main: version 0.12.0

This allows TinyGo-built binaries to run under wasmtime, for example:

    tinygo build -o test.wasm -no-debug -target=wasm examples/test
    wasmtime run test.wasm 0

.circleci/config.yml

@@ -18,15 +18,12 @@ 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 \
                 lld<<parameters.llvm>> \
                 gcc-arm-linux-gnueabihf \
-                libc6-dev-armel-cross \
                 gcc-aarch64-linux-gnu \
-                libc6-dev-arm64-cross \
                 qemu-system-arm \
                 qemu-user \
                 gcc-avr \
@@ -52,6 +49,18 @@ commands:
           key: llvm-source-9-v0
           paths:
             - llvm-project
+  build-wasi-libc:
+    steps:
+      - restore_cache:
+          keys:
+            - wasi-libc-sysroot-v0
+      - run:
+          name: "Build wasi-libc"
+          command: make wasi-libc CLANG=$PWD/llvm-build/bin/clang LLVM_AR=$PWD/llvm-build/bin/llvm-ar LLVM_NM=$PWD/llvm-build/bin/llvm-nm
+      - save_cache:
+          key: wasi-libc-sysroot-v0
+          paths:
+            - lib/wasi-libc/sysroot
   test-linux:
     steps:
       - checkout
@@ -65,9 +74,17 @@ commands:
             - go-cache-v2-{{ checksum "go.mod" }}
       - llvm-source-linux
       - run: go install .
+      - restore_cache:
+          keys:
+            - wasi-libc-sysroot-systemclang-v0
+      - run: make wasi-libc
+      - save_cache:
+          key: wasi-libc-sysroot-systemclang-v0
+          paths:
+            - lib/wasi-libc/sysroot
       - 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 +100,6 @@ commands:
           name: "Install apt dependencies"
           command: |
             sudo apt-get install \
-                python3 \
                 gcc-arm-linux-gnueabihf \
                 binutils-arm-none-eabi \
                 libc6-dev-armel-cross \
@@ -122,13 +138,8 @@ 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
+      - build-wasi-libc
       - run:
           name: "Test TinyGo"
           command: make ASSERT=1 test
@@ -139,7 +150,7 @@ 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 +159,6 @@ 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 +197,7 @@ 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
+      - build-wasi-libc
       - run:
           name: "Test TinyGo"
           command: make test
@@ -216,11 +221,6 @@ 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 +264,16 @@ commands:
           key: llvm-build-9-macos-v0
           paths:
             llvm-build
+      - restore_cache:
+          keys:
+            - wasi-libc-sysroot-macos-v0
       - run:
-          name: "Create LLVM symlinks"
-          command: |
-            ln -s $PWD/llvm-build/bin/clang-9 /usr/local/bin/clang-9
+          name: "Build wasi-libc"
+          command: make wasi-libc CLANG=$PWD/llvm-build/bin/clang LLVM_AR=$PWD/llvm-build/bin/llvm-ar LLVM_NM=$PWD/llvm-build/bin/llvm-nm
+      - save_cache:
+          key: wasi-libc-sysroot-macos-v0
+          paths:
+            - lib/wasi-libc/sysroot
       - run:
           name: "Test TinyGo"
           command: make test

.gitmodules

@@ -14,3 +14,6 @@
 	path = lib/compiler-rt
 	url = https://github.com/llvm-mirror/compiler-rt.git
 	branch = release_80
+[submodule "lib/wasi-libc"]
+	path = lib/wasi-libc
+	url = https://github.com/CraneStation/wasi-libc

CHANGELOG.md

@@ -1,3 +1,93 @@
+0.12.0
+---
+* **command line**
+  - add initial FreeBSD support
+  - remove getting a serial port in gdb subcommand
+  - add support for debugging through JLinkGDBServer
+  - fix CGo when cross compiling
+  - remove default port check for Digispark as micronucleus communicates directly using HID
+  - differentiate between various serial/USB error messages
+* **builder**
+  - improve detection of Clang headers
+* **compiler**
+  - fix assertion on empty interface
+  - don't crash when encountering `types.Invalid`
+  - revise defer to use heap allocations when running a variable number of times
+  - improve error messages for failed imports
+  - improve "function redeclared" error
+  - add globaldce pass to start of optimization pipeline
+  - add support for debugging globals
+  - implement RISC-V CSR operations as intrinsics
+  - add support for CGO_ENABLED environment variable
+  - do not emit debug info for extern globals (bugfix)
+  - add support for interrupts
+  - implement maps for arbitrary keys
+  - interp: error location for "unknown GEP" error
+  - wasm-abi: create temporary allocas in the entry block
+* **cgo**
+  - add support for symbols in `#define`
+  - fix a bug in number tokenization
+* **standard library**
+  - `machine`: avoid bytes package in USB logic
+  - `runtime`: fix external address declarations
+  - `runtime`: provide implementation for `internal/bytealg.IndexByte`
+* **targets**
+  - `atsamd51`: fix volatile usage
+  - `atsamd51`: fix ADC, updating to 12-bits precision
+  - `atsamd51`: refactor SPI pin configuration to only look at pin numbers
+  - `atsamd51`: switch UART to use new pin configuration
+  - `atsamd51`: fix obvious bug in I2C code
+  - `atsamd51`: use only the necessary UART interrupts
+  - `atsamd51`: refactor I2C pin handling to auto-detect pin mode
+  - `avr`: use a garbage collector
+  - `fe310`: use CLINT peripheral for timekeeping
+  - `fe310`: add support for PLIC interrupts
+  - `fe310`: implement UART receive interrupts
+  - `riscv`: support sleeping in QEMU
+  - `riscv`: add bare-bones interrupt support
+  - `riscv`: print exception PC and code
+  - `wasm`: implement memcpy and memset
+  - `wasm`: include wasi-libc
+  - `wasm`: use wasi ABI for basic startup/stdout
+* **boards**
+  - `arduino`: make avrdude command line compatible with Windows
+  - `arduino-nano`: add this board
+  - `arduino-nano33`: fix UART1 and UART2
+  - `circuitplay-bluefruit`: add this board
+  - `digispark`: add clock speed and pin mappings
+  - `gameboy-advance`: include compiler-rt in build
+  - `gameboy-advance`: implement interrupt handler
+  - `hifive1b`: add support for gdb subcommand
+  - `pyportal`: add this board
+  - `pyportal`: remove manual SPI pin mapping as now handled by default
+
+
+0.11.0
+---
+* **command line**
+  - add support for QEMU in `gdb` subcommand
+  - use builtin Clang when building statically, dropping the clang-9 dependency
+  - search for default serial port on both macOS and Linux
+  - windows: support `tinygo flash` directly by using win32 wmi
+* **compiler**
+  - add location information to the IR checker
+  - make reflection sidetables constant globals
+  - improve error locations in goroutine lowering
+  - interp: improve support for maps with string keys
+  - interp: add runtime fallback for mapassign operations
+* **standard library**
+  - `machine`: add support for `SPI.Tx()` on play.tinygo.org
+  - `machine`: rename `CPU_FREQUENCY` to `CPUFrequency()`
+* **targets**
+  - `adafruit-pybadge`: add Adafruit Pybadge
+  - `arduino-nano33`: allow simulation on play.tinygo.org
+  - `arduino-nano33`: fix default SPI pin numbers to be D13/D11/D12
+  - `circuitplay-express`: allow simulation on play.tinygo.org
+  - `hifive1-qemu`: add target for testing RISC-V bare metal in QEMU
+  - `riscv`: fix heap corruption due to changes in LLVM 9
+  - `riscv`: add support for compiler-rt
+  - `qemu`: rename to `cortex-m-qemu`
+
 0.10.0
 ---
 * **command line**

CODE-OF-CONDUCT.md

@@ -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

CONTRIBUTORS

@@ -15,3 +15,4 @@ Ayke van Laethem <aykevanlaethem@gmail.com>
 Daniel Esteban <conejo@conejo.me>
 Loon, LLC.
 Ron Evans <ron@hybridgroup.com>
+Jaden Weiss <jaden@jadendw.dev>

Dockerfile

@@ -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"]

LICENSE

@@ -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:

Makefile

@@ -7,6 +7,11 @@ LLVM_BUILDDIR ?= llvm-build
 CLANG_SRC ?= llvm-project/clang
 LLD_SRC ?= llvm-project/lld
 
+# Default tool selection.
+CLANG ?= clang-9
+LLVM_AR ?= llvm-ar-9
+LLVM_NM ?= llvm-nm-9
+
 # Go binary and GOROOT to select
 GO ?= go
 export GOROOT = $(shell $(GO) env GOROOT)
@@ -14,9 +19,6 @@ export GOROOT = $(shell $(GO) env GOROOT)
 # md5sum binary
 MD5SUM = md5sum
 
-# Python binary
-PYTHON ?= python
-
 # tinygo binary for tests
 TINYGO ?= tinygo
 
@@ -34,7 +36,7 @@ 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 +67,11 @@ $(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 +85,7 @@ 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 +104,28 @@ 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 -interrupts=software 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
 
 
@@ -133,12 +144,19 @@ $(LLVM_BUILDDIR): $(LLVM_BUILDDIR)/build.ninja
 	cd $(LLVM_BUILDDIR); ninja
 
 
+# Build wasi-libc sysroot
+.PHONY: wasi-libc
+wasi-libc: lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a
+lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a:
+	cd lib/wasi-libc && make -j4 WASM_CC=$(CLANG) WASM_AR=$(LLVM_AR) WASM_NM=$(LLVM_NM)
+
+
 # Build the Go compiler.
 tinygo:
 	@if [ ! -f "$(LLVM_BUILDDIR)/bin/llvm-config" ]; then echo "Fetch and build LLVM first by running:"; echo "  make llvm-source"; echo "  make $(LLVM_BUILDDIR)"; exit 1; fi
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) build -o build/tinygo$(EXE) -tags byollvm .
 
