gnueabihf \
                binutils-arm-none-eabi \
                libc6-dev-armel-cross \
@@ -122,12 +120,6 @@ commands:
          key: llvm-build-9-linux-v0-assert
          paths:
            llvm-build
-      - run:
-          name: "Create LLVM symlinks"
-          command: |
-            ln -s $PWD/llvm-build/bin/clang-9 /go/bin/clang-9
-            ln -s $PWD/llvm-build/bin/ld.lld  /go/bin/ld.lld-9
-            ln -s $PWD/llvm-build/bin/wasm-ld /go/bin/wasm-ld-9
      - run: make ASSERT=1
      - run:
          name: "Test TinyGo"
@@ -139,7 +131,7 @@ commands:
            - ~/.cache/tinygo
            - /go/pkg/mod
      - run: make gen-device -j4
-      - run: make smoketest TINYGO=build/tinygo RISCV=0
+      - run: make smoketest TINYGO=build/tinygo
  build-linux:
    steps:
      - checkout
@@ -148,7 +140,6 @@ commands:
          name: "Install apt dependencies"
          command: |
            sudo apt-get install \
-                python3 \
                gcc-arm-linux-gnueabihf \
                binutils-arm-none-eabi \
                libc6-dev-armel-cross \
@@ -187,12 +178,6 @@ commands:
          key: llvm-build-9-linux-v0
          paths:
            llvm-build
-      - run:
-          name: "Create LLVM symlinks"
-          command: |
-            ln -s $PWD/llvm-build/bin/clang-9 /go/bin/clang-9
-            ln -s $PWD/llvm-build/bin/ld.lld  /go/bin/ld.lld-9
-            ln -s $PWD/llvm-build/bin/wasm-ld /go/bin/wasm-ld-9
      - run:
          name: "Test TinyGo"
          command: make test
@@ -216,11 +201,6 @@ commands:
            tar -C ~/lib -xf /tmp/tinygo.linux-amd64.tar.gz
            ln -s ~/lib/tinygo/bin/tinygo /go/bin/tinygo
            tinygo version
-      - run:
-          name: "Download SiFive GNU toolchain"
-          command: |
-            curl -O https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.2.0-2019.05.3-x86_64-linux-ubuntu14.tar.gz
-            sudo tar -C /usr/local --strip-components=1 -xf riscv64-unknown-elf-gcc-8.2.0-2019.05.3-x86_64-linux-ubuntu14.tar.gz
      - run: make smoketest
  build-macos:
    steps:
@@ -264,10 +244,6 @@ commands:
          key: llvm-build-9-macos-v0
          paths:
            llvm-build
-      - run:
-          name: "Create LLVM symlinks"
-          command: |
-            ln -s $PWD/llvm-build/bin/clang-9 /usr/local/bin/clang-9
      - run:
          name: "Test TinyGo"
          command: make test
@@ -1,3 +1,29 @@
+0.11.0
+---
+* **command line**
+  - add support for QEMU in `gdb` subcommand
+  - use builtin Clang when building statically, dropping the clang-9 dependency
+  - search for default serial port on both macOS and Linux
+  - windows: support `tinygo flash` directly by using win32 wmi
+* **compiler**
+  - add location information to the IR checker
+  - make reflection sidetables constant globals
+  - improve error locations in goroutine lowering
+  - interp: improve support for maps with string keys
+  - interp: add runtime fallback for mapassign operations
+* **standard library**
+  - `machine`: add support for `SPI.Tx()` on play.tinygo.org
+  - `machine`: rename `CPU_FREQUENCY` to `CPUFrequency()`
+* **targets**
+  - `adafruit-pybadge`: add Adafruit Pybadge
+  - `arduino-nano33`: allow simulation on play.tinygo.org
+  - `arduino-nano33`: fix default SPI pin numbers to be D13/D11/D12
+  - `circuitplay-express`: allow simulation on play.tinygo.org
+  - `hifive1-qemu`: add target for testing RISC-V bare metal in QEMU
+  - `riscv`: fix heap corruption due to changes in LLVM 9
+  - `riscv`: add support for compiler-rt
+  - `qemu`: rename to `cortex-m-qemu`
+
 0.10.0
 ---
 * **command line**
@@ -0,0 +1,76 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to make participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies within all project spaces, and it also applies when
+an individual is representing the project or its community in public spaces.
+Examples of representing a project or community include using an official
+project e-mail address, posting via an official social media account, or acting
+as an appointed representative at an online or offline event. Representation of
+a project may be further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at [conduct@tinygo.org](mailto:conduct@tinygo.org). All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see
+https://www.contributor-covenant.org/faq
@@ -41,9 +41,8 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

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

@@ -59,11 +58,8 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

 RUN cd /tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils python3 make clang-9 && \
-    make gen-device-nrf && make gen-device-stm32 && \
-    apt-get remove -y python3 && \
-    apt-get autoremove -y && \
-    apt-get clean
+    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.
 FROM tinygo-wasm AS tinygo-all
@@ -74,10 +70,7 @@ COPY --from=tinygo-base /tinygo/lib /tinygo/lib

 RUN cd /tinygo/ && \
    apt-get update && \
-    apt-get install -y apt-utils python3 make clang-9 binutils-avr gcc-avr avr-libc && \
-    make gen-device && \
-    apt-get remove -y python3 && \
-    apt-get autoremove -y && \
-    apt-get clean
+    apt-get install -y apt-utils make clang-9 binutils-avr gcc-avr avr-libc && \
+    make gen-device

 CMD ["tinygo"]
@@ -3,6 +3,9 @@ Copyright (c) 2018-2019 TinyGo Authors. All rights reserved.
 TinyGo includes portions of the Go standard library.
 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.
+
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
 met:
@@ -14,9 +14,6 @@ export GOROOT = $(shell $(GO) env GOROOT)
 # md5sum binary
 MD5SUM = md5sum

-# Python binary
-PYTHON ?= python
-
 # tinygo binary for tests
 TINYGO ?= tinygo

@@ -34,7 +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 debuginfodwarf executionengine 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
@@ -65,6 +62,11 @@ $(LIBCLANG_PATH): $(LIBCLANG_FILES)
 else ifeq ($(shell uname -s),Darwin)
    MD5SUM = md5
    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
+else ifeq ($(shell uname -s),FreeBSD)
+    MD5SUM = md5
+    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
+    START_GROUP = -Wl,--start-group
+    END_GROUP = -Wl,--end-group
 else
    LIBCLANG_PATH = $(abspath $(LLVM_BUILDDIR))/lib/libclang.a
    START_GROUP = -Wl,--start-group
@@ -78,7 +80,7 @@ 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 $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
+    CGO_CPPFLAGS=$(shell $(LLVM_BUILDDIR)/bin/llvm-config --cppflags) -I$(abspath $(LLVM_BUILDDIR))/tools/clang/include -I$(abspath $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
    CGO_CXXFLAGS=-std=c++11
    CGO_LDFLAGS+=$(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
@@ -97,24 +99,28 @@ fmt-check:
 gen-device: gen-device-avr gen-device-nrf gen-device-sam gen-device-sifive gen-device-stm32

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

-gen-device-nrf:
-	$(PYTHON) ./tools/gen-device-svd.py lib/nrfx/mdk/ src/device/nrf/ --source=https://github.com/NordicSemiconductor/nrfx/tree/master/mdk
+build/gen-device-svd: ./tools/gen-device-svd/*.go
+	$(GO) build -o $@ ./tools/gen-device-svd/
+
+gen-device-nrf: build/gen-device-svd
+	./build/gen-device-svd -source=https://github.com/NordicSemiconductor/nrfx/tree/master/mdk lib/nrfx/mdk/ src/device/nrf/
 	GO111MODULE=off $(GO) fmt ./src/device/nrf

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

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


@@ -187,6 +193,8 @@ smoketest:
 	@$(MD5SUM) test.wasm
 	$(TINYGO) build             -o test.wasm -tags=pca10056             examples/blinky2
 	@$(MD5SUM) test.wasm
+	$(TINYGO) build             -o test.wasm -tags=circuitplay_express  examples/blinky1
+	@$(MD5SUM) test.wasm
 	# test all targets/boards
 	$(TINYGO) build -size short -o test.hex -target=pca10040-s132v6     examples/blinky1
 	@$(MD5SUM) test.hex
@@ -226,6 +234,8 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-m4          examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pybadge             examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=metro-m4-airlift    examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nucleo-f103rb       examples/blinky1
@@ -242,10 +252,8 @@ ifneq ($(AVR), 0)
 	$(TINYGO) build -size short -o test.hex -target=digispark           examples/blinky1
 	@$(MD5SUM) test.hex
 endif
-ifneq ($(RISCV), 0)
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex
-endif
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/export
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/main

@@ -51,6 +51,7 @@ The following 22 microcontroller boards are currently supported:
 * [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 Trinket M0](https://www.adafruit.com/product/3500)
 * [Arduino Nano33 IoT](https://store.arduino.cc/nano-33-iot)
 * [Arduino Uno](https://store.arduino.cc/arduino-uno-rev3)
@@ -62,6 +63,7 @@ The following 22 microcontroller boards are currently supported:
 * [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)
 * [Phytec reel board](https://www.phytec.eu/product-eu/internet-of-things/reelboard/)
+* [PineTime DevKit](https://www.pine64.org/pinetime/)
 * [SiFIve HiFive1](https://www.sifive.com/boards/hifive1)
 * [ST Micro "Nucleo F103RB"](https://www.st.com/en/evaluation-tools/nucleo-f103rb.html)
 * [ST Micro STM32F103XX "Bluepill"](http://wiki.stm32duino.com/index.php?title=Blue_Pill)
@@ -125,3 +127,5 @@ The original reasoning was: if [Python](https://micropython.org/) can run on mic
 ## License

 This project is licensed under the BSD 3-clause license, just like the [Go project](https://golang.org/LICENSE) itself.
+
+Some code has been copied from the LLVM project and is therefore licensed under [a variant of the Apache 2.0 license](http://releases.llvm.org/9.0.0/LICENSE.TXT). This has been clearly indicated in the header of these files.
@@ -6,7 +6,7 @@ trigger:

 jobs:
 - job: Build
-  timeoutInMinutes: 180
+  timeoutInMinutes: 240 # 4h
  pool:
    vmImage: 'VS2017-Win2016'
  steps:
@@ -71,4 +71,4 @@ jobs:
        script: |
          export PATH="/c/Go1.13/bin:$PATH:./llvm-build/bin:/c/Program Files/qemu"
          unset GOROOT
-          make smoketest TINYGO=build/tinygo AVR=0 RISCV=0
+          make smoketest TINYGO=build/tinygo AVR=0
@@ -33,10 +33,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 	// Compile Go code to IR.
 	errs := c.Compile(pkgName)
 	if len(errs) != 0 {
-		if len(errs) == 1 {
-			return errs[0]
-		}
-		return &MultiError{errs}
+		return newMultiError(errs)
 	}
 	if config.Options.PrintIR {
 		fmt.Println("; Generated LLVM IR:")
@@ -72,22 +69,23 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri

 	// Optimization levels here are roughly the same as Clang, but probably not
 	// exactly.
+	errs = nil
 	switch config.Options.Opt {
 	case "none:", "0":
-		err = c.Optimize(0, 0, 0) // -O0
+		errs = c.Optimize(0, 0, 0) // -O0
 	case "1":
-		err = c.Optimize(1, 0, 0) // -O1
+		errs = c.Optimize(1, 0, 0) // -O1
 	case "2":
-		err = c.Optimize(2, 0, 225) // -O2
+		errs = c.Optimize(2, 0, 225) // -O2
 	case "s":
-		err = c.Optimize(2, 1, 225) // -Os
+		errs = c.Optimize(2, 1, 225) // -Os
 	case "z":
-		err = c.Optimize(2, 2, 5) // -Oz, default
+		errs = c.Optimize(2, 2, 5) // -Oz, default
 	default:
-		err = errors.New("unknown optimization level: -opt=" + config.Options.Opt)
+		errs = []error{errors.New("unknown optimization level: -opt=" + config.Options.Opt)}
 	}
-	if err != nil {
-		return err
+	if len(errs) > 0 {
+		return newMultiError(errs)
 	}
 	if err := c.Verify(); err != nil {
 		return errors.New("verification failure after LLVM optimization passes")
@@ -154,11 +152,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 		for i, path := range config.ExtraFiles() {
 			abspath := filepath.Join(root, path)
 			outpath := filepath.Join(dir, "extra-"+strconv.Itoa(i)+"-"+filepath.Base(path)+".o")
-			cmdNames := []string{config.Target.Compiler}
-			if names, ok := commands[config.Target.Compiler]; ok {
-				cmdNames = names
-			}
-			err := execCommand(cmdNames, append(config.CFlags(), "-c", "-o", outpath, abspath)...)
+			err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, abspath)...)
 			if err != nil {
 				return &commandError{"failed to build", path, err}
 			}
@@ -170,11 +164,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 			for _, file := range pkg.CFiles {
 				path := filepath.Join(pkg.Package.Dir, file)
 				outpath := filepath.Join(dir, "pkg"+strconv.Itoa(i)+"-"+file+".o")
-				cmdNames := []string{config.Target.Compiler}
-				if names, ok := commands[config.Target.Compiler]; ok {
-					cmdNames = names
-				}
-				err := execCommand(cmdNames, append(config.CFlags(), "-c", "-o", outpath, path)...)
+				err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, path)...)
 				if err != nil {
 					return &commandError{"failed to build", path, err}
 				}
@@ -236,7 +236,11 @@ func CompileBuiltins(target string, callback func(path string) error) error {
 		// Note: -fdebug-prefix-map is necessary to make the output archive
 		// reproducible. Otherwise the temporary directory is stored in the
 		// archive itself, which varies each run.
-		err := execCommand(commands["clang"], "-c", "-Oz", "-g", "-Werror", "-Wall", "-std=c11", "-fshort-enums", "-nostdlibinc", "-ffunction-sections", "-fdata-sections", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir, "-o", objpath, srcpath)
+		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}
 		}
@@ -0,0 +1,504 @@
+// +build byollvm
+
+//===-- cc1as.cpp - Clang Assembler  --------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This is the entry point to the clang -cc1as functionality, which implements
+// the direct interface to the LLVM MC based assembler.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/DiagnosticOptions.h"
+#include "clang/Driver/DriverDiagnostic.h"
+#include "clang/Driver/Options.h"
+#include "clang/Frontend/FrontendDiagnostic.h"
+#include "clang/Frontend/TextDiagnosticPrinter.h"
+#include "clang/Frontend/Utils.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCCodeEmitter.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCParser/MCAsmParser.h"
+#include "llvm/MC/MCParser/MCTargetAsmParser.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSectionMachO.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/MC/MCTargetOptions.h"
+#include "llvm/Option/Arg.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/Option/OptTable.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/Timer.h"
+#include "llvm/Support/raw_ostream.h"
+#include <memory>
+#include <system_error>
+using namespace clang;
+using namespace clang::driver;
+using namespace clang::driver::options;
+using namespace llvm;
+using namespace llvm::opt;
+
+#include "cc1as.h"
+
+bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
+                                         ArrayRef<const char *> Argv,
+                                         DiagnosticsEngine &Diags) {
+  bool Success = true;
+
+  // Parse the arguments.
+  std::unique_ptr<OptTable> OptTbl(createDriverOptTable());
+
+  const unsigned IncludedFlagsBitmask = options::CC1AsOption;
+  unsigned MissingArgIndex, MissingArgCount;
+  InputArgList Args = OptTbl->ParseArgs(Argv, MissingArgIndex, MissingArgCount,
+                                        IncludedFlagsBitmask);
+
+  // Check for missing argument error.
+  if (MissingArgCount) {
+    Diags.Report(diag::err_drv_missing_argument)
+        << Args.getArgString(MissingArgIndex) << MissingArgCount;
+    Success = false;
+  }
+
+  // Issue errors on unknown arguments.
+  for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
+    auto ArgString = A->getAsString(Args);
+    std::string Nearest;
+    if (OptTbl->findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
+      Diags.Report(diag::err_drv_unknown_argument) << ArgString;
+    else
+      Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
+          << ArgString << Nearest;
+    Success = false;
+  }
+
+  // Construct the invocation.
+
+  // Target Options
+  Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
+  Opts.CPU = Args.getLastArgValue(OPT_target_cpu);
+  Opts.Features = Args.getAllArgValues(OPT_target_feature);
+
+  // Use the default target triple if unspecified.
+  if (Opts.Triple.empty())
+    Opts.Triple = llvm::sys::getDefaultTargetTriple();
+
+  // Language Options
+  Opts.IncludePaths = Args.getAllArgValues(OPT_I);
+  Opts.NoInitialTextSection = Args.hasArg(OPT_n);
+  Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
+  // Any DebugInfoKind implies GenDwarfForAssembly.
+  Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
+
+  if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
+                                     OPT_compress_debug_sections_EQ)) {
+    if (A->getOption().getID() == OPT_compress_debug_sections) {
+      // TODO: be more clever about the compression type auto-detection
+      Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
+    } else {
+      Opts.CompressDebugSections =
+          llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
+              .Case("none", llvm::DebugCompressionType::None)
+              .Case("zlib", llvm::DebugCompressionType::Z)
+              .Case("zlib-gnu", llvm::DebugCompressionType::GNU)
+              .Default(llvm::DebugCompressionType::None);
+    }
+  }
+
+  Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
+  Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
+  Opts.DwarfDebugFlags = Args.getLastArgValue(OPT_dwarf_debug_flags);
+  Opts.DwarfDebugProducer = Args.getLastArgValue(OPT_dwarf_debug_producer);
+  Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
+  Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
+
+  for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
+    Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));
+
+  // Frontend Options
+  if (Args.hasArg(OPT_INPUT)) {
+    bool First = true;
+    for (const Arg *A : Args.filtered(OPT_INPUT)) {
+      if (First) {
+        Opts.InputFile = A->getValue();
+        First = false;
+      } else {
+        Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
+        Success = false;
+      }
+    }
+  }
+  Opts.LLVMArgs = Args.getAllArgValues(OPT_mllvm);
+  Opts.OutputPath = Args.getLastArgValue(OPT_o);
+  Opts.SplitDwarfOutput = Args.getLastArgValue(OPT_split_dwarf_output);
+  if (Arg *A = Args.getLastArg(OPT_filetype)) {
+    StringRef Name = A->getValue();
+    unsigned OutputType = StringSwitch<unsigned>(Name)
+      .Case("asm", FT_Asm)
+      .Case("null", FT_Null)
+      .Case("obj", FT_Obj)
+      .Default(~0U);
+    if (OutputType == ~0U) {
+      Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
+      Success = false;
+    } else
+      Opts.OutputType = FileType(OutputType);
+  }
+  Opts.ShowHelp = Args.hasArg(OPT_help);
+  Opts.ShowVersion = Args.hasArg(OPT_version);
+
+  // Transliterate Options
+  Opts.OutputAsmVariant =
+      getLastArgIntValue(Args, OPT_output_asm_variant, 0, Diags);
+  Opts.ShowEncoding = Args.hasArg(OPT_show_encoding);
+  Opts.ShowInst = Args.hasArg(OPT_show_inst);
+
+  // Assemble Options
+  Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
+  Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
+  Opts.FatalWarnings = Args.hasArg(OPT_massembler_fatal_warnings);
+  Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
+  Opts.TargetABI = Args.getLastArgValue(OPT_target_abi);
+  Opts.IncrementalLinkerCompatible =
+      Args.hasArg(OPT_mincremental_linker_compatible);
+  Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
+
+  // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
+  // EmbedBitcode behaves the same for all embed options for assembly files.
+  if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
+    Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
+                            .Case("all", 1)
+                            .Case("bitcode", 1)
+                            .Case("marker", 1)
+                            .Default(0);
+  }
+
+  return Success;
+}
+
+static std::unique_ptr<raw_fd_ostream>
+getOutputStream(StringRef Path, DiagnosticsEngine &Diags, bool Binary) {
+  // Make sure that the Out file gets unlinked from the disk if we get a
+  // SIGINT.
+  if (Path != "-")
+    sys::RemoveFileOnSignal(Path);
+
+  std::error_code EC;
+  auto Out = 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;
+  }
+
+  return Out;
+}
+
+bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags) {
+  // Get the target specific parser.
+  std::string Error;
+  const Target *TheTarget = TargetRegistry::lookupTarget(Opts.Triple, Error);
+  if (!TheTarget)
+    return Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
+
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer =
+      MemoryBuffer::getFileOrSTDIN(Opts.InputFile);
+
+  if (std::error_code EC = Buffer.getError()) {
+    Error = EC.message();
+    return Diags.Report(diag::err_fe_error_reading) << Opts.InputFile;
+  }
+
+  SourceMgr SrcMgr;
+
+  // Tell SrcMgr about this buffer, which is what the parser will pick up.
+  unsigned BufferIndex = SrcMgr.AddNewSourceBuffer(std::move(*Buffer), SMLoc());
+
+  // Record the location of the include directories so that the lexer can find
+  // it later.
+  SrcMgr.setIncludeDirs(Opts.IncludePaths);
+
+  std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(Opts.Triple));
+  assert(MRI && "Unable to create target register info!");
+
+  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
+  // may be created with a combination of default and explicit settings.
+  MAI->setCompressDebugSections(Opts.CompressDebugSections);
+
+  MAI->setRelaxELFRelocations(Opts.RelaxELFRelocations);
+
+  bool IsBinary = Opts.OutputType == AssemblerInvocation::FT_Obj;
+  if (Opts.OutputPath.empty())
+    Opts.OutputPath = "-";
+  std::unique_ptr<raw_fd_ostream> FDOS =
+      getOutputStream(Opts.OutputPath, Diags, IsBinary);
+  if (!FDOS)
+    return true;
+  std::unique_ptr<raw_fd_ostream> DwoOS;
+  if (!Opts.SplitDwarfOutput.empty())
+    DwoOS = getOutputStream(Opts.SplitDwarfOutput, Diags, IsBinary);
+
+  // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
+  // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
+  std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());
+
+  MCContext Ctx(MAI.get(), MRI.get(), MOFI.get(), &SrcMgr);
+
+  bool PIC = false;
+  if (Opts.RelocationModel == "static") {
+    PIC = false;
+  } else if (Opts.RelocationModel == "pic") {
+    PIC = true;
+  } else {
+    assert(Opts.RelocationModel == "dynamic-no-pic" &&
+           "Invalid PIC model!");
+    PIC = false;
+  }
+
+  MOFI->InitMCObjectFileInfo(Triple(Opts.Triple), PIC, Ctx);
+  if (Opts.SaveTemporaryLabels)
+    Ctx.setAllowTemporaryLabels(false);
+  if (Opts.GenDwarfForAssembly)
+    Ctx.setGenDwarfForAssembly(true);
+  if (!Opts.DwarfDebugFlags.empty())
+    Ctx.setDwarfDebugFlags(StringRef(Opts.DwarfDebugFlags));
+  if (!Opts.DwarfDebugProducer.empty())
+    Ctx.setDwarfDebugProducer(StringRef(Opts.DwarfDebugProducer));
+  if (!Opts.DebugCompilationDir.empty())
+    Ctx.setCompilationDir(Opts.DebugCompilationDir);
+  else {
+    // If no compilation dir is set, try to use the current directory.
+    SmallString<128> CWD;
+    if (!sys::fs::current_path(CWD))
+      Ctx.setCompilationDir(CWD);
+  }
+  if (!Opts.DebugPrefixMap.empty())
+    for (const auto &KV : Opts.DebugPrefixMap)
+      Ctx.addDebugPrefixMapEntry(KV.first, KV.second);
+  if (!Opts.MainFileName.empty())
+    Ctx.setMainFileName(StringRef(Opts.MainFileName));
+  Ctx.setDwarfVersion(Opts.DwarfVersion);
+  if (Opts.GenDwarfForAssembly)
+    Ctx.setGenDwarfRootFile(Opts.InputFile,
+                            SrcMgr.getMemoryBuffer(BufferIndex)->getBuffer());
+
+  // Build up the feature string from the target feature list.
+  std::string FS;
+  if (!Opts.Features.empty()) {
+    FS = Opts.Features[0];
+    for (unsigned i = 1, e = Opts.Features.size(); i != e; ++i)
+      FS += "," + Opts.Features[i];
+  }
+
+  std::unique_ptr<MCStreamer> Str;
+
+  std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
+  std::unique_ptr<MCSubtargetInfo> STI(
+      TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
+
+  raw_pwrite_stream *Out = FDOS.get();
+  std::unique_ptr<buffer_ostream> BOS;
+
+  MCTargetOptions MCOptions;
+  MCOptions.ABIName = Opts.TargetABI;
+
+  // FIXME: There is a bit of code duplication with addPassesToEmitFile.
+  if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
+    MCInstPrinter *IP = TheTarget->createMCInstPrinter(
+        llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
+
+    std::unique_ptr<MCCodeEmitter> CE;
+    if (Opts.ShowEncoding)
+      CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
+    std::unique_ptr<MCAsmBackend> MAB(
+        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
+
+    auto FOut = 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),
+        Opts.ShowInst));
+  } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
+    Str.reset(createNullStreamer(Ctx));
+  } else {
+    assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
+           "Invalid file type!");
+    if (!FDOS->supportsSeeking()) {
+      BOS = make_unique<buffer_ostream>(*FDOS);
+      Out = BOS.get();
+    }
+
+    std::unique_ptr<MCCodeEmitter> CE(
+        TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
+    std::unique_ptr<MCAsmBackend> MAB(
+        TheTarget->createMCAsmBackend(*STI, *MRI, MCOptions));
+    std::unique_ptr<MCObjectWriter> OW =
+        DwoOS ? MAB->createDwoObjectWriter(*Out, *DwoOS)
+              : MAB->createObjectWriter(*Out);
+
+    Triple T(Opts.Triple);
+    Str.reset(TheTarget->createMCObjectStreamer(
+        T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI,
+        Opts.RelaxAll, Opts.IncrementalLinkerCompatible,
+        /*DWARFMustBeAtTheEnd*/ true));
+    Str.get()->InitSections(Opts.NoExecStack);
+  }
+
+  // When -fembed-bitcode is passed to clang_as, a 1-byte marker
+  // is emitted in __LLVM,__asm section if the object file is MachO format.
+  if (Opts.EmbedBitcode && Ctx.getObjectFileInfo()->getObjectFileType() ==
+                               MCObjectFileInfo::IsMachO) {
+    MCSection *AsmLabel = Ctx.getMachOSection(
+        "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
+    Str.get()->SwitchSection(AsmLabel);
+    Str.get()->EmitZeros(1);
+  }
+
+  // Assembly to object compilation should leverage assembly info.
+  Str->setUseAssemblerInfoForParsing(true);
+
+  bool Failed = false;
+
+  std::unique_ptr<MCAsmParser> Parser(
+      createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
+
+  // FIXME: init MCTargetOptions from sanitizer flags here.
+  std::unique_ptr<MCTargetAsmParser> TAP(
+      TheTarget->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
+  if (!TAP)
+    Failed = Diags.Report(diag::err_target_unknown_triple) << Opts.Triple;
+
+  // Set values for symbols, if any.
+  for (auto &S : Opts.SymbolDefs) {
+    auto Pair = StringRef(S).split('=');
+    auto Sym = Pair.first;
+    auto Val = Pair.second;
+    int64_t Value;
+    // We have already error checked this in the driver.
+    Val.getAsInteger(0, Value);
+    Ctx.setSymbolValue(Parser->getStreamer(), Sym, Value);
+  }
+
+  if (!Failed) {
+    Parser->setTargetParser(*TAP.get());
+    Failed = Parser->Run(Opts.NoInitialTextSection);
+  }
+
+  // Close Streamer first.
+  // It might have a reference to the output stream.
+  Str.reset();
+  // Close the output stream early.
+  BOS.reset();
+  FDOS.reset();
+
+  // Delete output file if there were errors.
+  if (Failed) {
+    if (Opts.OutputPath != "-")
+      sys::fs::remove(Opts.OutputPath);
+    if (!Opts.SplitDwarfOutput.empty() && Opts.SplitDwarfOutput != "-")
+      sys::fs::remove(Opts.SplitDwarfOutput);
+  }
+
+  return Failed;
+}
+
+static void LLVMErrorHandler(void *UserData, const std::string &Message,
+                             bool GenCrashDiag) {
+  DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
+
+  Diags.Report(diag::err_fe_error_backend) << Message;
+
+  // We cannot recover from llvm errors.
+  exit(1);
+}
+
+int cc1as_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
+  // Initialize targets and assembly printers/parsers.
+  InitializeAllTargetInfos();
+  InitializeAllTargetMCs();
+  InitializeAllAsmParsers();
+
+  // Construct our diagnostic client.
+  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
+  TextDiagnosticPrinter *DiagClient
+    = new TextDiagnosticPrinter(errs(), &*DiagOpts);
+  DiagClient->setPrefix("clang -cc1as");
+  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
+  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
+
+  // Set an error handler, so that any LLVM backend diagnostics go through our
+  // error handler.
+  ScopedFatalErrorHandler FatalErrorHandler
+    (LLVMErrorHandler, static_cast<void*>(&Diags));
+
+  // Parse the arguments.
+  AssemblerInvocation Asm;
+  if (!AssemblerInvocation::CreateFromArgs(Asm, Argv, Diags))
+    return 1;
+
+  if (Asm.ShowHelp) {
+    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;
+  }
+
+  // Honor -version.
+  //
+  // FIXME: Use a better -version message?
+  if (Asm.ShowVersion) {
+    llvm::cl::PrintVersionMessage();
+    return 0;
+  }
+
+  // Honor -mllvm.
+  //
+  // FIXME: Remove this, one day.
+  if (!Asm.LLVMArgs.empty()) {
+    unsigned NumArgs = Asm.LLVMArgs.size();
+    auto Args = 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();
+    Args[NumArgs + 1] = nullptr;
+    llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
+  }
+
+  // Execute the invocation, unless there were parsing errors.
+  bool Failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
+
+  // If any timers were active but haven't been destroyed yet, print their
+  // results now.
+  TimerGroup::printAll(errs());
+
+  return !!Failed;
+}
@@ -0,0 +1,120 @@
+//===-- cc1as.h - Clang Assembler  ----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This is the entry point to the clang -cc1as functionality, which implements
+// the direct interface to the LLVM MC based assembler.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ArrayRef.h"
+
+/// Helper class for representing a single invocation of the assembler.
+struct AssemblerInvocation {
+  /// @name Target Options
+  /// @{
+
+  /// The name of the target triple to assemble for.
+  std::string Triple;
+
+  /// If given, the name of the target CPU to determine which instructions
+  /// are legal.
+  std::string CPU;
+
+  /// The list of target specific features to enable or disable -- this should
+  /// be a list of strings starting with '+' or '-'.
+  std::vector<std::string> Features;
+
+  /// The list of symbol definitions.
+  std::vector<std::string> SymbolDefs;
+
+  /// @}
+  /// @name Language Options
+  /// @{
+
+  std::vector<std::string> IncludePaths;
+  unsigned NoInitialTextSection : 1;
+  unsigned SaveTemporaryLabels : 1;
+  unsigned GenDwarfForAssembly : 1;
+  unsigned RelaxELFRelocations : 1;
+  unsigned DwarfVersion;
+  std::string DwarfDebugFlags;
+  std::string DwarfDebugProducer;
+  std::string DebugCompilationDir;
+  std::map<const std::string, const std::string> DebugPrefixMap;
+  llvm::DebugCompressionType CompressDebugSections =
+      llvm::DebugCompressionType::None;
+  std::string MainFileName;
+  std::string SplitDwarfOutput;
+
+  /// @}
+  /// @name Frontend Options
+  /// @{
+
+  std::string InputFile;
+  std::vector<std::string> LLVMArgs;
+  std::string OutputPath;
+  enum FileType {
+    FT_Asm,  ///< Assembly (.s) output, transliterate mode.
+    FT_Null, ///< No output, for timing purposes.
+    FT_Obj   ///< Object file output.
+  };
+  FileType OutputType;
+  unsigned ShowHelp : 1;
+  unsigned ShowVersion : 1;
+
+  /// @}
+  /// @name Transliterate Options
+  /// @{
+
+  unsigned OutputAsmVariant;
+  unsigned ShowEncoding : 1;
+  unsigned ShowInst : 1;
+
+  /// @}
+  /// @name Assembler Options
+  /// @{
+
+  unsigned RelaxAll : 1;
+  unsigned NoExecStack : 1;
+  unsigned FatalWarnings : 1;
+  unsigned IncrementalLinkerCompatible : 1;
+  unsigned EmbedBitcode : 1;
+
+  /// The name of the relocation model to use.
+  std::string RelocationModel;
+
+  /// The ABI targeted by the backend. Specified using -target-abi. Empty
+  /// otherwise.
+  std::string TargetABI;
+
+  /// @}
+
+public:
+  AssemblerInvocation() {
+    Triple = "";
+    NoInitialTextSection = 0;
+    InputFile = "-";
+    OutputPath = "-";
+    OutputType = FT_Asm;
+    OutputAsmVariant = 0;
+    ShowInst = 0;
+    ShowEncoding = 0;
+    RelaxAll = 0;
+    NoExecStack = 0;
+    FatalWarnings = 0;
+    IncrementalLinkerCompatible = 0;
+    DwarfVersion = 0;
+    EmbedBitcode = 0;
+  }
+
+  static bool CreateFromArgs(AssemblerInvocation &Res,
+                             ArrayRef<const char *> Argv,
+                             DiagnosticsEngine &Diags);
+};
+
+bool ExecuteAssembler(AssemblerInvocation &Opts, DiagnosticsEngine &Diags);
@@ -0,0 +1,97 @@
+// +build byollvm
+
+#include <clang/Basic/DiagnosticOptions.h>
+#include <clang/CodeGen/CodeGenAction.h>
+#include <clang/Driver/Compilation.h>
+#include <clang/Driver/Driver.h>
+#include <clang/Frontend/CompilerInstance.h>
+#include <clang/Frontend/CompilerInvocation.h>
+#include <clang/Frontend/FrontendDiagnostic.h>
+#include <clang/Frontend/TextDiagnosticPrinter.h>
+#include <clang/FrontendTool/Utils.h>
+#include <llvm/ADT/IntrusiveRefCntPtr.h>
+#include <llvm/Option/Option.h>
+
+using namespace llvm;
+using namespace clang;
+
+#include "cc1as.h"
+
+// This file provides C wrappers for the builtin tools cc1 and cc1as
+// provided by Clang, and calls them as the driver would call them.
+
+extern "C" {
+
+bool tinygo_clang_driver(int argc, char **argv) {
+	std::vector<const char*> args(argv, argv + argc);
+
+	// The compiler invocation needs a DiagnosticsEngine so it can report problems
+	llvm::IntrusiveRefCntPtr<clang::DiagnosticOptions> DiagOpts = new clang::DiagnosticOptions();
+	clang::TextDiagnosticPrinter DiagnosticPrinter(llvm::errs(), &*DiagOpts);
+	clang::DiagnosticsEngine Diags(llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs>(new clang::DiagnosticIDs()), &*DiagOpts, &DiagnosticPrinter, false);
+
+	// Create the clang driver
+	clang::driver::Driver TheDriver(args[0], llvm::sys::getDefaultTargetTriple(), Diags);
+
+	// Create the set of actions to perform
+	std::unique_ptr<clang::driver::Compilation> C(TheDriver.BuildCompilation(args));
+	if (!C) {
+		return false;
+	}
+	const clang::driver::JobList &Jobs = C->getJobs();
+
+	// There may be more than one job, for example for .S files
+	// (preprocessor + assembler).
+	for (auto Cmd : Jobs) {
+		// Select the tool: cc1 or cc1as.
+		const llvm::opt::ArgStringList &CCArgs = Cmd.getArguments();
+
+		if (strcmp(*CCArgs.data(), "-cc1") == 0) {
+			// This is the C frontend.
+			// Initialize a compiler invocation object from the clang (-cc1) arguments.
+			std::unique_ptr<clang::CompilerInstance> Clang(new clang::CompilerInstance());
+			bool success = clang::CompilerInvocation::CreateFromArgs(
+					Clang->getInvocation(),
+					const_cast<const char **>(CCArgs.data()),
+					const_cast<const char **>(CCArgs.data()) + CCArgs.size(),
+					Diags);
+			if (!success) {
+				return false;
+			}
+
+			// Create the actual diagnostics engine.
+			Clang->createDiagnostics();
+			if (!Clang->hasDiagnostics()) {
+				return false;
+			}
+
+			// Execute the frontend actions.
+			success = ExecuteCompilerInvocation(Clang.get());
+			if (!success) {
+				return false;
+			}
+
+		} else if (strcmp(*CCArgs.data(), "-cc1as") == 0) {
+			// This is the assembler frontend. Parse the arguments.
+			AssemblerInvocation Asm;
+			if (!AssemblerInvocation::CreateFromArgs(Asm, llvm::ArrayRef<const char*>(CCArgs).slice(1), Diags))
+				return false;
+
+			// Execute the invocation, unless there were parsing errors.
+			bool failed = Diags.hasErrorOccurred() || ExecuteAssembler(Asm, Diags);
+			if (failed) {
+				return false;
+			}
+
+		} else {
+			// Unknown tool, print the tool and exit.
+			fprintf(stderr, "unknown tool: %s\n", *CCArgs.data());
+			return false;
+		}
+	}
+
+	// Commands executed successfully.
+	return true;
+}
+
+} // extern "C"
@@ -34,6 +34,12 @@ 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 the llvm90 installed from ports
+	if runtime.GOOS == "freebsd" {
+		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")
+	}
 }

 func execCommand(cmdNames []string, args ...string) error {
@@ -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()
+}
@@ -71,7 +71,7 @@ func GorootVersionString(goroot string) (string, error) {
 // various ways.
 func getClangHeaderPath(TINYGOROOT string) string {
 	// Check whether we're running from the source directory.
-	path := filepath.Join(TINYGOROOT, "llvm", "tools", "clang", "lib", "Headers")
+	path := filepath.Join(TINYGOROOT, "llvm-project", "clang", "lib", "Headers")
 	if _, err := os.Stat(path); !os.IsNotExist(err) {
 		return path
 	}
@@ -12,6 +12,20 @@ func (e *MultiError) Error() string {
 	return e.Errs[0].Error()
 }

+// newMultiError returns a *MultiError if there is more than one error, or
+// returns that error directly when there is only one. Passing an empty slice
+// will lead to a panic.
+func newMultiError(errs []error) error {
+	switch len(errs) {
+	case 0:
+		panic("attempted to create empty MultiError")
+	case 1:
+		return errs[0]
+	default:
+		return &MultiError{errs}
+	}
+}
+
 // commandError is an error type to wrap os/exec.Command errors. This provides
 // some more information regarding what went wrong while running a command.
 type commandError struct {
@@ -22,11 +22,9 @@ var flagUpdate = flag.Bool("update", false, "Update images based on test output.
 func TestCGo(t *testing.T) {
 	var cflags = []string{"--target=armv6m-none-eabi"}

-	for _, name := range []string{"basic", "errors", "types", "flags"} {
+	for _, name := range []string{"basic", "errors", "types", "flags", "const"} {
 		name := name // avoid a race condition
 		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
 			// Read the AST in memory.
 			path := filepath.Join("testdata", name+".go")
 			fset := token.NewFileSet()
@@ -52,6 +52,13 @@ func parseConstExpr(t *tokenizer) (ast.Expr, *scanner.Error) {
 		}
 		t.Next()
 		return expr, nil
+	case token.IDENT:
+		expr := &ast.Ident{
+			NamePos: t.pos,
+			Name:    "C." + t.value,
+		}
+		t.Next()
+		return expr, nil
 	case token.EOF:
 		return nil, &scanner.Error{
 			Pos: t.fset.Position(t.pos),
@@ -133,8 +140,10 @@ func (t *tokenizer) Next() {
 				if c == '.' {
 					hasDot = true
 				}
-				if (c >= '0' && c <= '9') || c == '.' || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') {
+				if c >= '0' && c <= '9' || c == '.' || c == '_' || c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' {
 					tokenLen = i + 1
+				} else {
+					break
 				}
 			}
 			t.value = t.buf[:tokenLen]
@@ -150,6 +159,21 @@ func (t *tokenizer) Next() {
 				t.value = strings.TrimRight(t.value, "uUlL")
 			}
 			return
+		case c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c == '_':
+			// Identifier. Find all remaining tokens that are part of this
+			// identifier.
+			tokenLen := len(t.buf)
+			for i, c := range t.buf {
+				if c >= '0' && c <= '9' || c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c == '_' {
+					tokenLen = i + 1
+				} else {
+					break
+				}
+			}
+			t.value = t.buf[:tokenLen]
+			t.buf = t.buf[tokenLen:]
+			t.token = token.IDENT
+			return
 		case c == '"':
 			// String constant. Find the first '"' character that is not
 			// preceded by a backslash.
@@ -21,8 +21,8 @@ func TestParseConst(t *testing.T) {
 		{`5)`, `error: 1:2: unexpected token )`},
 		{"  \t)", `error: 1:4: unexpected token )`},
 		{`5.8f`, `5.8`},
-		{`foo`, `error: 1:1: unexpected token ILLEGAL`}, // identifiers unimplemented
-		{``, `error: 1:1: empty constant`},              // empty constants not allowed in Go
+		{`foo`, `C.foo`},
+		{``, `error: 1:1: empty constant`}, // empty constants not allowed in Go
 		{`"foo"`, `"foo"`},
 		{`"a\\n"`, `"a\\n"`},
 		{`"a\n"`, `"a\n"`},
@@ -30,6 +30,7 @@ func TestParseConst(t *testing.T) {
 		{`'a'`, `'a'`},
 		{`0b10`, `0b10`},
 		{`0x1234_5678`, `0x1234_5678`},
+		{`5 5`, `error: 1:3: unexpected token INT`}, // test for a bugfix
 	} {
 		fset := token.NewFileSet()
 		startPos := fset.AddFile("", -1, 1000).Pos(0)
@@ -5,7 +5,9 @@ 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/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"
@@ -0,0 +1,12 @@
+package main
+
+/*
+#define foo 3
+#define bar foo
+*/
+import "C"
+
+const (
+	Foo = C.foo
+	Bar = C.bar
+)
@@ -0,0 +1,29 @@
+package main
+
+import "unsafe"
+
+var _ unsafe.Pointer
+
+const C.bar = C.foo
+const C.foo = 3
+
+type C.int16_t = int16
+type C.int32_t = int32
+type C.int64_t = int64
+type C.int8_t = int8
+type C.uint16_t = uint16
+type C.uint32_t = uint32
+type C.uint64_t = uint64
+type C.uint8_t = uint8
+type C.uintptr_t = uintptr
+type C.char uint8
+type C.int int32
+type C.long int32
+type C.longlong int64
+type C.schar int8
+type C.short int16
+type C.uchar uint8
+type C.uint uint32
+type C.ulong uint32
+type C.ulonglong uint64
+type C.ushort uint16
@@ -98,76 +98,75 @@ func (c *Compiler) checkValue(v llvm.Value, types map[llvm.Type]struct{}, specia
 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 fmt.Errorf("failed to validate value of instruction %q: %s", inst.Name(), err.Error())
+		return errorAt(inst, err.Error())
 	}