-test:
+test: wasi-libc
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) test -v -tags byollvm ./cgo ./compileopts ./interp ./transform .
 
 tinygo-test:
@@ -187,6 +205,8 @@ 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
@@ -218,6 +238,8 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=stm32f4disco        examples/blinky2
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=circuitplay-bluefruit examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=circuitplay-express examples/i2s
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.gba -target=gameboy-advance     examples/gba-display
@@ -226,8 +248,12 @@ smoketest:
 	@$(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
+	$(TINYGO) build -size short -o test.hex -target=pyportal            examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nucleo-f103rb       examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pinetime-devkit0    examples/blinky1
@@ -239,22 +265,25 @@ smoketest:
 ifneq ($(AVR), 0)
 	$(TINYGO) build -size short -o test.hex -target=arduino             examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=arduino-nano        examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=digispark           examples/blinky1
 	@$(MD5SUM) test.hex
-endif
-ifneq ($(RISCV), 0)
-	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
+	$(TINYGO) build -size short -o test.hex -target=digispark -gc=leaking examples/blinky1
 	@$(MD5SUM) test.hex
 endif
+	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/export
 	$(TINYGO) build             -o wasm.wasm -target=wasm               examples/wasm/main
 
-release: tinygo gen-device
+release: tinygo gen-device wasi-libc
 	@mkdir -p build/release/tinygo/bin
 	@mkdir -p build/release/tinygo/lib/clang/include
 	@mkdir -p build/release/tinygo/lib/CMSIS/CMSIS
 	@mkdir -p build/release/tinygo/lib/compiler-rt/lib
 	@mkdir -p build/release/tinygo/lib/nrfx
+	@mkdir -p build/release/tinygo/lib/wasi-libc
 	@mkdir -p build/release/tinygo/pkg/armv6m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7em-none-eabi
@@ -267,6 +296,7 @@ release: tinygo gen-device
 	@cp -rp lib/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt
 	@cp -rp lib/compiler-rt/README.txt   build/release/tinygo/lib/compiler-rt
 	@cp -rp lib/nrfx/*                   build/release/tinygo/lib/nrfx
+	@cp -rp lib/wasi-libc/sysroot        build/release/tinygo/lib/wasi-libc/sysroot
 	@cp -rp src                          build/release/tinygo/src
 	@cp -rp targets                      build/release/tinygo/targets
 	./build/tinygo build-builtins -target=armv6m-none-eabi  -o build/release/tinygo/pkg/armv6m-none-eabi/compiler-rt.a

README.md

@@ -43,15 +43,19 @@ See the [getting started instructions](https://tinygo.org/getting-started/) for
 
 You can compile TinyGo programs for microcontrollers, WebAssembly and Linux.
 
-The following 22 microcontroller boards are currently supported:
+The following 27 microcontroller boards are currently supported:
 
+* [Adafruit Circuit Playground Bluefruit](https://www.adafruit.com/product/4333)
 * [Adafruit Circuit Playground Express](https://www.adafruit.com/product/3333)
 * [Adafruit Feather M0](https://www.adafruit.com/product/2772)
 * [Adafruit Feather M4](https://www.adafruit.com/product/3857)
 * [Adafruit ItsyBitsy M0](https://www.adafruit.com/product/3727)
 * [Adafruit ItsyBitsy M4](https://www.adafruit.com/product/3800)
 * [Adafruit Metro M4 Express Airlift](https://www.adafruit.com/product/4000)
+* [Adafruit PyBadge](https://www.adafruit.com/product/4200)
+* [Adafruit PyPortal](https://www.adafruit.com/product/4116)
 * [Adafruit Trinket M0](https://www.adafruit.com/product/3500)
+* [Arduino Nano](https://store.arduino.cc/arduino-nano)
 * [Arduino Nano33 IoT](https://store.arduino.cc/nano-33-iot)
 * [Arduino Uno](https://store.arduino.cc/arduino-uno-rev3)
 * [BBC micro:bit](https://microbit.org/)
@@ -62,6 +66,7 @@ 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 +130,5 @@ 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.

azure-pipelines.yml

@@ -6,7 +6,7 @@ trigger:
 
 jobs:
 - job: Build
-  timeoutInMinutes: 180
+  timeoutInMinutes: 240 # 4h
   pool:
     vmImage: 'VS2017-Win2016'
   steps:
@@ -45,6 +45,16 @@ jobs:
       inputs:
         targetType: inline
         script: choco install qemu
+    - task: CacheBeta@0
+      displayName: Cache wasi-libc sysroot
+      inputs:
+        key: wasi-libc-sysroot-v0
+        path: lib/wasi-libc/sysroot
+    - task: Bash@3
+      displayName: Build wasi-libc
+      inputs:
+        targetType: inline
+        script: PATH=/usr/bin:$PATH make wasi-libc CLANG=$PWD/llvm-build/bin/clang LLVM_AR=$PWD/llvm-build/bin/llvm-ar LLVM_NM=$PWD/llvm-build/bin/llvm-nm
     - task: Bash@3
       displayName: Test TinyGo
       inputs:
@@ -61,9 +71,9 @@ jobs:
           export PATH="/c/Go1.13/bin:$PATH:./llvm-build/bin:/c/Program Files/qemu"
           unset GOROOT
           make release -j4
-    - publish: $(System.DefaultWorkingDirectory)/build/release.tar.gz
-      displayName: Publish tarball as artifact
-      artifact: tinygo.windows-amd64.tar.gz
+    - publish: $(System.DefaultWorkingDirectory)/build/release/tinygo
+      displayName: Publish zip as artifact
+      artifact: tinygo
     - task: Bash@3
       displayName: Smoke tests
       inputs:
@@ -71,4 +81,4 @@ jobs:
         script: |
           export PATH="/c/Go1.13/bin:$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

builder/build.go

@@ -16,6 +16,7 @@ import (
 	"github.com/tinygo-org/tinygo/compiler"
 	"github.com/tinygo-org/tinygo/goenv"
 	"github.com/tinygo-org/tinygo/interp"
+	"github.com/tinygo-org/tinygo/transform"
 )
 
 // Build performs a single package to executable Go build. It takes in a package
@@ -33,10 +34,7 @@ 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:")
@@ -64,7 +62,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 	// stack-allocated values.
 	// Use -wasm-abi=generic to disable this behaviour.
 	if config.Options.WasmAbi == "js" && strings.HasPrefix(config.Triple(), "wasm") {
-		err := c.ExternalInt64AsPtr()
+		err := transform.ExternalInt64AsPtr(c.Module())
 		if err != nil {
 			return err
 		}
@@ -72,22 +70,23 @@ 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 +153,7 @@ 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 +165,7 @@ 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}
 				}
@@ -217,7 +208,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(stri
 		} else if outext == ".uf2" {
 			// Get UF2 from the .elf file.
 			tmppath = filepath.Join(dir, "main"+outext)
-			err := convertELFFileToUF2File(executable, tmppath)
+			err := convertELFFileToUF2File(executable, tmppath, config.Target.UF2FamilyID)
 			if err != nil {
 				return err
 			}

builder/builtins.go

@@ -158,7 +158,7 @@ var aeabiBuiltins = []string{
 
 func builtinFiles(target string) []string {
 	builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
-	if strings.HasPrefix(target, "arm") {
+	if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
 		builtins = append(builtins, aeabiBuiltins...)
 	}
 	return builtins
@@ -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}
 		}

builder/cc1as.cpp

@@ -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;
+}

builder/cc1as.h

@@ -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);

builder/clang.cpp

@@ -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"

builder/commands.go

@@ -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 {

builder/compiler-builtin.go

@@ -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()
+	}
+}

builder/compiler-external.go

@@ -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()
+}

builder/env.go

@@ -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
 	}

builder/error.go

@@ -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 {

builder/uf2.go

@@ -11,26 +11,33 @@ import (
 	"bytes"
 	"encoding/binary"
 	"io/ioutil"
+	"strconv"
 )
 
 // convertELFFileToUF2File converts an ELF file to a UF2 file.
-func convertELFFileToUF2File(infile, outfile string) error {
+func convertELFFileToUF2File(infile, outfile string, uf2FamilyID string) error {
 	// Read the .text segment.
 	targetAddress, data, err := extractROM(infile)
 	if err != nil {
 		return err
 	}
 
-	output, _ := convertBinToUF2(data, uint32(targetAddress))
+	output, _, err := convertBinToUF2(data, uint32(targetAddress), uf2FamilyID)
+	if err != nil {
+		return err
+	}
 	return ioutil.WriteFile(outfile, output, 0644)
 }
 
 // convertBinToUF2 converts the binary bytes in input to UF2 formatted data.
-func convertBinToUF2(input []byte, targetAddr uint32) ([]byte, int) {
+func convertBinToUF2(input []byte, targetAddr uint32, uf2FamilyID string) ([]byte, int, error) {
 	blocks := split(input, 256)
 	output := make([]byte, 0)
 
-	bl := newUF2Block(targetAddr)
+	bl, err := newUF2Block(targetAddr, uf2FamilyID)
+	if err != nil {
+		return nil, 0, err
+	}
 	bl.SetNumBlocks(len(blocks))
 
 	for i := 0; i < len(blocks); i++ {
@@ -41,7 +48,7 @@ func convertBinToUF2(input []byte, targetAddr uint32) ([]byte, int) {
 		bl.IncrementAddress(bl.payloadSize)
 	}
 