 	// check operands
 	for i := 0; i < inst.OperandsCount(); i++ {
 		if err := c.checkValue(inst.Operand(i), types, specials); err != nil {
-			return fmt.Errorf("failed to validate argument %d of instruction %q: %s", i, inst.Name(), err.Error())
+			return errorAt(inst, fmt.Sprintf("failed to validate operand %d of instruction %q: %s", i, inst.Name(), err.Error()))
 		}
 	}

 	return nil
 }

-func (c *Compiler) 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 {
-		return fmt.Errorf("failed to validate value of basic block %s: %s", bb.AsValue().Name(), err.Error())
+		errs = append(errs, errorAt(bb.Parent(), fmt.Sprintf("failed to validate value of basic block %s: %v", bb.AsValue().Name(), err)))
 	}

 	// check instructions
 	for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
 		if err := c.checkInstruction(inst, types, specials); err != nil {
-			return fmt.Errorf("failed to validate basic block %q: %s", bb.AsValue().Name(), err.Error())
+			errs = append(errs, err)
 		}
 	}

-	return nil
+	return errs
 }

-func (c *Compiler) 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 {
-		return fmt.Errorf("failed to validate value of function %s: %s", fn.Name(), err.Error())
+		errs = append(errs, fmt.Errorf("failed to validate value of function %s: %s", fn.Name(), err.Error()))
 	}

 	// check basic blocks
 	for bb := fn.FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
-		if err := c.checkBasicBlock(bb, types, specials); err != nil {
-			return fmt.Errorf("failed to validate basic block of function %s: %s", fn.Name(), err.Error())
-		}
+		errs = append(errs, c.checkBasicBlock(bb, types, specials)...)
 	}

-	return nil
+	return errs
 }

-func (c *Compiler) checkModule() error {
+func (c *Compiler) checkModule() []error {
 	// check for any context mismatches
+	var errs []error
 	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
-		return errors.New("module uses global context")
+		errs = append(errs, errors.New("module uses global context"))
 	default:
 		// we used some other context by accident
-		return fmt.Errorf("module uses context %v instead of the main context %v", c.mod.Context(), c.ctx)
+		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 := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-		if err := c.checkFunction(fn, types, specials); err != nil {
-			return err
-		}
+		errs = append(errs, c.checkFunction(fn, types, specials)...)
 	}
 	for g := c.mod.FirstGlobal(); !g.IsNil(); g = llvm.NextGlobal(g) {
 		if err := c.checkValue(g, types, specials); err != nil {
-			return fmt.Errorf("failed to verify global %s of module: %s", g.Name(), err.Error())
+			errs = append(errs, fmt.Errorf("failed to verify global %s of module: %s", g.Name(), err.Error()))
 		}
 	}

-	return nil
+	return errs
 }
@@ -217,7 +217,7 @@ func (c *Compiler) Compile(mainPath string) []error {
 				path = path[len(tinygoPath+"/src/"):]
 			}
 			switch path {
-			case "machine", "os", "reflect", "runtime", "runtime/volatile", "sync", "testing", "internal/reflectlite":
+			case "machine", "os", "reflect", "runtime", "runtime/interrupt", "runtime/volatile", "sync", "testing", "internal/reflectlite":
 				return path
 			default:
 				if strings.HasPrefix(path, "device/") || strings.HasPrefix(path, "examples/") {
@@ -251,13 +251,17 @@ func (c *Compiler) Compile(mainPath string) []error {
 			return []error{err}
 		}
 	} else {
-		_, err = lprogram.Import(mainPath, wd)
+		_, err = lprogram.Import(mainPath, wd, token.Position{
+			Filename: "build command-line-arguments",
+		})
 		if err != nil {
 			return []error{err}
 		}
 	}

-	_, err = lprogram.Import("runtime", "")
+	_, err = lprogram.Import("runtime", "", token.Position{
+		Filename: "build default import",
+	})
 	if err != nil {
 		return []error{err}
 	}
@@ -767,14 +771,6 @@ func (c *Compiler) attachDebugInfo(f *ir.Function) llvm.Metadata {
 }

 func (c *Compiler) attachDebugInfoRaw(f *ir.Function, llvmFn llvm.Value, suffix, filename string, line int) llvm.Metadata {
-	if _, ok := c.difiles[filename]; !ok {
-		dir, file := filepath.Split(filename)
-		if dir != "" {
-			dir = dir[:len(dir)-1]
-		}
-		c.difiles[filename] = c.dibuilder.CreateFile(file, dir)
-	}
-
 	// Debug info for this function.
 	diparams := make([]llvm.Metadata, 0, len(f.Params))
 	for _, param := range f.Params {
@@ -788,7 +784,7 @@ func (c *Compiler) attachDebugInfoRaw(f *ir.Function, llvmFn llvm.Value, suffix,
 	difunc := c.dibuilder.CreateFunction(c.difiles[filename], llvm.DIFunction{
 		Name:         f.RelString(nil) + suffix,
 		LinkageName:  f.LinkName() + suffix,
-		File:         c.difiles[filename],
+		File:         c.getDIFile(filename),
 		Line:         line,
 		Type:         diFuncType,
 		LocalToUnit:  true,
@@ -801,21 +797,37 @@ func (c *Compiler) attachDebugInfoRaw(f *ir.Function, llvmFn llvm.Value, suffix,
 	return difunc
 }

+// getDIFile returns a DIFile metadata node for the given filename. It tries to
+// use one that was already created, otherwise it falls back to creating a new
+// one.
+func (c *Compiler) getDIFile(filename string) llvm.Metadata {
+	if _, ok := c.difiles[filename]; !ok {
+		dir, file := filepath.Split(filename)
+		if dir != "" {
+			dir = dir[:len(dir)-1]
+		}
+		c.difiles[filename] = c.dibuilder.CreateFile(file, dir)
+	}
+	return c.difiles[filename]
+}
+
 func (c *Compiler) parseFunc(frame *Frame) {
 	if c.DumpSSA() {
 		fmt.Printf("\nfunc %s:\n", frame.fn.Function)
 	}
 	if !frame.fn.LLVMFn.IsDeclaration() {
-		c.addError(frame.fn.Pos(), "function is already defined:"+frame.fn.LLVMFn.Name())
+		errValue := frame.fn.LLVMFn.Name() + " redeclared in this program"
+		fnPos := getPosition(frame.fn.LLVMFn)
+		if fnPos.IsValid() {
+			errValue += "\n\tprevious declaration at " + fnPos.String()
+		}
+		c.addError(frame.fn.Pos(), errValue)
 		return
 	}
 	if !frame.fn.IsExported() {
 		frame.fn.LLVMFn.SetLinkage(llvm.InternalLinkage)
 		frame.fn.LLVMFn.SetUnnamedAddr(true)
 	}
-	if frame.fn.IsInterrupt() && strings.HasPrefix(c.Triple(), "avr") {
-		frame.fn.LLVMFn.SetFunctionCallConv(85) // CallingConv::AVR_SIGNAL
-	}

 	// Some functions have a pragma controlling the inlining level.
 	switch frame.fn.Inline() {
@@ -1297,6 +1309,8 @@ func (c *Compiler) parseCall(frame *Frame, instr *ssa.CallCommon) (llvm.Value, e
 			return c.emitVolatileLoad(frame, instr)
 		case strings.HasPrefix(name, "runtime/volatile.Store"):
 			return c.emitVolatileStore(frame, instr)
+		case name == "runtime/interrupt.New" && len(fn.Blocks) == 0:
+			return c.emitInterruptGlobal(frame, instr)
 		}

 		targetFunc := c.ir.GetFunction(fn)
@@ -14,6 +14,7 @@ package compiler
 //     frames.

 import (
+	"github.com/tinygo-org/tinygo/compiler/llvmutil"
 	"github.com/tinygo-org/tinygo/ir"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
@@ -34,6 +35,40 @@ func (c *Compiler) deferInitFunc(frame *Frame) {
 	c.builder.CreateStore(llvm.ConstPointerNull(deferType), frame.deferPtr)
 }

+// isInLoop checks if there is a path from a basic block to itself.
+func isInLoop(start *ssa.BasicBlock) bool {
+	// Use a breadth-first search to scan backwards through the block graph.
+	queue := []*ssa.BasicBlock{start}
+	checked := map[*ssa.BasicBlock]struct{}{}
+
+	for len(queue) > 0 {
+		// pop a block off of the queue
+		block := queue[len(queue)-1]
+		queue = queue[:len(queue)-1]
+
+		// Search through predecessors.
+		// Searching backwards means that this is pretty fast when the block is close to the start of the function.
+		// Defers are often placed near the start of the function.
+		for _, pred := range block.Preds {
+			if pred == start {
+				// cycle found
+				return true
+			}
+
+			if _, ok := checked[pred]; ok {
+				// block already checked
+				continue
+			}
+
+			// add to queue and checked map
+			queue = append(queue, pred)
+			checked[pred] = struct{}{}
+		}
+	}
+
+	return false
+}
+
 // emitDefer emits a single defer instruction, to be run when this function
 // returns.
 func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) {
@@ -127,12 +162,22 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) {
 		deferFrame = c.builder.CreateInsertValue(deferFrame, value, i, "")
 	}

-	// Put this struct in an alloca.
-	alloca := c.builder.CreateAlloca(deferFrameType, "defer.alloca")
-	c.builder.CreateStore(deferFrame, alloca)
+	// Put this struct in an allocation.
+	var alloca llvm.Value
+	if !isInLoop(instr.Block()) {
+		// This can safely use a stack allocation.
+		alloca = llvmutil.CreateEntryBlockAlloca(c.builder, deferFrameType, "defer.alloca")
+	} else {
+		// This may be hit a variable number of times, so use a heap allocation.
+		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 c.NeedsStackObjects() {
 		c.trackPointer(alloca)
 	}
+	c.builder.CreateStore(deferFrame, alloca)

 	// Push it on top of the linked list by replacing deferPtr.
 	allocaCast := c.builder.CreateBitCast(alloca, next.Type(), "defer.alloca.cast")
@@ -1,8 +1,12 @@
 package compiler

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

 func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
@@ -16,3 +20,42 @@ func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
 func (c *Compiler) addError(pos token.Pos, msg string) {
 	c.diagnostics = append(c.diagnostics, c.makeError(pos, msg))
 }
+
+// errorAt returns an error value at the location of the instruction.
+// The location information may not be complete as it depends on debug
+// information in the IR.
+func errorAt(inst llvm.Value, msg string) scanner.Error {
+	return scanner.Error{
+		Pos: getPosition(inst),
+		Msg: msg,
+	}
+}
+
+// getPosition returns the position information for the given value, as far as
+// it is available.
+func getPosition(val llvm.Value) token.Position {
+	if !val.IsAInstruction().IsNil() {
+		loc := val.InstructionDebugLoc()
+		if loc.IsNil() {
+			return token.Position{}
+		}
+		file := loc.LocationScope().ScopeFile()
+		return token.Position{
+			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
+			Line:     int(loc.LocationLine()),
+			Column:   int(loc.LocationColumn()),
+		}
+	} else if !val.IsAFunction().IsNil() {
+		loc := val.Subprogram()
+		if loc.IsNil() {
+			return token.Position{}
+		}
+		file := loc.ScopeFile()
+		return token.Position{
+			Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
+			Line:     int(loc.SubprogramLine()),
+		}
+	} else {
+		return token.Position{}
+	}
+}
@@ -104,7 +104,6 @@ package compiler
 // scheduler, which runs in the background scheduling all coroutines.

 import (
-	"errors"
 	"fmt"
 	"strings"

@@ -283,7 +282,7 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 			if use.IsConstant() && use.Opcode() == llvm.PtrToInt {
 				for _, call := range getUses(use) {
 					if call.IsACallInst().IsNil() || call.CalledValue().Name() != "runtime.makeGoroutine" {
-						return false, errors.New("async function " + f.Name() + " incorrectly used in ptrtoint, expected runtime.makeGoroutine")
+						return false, errorAt(call, "async function incorrectly used in ptrtoint, expected runtime.makeGoroutine")
 					}
 				}
 				// This is a go statement. Do not mark the parent as async, as
@@ -303,12 +302,19 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 				// Not a call instruction. Maybe a store to a global? In any
 				// case, this requires support for async calls across function
 				// pointers which is not yet supported.
-				return false, errors.New("async function " + f.Name() + " used as function pointer")
+				at := use
+				if use.IsAInstruction().IsNil() {
+					// The use might not be an instruction (for example, in the
+					// case of a const bitcast). Fall back to reporting the
+					// location of the function instead.
+					at = f
+				}
+				return false, errorAt(at, "async function "+f.Name()+" used as function pointer")
 			}
 			parent := use.InstructionParent().Parent()
 			for i := 0; i < use.OperandsCount()-1; i++ {
 				if use.Operand(i) == f {
-					return false, errors.New("async function " + f.Name() + " used as function pointer in " + parent.Name())
+					return false, errorAt(use, "async function "+f.Name()+" used as function pointer")
 				}
 			}
 			worklist = append(worklist, parent)
@@ -805,7 +811,7 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 				llvm.ConstNull(c.ctx.TokenType()),
 				llvm.ConstInt(c.ctx.Int1Type(), 0, false),
 			}, "")
-			wakeup := c.splitBasicBlock(inst, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.wakeup")
+			wakeup := llvmutil.SplitBasicBlock(c.builder, inst, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.wakeup")
 			c.builder.SetInsertPointBefore(inst)
 			sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
 			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), wakeup)
@@ -906,12 +912,12 @@ func (c *Compiler) lowerMakeGoroutineCalls(sched bool) error {
 		origFunc := ptrtointIn.Operand(0)
 		uses := getUses(goroutine)
 		if len(uses) != 1 || uses[0].IsAIntToPtrInst().IsNil() {
-			return errors.New("expected exactly 1 inttoptr use of runtime.makeGoroutine")
+			return errorAt(makeGoroutine, "expected exactly 1 inttoptr use of runtime.makeGoroutine")
 		}
 		inttoptrOut := uses[0]
 		uses = getUses(inttoptrOut)
 		if len(uses) != 1 || uses[0].IsACallInst().IsNil() {
-			return errors.New("expected exactly 1 call use of runtime.makeGoroutine bitcast")
+			return errorAt(inttoptrOut, "expected exactly 1 call use of runtime.makeGoroutine bitcast")
 		}
 		realCall := uses[0]

@@ -279,14 +279,14 @@ func (c *Compiler) getInterfaceMethodSet(typ *types.Named) llvm.Value {
 		return llvm.ConstGEP(global, []llvm.Value{zero, zero})
 	}

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

-	value := llvm.ConstArray(methods[0].Type(), methods)
+	value := llvm.ConstArray(c.i8ptrType, methods)
 	global = llvm.AddGlobal(c.mod, value.Type(), typ.String()+"$interface")
 	global.SetInitializer(value)
 	global.SetGlobalConstant(true)
@@ -295,7 +295,7 @@ func (c *Compiler) getInterfaceMethodSet(typ *types.Named) llvm.Value {
 }

 // getMethodSignature returns a global variable which is a reference to an
-// external *i16 indicating the indicating the signature of this method. It is
+// external *i8 indicating the indicating the signature of this method. It is
 // used during the interface lowering pass.
 func (c *Compiler) getMethodSignature(method *types.Func) llvm.Value {
 	signature := ir.MethodSignature(method)
@@ -0,0 +1,91 @@
+package compiler
+
+import (
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/ssa"
+	"tinygo.org/x/go-llvm"
+)
+
+// 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 (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{}, 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 := 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{}, c.makeError(instr.Pos(), "closures are not supported in interrupt.New")
+		}
+		// Fall back to a generic error.
+		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 := c.ir.Program.ImportedPackage("runtime/interrupt").Type("handle").Type()
+	globalLLVMType := c.getLLVMType(globalType)
+	globalName := "runtime/interrupt.$interrupt" + strconv.FormatInt(id.Int64(), 10)
+	if global := c.mod.NamedGlobal(globalName); !global.IsNil() {
+		return llvm.Value{}, c.makeError(instr.Pos(), "interrupt redeclared in this program")
+	}
+	global := llvm.AddGlobal(c.mod, globalLLVMType, globalName)
+	global.SetLinkage(llvm.PrivateLinkage)
+	global.SetGlobalConstant(true)
+	initializer := llvm.ConstNull(globalLLVMType)
+	initializer = llvm.ConstInsertValue(initializer, funcValue, []uint32{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 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:        c.getDIFile(pos.Filename),
+			Line:        pos.Line,
+			Type:        c.getDIType(globalType),
+			Expr:        c.dibuilder.CreateExpression(nil),
+			LocalToUnit: false,
+		})
+		global.AddMetadata(0, diglobal)
+	}
+
+	// Create the runtime/interrupt.Interrupt type. It is a struct with a single
+	// member of type int.
+	num := llvm.ConstPtrToInt(global, 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(c.Triple(), "avr") {
+		useFn := c.mod.NamedFunction("runtime/interrupt.use")
+		if useFn.IsNil() {
+			useFnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{interrupt.Type()}, false)
+			useFn = llvm.AddFunction(c.mod, "runtime/interrupt.use", useFnType)
+		}
+		c.builder.CreateCall(useFn, []llvm.Value{interrupt}, "")
+	}
+
+	return interrupt, nil
+}
@@ -52,78 +52,6 @@ func (c *Compiler) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []l
 	return llvmutil.EmitPointerUnpack(c.builder, c.mod, ptr, valueTypes)
 }

-// splitBasicBlock splits a LLVM basic block into two parts. All instructions
-// after afterInst are moved into a new basic block (created right after the
-// current one) with the given name.
-func (c *Compiler) splitBasicBlock(afterInst llvm.Value, insertAfter llvm.BasicBlock, name string) llvm.BasicBlock {
-	oldBlock := afterInst.InstructionParent()
-	newBlock := c.ctx.InsertBasicBlock(insertAfter, name)
-	var nextInstructions []llvm.Value // values to move
-
-	// Collect to-be-moved instructions.
-	inst := afterInst
-	for {
-		inst = llvm.NextInstruction(inst)
-		if inst.IsNil() {
-			break
-		}
-		nextInstructions = append(nextInstructions, inst)
-	}
-
-	// Move instructions.
-	c.builder.SetInsertPointAtEnd(newBlock)
-	for _, inst := range nextInstructions {
-		inst.RemoveFromParentAsInstruction()
-		c.builder.Insert(inst)
-	}
-
-	// Find PHI nodes to update.
-	var phiNodes []llvm.Value // PHI nodes to update
-	for bb := insertAfter.Parent().FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
-		for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
-			if inst.IsAPHINode().IsNil() {
-				continue
-			}
-			needsUpdate := false
-			incomingCount := inst.IncomingCount()
-			for i := 0; i < incomingCount; i++ {
-				if inst.IncomingBlock(i) == oldBlock {
-					needsUpdate = true
-					break
-				}
-			}
-			if !needsUpdate {
-				// PHI node has no incoming edge from the old block.
-				continue
-			}
-			phiNodes = append(phiNodes, inst)
-		}
-	}
-
-	// Update PHI nodes.
-	for _, phi := range phiNodes {
-		c.builder.SetInsertPointBefore(phi)
-		newPhi := c.builder.CreatePHI(phi.Type(), "")
-		incomingCount := phi.IncomingCount()
-		incomingVals := make([]llvm.Value, incomingCount)
-		incomingBlocks := make([]llvm.BasicBlock, incomingCount)
-		for i := 0; i < incomingCount; i++ {
-			value := phi.IncomingValue(i)
-			block := phi.IncomingBlock(i)
-			if block == oldBlock {
-				block = newBlock
-			}
-			incomingVals[i] = value
-			incomingBlocks[i] = block
-		}
-		newPhi.AddIncoming(incomingVals, incomingBlocks)
-		phi.ReplaceAllUsesWith(newPhi)
-		phi.EraseFromParentAsInstruction()
-	}
-
-	return newBlock
-}
-
 // makeGlobalArray creates a new LLVM global with the given name and integers as
 // contents, and returns the global.
 // Note that it is left with the default linkage etc., you should set
@@ -94,3 +94,75 @@ func getLifetimeEndFunc(mod llvm.Module) llvm.Value {
 	}
 	return fn
 }
+
+// SplitBasicBlock splits a LLVM basic block into two parts. All instructions
+// after afterInst are moved into a new basic block (created right after the
+// current one) with the given name.
+func SplitBasicBlock(builder llvm.Builder, afterInst llvm.Value, insertAfter llvm.BasicBlock, name string) llvm.BasicBlock {
+	oldBlock := afterInst.InstructionParent()
+	newBlock := afterInst.Type().Context().InsertBasicBlock(insertAfter, name)
+	var nextInstructions []llvm.Value // values to move
+
+	// Collect to-be-moved instructions.
+	inst := afterInst
+	for {
+		inst = llvm.NextInstruction(inst)
+		if inst.IsNil() {
+			break
+		}
+		nextInstructions = append(nextInstructions, inst)
+	}
+
+	// Move instructions.
+	builder.SetInsertPointAtEnd(newBlock)
+	for _, inst := range nextInstructions {
+		inst.RemoveFromParentAsInstruction()
+		builder.Insert(inst)
+	}
+
+	// Find PHI nodes to update.
+	var phiNodes []llvm.Value // PHI nodes to update
+	for bb := insertAfter.Parent().FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
+		for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
+			if inst.IsAPHINode().IsNil() {
+				continue
+			}
+			needsUpdate := false
+			incomingCount := inst.IncomingCount()
+			for i := 0; i < incomingCount; i++ {
+				if inst.IncomingBlock(i) == oldBlock {
+					needsUpdate = true
+					break
+				}
+			}
+			if !needsUpdate {
+				// PHI node has no incoming edge from the old block.
+				continue
+			}
+			phiNodes = append(phiNodes, inst)
+		}
+	}
+
+	// Update PHI nodes.
+	for _, phi := range phiNodes {
+		builder.SetInsertPointBefore(phi)
+		newPhi := builder.CreatePHI(phi.Type(), "")
+		incomingCount := phi.IncomingCount()
+		incomingVals := make([]llvm.Value, incomingCount)
+		incomingBlocks := make([]llvm.BasicBlock, incomingCount)
+		for i := 0; i < incomingCount; i++ {
+			value := phi.IncomingValue(i)
+			block := phi.IncomingBlock(i)
+			if block == oldBlock {
+				block = newBlock
+			}
+			incomingVals[i] = value
+			incomingBlocks[i] = block
+		}
+		newPhi.AddIncoming(incomingVals, incomingBlocks)
+		phi.ReplaceAllUsesWith(newPhi)
+		phi.EraseFromParentAsInstruction()
+	}
+
+	return newBlock
+}
@@ -9,7 +9,7 @@ import (