-	return output, len(blocks)
+	return output, len(blocks), nil
 }
 
 const (
@@ -65,18 +72,32 @@ type uf2Block struct {
 }
 
 // newUF2Block returns a new uf2Block struct that has been correctly populated
-func newUF2Block(targetAddr uint32) *uf2Block {
+func newUF2Block(targetAddr uint32, uf2FamilyID string) (*uf2Block, error) {
+	var flags uint32
+	var familyID uint32
+	if uf2FamilyID != "" {
+		flags |= flagFamilyIDPresent
+		v, err := strconv.ParseUint(uf2FamilyID, 0, 32)
+		if err != nil {
+			return nil, err
+		}
+		familyID = uint32(v)
+	}
 	return &uf2Block{magicStart0: uf2MagicStart0,
 		magicStart1: uf2MagicStart1,
 		magicEnd:    uf2MagicEnd,
 		targetAddr:  targetAddr,
-		flags:       0x0,
-		familyID:    0x0,
+		flags:       flags,
+		familyID:    familyID,
 		payloadSize: 256,
 		data:        make([]byte, 476),
-	}
+	}, nil
 }
 
+const (
+	flagFamilyIDPresent = 0x00002000
+)
+
 // Bytes converts the uf2Block to a slice of bytes that can be written to file.
 func (b *uf2Block) Bytes() []byte {
 	buf := bytes.NewBuffer(make([]byte, 0, 512))

cgo/cgo_test.go

@@ -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()

cgo/const.go

@@ -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.

cgo/const_test.go

@@ -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)

cgo/libclang_config.go

@@ -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"

cgo/testdata/const.go

@@ -0,0 +1,12 @@
+package main
+
+/*
+#define foo 3
+#define bar foo
+*/
+import "C"
+
+const (
+	Foo = C.foo
+	Bar = C.bar
+)

cgo/testdata/const.out.go

@@ -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

compileopts/config.go

@@ -65,6 +65,12 @@ func (c *Config) BuildTags() []string {
 	return tags
 }
 
+// CgoEnabled returns true if (and only if) CGo is enabled. It is true by
+// default and false if CGO_ENABLED is set to "0".
+func (c *Config) CgoEnabled() bool {
+	return goenv.Get("CGO_ENABLED") == "1"
+}
+
 // GC returns the garbage collection strategy in use on this platform. Valid
 // values are "none", "leaking", and "conservative".
 func (c *Config) GC() string {

compileopts/target.go

@@ -43,9 +43,11 @@ type TargetSpec struct {
 	FlashMethod      string   `json:"flash-method"`
 	FlashVolume      string   `json:"msd-volume-name"`
 	FlashFilename    string   `json:"msd-firmware-name"`
+	UF2FamilyID      string   `json:"uf2-family-id"`
 	OpenOCDInterface string   `json:"openocd-interface"`
 	OpenOCDTarget    string   `json:"openocd-target"`
 	OpenOCDTransport string   `json:"openocd-transport"`
+	JLinkDevice      string   `json:"jlink-device"`
 }
 
 // copyProperties copies all properties that are set in spec2 into itself.
@@ -109,6 +111,9 @@ func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
 	if spec2.FlashFilename != "" {
 		spec.FlashFilename = spec2.FlashFilename
 	}
+	if spec2.UF2FamilyID != "" {
+		spec.UF2FamilyID = spec2.UF2FamilyID
+	}
 	if spec2.OpenOCDInterface != "" {
 		spec.OpenOCDInterface = spec2.OpenOCDInterface
 	}
@@ -118,6 +123,9 @@ func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
 	if spec2.OpenOCDTransport != "" {
 		spec.OpenOCDTransport = spec2.OpenOCDTransport
 	}
+	if spec2.JLinkDevice != "" {
+		spec.JLinkDevice = spec2.JLinkDevice
+	}
 }
 
 // load reads a target specification from the JSON in the given io.Reader. It
@@ -221,6 +229,14 @@ func LoadTarget(target string) (*TargetSpec, error) {
 		if len(tripleSplit) < 3 {
 			return nil, errors.New("expected a full LLVM target or a custom target in -target flag")
 		}
+		if tripleSplit[0] == "arm" {
+			// LLVM and Clang have a different idea of what "arm" means, so
+			// upgrade to a slightly more modern ARM. In fact, when you pass
+			// --target=arm--linux-gnueabihf to Clang, it will convert that
+			// internally to armv7-unknown-linux-gnueabihf. Changing the
+			// architecture to armv7 will keep things consistent.
+			tripleSplit[0] = "armv7"
+		}
 		goos := tripleSplit[2]
 		if strings.HasPrefix(goos, "darwin") {
 			goos = "darwin"
@@ -229,11 +245,12 @@ func LoadTarget(target string) (*TargetSpec, error) {
 			"i386":    "386",
 			"x86_64":  "amd64",
 			"aarch64": "arm64",
+			"armv7":   "arm",
 		}[tripleSplit[0]]
 		if goarch == "" {
 			goarch = tripleSplit[0]
 		}
-		return defaultTarget(goos, goarch, target)
+		return defaultTarget(goos, goarch, strings.Join(tripleSplit, "-"))
 	}
 }
 
@@ -247,6 +264,7 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		BuildTags:   []string{goos, goarch},
 		Compiler:    "clang",
 		Linker:      "cc",
+		CFlags:      []string{"--target=" + triple},
 		GDB:         "gdb",
 		PortReset:   "false",
 		FlashMethod: "native",
@@ -259,11 +277,13 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	if goarch != runtime.GOARCH {
 		// Some educated guesses as to how to invoke helper programs.
 		if goarch == "arm" && goos == "linux" {
+			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/arm-linux-gnueabihf")
 			spec.Linker = "arm-linux-gnueabihf-gcc"
 			spec.GDB = "arm-linux-gnueabihf-gdb"
 			spec.Emulator = []string{"qemu-arm", "-L", "/usr/arm-linux-gnueabihf"}
 		}
 		if goarch == "arm64" && goos == "linux" {
+			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/aarch64-linux-gnu")
 			spec.Linker = "aarch64-linux-gnu-gcc"
 			spec.GDB = "aarch64-linux-gnu-gdb"
 			spec.Emulator = []string{"qemu-aarch64", "-L", "/usr/aarch64-linux-gnu"}

compiler/check.go

@@ -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
 }

compiler/compiler.go

@@ -193,7 +193,7 @@ func (c *Compiler) Compile(mainPath string) []error {
 			GOOS:        c.GOOS(),
 			GOROOT:      goenv.Get("GOROOT"),
 			GOPATH:      goenv.Get("GOPATH"),
-			CgoEnabled:  true,
+			CgoEnabled:  c.CgoEnabled(),
 			UseAllFiles: false,
 			Compiler:    "gc", // must be one of the recognized compilers
 			BuildTags:   c.BuildTags(),
@@ -203,7 +203,7 @@ func (c *Compiler) Compile(mainPath string) []error {
 			GOOS:        c.GOOS(),
 			GOROOT:      goenv.Get("TINYGOROOT"),
 			GOPATH:      overlayGopath,
-			CgoEnabled:  true,
+			CgoEnabled:  c.CgoEnabled(),
 			UseAllFiles: false,
 			Compiler:    "gc", // must be one of the recognized compilers
 			BuildTags:   c.BuildTags(),
@@ -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() {
@@ -1291,12 +1303,16 @@ func (c *Compiler) parseCall(frame *Frame, instr *ssa.CallCommon) (llvm.Value, e
 			return c.emitAsmFull(frame, instr)
 		case strings.HasPrefix(name, "device/arm.SVCall"):
 			return c.emitSVCall(frame, instr.Args)
+		case strings.HasPrefix(name, "(device/riscv.CSR)."):
+			return c.emitCSROperation(frame, instr)
 		case strings.HasPrefix(name, "syscall.Syscall"):
 			return c.emitSyscall(frame, instr)
 		case strings.HasPrefix(name, "runtime/volatile.Load"):
 			return c.emitVolatileLoad(frame, instr)
 		case strings.HasPrefix(name, "runtime/volatile.Store"):
 			return c.emitVolatileStore(frame, instr)
+		case name == "runtime/interrupt.New":
+			return c.emitInterruptGlobal(frame, instr)
 		}
 
 		targetFunc := c.ir.GetFunction(fn)
@@ -1569,24 +1585,7 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
 		val := c.getValue(frame, expr.X)
 		return c.parseMakeInterface(val, expr.X.Type(), expr.Pos()), nil
 	case *ssa.MakeMap:
-		mapType := expr.Type().Underlying().(*types.Map)
-		llvmKeyType := c.getLLVMType(mapType.Key().Underlying())
-		llvmValueType := c.getLLVMType(mapType.Elem().Underlying())
-		keySize := c.targetData.TypeAllocSize(llvmKeyType)
-		valueSize := c.targetData.TypeAllocSize(llvmValueType)
-		llvmKeySize := llvm.ConstInt(c.ctx.Int8Type(), keySize, false)
-		llvmValueSize := llvm.ConstInt(c.ctx.Int8Type(), valueSize, false)
-		sizeHint := llvm.ConstInt(c.uintptrType, 8, false)
-		if expr.Reserve != nil {
-			sizeHint = c.getValue(frame, expr.Reserve)
-			var err error
-			sizeHint, err = c.parseConvert(expr.Reserve.Type(), types.Typ[types.Uintptr], sizeHint, expr.Pos())
-			if err != nil {
-				return llvm.Value{}, err
-			}
-		}
-		hashmap := c.createRuntimeCall("hashmapMake", []llvm.Value{llvmKeySize, llvmValueSize, sizeHint}, "")
-		return hashmap, nil
+		return c.emitMakeMap(frame, expr)
 	case *ssa.MakeSlice:
 		sliceLen := c.getValue(frame, expr.Len)
 		sliceCap := c.getValue(frame, expr.Cap)
@@ -2551,138 +2550,6 @@ func (c *Compiler) NonConstGlobals() {
 	}
 }
 
-// When -wasm-abi flag set to "js" (default),
-// replace i64 in an external function with a stack-allocated i64*, to work
-// around the lack of 64-bit integers in JavaScript (commonly used together with
-// WebAssembly). Once that's resolved, this pass may be avoided.
-// See also the -wasm-abi= flag
-// https://github.com/WebAssembly/design/issues/1172
-func (c *Compiler) ExternalInt64AsPtr() error {
-	int64Type := c.ctx.Int64Type()
-	int64PtrType := llvm.PointerType(int64Type, 0)
-	for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
-		if fn.Linkage() != llvm.ExternalLinkage {
-			// Only change externally visible functions (exports and imports).
-			continue
-		}
-		if strings.HasPrefix(fn.Name(), "llvm.") || strings.HasPrefix(fn.Name(), "runtime.") {
-			// Do not try to modify the signature of internal LLVM functions and
-			// assume that runtime functions are only temporarily exported for
-			// coroutine lowering.
-			continue
-		}
-
-		hasInt64 := false
-		paramTypes := []llvm.Type{}
-
-		// Check return type for 64-bit integer.
-		fnType := fn.Type().ElementType()
-		returnType := fnType.ReturnType()
-		if returnType == int64Type {
-			hasInt64 = true
-			paramTypes = append(paramTypes, int64PtrType)
-			returnType = c.ctx.VoidType()
-		}
-
-		// Check param types for 64-bit integers.
-		for param := fn.FirstParam(); !param.IsNil(); param = llvm.NextParam(param) {
-			if param.Type() == int64Type {
-				hasInt64 = true
-				paramTypes = append(paramTypes, int64PtrType)
-			} else {
-				paramTypes = append(paramTypes, param.Type())
-			}
-		}
-
-		if !hasInt64 {
-			// No i64 in the paramter list.
-			continue
-		}
-
-		// Add $i64wrapper to the real function name as it is only used
-		// internally.
-		// Add a new function with the correct signature that is exported.
-		name := fn.Name()
-		fn.SetName(name + "$i64wrap")
-		externalFnType := llvm.FunctionType(returnType, paramTypes, fnType.IsFunctionVarArg())
-		externalFn := llvm.AddFunction(c.mod, name, externalFnType)
-
-		if fn.IsDeclaration() {
-			// Just a declaration: the definition doesn't exist on the Go side
-			// so it cannot be called from external code.
-			// Update all users to call the external function.
-			// The old $i64wrapper function could be removed, but it may as well
-			// be left in place.
-			for use := fn.FirstUse(); !use.IsNil(); use = use.NextUse() {
-				call := use.User()
-				c.builder.SetInsertPointBefore(call)
-				callParams := []llvm.Value{}
-				var retvalAlloca llvm.Value
-				if fnType.ReturnType() == int64Type {
-					retvalAlloca = c.builder.CreateAlloca(int64Type, "i64asptr")
-					callParams = append(callParams, retvalAlloca)
-				}
-				for i := 0; i < call.OperandsCount()-1; i++ {
-					operand := call.Operand(i)
-					if operand.Type() == int64Type {
-						// Pass a stack-allocated pointer instead of the value
-						// itself.
-						alloca := c.builder.CreateAlloca(int64Type, "i64asptr")
-						c.builder.CreateStore(operand, alloca)
-						callParams = append(callParams, alloca)
-					} else {
-						// Unchanged parameter.
-						callParams = append(callParams, operand)
-					}
-				}
-				if fnType.ReturnType() == int64Type {
-					// Pass a stack-allocated pointer as the first parameter
-					// where the return value should be stored, instead of using
-					// the regular return value.
-					c.builder.CreateCall(externalFn, callParams, call.Name())
-					returnValue := c.builder.CreateLoad(retvalAlloca, "retval")
-					call.ReplaceAllUsesWith(returnValue)
-					call.EraseFromParentAsInstruction()
-				} else {
-					newCall := c.builder.CreateCall(externalFn, callParams, call.Name())
-					call.ReplaceAllUsesWith(newCall)
-					call.EraseFromParentAsInstruction()
-				}
-			}
-		} else {
-			// The function has a definition in Go. This means that it may still
-			// be called both Go and from external code.
-			// Keep existing calls with the existing convention in place (for
-			// better performance), but export a new wrapper function with the
-			// correct calling convention.
-			fn.SetLinkage(llvm.InternalLinkage)
-			fn.SetUnnamedAddr(true)
-			entryBlock := c.ctx.AddBasicBlock(externalFn, "entry")
-			c.builder.SetInsertPointAtEnd(entryBlock)
-			var callParams []llvm.Value
-			if fnType.ReturnType() == int64Type {
-				return errors.New("not yet implemented: exported function returns i64 with -wasm-abi=js; " +
-					"see https://tinygo.org/compiler-internals/calling-convention/")
-			}
-			for i, origParam := range fn.Params() {
-				paramValue := externalFn.Param(i)
-				if origParam.Type() == int64Type {
-					paramValue = c.builder.CreateLoad(paramValue, "i64")
-				}
-				callParams = append(callParams, paramValue)
-			}
-			retval := c.builder.CreateCall(fn, callParams, "")
-			if retval.Type().TypeKind() == llvm.VoidTypeKind {
-				c.builder.CreateRetVoid()
-			} else {
-				c.builder.CreateRet(retval)
-			}
-		}
-	}
-
-	return nil
-}
-
 // Emit object file (.o).
 func (c *Compiler) EmitObject(path string) error {
 	llvmBuf, err := c.machine.EmitToMemoryBuffer(c.mod, llvm.ObjectFile)

compiler/defer.go

@@ -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")

compiler/errors.go

@@ -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{}
+	}
+}

compiler/goroutine-lowering.go

@@ -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]
 

compiler/inlineasm.go

@@ -162,3 +162,48 @@ func (c *Compiler) emitSVCall(frame *Frame, args []ssa.Value) (llvm.Value, error
 	target := llvm.InlineAsm(fnType, asm, constraints, true, false, 0)
 	return c.builder.CreateCall(target, llvmArgs, ""), nil
 }
+
+// This is a compiler builtin which emits CSR instructions. It can be one of:
+//
+//     func (csr CSR) Get() uintptr
+//     func (csr CSR) Set(uintptr)
+//     func (csr CSR) SetBits(uintptr) uintptr
+//     func (csr CSR) ClearBits(uintptr) uintptr
+//
+// The csr parameter (method receiver) must be a constant. Other parameter can
+// be any value.
+func (c *Compiler) emitCSROperation(frame *Frame, call *ssa.CallCommon) (llvm.Value, error) {
+	csrConst, ok := call.Args[0].(*ssa.Const)
+	if !ok {
+		return llvm.Value{}, c.makeError(call.Pos(), "CSR must be constant")
+	}
+	csr := csrConst.Uint64()
+	switch name := call.StaticCallee().Name(); name {
+	case "Get":
+		// Note that this instruction may have side effects, and thus must be
+		// marked as such.
+		fnType := llvm.FunctionType(c.uintptrType, nil, false)
+		asm := fmt.Sprintf("csrr $0, %d", csr)
+		target := llvm.InlineAsm(fnType, asm, "=r", true, false, 0)
+		return c.builder.CreateCall(target, nil, ""), nil
+	case "Set":
+		fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.uintptrType}, false)
+		asm := fmt.Sprintf("csrw %d, $0", csr)
+		target := llvm.InlineAsm(fnType, asm, "r", true, false, 0)
+		return c.builder.CreateCall(target, []llvm.Value{c.getValue(frame, call.Args[1])}, ""), nil
+	case "SetBits":
+		// Note: it may be possible to optimize this to csrrsi in many cases.
+		fnType := llvm.FunctionType(c.uintptrType, []llvm.Type{c.uintptrType}, false)
+		asm := fmt.Sprintf("csrrs $0, %d, $1", csr)
+		target := llvm.InlineAsm(fnType, asm, "=r,r", true, false, 0)
+		return c.builder.CreateCall(target, []llvm.Value{c.getValue(frame, call.Args[1])}, ""), nil
+	case "ClearBits":
+		// Note: it may be possible to optimize this to csrrci in many cases.
+		fnType := llvm.FunctionType(c.uintptrType, []llvm.Type{c.uintptrType}, false)
+		asm := fmt.Sprintf("csrrc $0, %d, $1", csr)
+		target := llvm.InlineAsm(fnType, asm, "=r,r", true, false, 0)
+		return c.builder.CreateCall(target, []llvm.Value{c.getValue(frame, call.Args[1])}, ""), nil
+	default:
+		return llvm.Value{}, c.makeError(call.Pos(), "unknown CSR operation: "+name)
+	}
+}

compiler/interface.go

@@ -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)

compiler/interrupt.go

@@ -0,0 +1,92 @@
+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)
+	global.SetUnnamedAddr(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
+}

compiler/llvm.go

@@ -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

compiler/llvmutil/llvm.go

@@ -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
+}

compiler/map.go

@@ -6,9 +6,45 @@ import (
 	"go/token"
 	"go/types"
 
+	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )
 
+// emitMakeMap creates a new map object (runtime.hashmap) by allocating and
+// initializing an appropriately sized object.
+func (c *Compiler) emitMakeMap(frame *Frame, expr *ssa.MakeMap) (llvm.Value, error) {
+	mapType := expr.Type().Underlying().(*types.Map)
+	keyType := mapType.Key().Underlying()
+	llvmValueType := c.getLLVMType(mapType.Elem().Underlying())
+	var llvmKeyType llvm.Type
+	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
+		// String keys.
+		llvmKeyType = c.getLLVMType(keyType)
+	} else if hashmapIsBinaryKey(keyType) {
+		// Trivially comparable keys.
+		llvmKeyType = c.getLLVMType(keyType)
+	} else {
+		// All other keys. Implemented as map[interface{}]valueType for ease of
+		// implementation.
+		llvmKeyType = c.getLLVMRuntimeType("_interface")
+	}
+	keySize := c.targetData.TypeAllocSize(llvmKeyType)
+	valueSize := c.targetData.TypeAllocSize(llvmValueType)
+	llvmKeySize := llvm.ConstInt(c.ctx.Int8Type(), keySize, false)
+	llvmValueSize := llvm.ConstInt(c.ctx.Int8Type(), valueSize, false)
+	sizeHint := llvm.ConstInt(c.uintptrType, 8, false)
+	if expr.Reserve != nil {
+		sizeHint = c.getValue(frame, expr.Reserve)
+		var err error
+		sizeHint, err = c.parseConvert(expr.Reserve.Type(), types.Typ[types.Uintptr], sizeHint, expr.Pos())
+		if err != nil {
+			return llvm.Value{}, err
+		}
+	}
+	hashmap := c.createRuntimeCall("hashmapMake", []llvm.Value{llvmKeySize, llvmValueSize, sizeHint}, "")
+	return hashmap, nil
+}
+
 func (c *Compiler) emitMapLookup(keyType, valueType types.Type, m, key llvm.Value, commaOk bool, pos token.Pos) (llvm.Value, error) {
 	llvmValueType := c.getLLVMType(valueType)
 