 // 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 {
+func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) []error {
 	builder := llvm.NewPassManagerBuilder()
 	defer builder.Dispose()
 	builder.SetOptLevel(optLevel)
@@ -25,9 +25,9 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro

 	// run a check of all of our code
 	if c.VerifyIR() {
-		err := c.checkModule()
-		if err != nil {
-			return err
+		errs := c.checkModule()
+		if errs != nil {
+			return errs
 		}
 	}

@@ -45,6 +45,7 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro
 		// Run some preparatory passes for the Go optimizer.
 		goPasses := llvm.NewPassManager()
 		defer goPasses.Dispose()
+		goPasses.AddGlobalDCEPass()
 		goPasses.AddGlobalOptimizerPass()
 		goPasses.AddConstantPropagationPass()
 		goPasses.AddAggressiveDCEPass()
@@ -56,7 +57,15 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro
 		transform.OptimizeStringToBytes(c.mod)
 		transform.OptimizeAllocs(c.mod)
 		transform.LowerInterfaces(c.mod)
-		c.LowerFuncValues()
+
+		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
@@ -85,24 +94,30 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro

 		err := c.LowerGoroutines()
 		if err != nil {
-			return err
+			return []error{err}
 		}
 	} else {
 		// Must be run at any optimization level.
 		transform.LowerInterfaces(c.mod)
-		c.LowerFuncValues()
+		if c.funcImplementation() == funcValueSwitch {
+			transform.LowerFuncValues(c.mod)
+		}
 		err := c.LowerGoroutines()
 		if err != nil {
-			return err
+			return []error{err}
+		}
+		errs := transform.LowerInterruptRegistrations(c.mod)
+		if len(errs) > 0 {
+			return errs
 		}
 	}
 	if c.VerifyIR() {
-		if err := c.checkModule(); err != nil {
-			return err
+		if errs := c.checkModule(); errs != nil {
+			return errs
 		}
 	}
 	if err := c.Verify(); err != nil {
-		return errors.New("optimizations caused a verification failure")
+		return []error{errors.New("optimizations caused a verification failure")}
 	}

 	if sizeLevel >= 2 {
@@ -141,7 +156,7 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro
 	hasGCPass = transform.MakeGCStackSlots(c.mod) || hasGCPass
 	if hasGCPass {
 		if err := c.Verify(); err != nil {
-			return errors.New("GC pass caused a verification failure")
+			return []error{errors.New("GC pass caused a verification failure")}
 		}
 	}

@@ -110,6 +110,9 @@ func (s *StdSizes) Sizeof(T types.Type) int64 {
 		if k == types.UnsafePointer {
 			return s.PtrSize
 		}
+		if k == types.Invalid {
+			return 0 // only relevant when there is a type error somewhere
+		}
 		panic("unknown basic type: " + t.String())
 	case *types.Array:
 		n := t.Len()
@@ -60,14 +60,44 @@ func (c *Compiler) getGlobal(g *ssa.Global) llvm.Value {
 	info := c.getGlobalInfo(g)
 	llvmGlobal := c.mod.NamedGlobal(info.linkName)
 	if llvmGlobal.IsNil() {
-		llvmType := c.getLLVMType(g.Type().(*types.Pointer).Elem())
+		typ := g.Type().(*types.Pointer).Elem()
+		llvmType := c.getLLVMType(typ)
 		llvmGlobal = llvm.AddGlobal(c.mod, llvmType, info.linkName)
 		if !info.extern {
 			llvmGlobal.SetInitializer(llvm.ConstNull(llvmType))
 			llvmGlobal.SetLinkage(llvm.InternalLinkage)
 		}
-		if info.align > c.targetData.ABITypeAlignment(llvmType) {
-			llvmGlobal.SetAlignment(info.align)
+
+		// Set alignment from the //go:align comment.
+		var alignInBits uint32
+		if info.align < 0 || info.align&(info.align-1) != 0 {
+			// Check for power-of-two (or 0).
+			// See: https://stackoverflow.com/a/108360
+			c.addError(g.Pos(), "global variable alignment must be a positive power of two")
+		} else {
+			// Set the alignment only when it is a power of two.
+			alignInBits = uint32(info.align) ^ uint32(info.align-1)
+			if info.align > c.targetData.ABITypeAlignment(llvmType) {
+				llvmGlobal.SetAlignment(info.align)
+			}
+		}
+
+		if c.Debug() {
+			// Add debug info.
+			// TODO: this should be done for every global in the program, not just
+			// the ones that are referenced from some code.
+			pos := c.ir.Program.Fset.Position(g.Pos())
+			diglobal := c.dibuilder.CreateGlobalVariableExpression(c.difiles[pos.Filename], llvm.DIGlobalVariableExpression{
+				Name:        g.RelString(nil),
+				LinkageName: info.linkName,
+				File:        c.getDIFile(pos.Filename),
+				Line:        pos.Line,
+				Type:        c.getDIType(typ),
+				LocalToUnit: false,
+				Expr:        c.dibuilder.CreateExpression(nil),
+				AlignInBits: alignInBits,
+			})
+			llvmGlobal.AddMetadata(0, diglobal)
 		}
 	}
 	return llvmGlobal
@@ -152,7 +152,7 @@ func (c *Compiler) emitSyscall(frame *Frame, call *ssa.CallCommon) (llvm.Value,
 		return llvm.Value{}, c.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+c.GOOS()+"/"+c.GOARCH())
 	}
 	switch c.GOOS() {
-	case "linux":
+	case "linux", "freebsd":
 		// Return values: r0, r1 uintptr, err Errno
 		// Pseudocode:
 		//     var err uintptr
@@ -10,5 +10,5 @@ require (
 	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 v0.0.0-20191124211856-b2db3df3f257
+	tinygo.org/x/go-llvm v0.0.0-20200104190746-1ff21df33566
 )
@@ -30,3 +30,7 @@ tinygo.org/x/go-llvm v0.0.0-20191113125529-bad6d01809e8 h1:9Bfvso+tTVQg16UzOA614
 tinygo.org/x/go-llvm v0.0.0-20191113125529-bad6d01809e8/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
 tinygo.org/x/go-llvm v0.0.0-20191124211856-b2db3df3f257 h1:o8VDylrMN7gWemBMu8rEyuogKPhcLTdx5KrUAp9macc=
 tinygo.org/x/go-llvm v0.0.0-20191124211856-b2db3df3f257/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
+tinygo.org/x/go-llvm v0.0.0-20191215173731-ad71f3d24aae h1:s8J5EyxCkHxXB08UI3gk9W9IS/ekizRvSX+PfZxnAB0=
+tinygo.org/x/go-llvm v0.0.0-20191215173731-ad71f3d24aae/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
+tinygo.org/x/go-llvm v0.0.0-20200104190746-1ff21df33566 h1:a4y30bTf7U0zDA75v2PTL+XQ2OzJetj19gK8XwQpUNY=
+tinygo.org/x/go-llvm v0.0.0-20200104190746-1ff21df33566/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
@@ -278,24 +278,49 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				}
 			case callee.Name() == "runtime.hashmapStringSet":
 				// set a string key in the map
-				m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
-				if !ok {
-					return nil, nil, fr.errorAt(inst, "could not update map with string key")
-				}
-				// "key" is a Go string value, which in the TinyGo calling convention is split up
-				// into separate pointer and length parameters.
 				keyBuf := fr.getLocal(inst.Operand(1)).(*LocalValue)
 				keyLen := fr.getLocal(inst.Operand(2)).(*LocalValue)
 				valPtr := fr.getLocal(inst.Operand(3)).(*LocalValue)
+				m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
+				if !ok || !keyBuf.IsConstant() || !keyLen.IsConstant() || !valPtr.IsConstant() {
+					// The mapassign operation could not be done at compile
+					// time. Do it at runtime instead.
+					m := fr.getLocal(inst.Operand(0)).Value()
+					fr.markDirty(m)
+					llvmParams := []llvm.Value{
+						m,                                    // *runtime.hashmap
+						fr.getLocal(inst.Operand(1)).Value(), // key.ptr
+						fr.getLocal(inst.Operand(2)).Value(), // key.len
+						fr.getLocal(inst.Operand(3)).Value(), // value (unsafe.Pointer)
+						fr.getLocal(inst.Operand(4)).Value(), // context
+						fr.getLocal(inst.Operand(5)).Value(), // parentHandle
+					}
+					fr.builder.CreateCall(callee, llvmParams, "")
+					continue
+				}
+				// "key" is a Go string value, which in the TinyGo calling convention is split up
+				// into separate pointer and length parameters.
 				m.PutString(keyBuf, keyLen, valPtr)
 			case callee.Name() == "runtime.hashmapBinarySet":
 				// set a binary (int etc.) key in the map
-				m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
-				if !ok {
-					return nil, nil, fr.errorAt(inst, "could not update map")
-				}
 				keyBuf := fr.getLocal(inst.Operand(1)).(*LocalValue)
 				valPtr := fr.getLocal(inst.Operand(2)).(*LocalValue)
+				m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
+				if !ok || !keyBuf.IsConstant() || !valPtr.IsConstant() {
+					// The mapassign operation could not be done at compile
+					// time. Do it at runtime instead.
+					m := fr.getLocal(inst.Operand(0)).Value()
+					fr.markDirty(m)
+					llvmParams := []llvm.Value{
+						m,                                    // *runtime.hashmap
+						fr.getLocal(inst.Operand(1)).Value(), // key
+						fr.getLocal(inst.Operand(2)).Value(), // value
+						fr.getLocal(inst.Operand(3)).Value(), // context
+						fr.getLocal(inst.Operand(4)).Value(), // parentHandle
+					}
+					fr.builder.CreateCall(callee, llvmParams, "")
+					continue
+				}
 				m.PutBinary(keyBuf, valPtr)
 			case callee.Name() == "runtime.stringConcat":
 				// adding two strings together
@@ -433,6 +458,8 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int64Type(), 0, false)}
 			case callee.Name() == "llvm.dbg.value":
 				// do nothing
+			case strings.HasPrefix(callee.Name(), "llvm.lifetime."):
+				// do nothing
 			case callee.Name() == "runtime.trackPointer":
 				// do nothing
 			case strings.HasPrefix(callee.Name(), "runtime.print") || callee.Name() == "runtime._panic":
@@ -14,6 +14,7 @@ func TestInterp(t *testing.T) {
 		"basic",
 		"slice-copy",
 		"consteval",
+		"map",
 	} {
 		name := name // make tc local to this closure
 		t.Run(name, func(t *testing.T) {
@@ -1,6 +1,8 @@
 package interp

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

@@ -39,22 +41,25 @@ type sideEffectResult struct {
 // 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) {
-	switch fn.Name() {
-	case "runtime.alloc":
+	name := fn.Name()
+	switch {
+	case name == "runtime.alloc":
 		// Cannot be scanned but can be interpreted.
 		return &sideEffectResult{severity: sideEffectNone}, nil
-	case "runtime.nanotime":
+	case name == "runtime.nanotime":
 		// Fixed value at compile time.
 		return &sideEffectResult{severity: sideEffectNone}, nil
-	case "runtime._panic":
+	case name == "runtime._panic":
 		return &sideEffectResult{severity: sideEffectLimited}, nil
-	case "runtime.interfaceImplements":
+	case name == "runtime.interfaceImplements":
 		return &sideEffectResult{severity: sideEffectNone}, nil
-	case "runtime.sliceCopy":
+	case name == "runtime.sliceCopy":
 		return &sideEffectResult{severity: sideEffectNone}, nil
-	case "runtime.trackPointer":
+	case name == "runtime.trackPointer":
 		return &sideEffectResult{severity: sideEffectNone}, nil
-	case "llvm.dbg.value":
+	case name == "llvm.dbg.value":
+		return &sideEffectResult{severity: sideEffectNone}, nil
+	case strings.HasPrefix(name, "llvm.lifetime."):
 		return &sideEffectResult{severity: sideEffectNone}, nil
 	}
 	if fn.IsDeclaration() {
@@ -0,0 +1,76 @@
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv6m-none-eabi"
+
+%runtime._string = type { i8*, i32 }
+%runtime.hashmap = type { %runtime.hashmap*, i8*, i32, i8, i8, i8 }
+
+@main.m = global %runtime.hashmap* null
+@main.binaryMap = global %runtime.hashmap* null
+@main.stringMap = global %runtime.hashmap* null
+@main.init.string = internal unnamed_addr constant [7 x i8] c"CONNECT"
+
+declare %runtime.hashmap* @runtime.hashmapMake(i8, i8, i32, i8* %context, i8* %parentHandle)
+declare void @runtime.hashmapBinarySet(%runtime.hashmap*, i8*, i8*, i8* %context, i8* %parentHandle)
+declare void @runtime.hashmapStringSet(%runtime.hashmap*, i8*, i32, i8*, i8* %context, i8* %parentHandle)
+declare void @llvm.lifetime.end.p0i8(i64, i8*)
+declare void @llvm.lifetime.start.p0i8(i64, i8*)
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  call void @main.init(i8* undef, i8* null)
+  ret void
+}
+
+define internal void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+; Test that hashmap optimizations generally work (even with lifetimes).
+  %hashmap.key = alloca i8
+  %hashmap.value = alloca %runtime._string
+  %0 = call %runtime.hashmap* @runtime.hashmapMake(i8 1, i8 8, i32 1, i8* undef, i8* null)
+  %hashmap.value.bitcast = bitcast %runtime._string* %hashmap.value to i8*
+  call void @llvm.lifetime.start.p0i8(i64 8, i8* %hashmap.value.bitcast)
+  store %runtime._string { i8* getelementptr inbounds ([7 x i8], [7 x i8]* @main.init.string, i32 0, i32 0), i32 7 }, %runtime._string* %hashmap.value
+  call void @llvm.lifetime.start.p0i8(i64 1, i8* %hashmap.key)
+  store i8 1, i8* %hashmap.key
+  call void @runtime.hashmapBinarySet(%runtime.hashmap* %0, i8* %hashmap.key, i8* %hashmap.value.bitcast, i8* undef, i8* null)
+  call void @llvm.lifetime.end.p0i8(i64 1, i8* %hashmap.key)
+  call void @llvm.lifetime.end.p0i8(i64 8, i8* %hashmap.value.bitcast)
+  store %runtime.hashmap* %0, %runtime.hashmap** @main.m
+
+  ; Other tests, that can be done in a separate function.
+  call void @main.testNonConstantBinarySet()
+  call void @main.testNonConstantStringSet()
+  ret void
+}
+
+; Test that a map loaded from a global can still be used for mapassign
+; operations (with binary keys).
+define internal void @main.testNonConstantBinarySet() {
+  %hashmap.key = alloca i8
+  %hashmap.value = alloca i8
+  ; Create hashmap from global. This breaks the normal hashmapBinarySet
+  ; optimization, to test the fallback.
+  %map.new = call %runtime.hashmap* @runtime.hashmapMake(i8 1, i8 1, i32 1, i8* undef, i8* null)
+  store %runtime.hashmap* %map.new, %runtime.hashmap** @main.binaryMap
+  %map = load %runtime.hashmap*, %runtime.hashmap** @main.binaryMap
+  ; Do the binary set to the newly loaded map.
+  store i8 1, i8* %hashmap.key
+  store i8 2, i8* %hashmap.value
+  call void @runtime.hashmapBinarySet(%runtime.hashmap* %map, i8* %hashmap.key, i8* %hashmap.value, i8* undef, i8* null)
+  ret void
+}
+
+; Test that a map loaded from a global can still be used for mapassign
+; operations (with string keys).
+define internal void @main.testNonConstantStringSet() {
+  %hashmap.value = alloca i8
+  ; Create hashmap from global. This breaks the normal hashmapStringSet
+  ; optimization, to test the fallback.
+  %map.new = call %runtime.hashmap* @runtime.hashmapMake(i8 8, i8 1, i32 1, i8* undef, i8* null)
+  store %runtime.hashmap* %map.new, %runtime.hashmap** @main.stringMap
+  %map = load %runtime.hashmap*, %runtime.hashmap** @main.stringMap
+  ; Do the string set to the newly loaded map.
+  store i8 2, i8* %hashmap.value
+  call void @runtime.hashmapStringSet(%runtime.hashmap* %map, i8* getelementptr inbounds ([7 x i8], [7 x i8]* @main.init.string, i32 0, i32 0), i32 7, i8* %hashmap.value, i8* undef, i8* null)
+  ret void
+}
@@ -0,0 +1,28 @@
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv6m-none-eabi"
+
+%runtime.hashmap = type { %runtime.hashmap*, i8*, i32, i8, i8, i8 }
+%runtime._string = type { i8*, i32 }
+
+@main.m = local_unnamed_addr global %runtime.hashmap* @"main$map"
+@main.binaryMap = local_unnamed_addr global %runtime.hashmap* @"main$map.4"
+@main.stringMap = local_unnamed_addr global %runtime.hashmap* @"main$map.6"
+@main.init.string = internal unnamed_addr constant [7 x i8] c"CONNECT"
+@"main$mapbucket" = internal unnamed_addr global { [8 x i8], i8*, [8 x i8], [8 x %runtime._string] } { [8 x i8] c"\04\00\00\00\00\00\00\00", i8* null, [8 x i8] c"\01\00\00\00\00\00\00\00", [8 x %runtime._string] [%runtime._string { i8* getelementptr inbounds ([7 x i8], [7 x i8]* @main.init.string, i32 0, i32 0), i32 7 }, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer, %runtime._string zeroinitializer] }
+@"main$map" = internal unnamed_addr global %runtime.hashmap { %runtime.hashmap* null, i8* getelementptr inbounds ({ [8 x i8], i8*, [8 x i8], [8 x %runtime._string] }, { [8 x i8], i8*, [8 x i8], [8 x %runtime._string] }* @"main$mapbucket", i32 0, i32 0, i32 0), i32 1, i8 1, i8 8, i8 0 }
+@"main$alloca.2" = internal global i8 1
+@"main$alloca.3" = internal global i8 2
+@"main$map.4" = internal unnamed_addr global %runtime.hashmap { %runtime.hashmap* null, i8* null, i32 0, i8 1, i8 1, i8 0 }
+@"main$alloca.5" = internal global i8 2
+@"main$map.6" = internal unnamed_addr global %runtime.hashmap { %runtime.hashmap* null, i8* null, i32 0, i8 8, i8 1, i8 0 }
+
+declare void @runtime.hashmapBinarySet(%runtime.hashmap*, i8*, i8*, i8*, i8*) local_unnamed_addr
+
+declare void @runtime.hashmapStringSet(%runtime.hashmap*, i8*, i32, i8*, i8*, i8*) local_unnamed_addr
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  call void @runtime.hashmapBinarySet(%runtime.hashmap* @"main$map.4", i8* @"main$alloca.2", i8* @"main$alloca.3", i8* undef, i8* null)
+  call void @runtime.hashmapStringSet(%runtime.hashmap* @"main$map.6", i8* getelementptr inbounds ([7 x i8], [7 x i8]* @main.init.string, i32 0, i32 0), i32 7, i8* @"main$alloca.5", i8* undef, i8* null)
+  ret void
+}
@@ -367,10 +367,12 @@ func (v *MapValue) PutBinary(keyPtr, valPtr *LocalValue) {
 		}
 	}

-	if keyPtr.Underlying.Opcode() == llvm.BitCast {
-		keyPtr = &LocalValue{v.Eval, keyPtr.Underlying.Operand(0)}
-	} else if keyPtr.Underlying.Opcode() == llvm.GetElementPtr {
-		keyPtr = &LocalValue{v.Eval, keyPtr.Underlying.Operand(0)}
+	if !keyPtr.Underlying.IsAConstantExpr().IsNil() {
+		if keyPtr.Underlying.Opcode() == llvm.BitCast {
+			keyPtr = &LocalValue{v.Eval, keyPtr.Underlying.Operand(0)}
+		} else if keyPtr.Underlying.Opcode() == llvm.GetElementPtr {
+			keyPtr = &LocalValue{v.Eval, keyPtr.Underlying.Operand(0)}
+		}
 	}
 	key := keyPtr.Load()
 	if v.KeyType.IsNil() {
@@ -27,14 +27,13 @@ type Program struct {
 // Function or method.
 type Function struct {
 	*ssa.Function
-	LLVMFn    llvm.Value
-	module    string     // go:wasm-module
-	linkName  string     // go:linkname, go:export, go:interrupt
-	exported  bool       // go:export
-	nobounds  bool       // go:nobounds
-	flag      bool       // used by dead code elimination
-	interrupt bool       // go:interrupt
-	inline    InlineType // go:inline
+	LLVMFn   llvm.Value
+	module   string     // go:wasm-module
+	linkName string     // go:linkname, go:export
+	exported bool       // go:export
+	nobounds bool       // go:nobounds
+	flag     bool       // used by dead code elimination
+	inline   InlineType // go:inline
 }