@@ -19,6 +55,7 @@ func (c *Compiler) emitMapLookup(keyType, valueType types.Type, m, key llvm.Valu
 
 	// Do the lookup. How it is done depends on the key type.
 	var commaOkValue llvm.Value
+	keyType = keyType.Underlying()
 	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
 		// key is a string
 		params := []llvm.Value{m, key, mapValuePtr}
@@ -34,8 +71,14 @@ func (c *Compiler) emitMapLookup(keyType, valueType types.Type, m, key llvm.Valu
 		commaOkValue = c.createRuntimeCall("hashmapBinaryGet", params, "")
 		c.emitLifetimeEnd(mapKeyPtr, mapKeySize)
 	} else {
-		// Not trivially comparable using memcmp.
-		return llvm.Value{}, c.makeError(pos, "only strings, bools, ints, pointers or structs of bools/ints are supported as map keys, but got: "+keyType.String())
+		// Not trivially comparable using memcmp. Make it an interface instead.
+		itfKey := key
+		if _, ok := keyType.(*types.Interface); !ok {
+			// Not already an interface, so convert it to an interface now.
+			itfKey = c.parseMakeInterface(key, keyType, pos)
+		}
+		params := []llvm.Value{m, itfKey, mapValuePtr}
+		commaOkValue = c.createRuntimeCall("hashmapInterfaceGet", params, "")
 	}
 
 	// Load the resulting value from the hashmap. The value is set to the zero
@@ -69,7 +112,14 @@ func (c *Compiler) emitMapUpdate(keyType types.Type, m, key, value llvm.Value, p
 		c.createRuntimeCall("hashmapBinarySet", params, "")
 		c.emitLifetimeEnd(keyPtr, keySize)
 	} else {
-		c.addError(pos, "only strings, bools, ints, pointers or structs of bools/ints are supported as map keys, but got: "+keyType.String())
+		// Key is not trivially comparable, so compare it as an interface instead.
+		itfKey := key
+		if _, ok := keyType.(*types.Interface); !ok {
+			// Not already an interface, so convert it to an interface first.
+			itfKey = c.parseMakeInterface(key, keyType, pos)
+		}
+		params := []llvm.Value{m, itfKey, valuePtr}
+		c.createRuntimeCall("hashmapInterfaceSet", params, "")
 	}
 	c.emitLifetimeEnd(valuePtr, valueSize)
 }
@@ -89,32 +139,19 @@ func (c *Compiler) emitMapDelete(keyType types.Type, m, key llvm.Value, pos toke
 		c.emitLifetimeEnd(keyPtr, keySize)
 		return nil
 	} else {
-		return c.makeError(pos, "only strings, bools, ints, pointers or structs of bools/ints are supported as map keys, but got: "+keyType.String())
+		// Key is not trivially comparable, so compare it as an interface
+		// instead.
+		itfKey := key
+		if _, ok := keyType.(*types.Interface); !ok {
+			// Not already an interface, so convert it to an interface first.
+			itfKey = c.parseMakeInterface(key, keyType, pos)
+		}
+		params := []llvm.Value{m, itfKey}
+		c.createRuntimeCall("hashmapInterfaceDelete", params, "")
+		return nil
 	}
 }
 
-// Get FNV-1a hash of this string.
-//
-// https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
-func hashmapHash(data []byte) uint32 {
-	var result uint32 = 2166136261 // FNV offset basis
-	for _, c := range data {
-		result ^= uint32(c)
-		result *= 16777619 // FNV prime
-	}
-	return result
-}
-
-// Get the topmost 8 bits of the hash, without using a special value (like 0).
-func hashmapTopHash(hash uint32) uint8 {
-	tophash := uint8(hash >> 24)
-	if tophash < 1 {
-		// 0 means empty slot, so make it bigger.
-		tophash += 1
-	}
-	return tophash
-}
-
 // Returns true if this key type does not contain strings, interfaces etc., so
 // can be compared with runtime.memequal.
 func hashmapIsBinaryKey(keyType types.Type) bool {

compiler/optimizer.go

@@ -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.LowerInterrupts(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.LowerInterrupts(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")}
 		}
 	}
 

compiler/sizes.go

@@ -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()

compiler/symbol.go

@@ -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() && !info.extern {
+			// Add debug info.
+			// TODO: this should be done for every global in the program, not just
+			// the ones that are referenced from some code.
+			pos := c.ir.Program.Fset.Position(g.Pos())
+			diglobal := c.dibuilder.CreateGlobalVariableExpression(c.difiles[pos.Filename], llvm.DIGlobalVariableExpression{
+				Name:        g.RelString(nil),
+				LinkageName: info.linkName,
+				File:        c.getDIFile(pos.Filename),
+				Line:        pos.Line,
+				Type:        c.getDIType(typ),
+				LocalToUnit: false,
+				Expr:        c.dibuilder.CreateExpression(nil),
+				AlignInBits: alignInBits,
+			})
+			llvmGlobal.AddMetadata(0, diglobal)
 		}
 	}
 	return llvmGlobal

compiler/syscall.go

@@ -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

go.mod

@@ -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
 )

go.sum

@@ -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=

goenv/goenv.go

@@ -18,6 +18,7 @@ var Keys = []string{
 	"GOROOT",
 	"GOPATH",
 	"GOCACHE",
+	"CGO_ENABLED",
 	"TINYGOROOT",
 }
 
@@ -57,6 +58,13 @@ func Get(name string) string {
 			panic("could not find cache dir: " + err.Error())
 		}
 		return filepath.Join(dir, "tinygo")
+	case "CGO_ENABLED":
+		val := os.Getenv("CGO_ENABLED")
+		if val == "1" || val == "0" {
+			return val
+		}
+		// Default to enabling CGo.
+		return "1"
 	case "TINYGOROOT":
 		return sourceDir()
 	default:

interp/frame.go

@@ -125,7 +125,10 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				}
 				indices[i] = uint32(operand.Value().ZExtValue())
 			}
-			result := value.GetElementPtr(indices)
+			result, err := value.GetElementPtr(indices)
+			if err != nil {
+				return nil, nil, fr.errorAt(inst, err.Error())
+			}
 			if result.Type() != inst.Type() {
 				return nil, nil, fr.errorAt(inst, "interp: gep: type does not match")
 			}
@@ -264,7 +267,11 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 				if elementCount == 1 {
 					fr.locals[resultInst] = result
 				} else {
-					fr.locals[resultInst] = result.GetElementPtr([]uint32{0, 0})
+					result, err := result.GetElementPtr([]uint32{0, 0})
+					if err != nil {
+						return nil, nil, errorAt(inst, err.Error())
+					}
+					fr.locals[resultInst] = result
 				}
 			case callee.Name() == "runtime.hashmapMake":
 				// create a map
@@ -278,24 +285,49 @@ 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
@@ -340,8 +372,16 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					// a bitcast of the original array instead of the GEP,
 					// which breaks our assumptions.
 					// Re-add this GEP, in the hope that it it is then of the correct type...
-					dstArray = dstArray.GetElementPtr([]uint32{0, 0}).(*LocalValue)
-					srcArray = srcArray.GetElementPtr([]uint32{0, 0}).(*LocalValue)
+					dstArrayValue, err := dstArray.GetElementPtr([]uint32{0, 0})
+					if err != nil {
+						return nil, nil, errorAt(inst, err.Error())
+					}
+					dstArray = dstArrayValue.(*LocalValue)
+					srcArrayValue, err := srcArray.GetElementPtr([]uint32{0, 0})
+					if err != nil {
+						return nil, nil, errorAt(inst, err.Error())
+					}
+					srcArray = srcArrayValue.(*LocalValue)
 				}
 				if fr.Eval.TargetData.TypeAllocSize(dstArray.Type().ElementType()) != elementSize {
 					return nil, nil, fr.errorAt(inst, "interp: slice dst element size does not match pointer type")
@@ -360,12 +400,21 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
 					return nil, nil, fr.errorAt(inst, "interp: trying to copy a slice with negative length?")
 				}
 				for i := int64(0); i < length; i++ {
+					var err error
 					// *dst = *src
 					dstArray.Store(srcArray.Load())
 					// dst++
-					dstArray = dstArray.GetElementPtr([]uint32{1}).(*LocalValue)
+					dstArrayValue, err := dstArray.GetElementPtr([]uint32{1})
+					if err != nil {
+						return nil, nil, errorAt(inst, err.Error())
+					}
+					dstArray = dstArrayValue.(*LocalValue)
 					// src++
-					srcArray = srcArray.GetElementPtr([]uint32{1}).(*LocalValue)
+					srcArrayValue, err := srcArray.GetElementPtr([]uint32{1})
+					if err != nil {
+						return nil, nil, errorAt(inst, err.Error())
+					}
+					srcArray = srcArrayValue.(*LocalValue)
 				}
 			case callee.Name() == "runtime.stringToBytes":
 				// convert a string to a []byte
@@ -433,6 +482,8 @@ 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":

interp/interp_test.go

@@ -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) {

interp/scan.go

@@ -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() {

interp/testdata/map.ll

@@ -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
+}

interp/testdata/map.out.ll

@@ -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
+}

interp/utils.go

@@ -24,7 +24,11 @@ func getStringBytes(strPtr Value, strLen llvm.Value) []byte {
 	}
 	buf := make([]byte, strLen.ZExtValue())
 	for i := range buf {
-		c := strPtr.GetElementPtr([]uint32{uint32(i)}).Load()
+		gep, err := strPtr.GetElementPtr([]uint32{uint32(i)})
+		if err != nil {
+			panic(err) // TODO
+		}
+		c := gep.Load()
 		buf[i] = byte(c.ZExtValue())
 	}
 	return buf

interp/values.go

@@ -3,6 +3,7 @@ package interp
 // This file provides a litte bit of abstraction around LLVM values.
 