 // Interface type that is at some point used in a type assert (to check whether
@@ -243,18 +242,6 @@ func (f *Function) parsePragmas() {
 				f.inline = InlineHint
 			case "//go:noinline":
 				f.inline = InlineNone
-			case "//go:interrupt":
-				if len(parts) != 2 {
-					continue
-				}
-				name := parts[1]
-				if strings.HasSuffix(name, "_vect") {
-					// AVR vector naming
-					name = "__vector_" + name[:len(name)-5]
-				}
-				f.linkName = name
-				f.exported = true
-				f.interrupt = true
 			case "//go:linkname":
 				if len(parts) != 3 || parts[1] != f.Name() {
 					continue
@@ -288,14 +275,6 @@ func (f *Function) IsExported() bool {
 	return f.exported || f.CName() != ""
 }

-// Return true for functions annotated with //go:interrupt. The function name is
-// already customized in LinkName() to hook up in the interrupt vector.
-//
-// On some platforms (like AVR), interrupts need a special compiler flag.
-func (f *Function) IsInterrupt() bool {
-	return f.interrupt
-}
-
 // Return the inline directive of this function.
 func (f *Function) Inline() InlineType {
 	return f.inline
@@ -6,6 +6,7 @@ import (
 	"go/ast"
 	"go/build"
 	"go/parser"
+	"go/scanner"
 	"go/token"
 	"go/types"
 	"os"
@@ -46,7 +47,7 @@ type Package struct {

 // Import loads the given package relative to srcDir (for the vendor directory).
 // It only loads the current package without recursion.
-func (p *Program) Import(path, srcDir string) (*Package, error) {
+func (p *Program) Import(path, srcDir string, pos token.Position) (*Package, error) {
 	if p.Packages == nil {
 		p.Packages = make(map[string]*Package)
 	}
@@ -59,7 +60,10 @@ func (p *Program) Import(path, srcDir string) (*Package, error) {
 	}
 	buildPkg, err := ctx.Import(path, srcDir, build.ImportComment)
 	if err != nil {
-		return nil, err
+		return nil, scanner.Error{
+			Pos: pos,
+			Msg: err.Error(), // TODO: define a new error type that will wrap the inner error
+		}
 	}
 	if existingPkg, ok := p.Packages[buildPkg.ImportPath]; ok {
 		// Already imported, or at least started the import.
@@ -467,7 +471,14 @@ func (p *Package) importRecursively(includeTests bool) error {
 		if _, ok := p.Imports[to]; ok {
 			continue
 		}
-		importedPkg, err := p.Program.Import(to, p.Package.Dir)
+		// Find error location.
+		var pos token.Position
+		if len(p.Package.ImportPos[to]) > 0 {
+			pos = p.Package.ImportPos[to][0]
+		} else {
+			pos = token.Position{Filename: p.Package.ImportPath}
+		}
+		importedPkg, err := p.Program.Import(to, p.Package.Dir, pos)
 		if err != nil {
 			if err, ok := err.(*ImportCycleError); ok {
 				err.Packages = append([]string{p.ImportPath}, err.Packages...)
@@ -1,6 +1,7 @@
 package main

 import (
+	"bytes"
 	"errors"
 	"flag"
 	"fmt"
@@ -144,6 +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
@@ -201,7 +210,18 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			flashCmd = strings.Replace(flashCmd, "{port}", port, -1)

 			// Execute the command.
-			cmd := exec.Command("/bin/sh", "-c", flashCmd)
+			var cmd *exec.Cmd
+			switch runtime.GOOS {
+			case "windows":
+				command := strings.Split(flashCmd, " ")
+				if len(command) < 2 {
+					return errors.New("invalid flash command")
+				}
+				cmd = exec.Command(command[0], command[1:]...)
+			default:
+				cmd = exec.Command("/bin/sh", "-c", flashCmd)
+			}
+
 			cmd.Stdout = os.Stdout
 			cmd.Stderr = os.Stderr
 			cmd.Dir = goenv.Get("TINYGOROOT")
@@ -254,7 +274,7 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 //
 // Note: this command is expected to execute just before exiting, as it
 // modifies global state.
-func FlashGDB(pkgName, port string, ocdOutput bool, options *compileopts.Options) error {
+func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) error {
 	config, err := builder.NewConfig(options)
 	if err != nil {
 		return err
@@ -268,12 +288,13 @@ func FlashGDB(pkgName, port string, ocdOutput bool, options *compileopts.Options
 		gdbInterface, openocdInterface := config.Programmer()
 		switch gdbInterface {
 		case "msd", "command", "":
-			if gdbInterface == "" {
-				gdbInterface = "command"
-			}
 			if openocdInterface != "" && config.Target.OpenOCDTarget != "" {
 				gdbInterface = "openocd"
 			}
+			if len(config.Target.Emulator) != 0 {
+				// Assume QEMU as an emulator.
+				gdbInterface = "qemu"
+			}
 		}

 		// Run the GDB server, if necessary.
@@ -303,6 +324,26 @@ func FlashGDB(pkgName, port string, ocdOutput bool, options *compileopts.Options
 			// 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 "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() {
@@ -401,9 +442,18 @@ func touchSerialPortAt1200bps(port string) error {

 func flashUF2UsingMSD(volume, tmppath string) error {
 	// find standard UF2 info path
-	infoPath := "/media/*/" + volume + "/INFO_UF2.TXT"
-	if runtime.GOOS == "darwin" {
+	var infoPath string
+	switch runtime.GOOS {
+	case "linux", "freebsd":
+		infoPath = "/media/*/" + volume + "/INFO_UF2.TXT"
+	case "darwin":
 		infoPath = "/Volumes/" + volume + "/INFO_UF2.TXT"
+	case "windows":
+		path, err := windowsFindUSBDrive(volume)
+		if err != nil {
+			return err
+		}
+		infoPath = path + "/INFO_UF2.TXT"
 	}

 	d, err := filepath.Glob(infoPath)
@@ -419,9 +469,18 @@ func flashUF2UsingMSD(volume, tmppath string) error {

 func flashHexUsingMSD(volume, tmppath string) error {
 	// find expected volume path
-	destPath := "/media/*/" + volume
-	if runtime.GOOS == "darwin" {
+	var destPath string
+	switch runtime.GOOS {
+	case "linux", "freebsd":
+		destPath = "/media/*/" + volume
+	case "darwin":
 		destPath = "/Volumes/" + volume
+	case "windows":
+		path, err := windowsFindUSBDrive(volume)
+		if err != nil {
+			return err
+		}
+		destPath = path + "/"
 	}

 	d, err := filepath.Glob(destPath)
@@ -435,6 +494,29 @@ func flashHexUsingMSD(volume, tmppath string) error {
 	return moveFile(tmppath, d[0]+"/flash.hex")
 }

+func windowsFindUSBDrive(volume string) (string, error) {
+	cmd := exec.Command("wmic",
+		"PATH", "Win32_LogicalDisk", "WHERE", "VolumeName = '"+volume+"'",
+		"get", "DeviceID,VolumeName,FileSystem,DriveType")
+
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	err := cmd.Run()
+	if err != nil {
+		return "", err
+	}
+
+	for _, line := range strings.Split(out.String(), "\n") {
+		words := strings.Fields(line)
+		if len(words) >= 3 {
+			if words[1] == "2" && words[2] == "FAT" {
+				return words[0], nil
+			}
+		}
+	}
+	return "", errors.New("unable to locate a USB device to be flashed")
+}
+
 // parseSize converts a human-readable size (with k/m/g suffix) into a plain
 // number.
 func parseSize(s string) (int64, error) {
@@ -459,6 +541,56 @@ func parseSize(s string) (int64, error) {
 	return n, err
 }

+// 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 {
+	case "darwin":
+		portPath = "/dev/cu.usb*"
+	case "linux":
+		portPath = "/dev/ttyACM*"
+	case "freebsd":
+		portPath = "/dev/cuaU*"
+	case "windows":
+		cmd := exec.Command("wmic",
+			"PATH", "Win32_SerialPort", "WHERE", "Caption LIKE 'USB Serial%'", "GET", "DeviceID")
+
+		var out bytes.Buffer
+		cmd.Stdout = &out
+		err := cmd.Run()
+		if err != nil {
+			return "", err
+		}
+
+		if out.String() == "No Instance(s) Available." {
+			return "", errors.New("unable to locate a USB device to be flashed")
+		}
+
+		for _, line := range strings.Split(out.String(), "\n") {
+			words := strings.Fields(line)
+			if len(words) == 1 {
+				if strings.Contains(words[0], "COM") {
+					return words[0], nil
+				}
+			}
+		}
+		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")
+	}
+
+	d, err := filepath.Glob(portPath)
+	if err != nil {
+		return "", err
+	}
+	if d == nil {
+		return "", errors.New("unable to locate a USB device to be flashed")
+	}
+
+	return d[0], nil
+}
+
 func usage() {
 	fmt.Fprintln(os.Stderr, "TinyGo is a Go compiler for small places.")
 	fmt.Fprintln(os.Stderr, "version:", version)
@@ -526,7 +658,7 @@ func main() {
 	printSize := flag.String("size", "", "print sizes (none, short, full)")
 	nodebug := flag.Bool("no-debug", false, "disable DWARF debug symbol generation")
 	ocdOutput := flag.Bool("ocd-output", false, "print OCD daemon output during debug")
-	port := flag.String("port", "/dev/ttyACM0", "flash port")
+	port := flag.String("port", "", "flash port")
 	programmer := flag.String("programmer", "", "which hardware programmer to use")
 	cFlags := flag.String("cflags", "", "additional cflags for compiler")
 	ldFlags := flag.String("ldflags", "", "additional ldflags for linker")
@@ -629,7 +761,7 @@ func main() {
 				usage()
 				os.Exit(1)
 			}
-			err := FlashGDB(flag.Arg(0), *port, *ocdOutput, options)
+			err := FlashGDB(flag.Arg(0), *ocdOutput, options)
 			handleCompilerError(err)
 		}
 	case "run":
@@ -12,7 +12,9 @@ import (
 	"path/filepath"
 	"runtime"
 	"sort"
+	"sync"
 	"testing"
+	"time"

 	"github.com/tinygo-org/tinygo/compileopts"
 	"github.com/tinygo-org/tinygo/loader"
@@ -50,7 +52,7 @@ func TestCompiler(t *testing.T) {
 	}

 	t.Run("EmulatedCortexM3", func(t *testing.T) {
-		runPlatTests("qemu", matches, t)
+		runPlatTests("cortex-m-qemu", matches, t)
 	})

 	if runtime.GOOS == "linux" {
@@ -67,6 +69,8 @@ func TestCompiler(t *testing.T) {
 }

 func runPlatTests(target string, matches []string, t *testing.T) {
+	t.Parallel()
+
 	for _, path := range matches {
 		switch {
 		case target == "wasm":
@@ -76,7 +80,7 @@ func runPlatTests(target string, matches []string, t *testing.T) {
 			}
 		case target == "":
 			// run all tests on host
-		case target == "qemu":
+		case target == "cortex-m-qemu":
 			// all tests are supported
 		default:
 			// cross-compilation of cgo is not yet supported
@@ -86,22 +90,32 @@ func runPlatTests(target string, matches []string, t *testing.T) {
 		}

 		t.Run(filepath.Base(path), func(t *testing.T) {
+			t.Parallel()
+
 			runTest(path, target, t)
 		})
 	}
 }

+// Due to some problems with LLD, we cannot run links in parallel, or in parallel with compiles.
+// Therefore, we put a lock around builds and run everything else in parallel.
+var buildLock sync.Mutex
+
+// runBuild is a thread-safe wrapper around Build.
+func runBuild(src, out string, opts *compileopts.Options) error {
+	buildLock.Lock()
+	defer buildLock.Unlock()
+
+	return Build(src, out, opts)
+}
+
 func runTest(path, target string, t *testing.T) {
 	// Get the expected output for this test.
 	txtpath := path[:len(path)-3] + ".txt"
 	if path[len(path)-1] == os.PathSeparator {
 		txtpath = path + "out.txt"
 	}
-	f, err := os.Open(txtpath)
-	if err != nil {
-		t.Fatal("could not open expected output file:", err)
-	}
-	expected, err := ioutil.ReadAll(f)
+	expected, err := ioutil.ReadFile(txtpath)
 	if err != nil {
 		t.Fatal("could not read expected output file:", err)
 	}
@@ -130,7 +144,7 @@ func runTest(path, target string, t *testing.T) {
 		WasmAbi:    "js",
 	}
 	binary := filepath.Join(tmpdir, "test")
-	err = Build("./"+path, binary, config)
+	err = runBuild("./"+path, binary, config)
 	if err != nil {
 		if errLoader, ok := err.(loader.Errors); ok {
 			for _, err := range errLoader.Errs {
@@ -144,7 +158,9 @@ func runTest(path, target string, t *testing.T) {
 	}

 	// Run the test.
+	runComplete := make(chan struct{})
 	var cmd *exec.Cmd
+	ranTooLong := false
 	if target == "" {
 		cmd = exec.Command(binary)
 	} else {
@@ -160,13 +176,35 @@ func runTest(path, target string, t *testing.T) {
 	}
 	stdout := &bytes.Buffer{}
 	cmd.Stdout = stdout
-	if target != "" {
-		cmd.Stderr = os.Stderr
+	cmd.Stderr = os.Stderr
+	err = cmd.Start()
+	if err != nil {
+		t.Fatal("failed to start:", err)
 	}
-	err = cmd.Run()
+	go func() {
+		// Terminate the process if it runs too long.
+		timer := time.NewTimer(1 * time.Second)
+		select {
+		case <-runComplete:
+			timer.Stop()
+		case <-timer.C:
+			ranTooLong = true
+			if runtime.GOOS == "windows" {
+				cmd.Process.Signal(os.Kill) // Windows doesn't support SIGINT.
+			} else {
+				cmd.Process.Signal(os.Interrupt)
+			}
+		}
+	}()
+	err = cmd.Wait()
 	if _, ok := err.(*exec.ExitError); ok && target != "" {
 		err = nil // workaround for QEMU
 	}
+	close(runComplete)
+
+	if ranTooLong {
+		stdout.WriteString("--- test ran too long, terminating...\n")
+	}

 	// putchar() prints CRLF, convert it to LF.
 	actual := bytes.Replace(stdout.Bytes(), []byte{'\r', '\n'}, []byte{'\n'}, -1)
@@ -3,11 +3,10 @@
 .type _start,@function

 _start:
-    // Workaround for missing support of the la pseudo-instruction in Clang 8:
-    // https://reviews.llvm.org/D55325
-    lui sp,      %hi(_stack_top)
-    addi sp, sp, %lo(_stack_top)
-    // see https://gnu-mcu-eclipse.github.io/arch/riscv/programmer/#the-gp-global-pointer-register
-    lui gp,      %hi(__global_pointer$)
-    addi gp, gp, %lo(__global_pointer$)
+    // 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$
    call main
@@ -1,5 +1,5 @@
 // Hand created file. DO NOT DELETE.
-// STM32F103XX bitfield definitions that are not auto-generated by gen-device-svd.py
+// STM32F103XX bitfield definitions that are not auto-generated by gen-device-svd.go

 // +build stm32,stm32f103xx

@@ -9,7 +9,7 @@ func main() {
 	machine.LED.Configure(machine.PinConfig{Mode: machine.PinOutput})

 	// timer fires 10 times per second
-	arm.SetupSystemTimer(machine.CPU_FREQUENCY / 10)
+	arm.SetupSystemTimer(machine.CPUFrequency() / 10)

 	for {
 	}
@@ -2,7 +2,10 @@

 package machine

-const CPU_FREQUENCY = 16000000
+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 16000000
+}

 // LED on the Arduino
 const LED Pin = 13
@@ -1,4 +1,4 @@
-// +build sam,atsamd21,arduino_nano33
+// +build arduino_nano33

 // This contains the pin mappings for the Arduino Nano33 IoT board.
 //
@@ -6,8 +6,6 @@
 //
 package machine

-import "device/sam"
-
 // used to reset into bootloader
 const RESET_MAGIC_VALUE = 0x07738135

@@ -54,69 +52,23 @@ const (
 	USBCDC_DP_PIN Pin = PA25
 )

-// UART1 on the Arduino Nano 33 connects to the onboard NINA-W102 WiFi chip.
-var (
-	UART1 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    sam.SERCOM5_USART,
-		SERCOM: 5,
-	}
-)
-
 // UART1 pins
 const (
 	UART_TX_PIN Pin = PA22
 	UART_RX_PIN Pin = PA23
 )

-//go:export SERCOM5_IRQHandler
-func handleUART1() {
-	defaultUART1Handler()
-}
-
-// UART2 on the Arduino Nano 33 connects to the normal TX/RX pins.
-var (
-	UART2 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    sam.SERCOM3_USART,
-		SERCOM: 3,
-	}
-)
-
-//go:export SERCOM3_IRQHandler
-func handleUART2() {
-	// should reset IRQ
-	UART2.Receive(byte((UART2.Bus.DATA.Get() & 0xFF)))
-	UART2.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INTFLAG_RXC)
-}
-
 // I2C pins
 const (
 	SDA_PIN Pin = A4 // SDA: SERCOM4/PAD[1]
 	SCL_PIN Pin = A5 // SCL: SERCOM4/PAD[1]
 )

-// I2C on the Arduino Nano 33.
-var (
-	I2C0 = I2C{
-		Bus:    sam.SERCOM4_I2CM,
-		SERCOM: 4,
-	}
-)
-
 // SPI pins
 const (
-	SPI0_SCK_PIN  Pin = A2 // SCK: SERCOM0/PAD[3]
-	SPI0_MOSI_PIN Pin = A3 // MOSI: SERCOM0/PAD[2]
-	SPI0_MISO_PIN Pin = A6 // MISO: SERCOM0/PAD[1]
-)
-
-// SPI on the Arduino Nano 33.
-var (
-	SPI0 = SPI{
-		Bus:    sam.SERCOM0_SPI,
-		SERCOM: 0,
-	}
+	SPI0_SCK_PIN  Pin = D13 // SCK: SERCOM1/PAD[1]
+	SPI0_MOSI_PIN Pin = D11 // MOSI: SERCOM1/PAD[0]
+	SPI0_MISO_PIN Pin = D12 // MISO: SERCOM1/PAD[3]
 )

 // NINA-W102 Pins
@@ -132,23 +84,9 @@ const (
 	NINA_RX     Pin = PA23
 )

-// SPI1 is connected to the NINA-W102 chip on the Arduino Nano 33.
-var (
-	SPI1 = SPI{
-		Bus:    sam.SERCOM2_SPI,
-		SERCOM: 2,
-	}
-	NINA_SPI = SPI1
-)
-
 // I2S pins
 const (
 	I2S_SCK_PIN Pin = PA10
 	I2S_SD_PIN  Pin = PA08
 	I2S_WS_PIN      = NoPin // TODO: figure out what this is on Arduino Nano 33.
 )
-
-// I2S on the Arduino Nano 33.
-var (
-	I2S0 = I2S{Bus: sam.I2S}
-)
@@ -0,0 +1,62 @@
+// +build sam,atsamd21,arduino_nano33
+
+package machine
+
+import (
+	"device/sam"
+	"runtime/interrupt"
+)
+
+// UART1 on the Arduino Nano 33 connects to the onboard NINA-W102 WiFi chip.
+var (
+	UART1 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    sam.SERCOM3_USART,
+		SERCOM: 3,
+	}
+)
+
+// UART2 on the Arduino Nano 33 connects to the normal TX/RX pins.
+var (
+	UART2 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    sam.SERCOM5_USART,
+		SERCOM: 5,
+	}
+)
+
+func init() {
+	// Work around circular definitions.
+	UART1.interrupt = interrupt.New(sam.IRQ_SERCOM3, UART1.handleInterrupt)
+	UART2.interrupt = interrupt.New(sam.IRQ_SERCOM5, UART2.handleInterrupt)
+}
+
+// I2C on the Arduino Nano 33.
+var (
+	I2C0 = I2C{
+		Bus:    sam.SERCOM4_I2CM,
+		SERCOM: 4,
+	}
+)
+
+// SPI on the Arduino Nano 33.
+var (
+	SPI0 = SPI{
+		Bus:    sam.SERCOM1_SPI,
+		SERCOM: 1,
+	}
+)
+
+// SPI1 is connected to the NINA-W102 chip on the Arduino Nano 33.
+var (
+	SPI1 = SPI{
+		Bus:    sam.SERCOM2_SPI,
+		SERCOM: 2,
+	}
+	NINA_SPI = SPI1
+)
+
+// I2S on the Arduino Nano 33.
+var (
+	I2S0 = I2S{Bus: sam.I2S}
+)
@@ -0,0 +1,76 @@
+// +build sam,atsamd21 arduino_nano33 circuitplay_express
+
+package machine
+
+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 48000000
+}
+
+// Hardware pins
+const (
+	PA00 Pin = 0
+	PA01 Pin = 1
+	PA02 Pin = 2
+	PA03 Pin = 3
+	PA04 Pin = 4
+	PA05 Pin = 5
+	PA06 Pin = 6
+	PA07 Pin = 7
+	PA08 Pin = 8
+	PA09 Pin = 9
+	PA10 Pin = 10
+	PA11 Pin = 11
+	PA12 Pin = 12
+	PA13 Pin = 13
+	PA14 Pin = 14
+	PA15 Pin = 15
+	PA16 Pin = 16
+	PA17 Pin = 17
+	PA18 Pin = 18
+	PA19 Pin = 19
+	PA20 Pin = 20
+	PA21 Pin = 21
+	PA22 Pin = 22
+	PA23 Pin = 23
+	PA24 Pin = 24
+	PA25 Pin = 25
+	PA26 Pin = 26
+	PA27 Pin = 27
+	PA28 Pin = 28
+	PA29 Pin = 29
+	PA30 Pin = 30
+	PA31 Pin = 31
+	PB00 Pin = 32
+	PB01 Pin = 33
+	PB02 Pin = 34
+	PB03 Pin = 35
+	PB04 Pin = 36
+	PB05 Pin = 37
+	PB06 Pin = 38
+	PB07 Pin = 39
+	PB08 Pin = 40
+	PB09 Pin = 41
+	PB10 Pin = 42
+	PB11 Pin = 43
+	PB12 Pin = 44
+	PB13 Pin = 45
+	PB14 Pin = 46
+	PB15 Pin = 47
+	PB16 Pin = 48
+	PB17 Pin = 49
+	PB18 Pin = 50
+	PB19 Pin = 51
+	PB20 Pin = 52
+	PB21 Pin = 53
+	PB22 Pin = 54
+	PB23 Pin = 55
+	PB24 Pin = 56
+	PB25 Pin = 57
+	PB26 Pin = 58
+	PB27 Pin = 59
+	PB28 Pin = 60
+	PB29 Pin = 61
+	PB30 Pin = 62
+	PB31 Pin = 63
+)
@@ -2,7 +2,10 @@

 package machine

-import "device/stm32"
+import (
+	"device/stm32"
+	"runtime/interrupt"
+)