 import (
+	"errors"
 	"strconv"
 
 	"tinygo.org/x/go-llvm"
@@ -11,13 +12,13 @@ import (
 // A Value is a LLVM value with some extra methods attached for easier
 // interpretation.
 type Value interface {
-	Value() llvm.Value            // returns a LLVM value
-	Type() llvm.Type              // equal to Value().Type()
-	IsConstant() bool             // returns true if this value is a constant value
-	Load() llvm.Value             // dereference a pointer
-	Store(llvm.Value)             // store to a pointer
-	GetElementPtr([]uint32) Value // returns an interior pointer
-	String() string               // string representation, for debugging
+	Value() llvm.Value                     // returns a LLVM value
+	Type() llvm.Type                       // equal to Value().Type()
+	IsConstant() bool                      // returns true if this value is a constant value
+	Load() llvm.Value                      // dereference a pointer
+	Store(llvm.Value)                      // store to a pointer
+	GetElementPtr([]uint32) (Value, error) // returns an interior pointer
+	String() string                        // string representation, for debugging
 }
 
 // A type that simply wraps a LLVM constant value.
@@ -97,21 +98,21 @@ func (v *LocalValue) Store(value llvm.Value) {
 }
 
 // GetElementPtr returns a GEP when the underlying value is of pointer type.
-func (v *LocalValue) GetElementPtr(indices []uint32) Value {
+func (v *LocalValue) GetElementPtr(indices []uint32) (Value, error) {
 	if !v.Underlying.IsAGlobalVariable().IsNil() {
 		int32Type := v.Underlying.Type().Context().Int32Type()
 		gep := llvm.ConstGEP(v.Underlying, getLLVMIndices(int32Type, indices))
-		return &LocalValue{v.Eval, gep}
+		return &LocalValue{v.Eval, gep}, nil
 	}
 	if !v.Underlying.IsAConstantExpr().IsNil() {
 		switch v.Underlying.Opcode() {
 		case llvm.GetElementPtr, llvm.IntToPtr, llvm.BitCast:
 			int32Type := v.Underlying.Type().Context().Int32Type()
 			llvmIndices := getLLVMIndices(int32Type, indices)
-			return &LocalValue{v.Eval, llvm.ConstGEP(v.Underlying, llvmIndices)}
+			return &LocalValue{v.Eval, llvm.ConstGEP(v.Underlying, llvmIndices)}, nil
 		}
 	}
-	panic("interp: unknown GEP")
+	return nil, errors.New("interp: unknown GEP")
 }
 
 // stripPointerCasts removes all const bitcasts from pointer values, if there
@@ -309,8 +310,8 @@ func (v *MapValue) Store(value llvm.Value) {
 
 // GetElementPtr panics: maps are of reference type so their (interior)
 // addresses cannot be calculated.
-func (v *MapValue) GetElementPtr(indices []uint32) Value {
-	panic("interp: GEP on a map")
+func (v *MapValue) GetElementPtr(indices []uint32) (Value, error) {
+	return nil, errors.New("interp: GEP on a map")
 }
 
 // PutString does a map assign operation, assuming that the map is of type
@@ -367,10 +368,12 @@ 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() {

ir/ir.go

@@ -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

loader/loader.go

@@ -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...)

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"errors"
 	"flag"
 	"fmt"
@@ -183,6 +184,14 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 	return builder.Build(pkgName, fileExt, config, func(tmppath string) error {
 		// do we need port reset to put MCU into bootloader mode?
 		if config.Target.PortReset == "true" {
+			if port == "" {
+				var err error
+				port, err = getDefaultPort()
+				if err != nil {
+					return err
+				}
+			}
+
 			err := touchSerialPortAt1200bps(port)
 			if err != nil {
 				return &commandError{"failed to reset port", tmppath, err}
@@ -198,10 +207,30 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			flashCmd := config.Target.FlashCommand
 			fileToken := "{" + fileExt[1:] + "}"
 			flashCmd = strings.Replace(flashCmd, fileToken, tmppath, -1)
+
+			if port == "" && strings.Contains(flashCmd, "{port}") {
+				var err error
+				port, err = getDefaultPort()
+				if err != nil {
+					return err
+				}
+			}
+
 			flashCmd = strings.Replace(flashCmd, "{port}", port, -1)
 
 			// Execute the command.
-			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 +283,7 @@ 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
@@ -268,11 +297,13 @@ 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 != "" {
+			if len(config.Target.Emulator) != 0 {
+				// Assume QEMU as an emulator.
+				gdbInterface = "qemu"
+			} else if openocdInterface != "" && config.Target.OpenOCDTarget != "" {
 				gdbInterface = "openocd"
+			} else if config.Target.JLinkDevice != "" {
+				gdbInterface = "jlink"
 			}
 		}
 
@@ -303,6 +334,51 @@ 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 "jlink":
+			gdbCommands = append(gdbCommands, "target remote :2331", "load", "monitor reset halt")
+
+			// We need a separate debugging daemon for on-chip debugging.
+			daemon := exec.Command("JLinkGDBServer", "-device", config.Target.JLinkDevice)
+			if ocdOutput {
+				// Make it clear which output is from the daemon.
+				w := &ColorWriter{
+					Out:    os.Stderr,
+					Prefix: "jlink: ",
+					Color:  TermColorYellow,
+				}
+				daemon.Stdout = w
+				daemon.Stderr = w
+			}
+			// 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 +477,18 @@ 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 +504,18 @@ 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 +529,29 @@ 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 +576,55 @@ func parseSize(s string) (int64, error) {
 	return n, err
 }
 
+// getDefaultPort returns the default serial port depending on the operating system.
+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("no serial ports available")
+		}
+
+		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 serial port")
+	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 serial port")
+	}
+
+	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 +692,7 @@ 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 +795,7 @@ 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":

main_test.go

@@ -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" {
@@ -67,41 +69,38 @@ func TestCompiler(t *testing.T) {
 }
 
 func runPlatTests(target string, matches []string, t *testing.T) {
+	t.Parallel()
+
 	for _, path := range matches {
-		switch {
-		case target == "wasm":
-			// testdata/gc.go is known not to work on WebAssembly
-			if path == filepath.Join("testdata", "gc.go") {
-				continue
-			}
-		case target == "":
-			// run all tests on host
-		case target == "qemu":
-			// all tests are supported
-		default:
-			// cross-compilation of cgo is not yet supported
-			if path == filepath.Join("testdata", "cgo")+string(filepath.Separator) {
-				continue
-			}
-		}
+		path := path // redefine to avoid race condition
 
 		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 +129,7 @@ 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 +143,9 @@ 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 +161,35 @@ 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)