 // https://wiki.stm32duino.com/index.php?title=File:Bluepillpinout.gif
 const (
@@ -61,14 +64,12 @@ var (
 	UART0 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    stm32.USART1,
-		IRQVal: stm32.IRQ_USART1,
 	}
 	UART1 = &UART0
 )

-//go:export USART1_IRQHandler
-func handleUART1() {
-	UART1.Receive(byte((UART1.Bus.DR.Get() & 0xFF)))
+func init() {
+	UART0.interrupt = interrupt.New(stm32.IRQ_USART1, UART0.handleInterrupt)
 }

 // SPI pins
@@ -1,9 +1,7 @@
-// +build sam,atsamd21,circuitplay_express
+// +build circuitplay_express

 package machine

-import "device/sam"
-
 // used to reset into bootloader
 const RESET_MAGIC_VALUE = 0xf01669ef

@@ -68,20 +66,6 @@ const (
 	UART_RX_PIN = PB09 // PORTB
 )

-// UART1 on the Circuit Playground Express.
-var (
-	UART1 = UART{
-		Buffer: NewRingBuffer(),
-		Bus:    sam.SERCOM4_USART,
-		SERCOM: 4,
-	}
-)
-
-//go:export SERCOM1_IRQHandler
-func handleUART1() {
-	defaultUART1Handler()
-}
-
 // I2C pins
 const (
 	SDA_PIN = PB02 // I2C0 external
@@ -91,20 +75,6 @@ const (
 	SCL1_PIN = PA01 // I2C1 internal
 )

-// I2C on the Circuit Playground Express.
-var (
-	// external device
-	I2C0 = I2C{
-		Bus:    sam.SERCOM5_I2CM,
-		SERCOM: 5,
-	}
-	// internal device
-	I2C1 = I2C{
-		Bus:    sam.SERCOM1_I2CM,
-		SERCOM: 1,
-	}
-)
-
 // SPI pins (internal flash)
 const (
 	SPI0_SCK_PIN  = PA21 // SCK: SERCOM3/PAD[3]
@@ -112,22 +82,9 @@ const (
 	SPI0_MISO_PIN = PA16 // MISO: SERCOM3/PAD[0]
 )

-// SPI on the Circuit Playground Express.
-var (
-	SPI0 = SPI{
-		Bus:    sam.SERCOM3_SPI,
-		SERCOM: 3,
-	}
-)
-
 // I2S pins
 const (
 	I2S_SCK_PIN = PA10
 	I2S_SD_PIN  = PA08
 	I2S_WS_PIN  = NoPin // no WS, instead uses SCK to sync
 )
-
-// I2S on the Circuit Playground Express.
-var (
-	I2S0 = I2S{Bus: sam.I2S}
-)
@@ -0,0 +1,48 @@
+// +build sam,atsamd21,circuitplay_express
+
+package machine
+
+import (
+	"device/sam"
+	"runtime/interrupt"
+)
+
+// UART1 on the Circuit Playground Express.
+var (
+	UART1 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    sam.SERCOM4_USART,
+		SERCOM: 4,
+	}
+)
+
+func init() {
+	UART1.interrupt = interrupt.New(sam.IRQ_SERCOM4, UART1.handleInterrupt)
+}
+
+// I2C on the Circuit Playground Express.
+var (
+	// external device
+	I2C0 = I2C{
+		Bus:    sam.SERCOM5_I2CM,
+		SERCOM: 5,
+	}
+	// internal device
+	I2C1 = I2C{
+		Bus:    sam.SERCOM1_I2CM,
+		SERCOM: 1,
+	}
+)
+
+// SPI on the Circuit Playground Express.
+var (
+	SPI0 = SPI{
+		Bus:    sam.SERCOM3_SPI,
+		SERCOM: 3,
+	}
+)
+
+// I2S on the Circuit Playground Express.
+var (
+	I2S0 = I2S{Bus: sam.I2S}
+)
@@ -2,7 +2,10 @@

 package machine

-import "device/sam"
+import (
+	"device/sam"
+	"runtime/interrupt"
+)

 // used to reset into bootloader
 const RESET_MAGIC_VALUE = 0xf01669ef
@@ -60,9 +63,8 @@ var (
 	}
 )

-//go:export SERCOM1_IRQHandler
-func handleUART1() {
-	defaultUART1Handler()
+func init() {
+	UART1.interrupt = interrupt.New(sam.IRQ_SERCOM1, UART1.handleInterrupt)
 }

 // I2C pins
@@ -4,6 +4,7 @@ package machine

 import (
 	"device/sam"
+	"runtime/interrupt"
 )

 // used to reset into bootloader
@@ -62,9 +63,8 @@ var (
 	}
 )

-//go:export SERCOM1_IRQHandler
-func handleUART1() {
-	defaultUART1Handler()
+func init() {
+	UART1.interrupt = interrupt.New(sam.IRQ_SERCOM1, UART1.handleInterrupt)
 }

 // I2C pins
@@ -2,7 +2,10 @@

 package machine

-import "device/stm32"
+import (
+	"device/stm32"
+	"runtime/interrupt"
+)

 const (
 	PA0  = portA + 0
@@ -100,14 +103,12 @@ var (
 	UART0 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    stm32.USART2,
-		IRQVal: stm32.IRQ_USART2,
 	}
 	UART2 = &UART0
 )

-//go:export USART2_IRQHandler
-func handleUART2() {
-	UART2.Receive(byte((UART2.Bus.DR.Get() & 0xFF)))
+func init() {
+	UART0.interrupt = interrupt.New(stm32.IRQ_USART2, UART0.handleInterrupt)
 }

 // SPI pins
@@ -0,0 +1,150 @@
+// +build sam,atsamd51,pybadge
+
+package machine
+
+import "device/sam"
+
+// used to reset into bootloader
+const RESET_MAGIC_VALUE = 0xf01669ef
+
+// GPIO Pins
+const (
+	D0  = PB17 // UART0 RX/PWM available
+	D1  = PB16 // UART0 TX/PWM available
+	D2  = PB03
+	D3  = PB02
+	D4  = PA14 // PWM available
+	D5  = PA16 // PWM available
+	D6  = PA18 // PWM available
+	D7  = PB14
+	D8  = PA15 // built-in neopixel
+	D9  = PA19 // PWM available
+	D10 = PA20 // can be used for PWM or UART1 TX
+	D11 = PA21 // can be used for PWM or UART1 RX
+	D12 = PA22 // PWM available
+	D13 = PA23 // PWM available
+)
+
+// Analog pins
+const (
+	A0 = PA02 // ADC/AIN[0]
+	A1 = PA05 // ADC/AIN[2]
+	A2 = PB08 // ADC/AIN[3]
+	A3 = PB09 // ADC/AIN[4]
+	A4 = PA04 // ADC/AIN[5]
+	A5 = PA06 // ADC/AIN[6]
+	A6 = PB01 // ADC/AIN[12]/VMEAS
+	A7 = PB04 // ADC/AIN[6]/LIGHT
+	A8 = D2   // ADC/AIN[14]
+	A9 = D3   // ADC/AIN[15]
+)
+
+const (
+	LED       = D13
+	NEOPIXELS = D8
+
+	LIGHTSENSOR = A7
+
+	BUTTON_LATCH = PB00
+	BUTTON_OUT   = PB30
+	BUTTON_CLK   = PB31
+
+	TFT_DC   = PB05
+	TFT_CS   = PB07
+	TFT_RST  = PA00
+	TFT_LITE = PA01
+
+	SPEAKER_ENABLE = PA27
+
+	QSPI_SCK    = PB10
+	QSPI_CS     = PB11
+	QSPI_DATA_1 = PA08
+	QSPI_DATA_2 = PA09
+	QSPI_DATA_3 = PA10
+	QSPI_DATA_4 = PA11
+)
+
+const (
+	BUTTON_LEFT_MASK   = 1
+	BUTTON_UP_MASK     = 2
+	BUTTON_DOWN_MASK   = 4
+	BUTTON_RIGHT_MASK  = 8
+	BUTTON_SELECT_MASK = 16
+	BUTTON_START_MASK  = 32
+	BUTTON_A_MASK      = 64
+	BUTTON_B_MASK      = 128
+)
+
+// UART0 aka USBCDC pins
+const (
+	USBCDC_DM_PIN = PA24
+	USBCDC_DP_PIN = PA25
+)
+
+// UART1 pins
+const (
+	UART_TX_PIN = D1
+	UART_RX_PIN = D0
+)
+
+// UART1 var is on SERCOM3, defined in atsamd51.go
+
+// UART2 pins
+const (
+	UART2_TX_PIN = A4
+	UART2_RX_PIN = A5
+)
+
+// UART2 var is on SERCOM0, defined in atsamd51.go
+
+// I2C pins
+const (
+	SDA_PIN = PA12 // SDA: SERCOM2/PAD[0]
+	SCL_PIN = PA13 // SCL: SERCOM2/PAD[1]
+)
+
+// I2C on the ItsyBitsy M4.
+var (
+	I2C0 = I2C{Bus: sam.SERCOM2_I2CM,
+		SDA:     SDA_PIN,
+		SCL:     SCL_PIN,
+		PinMode: PinSERCOM}
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN  = PA17 // SCK: SERCOM1/PAD[1]
+	SPI0_MOSI_PIN = PB23 // MOSI: SERCOM1/PAD[3]
+	SPI0_MISO_PIN = PB22 // MISO: SERCOM1/PAD[2]
+)
+
+// SPI on the PyBadge.
+var (
+	SPI0 = SPI{Bus: sam.SERCOM1_SPIM,
+		SCK:         SPI0_SCK_PIN,
+		MOSI:        SPI0_MOSI_PIN,
+		MISO:        SPI0_MISO_PIN,
+		DOpad:       spiTXPad3SCK1,
+		DIpad:       sercomRXPad2,
+		MISOPinMode: PinSERCOM,
+		MOSIPinMode: PinSERCOM,
+		SCKPinMode:  PinSERCOM,
+	}
+)
+
+// TFT SPI pins
+const (
+	SPI1_SCK_PIN  = PB13 // SCK: SERCOM4/PAD[1]
+	SPI1_MOSI_PIN = PB15 // MOSI: SERCOM4/PAD[3]
+)
+
+// TFT SPI on the PyBadge.
+var (
+	SPI1 = SPI{Bus: sam.SERCOM4_SPIM,
+		SCK:         SPI1_SCK_PIN,
+		MOSI:        SPI1_MOSI_PIN,
+		DOpad:       spiTXPad3SCK1,
+		MOSIPinMode: PinSERCOM,
+		SCKPinMode:  PinSERCOM,
+	}
+)
@@ -2,7 +2,10 @@

 package machine

-import "device/sam"
+import (
+	"device/sam"
+	"runtime/interrupt"
+)

 // used to reset into bootloader
 const RESET_MAGIC_VALUE = 0xf01669ef
@@ -51,9 +54,8 @@ var (
 	}
 )

-//go:export SERCOM1_IRQHandler
-func handleUART1() {
-	defaultUART1Handler()
+func init() {
+	UART1.interrupt = interrupt.New(sam.IRQ_SERCOM0, UART1.handleInterrupt)
 }

 // SPI pins
@@ -4,6 +4,7 @@ package machine

 import (
 	"device/avr"
+	"runtime/interrupt"
 	"runtime/volatile"
 )

@@ -140,7 +141,7 @@ func (i2c I2C) Configure(config I2CConfig) {
 	// SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
 	// NOTE: TWBR should be 10 or higher for master mode.
 	// It is 72 for a 16mhz board with 100kHz TWI
-	avr.TWBR.Set(uint8(((CPU_FREQUENCY / config.Frequency) - 16) / 2))
+	avr.TWBR.Set(uint8(((CPUFrequency() / config.Frequency) - 16) / 2))

 	// Enable twi module.
 	avr.TWCR.Set(avr.TWCR_TWEN)
@@ -232,10 +233,22 @@ func (uart UART) Configure(config UARTConfig) {
 		config.BaudRate = 9600
 	}

+	// Register the UART interrupt.
+	interrupt.New(avr.IRQ_USART_RX, func(intr interrupt.Interrupt) {
+		// Read register to clear it.
+		data := avr.UDR0.Get()
+
+		// Ensure no error.
+		if !avr.UCSR0A.HasBits(avr.UCSR0A_FE0 | avr.UCSR0A_DOR0 | avr.UCSR0A_UPE0) {
+			// Put data from UDR register into buffer.
+			UART0.Receive(byte(data))
+		}
+	})
+
 	// Set baud rate based on prescale formula from
 	// https://www.microchip.com/webdoc/AVRLibcReferenceManual/FAQ_1faq_wrong_baud_rate.html
 	// ((F_CPU + UART_BAUD_RATE * 8L) / (UART_BAUD_RATE * 16L) - 1)
-	ps := ((CPU_FREQUENCY+config.BaudRate*8)/(config.BaudRate*16) - 1)
+	ps := ((CPUFrequency()+config.BaudRate*8)/(config.BaudRate*16) - 1)
 	avr.UBRR0H.Set(uint8(ps >> 8))
 	avr.UBRR0L.Set(uint8(ps & 0xff))

@@ -254,15 +267,3 @@ func (uart UART) WriteByte(c byte) error {
 	avr.UDR0.Set(c) // send char
 	return nil
 }
-
-//go:interrupt USART_RX_vect
-func handleUSART_RX() {
-	// Read register to clear it.
-	data := avr.UDR0.Get()
-
-	// Ensure no error.
-	if !avr.UCSR0A.HasBits(avr.UCSR0A_FE0 | avr.UCSR0A_DOR0 | avr.UCSR0A_UPE0) {
-		// Put data from UDR register into buffer.
-		UART0.Receive(byte(data))
-	}
-}
@@ -11,11 +11,10 @@ import (
 	"device/arm"
 	"device/sam"
 	"errors"
+	"runtime/interrupt"
 	"unsafe"
 )

-const CPU_FREQUENCY = 48000000
-
 type PinMode uint8

 const (
@@ -35,74 +34,6 @@ const (
 	PinInputPulldown PinMode = 12
 )

-// Hardware pins
-const (
-	PA00 Pin = 0
-	PA01 Pin = 1
-	PA02 Pin = 2
-	PA03 Pin = 3
-	PA04 Pin = 4
-	PA05 Pin = 5
-	PA06 Pin = 6
-	PA07 Pin = 7
-	PA08 Pin = 8
-	PA09 Pin = 9
-	PA10 Pin = 10
-	PA11 Pin = 11
-	PA12 Pin = 12
-	PA13 Pin = 13
-	PA14 Pin = 14
-	PA15 Pin = 15
-	PA16 Pin = 16
-	PA17 Pin = 17
-	PA18 Pin = 18
-	PA19 Pin = 19
-	PA20 Pin = 20
-	PA21 Pin = 21
-	PA22 Pin = 22
-	PA23 Pin = 23
-	PA24 Pin = 24
-	PA25 Pin = 25
-	PA26 Pin = 26
-	PA27 Pin = 27
-	PA28 Pin = 28
-	PA29 Pin = 29
-	PA30 Pin = 30
-	PA31 Pin = 31
-	PB00 Pin = 32
-	PB01 Pin = 33
-	PB02 Pin = 34
-	PB03 Pin = 35
-	PB04 Pin = 36
-	PB05 Pin = 37
-	PB06 Pin = 38
-	PB07 Pin = 39
-	PB08 Pin = 40
-	PB09 Pin = 41
-	PB10 Pin = 42
-	PB11 Pin = 43
-	PB12 Pin = 44
-	PB13 Pin = 45
-	PB14 Pin = 46
-	PB15 Pin = 47
-	PB16 Pin = 48
-	PB17 Pin = 49
-	PB18 Pin = 50
-	PB19 Pin = 51
-	PB20 Pin = 52
-	PB21 Pin = 53
-	PB22 Pin = 54
-	PB23 Pin = 55
-	PB24 Pin = 56
-	PB25 Pin = 57
-	PB26 Pin = 58
-	PB27 Pin = 59
-	PB28 Pin = 60
-	PB29 Pin = 61
-	PB30 Pin = 62
-	PB31 Pin = 63
-)
-
 const (
 	pinPadMapSERCOM0Pad0 byte = (0x10 << 1) | 0x00
 	pinPadMapSERCOM1Pad0 byte = (0x20 << 1) | 0x00
@@ -362,9 +293,10 @@ func waitADCSync() {

 // UART on the SAMD21.
 type UART struct {
-	Buffer *RingBuffer
-	Bus    *sam.SERCOM_USART_Type
-	SERCOM uint8
+	Buffer    *RingBuffer
+	Bus       *sam.SERCOM_USART_Type
+	SERCOM    uint8
+	interrupt interrupt.Interrupt
 }

 var (
@@ -471,10 +403,7 @@ func (uart UART) Configure(config UARTConfig) error {
 	uart.Bus.INTENSET.Set(sam.SERCOM_USART_INTENSET_RXC)

 	// Enable RX IRQ.
-	// IRQ lines are in the same order as SERCOM instance numbers on SAMD21
-	// chips, so the IRQ number can be trivially determined from the SERCOM
-	// number.
-	arm.EnableIRQ(sam.IRQ_SERCOM0 + uint32(uart.SERCOM))
+	uart.interrupt.Enable()

 	return nil
 }
@@ -485,7 +414,7 @@ func (uart UART) SetBaudRate(br uint32) {
 	//   BAUD = fref / (sampleRateValue * fbaud)
 	// (multiply by 8, to calculate fractional piece)
 	// uint32_t baudTimes8 = (SystemCoreClock * 8) / (16 * baudrate);
-	baud := (CPU_FREQUENCY * 8) / (sampleRate16X * br)
+	baud := (CPUFrequency() * 8) / (sampleRate16X * br)

 	// sercom->USART.BAUD.FRAC.FP   = (baudTimes8 % 8);
 	// sercom->USART.BAUD.FRAC.BAUD = (baudTimes8 / 8);
@@ -502,11 +431,12 @@ func (uart UART) WriteByte(c byte) error {
 	return nil
 }

-// defaultUART1Handler handles the UART1 IRQ.
-func defaultUART1Handler() {
+// handleInterrupt should be called from the appropriate interrupt handler for
+// this UART instance.
+func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	// should reset IRQ
-	UART1.Receive(byte((UART1.Bus.DATA.Get() & 0xFF)))
-	UART1.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INTFLAG_RXC)
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INTFLAG_RXC)
 }

 // I2C on the SAMD21.
@@ -601,7 +531,7 @@ func (i2c I2C) Configure(config I2CConfig) error {
 func (i2c I2C) SetBaudRate(br uint32) {
 	// Synchronous arithmetic baudrate, via Arduino SAMD implementation:
 	// SystemCoreClock / ( 2 * baudrate) - 5 - (((SystemCoreClock / 1000000) * WIRE_RISE_TIME_NANOSECONDS) / (2 * 1000));
-	baud := CPU_FREQUENCY/(2*br) - 5 - (((CPU_FREQUENCY / 1000000) * riseTimeNanoseconds) / (2 * 1000))
+	baud := CPUFrequency()/(2*br) - 5 - (((CPUFrequency() / 1000000) * riseTimeNanoseconds) / (2 * 1000))
 	i2c.Bus.BAUD.Set(baud)
 }

@@ -793,7 +723,7 @@ func (i2s I2S) Configure(config I2SConfig) {
 	sam.PM.APBCMASK.SetBits(sam.PM_APBCMASK_I2S_)

 	// setting clock rate for sample.
-	division_factor := CPU_FREQUENCY / (config.AudioFrequency * uint32(config.DataFormat))
+	division_factor := CPUFrequency() / (config.AudioFrequency * uint32(config.DataFormat))

 	// Switch Generic Clock Generator 3 to DFLL48M.
 	sam.GCLK.GENDIV.Set((sam.GCLK_CLKCTRL_GEN_GCLK3 << sam.GCLK_GENDIV_ID_Pos) |
@@ -1113,7 +1043,7 @@ func (spi SPI) Configure(config SPIConfig) error {
 	}

 	// Set synch speed for SPI
-	baudRate := (CPU_FREQUENCY / (2 * config.Frequency)) - 1
+	baudRate := (CPUFrequency() / (2 * config.Frequency)) - 1
 	spi.Bus.BAUD.Set(uint8(baudRate))

 	// Enable SPI port.
@@ -1438,7 +1368,8 @@ func (usbcdc USBCDC) Configure(config UARTConfig) {
 	sam.USB_DEVICE.CTRLA.SetBits(sam.USB_DEVICE_CTRLA_ENABLE)