src/device/riscv/csr.go

@@ -0,0 +1,277 @@
+package riscv
+
+// This file lists constants for CSR operations and defines methods on CSRs that
+// are implemented as compiler intrinsics.
+
+// CSR constants are used for use in CSR (Control and Status Register) compiler
+// intrinsics.
+type CSR int16
+
+// Get returns the value of the given CSR.
+func (csr CSR) Get() uintptr
+
+// Set stores a new value in the given CSR.
+func (csr CSR) Set(uintptr)
+
+// SetBits atomically sets the given bits in this ISR and returns the old value.
+func (csr CSR) SetBits(uintptr) uintptr
+
+// ClearBits atomically clears the given bits in this ISR and returns the old
+// value.
+func (csr CSR) ClearBits(uintptr) uintptr
+
+// CSR values defined in the RISC-V privileged specification. Not all values may
+// be available on any given chip.
+//
+// Source: https://github.com/riscv/riscv-isa-manual/blob/riscv-priv-1.10/src/priv-csrs.tex
+const (
+	// User Trap Setup
+	USTATUS CSR = 0x000 // User status register.
+	UIE     CSR = 0x004 // User interrupt-enable register.
+	UTVEC   CSR = 0x005 // User trap handler base address.
+
+	// User Trap Handling
+	USCRATCH CSR = 0x040 // Scratch register for user trap handlers.
+	UEPC     CSR = 0x041 // User exception program counter.
+	UCAUSE   CSR = 0x042 // User trap cause.
+	UTVAL    CSR = 0x043 // User bad address or instruction.
+	UIP      CSR = 0x044 // User interrupt pending.
+
+	// User Floating-Point CSRs
+	FFLAGS CSR = 0x001 // Floating-Point Accrued Exceptions.
+	FRM    CSR = 0x002 // Floating-Point Dynamic Rounding Mode.
+	FCSR   CSR = 0x003 // Floating-Point Control and Status
+
+	// User Counter/Timers
+	CYCLE         CSR = 0xC00 // Cycle counter for RDCYCLE instruction.
+	TIME          CSR = 0xC01 // Timer for RDTIME instruction.
+	INSTRET       CSR = 0xC02 // Instructions-retired counter for RDINSTRET instruction.
+	HPMCOUNTER3   CSR = 0xC03 // Performance-monitoring counter 3.
+	HPMCOUNTER4   CSR = 0xC04 // Performance-monitoring counter 4.
+	HPMCOUNTER5   CSR = 0xC05 // Performance-monitoring counter 5.
+	HPMCOUNTER6   CSR = 0xC06 // Performance-monitoring counter 6.
+	HPMCOUNTER7   CSR = 0xC07 // Performance-monitoring counter 7.
+	HPMCOUNTER8   CSR = 0xC08 // Performance-monitoring counter 8.
+	HPMCOUNTER9   CSR = 0xC09 // Performance-monitoring counter 9.
+	HPMCOUNTER10  CSR = 0xC0A // Performance-monitoring counter 10.
+	HPMCOUNTER11  CSR = 0xC0B // Performance-monitoring counter 11.
+	HPMCOUNTER12  CSR = 0xC0C // Performance-monitoring counter 12.
+	HPMCOUNTER13  CSR = 0xC0D // Performance-monitoring counter 13.
+	HPMCOUNTER14  CSR = 0xC0E // Performance-monitoring counter 14.
+	HPMCOUNTER15  CSR = 0xC0F // Performance-monitoring counter 15.
+	HPMCOUNTER16  CSR = 0xC10 // Performance-monitoring counter 16.
+	HPMCOUNTER17  CSR = 0xC11 // Performance-monitoring counter 17.
+	HPMCOUNTER18  CSR = 0xC12 // Performance-monitoring counter 18.
+	HPMCOUNTER19  CSR = 0xC13 // Performance-monitoring counter 19.
+	HPMCOUNTER20  CSR = 0xC14 // Performance-monitoring counter 20.
+	HPMCOUNTER21  CSR = 0xC15 // Performance-monitoring counter 21.
+	HPMCOUNTER22  CSR = 0xC16 // Performance-monitoring counter 22.
+	HPMCOUNTER23  CSR = 0xC17 // Performance-monitoring counter 23.
+	HPMCOUNTER24  CSR = 0xC18 // Performance-monitoring counter 24.
+	HPMCOUNTER25  CSR = 0xC19 // Performance-monitoring counter 25.
+	HPMCOUNTER26  CSR = 0xC1A // Performance-monitoring counter 26.
+	HPMCOUNTER27  CSR = 0xC1B // Performance-monitoring counter 27.
+	HPMCOUNTER28  CSR = 0xC1C // Performance-monitoring counter 28.
+	HPMCOUNTER29  CSR = 0xC1D // Performance-monitoring counter 29.
+	HPMCOUNTER30  CSR = 0xC1E // Performance-monitoring counter 30.
+	HPMCOUNTER31  CSR = 0xC1F // Performance-monitoring counter 31.
+	CYCLEH        CSR = 0xC80 // Upper 32 bits of CYCLE, RV32I only.
+	TIMEH         CSR = 0xC81 // Upper 32 bits of TIME, RV32I only.
+	INSTRETH      CSR = 0xC82 // Upper 32 bits of INSTRET, RV32I only.
+	HPMCOUNTER3H  CSR = 0xC83 // Upper 32 bits of HPMCOUNTER3, RV32I only.
+	HPMCOUNTER4H  CSR = 0xC84 // Upper 32 bits of HPMCOUNTER4, RV32I only.
+	HPMCOUNTER5H  CSR = 0xC85 // Upper 32 bits of HPMCOUNTER5, RV32I only.
+	HPMCOUNTER6H  CSR = 0xC86 // Upper 32 bits of HPMCOUNTER6, RV32I only.
+	HPMCOUNTER7H  CSR = 0xC87 // Upper 32 bits of HPMCOUNTER7, RV32I only.
+	HPMCOUNTER8H  CSR = 0xC88 // Upper 32 bits of HPMCOUNTER8, RV32I only.
+	HPMCOUNTER9H  CSR = 0xC89 // Upper 32 bits of HPMCOUNTER9, RV32I only.
+	HPMCOUNTER10H CSR = 0xC8A // Upper 32 bits of HPMCOUNTER10, RV32I only.
+	HPMCOUNTER11H CSR = 0xC8B // Upper 32 bits of HPMCOUNTER11, RV32I only.
+	HPMCOUNTER12H CSR = 0xC8C // Upper 32 bits of HPMCOUNTER12, RV32I only.
+	HPMCOUNTER13H CSR = 0xC8D // Upper 32 bits of HPMCOUNTER13, RV32I only.
+	HPMCOUNTER14H CSR = 0xC8E // Upper 32 bits of HPMCOUNTER14, RV32I only.
+	HPMCOUNTER15H CSR = 0xC8F // Upper 32 bits of HPMCOUNTER15, RV32I only.
+	HPMCOUNTER16H CSR = 0xC90 // Upper 32 bits of HPMCOUNTER16, RV32I only.
+	HPMCOUNTER17H CSR = 0xC91 // Upper 32 bits of HPMCOUNTER17, RV32I only.
+	HPMCOUNTER18H CSR = 0xC92 // Upper 32 bits of HPMCOUNTER18, RV32I only.
+	HPMCOUNTER19H CSR = 0xC93 // Upper 32 bits of HPMCOUNTER19, RV32I only.
+	HPMCOUNTER20H CSR = 0xC94 // Upper 32 bits of HPMCOUNTER20, RV32I only.
+	HPMCOUNTER21H CSR = 0xC95 // Upper 32 bits of HPMCOUNTER21, RV32I only.
+	HPMCOUNTER22H CSR = 0xC96 // Upper 32 bits of HPMCOUNTER22, RV32I only.
+	HPMCOUNTER23H CSR = 0xC97 // Upper 32 bits of HPMCOUNTER23, RV32I only.
+	HPMCOUNTER24H CSR = 0xC98 // Upper 32 bits of HPMCOUNTER24, RV32I only.
+	HPMCOUNTER25H CSR = 0xC99 // Upper 32 bits of HPMCOUNTER25, RV32I only.
+	HPMCOUNTER26H CSR = 0xC9A // Upper 32 bits of HPMCOUNTER26, RV32I only.
+	HPMCOUNTER27H CSR = 0xC9B // Upper 32 bits of HPMCOUNTER27, RV32I only.
+	HPMCOUNTER28H CSR = 0xC9C // Upper 32 bits of HPMCOUNTER28, RV32I only.
+	HPMCOUNTER29H CSR = 0xC9D // Upper 32 bits of HPMCOUNTER29, RV32I only.
+	HPMCOUNTER30H CSR = 0xC9E // Upper 32 bits of HPMCOUNTER30, RV32I only.
+	HPMCOUNTER31H CSR = 0xC9F // Upper 32 bits of HPMCOUNTER31, RV32I only.
+
+	// Supervisor Trap Setup
+	SSTATUS    CSR = 0x100 // Supervisor status register.
+	SEDELEG    CSR = 0x102 // Supervisor exception delegation register.
+	SIDELEG    CSR = 0x103 // Supervisor interrupt delegation register.
+	SIE        CSR = 0x104 // Supervisor interrupt-enable register.
+	STVEC      CSR = 0x105 // Supervisor trap handler base address.
+	SCOUNTEREN CSR = 0x106 // Supervisor counter enable.
+
+	// Supervisor Trap Handling
+	SSCRATCH CSR = 0x140 // Scratch register for supervisor trap handlers.
+	SEPC     CSR = 0x141 // Supervisor exception program counter.
+	SCAUSE   CSR = 0x142 // Supervisor trap cause.
+	STVAL    CSR = 0x143 // Supervisor bad address or instruction.
+	SIP      CSR = 0x144 // Supervisor interrupt pending.
+
+	// Supervisor Protection and Translation
+	SATP CSR = 0x180 // Supervisor address translation and protection.
+
+	// Machine Information Registers
+	MVENDORID CSR = 0xF11 // Vendor ID.
+	MARCHID   CSR = 0xF12 // Architecture ID.
+	MIMPID    CSR = 0xF13 // Implementation ID.
+	MHARTID   CSR = 0xF14 // Hardware thread ID.
+
+	// Machine Trap Setup
+	MSTATUS    CSR = 0x300 // Machine status register.
+	MISA       CSR = 0x301 // ISA and extensions
+	MEDELEG    CSR = 0x302 // Machine exception delegation register.
+	MIDELEG    CSR = 0x303 // Machine interrupt delegation register.
+	MIE        CSR = 0x304 // Machine interrupt-enable register.
+	MTVEC      CSR = 0x305 // Machine trap-handler base address.
+	MCOUNTEREN CSR = 0x306 // Machine counter enable.
+
+	// Machine Trap Handling
+	MSCRATCH CSR = 0x340 // Scratch register for machine trap handlers.
+	MEPC     CSR = 0x341 // Machine exception program counter.
+	MCAUSE   CSR = 0x342 // Machine trap cause.
+	MTVAL    CSR = 0x343 // Machine bad address or instruction.
+	MIP      CSR = 0x344 // Machine interrupt pending.
+
+	// Machine Protection and Translation