 	// enable IRQ
-	arm.EnableIRQ(sam.IRQ_USB)
+	intr := interrupt.New(sam.IRQ_USB, handleUSB)
+	intr.Enable()
 }

 func handlePadCalibration() {
@@ -1484,8 +1415,7 @@ func handlePadCalibration() {
 	sam.USB_DEVICE.PADCAL.SetBits(calibTrim << sam.USB_DEVICE_PADCAL_TRIM_Pos)
 }

-//go:export USB_IRQHandler
-func handleUSB() {
+func handleUSB(intr interrupt.Interrupt) {
 	// reset all interrupt flags
 	flags := sam.USB_DEVICE.INTFLAG.Get()
 	sam.USB_DEVICE.INTFLAG.Set(flags)
@@ -11,10 +11,13 @@ import (
 	"device/arm"
 	"device/sam"
 	"errors"
+	"runtime/interrupt"
 	"unsafe"
 )

-const CPU_FREQUENCY = 120000000
+func CPUFrequency() uint32 {
+	return 120000000
+}

 type PinMode uint8

@@ -1400,11 +1403,11 @@ func (usbcdc USBCDC) Configure(config UARTConfig) {
 	// enable USB
 	sam.USB_DEVICE.CTRLA.SetBits(sam.USB_DEVICE_CTRLA_ENABLE)

-	// enable IRQ
-	arm.EnableIRQ(sam.IRQ_USB_OTHER)
-	arm.EnableIRQ(sam.IRQ_USB_SOF_HSOF)
-	arm.EnableIRQ(sam.IRQ_USB_TRCPT0)
-	arm.EnableIRQ(sam.IRQ_USB_TRCPT1)
+	// enable IRQ at highest priority
+	interrupt.New(sam.IRQ_USB_OTHER, handleUSBIRQ).Enable()
+	interrupt.New(sam.IRQ_USB_SOF_HSOF, handleUSBIRQ).Enable()
+	interrupt.New(sam.IRQ_USB_TRCPT0, handleUSBIRQ).Enable()
+	interrupt.New(sam.IRQ_USB_TRCPT1, handleUSBIRQ).Enable()
 }

 func handlePadCalibration() {
@@ -1450,27 +1453,7 @@ func handlePadCalibration() {
 	sam.USB_DEVICE.PADCAL.SetBits(calibTrim << sam.USB_DEVICE_PADCAL_TRIM_Pos)
 }

-//go:export USB_OTHER_IRQHandler
-func handleUSBOther() {
-	handleUSBIRQ()
-}
-
-//go:export USB_SOF_HSOF_IRQHandler
-func handleUSBSOFHSOF() {
-	handleUSBIRQ()
-}
-
-//go:export USB_TRCPT0_IRQHandler
-func handleUSBTRCPT0() {
-	handleUSBIRQ()
-}
-
-//go:export USB_TRCPT1_IRQHandler
-func handleUSBTRCPT1() {
-	handleUSBIRQ()
-}
-
-func handleUSBIRQ() {
+func handleUSBIRQ(interrupt.Interrupt) {
 	// reset all interrupt flags
 	flags := sam.USB_DEVICE.INTFLAG.Get()
 	sam.USB_DEVICE.INTFLAG.Set(flags)
@@ -6,7 +6,9 @@ import (
 	"device/sifive"
 )

-const CPU_FREQUENCY = 16000000
+func CPUFrequency() uint32 {
+	return 16000000
+}

 type PinMode uint8

@@ -108,7 +110,7 @@ func (spi SPI) Configure(config SPIConfig) error {
 	}

 	// div = (SPI_CFG(dev)->f_sys / (2 * frequency)) - 1;
-	div := CPU_FREQUENCY/(2*config.Frequency) - 1
+	div := CPUFrequency()/(2*config.Frequency) - 1
 	spi.Bus.DIV.Set(div)

 	// set mode
@@ -3,9 +3,9 @@
 package machine

 import (
-	"device/arm"
 	"device/nrf"
 	"errors"
+	"runtime/interrupt"
 )

 var (
@@ -88,8 +88,11 @@ func (uart UART) Configure(config UARTConfig) {
 	nrf.UART0.INTENSET.Set(nrf.UART_INTENSET_RXDRDY_Msk)

 	// Enable RX IRQ.
-	arm.SetPriority(nrf.IRQ_UART0, 0xc0) // low priority
-	arm.EnableIRQ(nrf.IRQ_UART0)
+	intr := interrupt.New(nrf.IRQ_UART0, func(intr interrupt.Interrupt) {
+		UART0.handleInterrupt()
+	})
+	intr.SetPriority(0xc0) // low priority
+	intr.Enable()
 }

 // SetBaudRate sets the communication speed for the UART.
@@ -6,7 +6,9 @@ import (
 	"device/nrf"
 )

-const CPU_FREQUENCY = 16000000
+func CPUFrequency() uint32 {
+	return 16000000
+}

 // Get peripheral and pin number for this GPIO pin.
 func (p Pin) getPortPin() (*nrf.GPIO_Type, uint32) {
@@ -18,11 +20,6 @@ func (uart UART) setPins(tx, rx Pin) {
 	nrf.UART0.PSELRXD.Set(uint32(rx))
 }

-//go:export UART0_IRQHandler
-func handleUART0() {
-	UART0.handleInterrupt()
-}
-
 func (i2c I2C) setPins(scl, sda Pin) {
 	i2c.Bus.PSELSCL.Set(uint32(scl))
 	i2c.Bus.PSELSDA.Set(uint32(sda))
@@ -7,7 +7,9 @@ import (
 	"unsafe"
 )

-const CPU_FREQUENCY = 64000000
+func CPUFrequency() uint32 {
+	return 64000000
+}

 // Get peripheral and pin number for this GPIO pin.
 func (p Pin) getPortPin() (*nrf.GPIO_Type, uint32) {
@@ -19,11 +21,6 @@ func (uart UART) setPins(tx, rx Pin) {
 	nrf.UART0.PSELRXD.Set(uint32(rx))
 }

-//go:export UARTE0_UART0_IRQHandler
-func handleUART0() {
-	UART0.handleInterrupt()
-}
-
 func (i2c I2C) setPins(scl, sda Pin) {
 	i2c.Bus.PSELSCL.Set(uint32(scl))
 	i2c.Bus.PSELSDA.Set(uint32(sda))
@@ -7,7 +7,9 @@ import (
 	"unsafe"
 )

-const CPU_FREQUENCY = 64000000
+func CPUFrequency() uint32 {
+	return 64000000
+}

 // Get peripheral and pin number for this GPIO pin.
 func (p Pin) getPortPin() (*nrf.GPIO_Type, uint32) {
@@ -23,11 +25,6 @@ func (uart UART) setPins(tx, rx Pin) {
 	nrf.UART0.PSEL.RXD.Set(uint32(rx))
 }

-//go:export UARTE0_UART0_IRQHandler
-func handleUART0() {
-	UART0.handleInterrupt()
-}
-
 func (i2c I2C) setPins(scl, sda Pin) {
 	i2c.Bus.PSEL.SCL.Set(uint32(scl))
 	i2c.Bus.PSEL.SDA.Set(uint32(sda))
@@ -5,12 +5,14 @@ package machine
 // Peripheral abstraction layer for the stm32.

 import (
-	"device/arm"
 	"device/stm32"
 	"errors"
+	"runtime/interrupt"
 )

-const CPU_FREQUENCY = 72000000
+func CPUFrequency() uint32 {
+	return 72000000
+}

 const (
 	PinInput       PinMode = 0 // Input mode
@@ -109,9 +111,9 @@ func (p Pin) Get() bool {

 // UART
 type UART struct {
-	Buffer *RingBuffer
-	Bus    *stm32.USART_Type
-	IRQVal uint32
+	Buffer    *RingBuffer
+	Bus       *stm32.USART_Type
+	interrupt interrupt.Interrupt
 }

 // Configure the UART.
@@ -153,8 +155,8 @@ func (uart UART) Configure(config UARTConfig) {
 	uart.Bus.CR1.Set(stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE)

 	// Enable RX IRQ
-	arm.SetPriority(uart.IRQVal, 0xc0)
-	arm.EnableIRQ(uart.IRQVal)
+	uart.interrupt.SetPriority(0xc0)
+	uart.interrupt.Enable()
 }

 // SetBaudRate sets the communication speed for the UART.
@@ -163,10 +165,10 @@ func (uart UART) SetBaudRate(br uint32) {
 	var divider uint32
 	if uart.Bus == stm32.USART1 {
 		// first divide by PCLK2 prescaler (div 1) and then desired baudrate
-		divider = CPU_FREQUENCY / br
+		divider = CPUFrequency() / br
 	} else {
 		// first divide by PCLK1 prescaler (div 2) and then desired baudrate
-		divider = CPU_FREQUENCY / 2 / br
+		divider = CPUFrequency() / 2 / br
 	}
 	uart.Bus.BRR.Set(divider)
 }
@@ -180,6 +182,12 @@ func (uart UART) WriteByte(c byte) error {
 	return nil
 }

+// handleInterrupt should be called from the appropriate interrupt handler for
+// this UART instance.
+func (uart *UART) handleInterrupt(interrupt.Interrupt) {
+	uart.Receive(byte((uart.Bus.DR.Get() & 0xFF)))
+}
+
 // SPI on the STM32.
 type SPI struct {
 	Bus *stm32.SPI_Type
@@ -360,7 +368,7 @@ func (i2c I2C) Configure(config I2CConfig) {
 	i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_PE)

 	// pclk1 clock speed is main frequency divided by PCLK1 prescaler (div 2)
-	pclk1 := uint32(CPU_FREQUENCY / 2)
+	pclk1 := CPUFrequency() / 2

 	// set freqency range to PCLK1 clock speed in MHz
 	// aka setting the value 36 means to use 36 MHz clock
@@ -5,11 +5,13 @@ package machine
 // Peripheral abstraction layer for the stm32.

 import (
-	"device/arm"
 	"device/stm32"
+	"runtime/interrupt"
 )

-const CPU_FREQUENCY = 168000000
+func CPUFrequency() uint32 {
+	return 168000000
+}

 const (
 	// Mode Flag
@@ -201,8 +203,11 @@ func (uart UART) Configure(config UARTConfig) {
 	stm32.USART2.CR1.Set(stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE)

 	// Enable RX IRQ.
-	arm.SetPriority(stm32.IRQ_USART2, 0xc0)
-	arm.EnableIRQ(stm32.IRQ_USART2)
+	intr := interrupt.New(stm32.IRQ_USART2, func(interrupt.Interrupt) {
+		UART1.Receive(byte((stm32.USART2.DR.Get() & 0xFF)))
+	})
+	intr.SetPriority(0xc0)
+	intr.Enable()
 }

 // WriteByte writes a byte of data to the UART.
@@ -213,8 +218,3 @@ func (uart UART) WriteByte(c byte) error {
 	}
 	return nil
 }
-
-//go:export USART2_IRQHandler
-func handleUSART2() {
-	UART1.Receive(byte((stm32.USART2.DR.Get() & 0xFF)))
-}
@@ -1,4 +1,4 @@
-// +build sam stm32,!stm32f407 fe310
+// +build !baremetal sam stm32,!stm32f407 fe310

 package machine

@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal
+// +build darwin linux,!baremetal freebsd,!baremetal

 package os

@@ -0,0 +1,14 @@
+// Package interrupt provides access to hardware interrupts. It provides a way
+// to define interrupts and to enable/disable them.
+package interrupt
+
+// Interrupt provides direct access to hardware interrupts. You can configure
+// this interrupt through this interface.
+//
+// Do not use the zero value of an Interrupt object. Instead, call New to obtain
+// an interrupt handle.
+type Interrupt struct {
+	// Make this number unexported so it cannot be set directly. This provides
+	// some encapsulation.
+	num int
+}
@@ -0,0 +1,23 @@
+// +build cortexm
+
+package interrupt
+
+import (
+	"device/arm"
+)
+
+// Enable enables this interrupt. Right after calling this function, the
+// interrupt may be invoked if it was already pending.
+func (irq Interrupt) Enable() {
+	arm.EnableIRQ(uint32(irq.num))
+}
+
+// SetPriority sets the interrupt priority for this interrupt. A lower number
+// means a higher priority. Additionally, most hardware doesn't implement all
+// priority bits (only the uppoer bits).
+//
+// Examples: 0xff (lowest priority), 0xc0 (low priority), 0x00 (highest possible
+// priority).
+func (irq Interrupt) SetPriority(priority uint8) {
+	arm.SetPriority(uint32(irq.num), uint32(priority))
+}
@@ -0,0 +1,59 @@
+// +build gameboyadvance
+
+package interrupt
+
+import (
+	"runtime/volatile"
+	"unsafe"
+)
+
+var handlers = [14]func(Interrupt){}
+
+const (
+	IRQ_VBLANK  = 0
+	IRQ_HBLANK  = 1
+	IRQ_VCOUNT  = 2
+	IRQ_TIMER0  = 3
+	IRQ_TIMER1  = 4
+	IRQ_TIMER2  = 5
+	IRQ_TIMER3  = 6
+	IRQ_COM     = 7
+	IRQ_DMA0    = 8
+	IRQ_DMA1    = 9
+	IRQ_DMA2    = 10
+	IRQ_DMA3    = 11
+	IRQ_KEYPAD  = 12
+	IRQ_GAMEPAK = 13
+)
+
+var (
+	regInterruptEnable = (*volatile.Register16)(unsafe.Pointer(uintptr(0x4000200)))
+	regInterruptRequestFlags = (*volatile.Register16)(unsafe.Pointer(uintptr(0x4000202)))
+	regInterruptMasterEnable = (*volatile.Register16)(unsafe.Pointer(uintptr(0x4000208)))
+)
+
+// New creates a new Interrupt object. Do not call it multiple times. If you do,
+// make sure the interrupt is disabled while you do so. The last call will set
+// the active interrupt handler.
+func New(id int, handler func(Interrupt)) Interrupt {
+	handlers[id] = handler
+	return Interrupt{id}
+}
+
+// Enable enables this interrupt. Right after calling this function, the
+// interrupt may be invoked if it was already pending.
+func (irq Interrupt) Enable() {
+	regInterruptEnable.SetBits(1 << irq.num)
+}
+
+//export handleInterrupt
+func handleInterrupt() {
+	flags := regInterruptRequestFlags.Get()
+	for i := range handlers {
+		if flags & (1 << i) != 0 {
+			irq := Interrupt{i}
+			regInterruptRequestFlags.Set(1 << i) // acknowledge interrupt
+			handlers[i](irq)
+		}
+	}
+}
@@ -0,0 +1,19 @@
+// +build avr riscv,baremetal cortexm
+
+package interrupt
+
+// New is a compiler intrinsic that creates a new Interrupt object. You may call
+// it only once, and must pass constant parameters to it. That means that the
+// interrupt ID must be a Go constant and that the handler must be a simple
+// function: closures are not supported.
+func New(id int, handler func(Interrupt)) Interrupt
+
+// Register is used to declare an interrupt. You should not normally call this
+// function: it is only for telling the compiler about the mapping between an
+// interrupt number and the interrupt handler name.
+func Register(id int, handlerName string) int
+
+type handle struct {
+	handler func(Interrupt)
+	Interrupt
+}
@@ -0,0 +1,5 @@
+// +build freebsd
+
+package runtime
+
+const GOOS = "freebsd"
@@ -4,6 +4,7 @@ package runtime

 import (
 	"unsafe"
+	_ "runtime/interrupt" // make sure the interrupt handler is defined
 )

 type timeUnit int64
@@ -6,6 +6,7 @@ import (
 	"device/arm"
 	"device/sam"
 	"machine"
+	"runtime/interrupt"
 	"runtime/volatile"
 	"unsafe"
 )
@@ -214,8 +215,14 @@ func initRTC() {
 	sam.RTC_MODE0.CTRL.SetBits(sam.RTC_MODE0_CTRL_ENABLE)
 	waitForSync()

-	arm.SetPriority(sam.IRQ_RTC, 0xc0)
-	arm.EnableIRQ(sam.IRQ_RTC)
+	intr := interrupt.New(sam.IRQ_RTC, func(intr interrupt.Interrupt) {
+		// disable IRQ for CMP0 compare
+		sam.RTC_MODE0.INTFLAG.Set(sam.RTC_MODE0_INTENSET_CMP0)
+
+		timerWakeup.Set(1)
+	})
+	intr.SetPriority(0xc0)
+	intr.Enable()
 }

 func waitForSync() {
@@ -286,14 +293,6 @@ func timerSleep(ticks uint32) {
 	}
 }

-//go:export RTC_IRQHandler
-func handleRTC() {
-	// disable IRQ for CMP0 compare
-	sam.RTC_MODE0.INTFLAG.Set(sam.RTC_MODE0_INTENSET_CMP0)
-
-	timerWakeup.Set(1)
-}
-
 func initUSBClock() {
 	// Turn on clock for USB
 	sam.PM.APBBMASK.SetBits(sam.PM_APBBMASK_USB_)
@@ -1,4 +1,4 @@
-// +build qemu
+// +build cortexm,qemu

 package runtime

@@ -9,7 +9,6 @@ import (
 	"machine"
 	"unsafe"

-	"device/riscv"
 	"device/sifive"
 )

@@ -82,34 +81,4 @@ func putchar(c byte) {
 	machine.UART0.WriteByte(c)
 }

-func ticks() timeUnit {
-	// Combining the low bits and the high bits yields a time span of over 270
-	// years without counter rollover.
-	highBits := sifive.RTC.RTCHI.Get()
-	for {
-		lowBits := sifive.RTC.RTCLO.Get()
-		newHighBits := sifive.RTC.RTCHI.Get()
-		if newHighBits == highBits {
-			// High bits stayed the same.
-			return timeUnit(lowBits) | (timeUnit(highBits) << 32)
-		}
-		// Retry, because there was a rollover in the low bits (happening every
-		// 1.5 days).
-		highBits = newHighBits
-	}
-}
-
 const asyncScheduler = false
-
-func sleepTicks(d timeUnit) {
-	target := ticks() + d
-	for ticks() < target {
-	}
-}
-
-func abort() {
-	// lock up forever
-	for {
-		riscv.Asm("wfi")
-	}
-}
@@ -0,0 +1,39 @@
+// +build fe310,!qemu
+
+package runtime
+
+import (
+	"device/riscv"
+	"device/sifive"
+)
+
+func abort() {
+	// lock up forever
+	for {
+		riscv.Asm("wfi")
+	}
+}
+
+func ticks() timeUnit {
+	// Combining the low bits and the high bits yields a time span of over 270
+	// years without counter rollover.
+	highBits := sifive.RTC.RTCHI.Get()
+	for {
+		lowBits := sifive.RTC.RTCLO.Get()
+		newHighBits := sifive.RTC.RTCHI.Get()
+		if newHighBits == highBits {
+			// High bits stayed the same.
+			println("bits:", highBits, lowBits)
+			return timeUnit(lowBits) | (timeUnit(highBits) << 32)
+		}
+		// Retry, because there was a rollover in the low bits (happening every
+		// 1.5 days).
+		highBits = newHighBits
+	}
+}
+
+func sleepTicks(d timeUnit) {
+	target := ticks() + d
+	for ticks() < target {
+	}
+}
@@ -0,0 +1,28 @@
+// +build fe310,qemu
+
+package runtime
+
+import (
+	"runtime/volatile"
+	"unsafe"
+)
+
+// Special memory-mapped device to exit tests, created by SiFive.
+var testExit = (*volatile.Register32)(unsafe.Pointer(uintptr(0x100000)))
+
+var timestamp timeUnit
+
+func abort() {
+	// Signal a successful exit.
+	testExit.Set(0x5555)
+}
+
+func ticks() timeUnit {
+	return timestamp
+}
+
+func sleepTicks(d timeUnit) {
+	// Note: QEMU doesn't seem to support the RTC peripheral at the time of
+	// writing so just simulate sleeping here.
+	timestamp += d
+}
@@ -6,6 +6,7 @@ import (
 	"device/arm"
 	"device/nrf"
 	"machine"
+	"runtime/interrupt"
 	"runtime/volatile"
 )

@@ -43,8 +44,13 @@ func initLFCLK() {

 func initRTC() {
 	nrf.RTC1.TASKS_START.Set(1)
-	arm.SetPriority(nrf.IRQ_RTC1, 0xc0) // low priority
-	arm.EnableIRQ(nrf.IRQ_RTC1)
+	intr := interrupt.New(nrf.IRQ_RTC1, func(intr interrupt.Interrupt) {
+		nrf.RTC1.INTENCLR.Set(nrf.RTC_INTENSET_COMPARE0)
+		nrf.RTC1.EVENTS_COMPARE[0].Set(0)
+		rtc_wakeup.Set(1)
+	})
+	intr.SetPriority(0xc0) // low priority
+	intr.Enable()
 }

 func putchar(c byte) {
@@ -96,10 +102,3 @@ func rtc_sleep(ticks uint32) {
 		arm.Asm("wfi")
 	}
 }
-
-//go:export RTC1_IRQHandler
-func handleRTC1() {
-	nrf.RTC1.INTENCLR.Set(nrf.RTC_INTENSET_COMPARE0)
-	nrf.RTC1.EVENTS_COMPARE[0].Set(0)
-	rtc_wakeup.Set(1)
-}
@@ -6,6 +6,7 @@ import (
 	"device/arm"
 	"device/stm32"
 	"machine"
+	"runtime/interrupt"
 	"runtime/volatile"
 )

@@ -101,8 +102,9 @@ func initRTC() {
 func initTIM() {
 	stm32.RCC.APB1ENR.SetBits(stm32.RCC_APB1ENR_TIM3EN)

-	arm.SetPriority(stm32.IRQ_TIM3, 0xc3)
-	arm.EnableIRQ(stm32.IRQ_TIM3)
+	intr := interrupt.New(stm32.IRQ_TIM3, handleTIM3)
+	intr.SetPriority(0xc3)
+	intr.Enable()
 }

 const asyncScheduler = false
@@ -163,7 +165,7 @@ func timerSleep(ticks uint32) {
 	// The current scaling only supports a range of 200 usec to 6553 msec.

 	// prescale counter down from 72mhz to 10khz aka 0.1 ms frequency.
-	stm32.TIM3.PSC.Set(machine.CPU_FREQUENCY/10000 - 1) // 7199
+	stm32.TIM3.PSC.Set(machine.CPUFrequency()/10000 - 1) // 7199

 	// Set duty aka duration.
 	// STM32 dividers use n-1, i.e. n counts from 0 to n-1.
@@ -186,8 +188,7 @@ func timerSleep(ticks uint32) {
 	}
 }

-//go:export TIM3_IRQHandler
-func handleTIM3() {
+func handleTIM3(interrupt.Interrupt) {
 	if stm32.TIM3.SR.HasBits(stm32.TIM_SR_UIF) {
 		// Disable the timer.
 		stm32.TIM3.CR1.ClearBits(stm32.TIM_CR1_CEN)
@@ -6,6 +6,7 @@ import (
 	"device/arm"
 	"device/stm32"
 	"machine"
+	"runtime/interrupt"
 	"runtime/volatile"
 )

@@ -121,8 +122,9 @@ var timerWakeup volatile.Register8
 func initTIM3() {
 	stm32.RCC.APB1ENR.SetBits(stm32.RCC_APB1ENR_TIM3EN)

-	arm.SetPriority(stm32.IRQ_TIM3, 0xc3)
-	arm.EnableIRQ(stm32.IRQ_TIM3)
+	intr := interrupt.New(stm32.IRQ_TIM3, handleTIM3)
+	intr.SetPriority(0xc3)
+	intr.Enable()
 }

 // Enable the TIM7 clock.(tick count)
@@ -139,8 +141,9 @@ func initTIM7() {
 	// Enable the timer.
 	stm32.TIM7.CR1.SetBits(stm32.TIM_CR1_CEN)

-	arm.SetPriority(stm32.IRQ_TIM7, 0xc1)
-	arm.EnableIRQ(stm32.IRQ_TIM7)
+	intr := interrupt.New(stm32.IRQ_TIM7, handleTIM7)
+	intr.SetPriority(0xc1)
+	intr.Enable()
 }

 const asyncScheduler = false
@@ -183,8 +186,7 @@ func timerSleep(ticks uint32) {
 	}
 }

-//go:export TIM3_IRQHandler
-func handleTIM3() {
+func handleTIM3(interrupt.Interrupt) {
 	if stm32.TIM3.SR.HasBits(stm32.TIM_SR_UIF) {
 		// Disable the timer.
 		stm32.TIM3.CR1.ClearBits(stm32.TIM_CR1_CEN)
@@ -197,8 +199,7 @@ func handleTIM3() {
 	}
 }

-//go:export TIM7_IRQHandler
-func handleTIM7() {
+func handleTIM7(interrupt.Interrupt) {
 	if stm32.TIM7.SR.HasBits(stm32.TIM_SR_UIF) {
 		// clear the update flag
 		stm32.TIM7.SR.ClearBits(stm32.TIM_SR_UIF)
@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal
+// +build darwin linux,!baremetal freebsd,!baremetal

 package runtime

@@ -76,3 +76,17 @@ func memset(ptr unsafe.Pointer, c byte, size uintptr) unsafe.Pointer {
 	}
 	return ptr
 }
+
+// Implement memmove for LLVM and compiler-rt.
+//go:export memmove
+func libc_memmove(dst, src unsafe.Pointer, size uintptr) unsafe.Pointer {
+	memmove(dst, src, size)
+	return dst
+}
+
+// Implement memcpy for LLVM and compiler-rt.
+//go:export memcpy
+func libc_memcpy(dst, src unsafe.Pointer, size uintptr) unsafe.Pointer {
+	memcpy(dst, src, size)
+	return dst
+}
@@ -8,7 +8,7 @@
 	],
 	"linkerscript": "targets/lm3s6965.ld",
 	"extra-files": [
-		"targets/qemu.s"
+		"targets/cortex-m-qemu.s"
 	],
 	"emulator": ["qemu-system-arm", "-machine", "lm3s6965evb", "-semihosting", "-nographic", "-kernel"]
 }
@@ -1,5 +1,5 @@
 // Generic Cortex-M interrupt vector.
-// This vector is used by the QEMU target.
+// This vector is used by the Cortex-M QEMU target.

 .syntax unified

@@ -1,16 +1,17 @@
 OUTPUT_ARCH(arm)
 ENTRY(_start)

+/* Note: iwram is reduced by 96 bytes because the last part of that RAM
+ * (starting at 0x03007FA0) is used for interrupt handling.
+ */
 MEMORY {
-    ewram   : ORIGIN = 0x02000000, LENGTH = 256K /* on-board work RAM (2 wait states) */
-    iwram   : ORIGIN = 0x03000000, LENGTH = 32K  /* in-chip work RAM (faster) */
-    rom     : ORIGIN = 0x08000000, LENGTH = 32M  /* flash ROM */
+    ewram   : ORIGIN = 0x02000000, LENGTH = 256K   /* on-board work RAM (2 wait states) */
+    iwram   : ORIGIN = 0x03000000, LENGTH = 32K-96 /* in-chip work RAM (faster) */
+    rom     : ORIGIN = 0x08000000, LENGTH = 32M    /* flash ROM */
 }

-__iwram_top = ORIGIN(iwram) + LENGTH(iwram);;
-_stack_size = 3K;
-__sp_irq    = _stack_top;
-__sp_usr    = _stack_top - 1K;
+__stack_size_irq = 1K;
+__stack_size_usr = 2K;

 SECTIONS
 {
@@ -35,8 +36,10 @@ SECTIONS
    .stack (NOLOAD) :
    {
        . = ALIGN(4);
-        . += _stack_size;
-        _stack_top = .;
+        __sp_irq = .;
+        . += __stack_size_irq;
+        __sp_usr = .;
+        . += __stack_size_usr;
    } >iwram

    /* Start address (in flash) of .data, used by startup code. */
@@ -17,9 +17,7 @@ _start:
    .byte   0x00,0x00              // Checksum (80000BEh)

 start_vector:
-    mov     r0, #0x4000000                 // REG_BASE
-    str     r0, [r0, #0x208]
-
+    // Configure stacks
    mov     r0, #0x12                      // Switch to IRQ Mode
    msr     cpsr, r0
    ldr     sp, =__sp_irq                  // Set IRQ stack
@@ -27,7 +25,21 @@ start_vector:
    msr     cpsr, r0
    ldr     sp, =__sp_usr                  // Set user stack

+    // Configure interrupt handler
+    mov     r0, #0x4000000                 // REG_BASE
+    ldr     r1, =handleInterruptARM
+    str     r1, [r0, #-4]                  // actually storing to 0x03007FFC due to mirroring
+
+    // Enable interrupts
+    mov     r1, #1
+    str     r1, [r0, #0x208]               // 0x04000208 Interrupt Master Enable
+
    // Jump to user code (switching to Thumb mode)
    ldr     r3, =main
    bx      r3

+// Small interrupt handler that immediately jumps to a function defined in the
+// program (in Thumb) for further processing.
+handleInterruptARM:
+    ldr     r0, =handleInterrupt
+    bx      r0
@@ -0,0 +1,6 @@
+{
+	"inherits": ["fe310"],
+	"build-tags": ["hifive1b", "qemu"],
+	"linkerscript": "targets/hifive1-qemu.ld",
+	"emulator": ["qemu-system-riscv32", "-machine", "sifive_e", "-nographic", "-kernel"]
+}
@@ -0,0 +1,13 @@
+
+/* memory map:
+ * https://github.com/sifive/freedom-e-sdk/blob/v201908-branch/bsp/sifive-hifive1/metal.default.lds
+ */
+MEMORY
+{
+    FLASH_TEXT (rw) : ORIGIN = 0x20400000, LENGTH = 0x1fc00000
+    RAM (xrw)       : ORIGIN = 0x80000000, LENGTH = 0x4000
+}
+
+_stack_size = 2K;
+
+INCLUDE "targets/riscv.ld"
@@ -0,0 +1,8 @@
+{
+    "inherits": ["atsamd51j19a"],
+    "build-tags": ["sam", "atsamd51j19a", "pybadge"],
+    "flash-1200-bps-reset": "true",
+    "flash-method": "msd",
+    "msd-volume-name": "PYBADGEBOOT",
+    "msd-firmware-name": "arcade.uf2"
+}
@@ -4,9 +4,11 @@
 	"goarch": "arm",
 	"build-tags": ["tinygo.riscv", "baremetal", "linux", "arm"],
 	"gc": "conservative",
-	"compiler": "riscv64-unknown-elf-gcc",
-	"linker": "riscv64-unknown-elf-ld",
+	"compiler": "clang",
+	"linker": "ld.lld",
+	"rtlib": "compiler-rt",
 	"cflags": [
+		"--target=riscv32--none",
 		"-march=rv32imac",
 		"-mabi=ilp32",
 		"-Os",
@@ -21,5 +23,6 @@
 	],
 	"extra-files": [
 		"src/device/riscv/start.S"
-	]
+	],
+	"gdb": "riscv64-unknown-elf-gdb"
 }
--- 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
Ayke van Laethem	0933577e60	compiler: improve "function redeclared" error This error can normally only happen with //go:linkname and such, but it's nice to get an informative error message in that case.	2020-01-04 10:24:14 +01:00
Ayke van Laethem	69c1d802e1	loader: improve error messages for failed imports Add location information (whenever possible) to failed imports. This helps in debugging where an incorrect import came from. For example, show the following error message: /home/ayke/src/github.com/tinygo-org/tinygo/src/machine/machine.go:5:8: cannot find package "foobar" in any of: /usr/local/go/src/foobar (from $GOROOT) /home/ayke/src/foobar (from $GOPATH) Instead of the following: error: cannot find package "foobar" in any of: /usr/local/go/src/foobar (from $GOROOT) /home/ayke/src/foobar (from $GOPATH)	2020-01-04 00:01:07 +01:00
Ayke van Laethem	b424056721	cgo: fix a bug in number tokenization	2020-01-03 23:44:58 +01:00
Ayke van Laethem	d735df6e16	cgo: add support for symbols	2020-01-03 23:44:58 +01:00
Ayke van Laethem	d37bbadb54	machine/arduino-nano33: fix UART1 and UART2 UART2 was configured with the wrong SERCOM for the used pins (PB22 and PB23). However, after changing the SERCOM from 3 to 5 that led to a conflict with UART1 (used for the on-board WiFi). But the used pins are also usable from SERCOM 3, so in the end I switched SERCOM5 and SERCOM3 around. With this change, I was able to get examples/echo working.	2020-01-03 23:25:37 +01:00
Ayke van Laethem	ab7dc45288	wasm: implement memcpy and memset This was reported in issue #805.	2019-12-30 20:51:46 +01:00
Jaden Weiss	eee1b995f6	revise defer to use heap allocations when running a variable number of times	2019-12-30 18:12:40 +01:00
Ayke van Laethem	a4fa41b49d	compiler: don't crash when encountering types.Invalid This commit fixes a crash when trying to compile the following (invalid) code: package main import "unsafe" func main() { } type Foo struct { x DoesNotExist } const foo = unsafe.Sizeof(Foo{}) This commit fixes this situation. The result is a regular error message, indicating that DoesNotExist is not defined.	2019-12-30 13:40:37 +01:00
Ayke van Laethem	a5a90a57b9	main: remove getting a serial port in gdb subcommand Remove this code for two reasons: 1. It is not needed. 2. It breaks `tinygo gdb` for debugging QEMU targets (such as cortex-m-qemu).	2019-12-29 19:41:24 +01:00
Dmitri Goutnik	71a380ce8c	Add initial FreeBSD support	2019-12-29 10:48:28 +01:00
Ayke van Laethem	3b2a4b64c5	main: kill tests if they run too long Sometimes, tests suddenly hang somewhere (in particular in emulators where crashes often lead to hangs). Setting a limit has two advantages: 1. Quickly killing test processes that are frozen (as opposed to waiting for the default 10min go test timeout). 2. The output becomes visible, hopefully giving a clue what went wrong.	2019-12-28 21:10:13 +01:00
Ayke van Laethem	184827e4d8	riscv: support sleeping in QEMU QEMU doesn't support the RTC peripheral yet so work around it for now. This makes the following command work: tinygo run -target=hifive1-qemu ./testdata/coroutines.go	2019-12-26 09:57:58 +01:00
Ayke van Laethem	14474e7099	compiler: fix assertion on empty interface This fixes issue #453.	2019-12-26 09:20:22 +01:00
Ron Evans	3656ac2fc9	main: increment version to 0.12-dev Signed-off-by: Ron Evans <ron@hybridgroup.com>	2019-12-24 19:48:38 +01:00
Ayke van Laethem	08f01ba3ff	riscv: improve startup assembly Now that we've switched to LLVM 9, we don't need a workaround anymore for the 'la' pseudo-instruction.	2019-12-24 19:00:22 +01:00
Ayke van Laethem	699312f477	ci: remove symlink creation These symlinks are now unnecessary because Clang (and previously lld) have been integrated into TinyGo.	2019-12-24 08:59:33 +01:00
Ayke van Laethem	9644edcd5a	builder: update Clang header location We have long since moved towards a different location for these headers in the git checkout, so update where getClangHeaderPath looks for these headers. Also add an extra check to make sure a path has been detected.	2019-12-24 08:59:33 +01:00
Ayke van Laethem	46325910c5	ci: increase Azure Pipelines timeout to 4 hours 3 hours is too close to the edge. Extend to 4 hours to make sure a build including LLVM build will finish before the deadline.	2019-12-24 08:49:04 +01:00
Ayke van Laethem	923c2e7ada	main: version 0.11.0	2019-12-23 16:37:59 +01:00
Ron Evans	18e446561d	flash: use more precise searches for correct volume/port with default Windows matching Signed-off-by: Ron Evans <ron@hybridgroup.com>	2019-12-23 16:09:58 +01:00
Ron Evans	447537aebe	flash: use win32 wmi to try to find UF2 and COM ports Signed-off-by: Ron Evans <ron@hybridgroup.com>	2019-12-23 16:09:58 +01:00
Ayke van Laethem	74e32acf33	compiler: improve error locations in goroutine lowering	2019-12-23 08:33:04 +01:00
Ayke van Laethem	072f8c354e	interp: add runtime fallback for mapassign operations Some mapassign operations cannot (yet) be done by the interp package. Implement a fallback mechanism so that these operations can still be performed at runtime.	2019-12-23 08:15:09 +01:00
Daniel Esteban	0587934a44	added missing pinetime devkit to list of suppoerted boards/targets	2019-12-22 21:23:07 +01:00
Daniel Esteban	c2481b10f4	Added Adafruit's pybadge target (#795 ) * machine/pybadge: add support for Adafruit PyBadge board	2019-12-22 19:37:16 +01:00
Ayke van Laethem	d41f01f003	main: avoid leaving files open Eventually, open files should be closed when the GC runs and the finalizer is called. However we shouldn't rely on that. Using `ioutil.ReadFile` as it's a simpler pattern anyway.	2019-12-21 23:12:13 +01:00
Ayke van Laethem	5a70c88483	transform: make reflection sidetables constant globals These globals are (and must be!) never modified by the reflect package. By marking them as constant, they will be put in read-only memory. This reduces RAM consumption on microcontrollers.	2019-12-21 22:59:23 +01:00
Ayke van Laethem	5510dec846	compiler: add location information to the IR checker	2019-12-21 20:49:51 +01:00
Ayke van Laethem	dffb9fbfa7	tools: use byte padding to skip unused register ranges This simplifies the code. The fields are blank anyway so there is no way to access them anyway (volatile or not). Also do some other related simplifications of the code that result from this change.	2019-12-21 19:59:41 +01:00
Jaden Weiss	525ded3d90	run tests partially in parallel	2019-12-21 12:22:59 +01:00
Ayke van Laethem	ec2658ca79	interp: remove accidental debug print Accidentally left in the source in https://github.com/tinygo-org/tinygo/pull/787.	2019-12-20 14:47:20 +01:00
Ayke van Laethem	2004555fe2	interp: check whether the map update key/value are constant This is a limitation in the PutString/PutBinary calls, make sure that they won't get non-constant values as a safety measure.	2019-12-20 01:43:12 +01:00
Ayke van Laethem	9aeb8d9e06	interp: support llvm.lifetime.* calls This fixes a bug found when updating a map with string keys. Originally reported here: https://github.com/hybridgroup/gdg-2019/issues/6	2019-12-20 01:43:12 +01:00
Ron Evans	34ee3883d6	flash: search for default serial port on both macOS and Linux Signed-off-by: Ron Evans <ron@hybridgroup.com>	2019-12-17 02:15:06 +01:00
Ayke van Laethem	768c652468	machine: rename CPU_FREQUENCY -> CPUFrequency() These all-caps constants aren't in the Go style, so rename it to CPUFrequency (which is more aligned with Go style). Additionally, make it a function so that it is possible to add support for changing the frequency in the future. Tested by running `make smoketest`. None of the outputs did change.	2019-12-16 20:34:39 +01:00
Daniel Esteban	2778377ac9	Nano33 IoT: default SPI should be D13/D11/D12 instead of A2/A3/A6 (#781 ) * Nano33 IoT: default SPI should be D13/D11/D12 instead of A2/A3/A6	2019-12-15 15:21:33 +01:00
Ayke van Laethem	cf32607306	tools: rewrite gen-device-svd in Go This should make it more maintainable. Another big advantage that generation time (including gofmt) is now 3 times faster. No real attempt at refactoring has been made, that will need to be done at a later time.	2019-12-14 22:27:45 +01:00
Ayke van Laethem	ad022ef23d	riscv: add support for compiler-rt This gets all the tests to compile and many of them to pass. There are some issues left, but those are probably unrelated to compiler-rt.	2019-12-14 12:48:21 +01:00
Ayke van Laethem	c97b7221bd	machine: support arduino-nano33 on play.tinygo.org	2019-12-11 21:49:19 +01:00
Ayke van Laethem	8d32a7c3a3	builder: use builtin Clang when building statically This will be a huge help for people installing TinyGo that don't have LLVM/Clang 9 already installed and in the $PATH variable.	2019-12-11 20:17:35 +01:00
Ayke van Laethem	49eb414530	machine: add Tx method to simulated SPI bus This allows display drivers like st7789 to be used on the TinyGo Playground.	2019-12-08 19:08:37 +01:00
Ayke van Laethem	39d21e21f1	targets: simulate Circuit Playground Express in play.tinygo.org This requires a number of changes to atsamd21 code. It's not a very clean separation, but I couldn't come up with a better one.	2019-12-08 13:11:39 +01:00
Ayke van Laethem	fa8a93b4e7	cgo: don't run tests in parallel Since LLVM 9, CGo sometimes randomly breaks with weird error messages on Windows. I'm not sure why this is the case, but it might be related to concurrency. Disable concurrency for now, and hope that will make the errors go away.	2019-12-08 12:35:43 +01:00
Ayke van Laethem	8f9419a35d	targets: add hifive1-qemu for testing RISC-V bare metal in QEMU Most tests don't pass yet, so can't add this test to the standard tests, yet.	2019-12-07 16:47:40 +01:00
Ayke van Laethem	7bdd4a1186	main: add support for QEMU in the gdb subcommand This allows debugging QEMU-only targets with GDB, which can be super useful.	2019-12-07 16:47:40 +01:00
Ayke van Laethem	0105f815c6	targets: rename qemu target to cortex-m-qemu The target is intended to emulate the Cortex-M, not to be a generic QEMU target.	2019-12-07 16:47:40 +01:00
Ayke van Laethem	d441f0152f	riscv: use LLVM tools instead of GNU toolchain Now that we use LLVM 9, RISC-V support in LLVM has far fewer bugs and we can avoid the GNU toolchain. * replace GNU linker with lld * replace GCC with clang Additionally, RISC-V was promoted to stable so it can be enabled by default in CI.	2019-12-07 16:27:10 +01:00
Ayke van Laethem	06647aab24	tools/gen-device-avr: process files in parallel This significantly speeds up processing of the files.	2019-12-07 16:04:47 +01:00
Ayke van Laethem	24259cbb5f	tools: rewrite gen-device-avr in Go This brings a big speedup. Not counting gofmt time, `make gen-device-avr` became about 3x faster. In the future, it might be an idea to generate the AST in-memory and write it out already formatted.	2019-12-07 16:04:47 +01:00
Ayke van Laethem	2f932a9eee	riscv: fix heap corruption The .sdata and .sbss sections are created by the compiler, but were not present in the linker script. That means that the linker put them after all other data/bss section, which happens to be where the heap also resides. This commit adds the .sdata and .sbss sections to the linker script, which gets the blinky examples to work again on RISC-V.	2019-12-05 20:27:28 +01:00
Ayke van Laethem	93a06d1157	tools: avoid _paddingX in generated struct fields This makes the generation script slightly simpler.	2019-12-04 23:11:42 +01:00
Ayke van Laethem	374349cfa5	compiler: refactor func lowering to the transform package This commit makes a number of changes: * It avoids a dependency on Compiler.emitStartGoroutine. * It moves the func-lowering pass to the transform package. * It adds testing to func lowering. No functionality should have changed with this commit.	2019-12-04 22:19:49 +01:00
Ron Evans	024a0827ea	docs: add official code of conduct using 'Contributor Covenant' Signed-off-by: Ron Evans <ron@hybridgroup.com>	2019-12-04 21:53:46 +01:00
Ayke van Laethem	fadddc54a3	main: increment version to 0.11-dev	2019-12-03 21:02:37 +00:00