+	PMPCFG0   CSR = 0x3A0 // Physical memory protection configuration.
+	PMPCFG1   CSR = 0x3A1 // Physical memory protection configuration, RV32 only.
+	PMPCFG2   CSR = 0x3A2 // Physical memory protection configuration.
+	PMPCFG3   CSR = 0x3A3 // Physical memory protection configuration, RV32 only.
+	PMPADDR0  CSR = 0x3B0 // Physical memory protection address register 0.
+	PMPADDR1  CSR = 0x3B1 // Physical memory protection address register 1.
+	PMPADDR2  CSR = 0x3B2 // Physical memory protection address register 2.
+	PMPADDR3  CSR = 0x3B3 // Physical memory protection address register 3.
+	PMPADDR4  CSR = 0x3B4 // Physical memory protection address register 4.
+	PMPADDR5  CSR = 0x3B5 // Physical memory protection address register 5.
+	PMPADDR6  CSR = 0x3B6 // Physical memory protection address register 6.
+	PMPADDR7  CSR = 0x3B7 // Physical memory protection address register 7.
+	PMPADDR8  CSR = 0x3B8 // Physical memory protection address register 8.
+	PMPADDR9  CSR = 0x3B9 // Physical memory protection address register 9.
+	PMPADDR10 CSR = 0x3BA // Physical memory protection address register 10.
+	PMPADDR11 CSR = 0x3BB // Physical memory protection address register 11.
+	PMPADDR12 CSR = 0x3BC // Physical memory protection address register 12.
+	PMPADDR13 CSR = 0x3BD // Physical memory protection address register 13.
+	PMPADDR14 CSR = 0x3BE // Physical memory protection address register 14.
+	PMPADDR15 CSR = 0x3BF // Physical memory protection address register 15.
+
+	// Machine Counter/Timers
+	mcycle         CSR = 0xB00 // Machine cycle counter.
+	minstret       CSR = 0xB02 // Machine instructions-retired counter.
+	MHPMCOUNTER3   CSR = 0xB03 // Machine performance-monitoring counter 3.
+	MHPMCOUNTER4   CSR = 0xB04 // Machine performance-monitoring counter 4.
+	MHPMCOUNTER5   CSR = 0xB05 // Machine performance-monitoring counter 5.
+	MHPMCOUNTER6   CSR = 0xB06 // Machine performance-monitoring counter 6.
+	MHPMCOUNTER7   CSR = 0xB07 // Machine performance-monitoring counter 7.
+	MHPMCOUNTER8   CSR = 0xB08 // Machine performance-monitoring counter 8.
+	MHPMCOUNTER9   CSR = 0xB09 // Machine performance-monitoring counter 9.
+	MHPMCOUNTER10  CSR = 0xB0A // Machine performance-monitoring counter 10.
+	MHPMCOUNTER11  CSR = 0xB0B // Machine performance-monitoring counter 11.
+	MHPMCOUNTER12  CSR = 0xB0C // Machine performance-monitoring counter 12.
+	MHPMCOUNTER13  CSR = 0xB0D // Machine performance-monitoring counter 13.
+	MHPMCOUNTER14  CSR = 0xB0E // Machine performance-monitoring counter 14.
+	MHPMCOUNTER15  CSR = 0xB0F // Machine performance-monitoring counter 15.
+	MHPMCOUNTER16  CSR = 0xB10 // Machine performance-monitoring counter 16.
+	MHPMCOUNTER17  CSR = 0xB11 // Machine performance-monitoring counter 17.
+	MHPMCOUNTER18  CSR = 0xB12 // Machine performance-monitoring counter 18.
+	MHPMCOUNTER19  CSR = 0xB13 // Machine performance-monitoring counter 19.
+	MHPMCOUNTER20  CSR = 0xB14 // Machine performance-monitoring counter 20.
+	MHPMCOUNTER21  CSR = 0xB15 // Machine performance-monitoring counter 21.
+	MHPMCOUNTER22  CSR = 0xB16 // Machine performance-monitoring counter 22.
+	MHPMCOUNTER23  CSR = 0xB17 // Machine performance-monitoring counter 23.
+	MHPMCOUNTER24  CSR = 0xB18 // Machine performance-monitoring counter 24.
+	MHPMCOUNTER25  CSR = 0xB19 // Machine performance-monitoring counter 25.
+	MHPMCOUNTER26  CSR = 0xB1A // Machine performance-monitoring counter 26.
+	MHPMCOUNTER27  CSR = 0xB1B // Machine performance-monitoring counter 27.
+	MHPMCOUNTER28  CSR = 0xB1C // Machine performance-monitoring counter 28.
+	MHPMCOUNTER29  CSR = 0xB1D // Machine performance-monitoring counter 29.
+	MHPMCOUNTER30  CSR = 0xB1E // Machine performance-monitoring counter 30.
+	MHPMCOUNTER31  CSR = 0xB1F // Machine performance-monitoring counter 31.
+	MCYCLEH        CSR = 0xB80 // Upper 32 bits of MCYCLE, RV32I only.
+	MINSTRETH      CSR = 0xB82 // Upper 32 bits of MINSTRET, RV32I only.
+	MHPMCOUNTER3H  CSR = 0xB83 // Upper 32 bits of MHPMCOUNTER3, RV32I only.
+	MHPMCOUNTER4H  CSR = 0xB84 // Upper 32 bits of MHPMCOUNTER4, RV32I only.
+	MHPMCOUNTER5H  CSR = 0xB85 // Upper 32 bits of MHPMCOUNTER5, RV32I only.
+	MHPMCOUNTER6H  CSR = 0xB86 // Upper 32 bits of MHPMCOUNTER6, RV32I only.
+	MHPMCOUNTER7H  CSR = 0xB87 // Upper 32 bits of MHPMCOUNTER7, RV32I only.
+	MHPMCOUNTER8H  CSR = 0xB88 // Upper 32 bits of MHPMCOUNTER8, RV32I only.
+	MHPMCOUNTER9H  CSR = 0xB89 // Upper 32 bits of MHPMCOUNTER9, RV32I only.
+	MHPMCOUNTER10H CSR = 0xB8A // Upper 32 bits of MHPMCOUNTER10, RV32I only.
+	MHPMCOUNTER11H CSR = 0xB8B // Upper 32 bits of MHPMCOUNTER11, RV32I only.
+	MHPMCOUNTER12H CSR = 0xB8C // Upper 32 bits of MHPMCOUNTER12, RV32I only.
+	MHPMCOUNTER13H CSR = 0xB8D // Upper 32 bits of MHPMCOUNTER13, RV32I only.
+	MHPMCOUNTER14H CSR = 0xB8E // Upper 32 bits of MHPMCOUNTER14, RV32I only.
+	MHPMCOUNTER15H CSR = 0xB8F // Upper 32 bits of MHPMCOUNTER15, RV32I only.
+	MHPMCOUNTER16H CSR = 0xB90 // Upper 32 bits of MHPMCOUNTER16, RV32I only.
+	MHPMCOUNTER17H CSR = 0xB91 // Upper 32 bits of MHPMCOUNTER17, RV32I only.
+	MHPMCOUNTER18H CSR = 0xB92 // Upper 32 bits of MHPMCOUNTER18, RV32I only.
+	MHPMCOUNTER19H CSR = 0xB93 // Upper 32 bits of MHPMCOUNTER19, RV32I only.
+	MHPMCOUNTER20H CSR = 0xB94 // Upper 32 bits of MHPMCOUNTER20, RV32I only.
+	MHPMCOUNTER21H CSR = 0xB95 // Upper 32 bits of MHPMCOUNTER21, RV32I only.
+	MHPMCOUNTER22H CSR = 0xB96 // Upper 32 bits of MHPMCOUNTER22, RV32I only.
+	MHPMCOUNTER23H CSR = 0xB97 // Upper 32 bits of MHPMCOUNTER23, RV32I only.
+	MHPMCOUNTER24H CSR = 0xB98 // Upper 32 bits of MHPMCOUNTER24, RV32I only.
+	MHPMCOUNTER25H CSR = 0xB99 // Upper 32 bits of MHPMCOUNTER25, RV32I only.
+	MHPMCOUNTER26H CSR = 0xB9A // Upper 32 bits of MHPMCOUNTER26, RV32I only.
+	MHPMCOUNTER27H CSR = 0xB9B // Upper 32 bits of MHPMCOUNTER27, RV32I only.
+	MHPMCOUNTER28H CSR = 0xB9C // Upper 32 bits of MHPMCOUNTER28, RV32I only.
+	MHPMCOUNTER29H CSR = 0xB9D // Upper 32 bits of MHPMCOUNTER29, RV32I only.
+	MHPMCOUNTER30H CSR = 0xB9E // Upper 32 bits of MHPMCOUNTER30, RV32I only.
+	MHPMCOUNTER31H CSR = 0xB9F // Upper 32 bits of MHPMCOUNTER31, RV32I only.
+
+	// Machine Counter Setup
+	MHPMEVENT4  CSR = 0x324 // Machine performance-monitoring event selector 4.
+	MHPMEVENT5  CSR = 0x325 // Machine performance-monitoring event selector 5.
+	MHPMEVENT6  CSR = 0x326 // Machine performance-monitoring event selector 6.
+	MHPMEVENT7  CSR = 0x327 // Machine performance-monitoring event selector 7.
+	MHPMEVENT8  CSR = 0x328 // Machine performance-monitoring event selector 8.
+	MHPMEVENT9  CSR = 0x329 // Machine performance-monitoring event selector 9.
+	MHPMEVENT10 CSR = 0x32A // Machine performance-monitoring event selector 10.
+	MHPMEVENT11 CSR = 0x32B // Machine performance-monitoring event selector 11.
+	MHPMEVENT12 CSR = 0x32C // Machine performance-monitoring event selector 12.
+	MHPMEVENT13 CSR = 0x32D // Machine performance-monitoring event selector 13.
+	MHPMEVENT14 CSR = 0x32E // Machine performance-monitoring event selector 14.
+	MHPMEVENT15 CSR = 0x32F // Machine performance-monitoring event selector 15.
+	MHPMEVENT16 CSR = 0x330 // Machine performance-monitoring event selector 16.
+	MHPMEVENT17 CSR = 0x331 // Machine performance-monitoring event selector 17.
+	MHPMEVENT18 CSR = 0x332 // Machine performance-monitoring event selector 18.
+	MHPMEVENT19 CSR = 0x333 // Machine performance-monitoring event selector 19.
+	MHPMEVENT20 CSR = 0x334 // Machine performance-monitoring event selector 20.
+	MHPMEVENT21 CSR = 0x335 // Machine performance-monitoring event selector 21.
+	MHPMEVENT22 CSR = 0x336 // Machine performance-monitoring event selector 22.
+	MHPMEVENT23 CSR = 0x337 // Machine performance-monitoring event selector 23.
+	MHPMEVENT24 CSR = 0x338 // Machine performance-monitoring event selector 24.
+	MHPMEVENT25 CSR = 0x339 // Machine performance-monitoring event selector 25.
+	MHPMEVENT26 CSR = 0x33A // Machine performance-monitoring event selector 26.
+	MHPMEVENT27 CSR = 0x33B // Machine performance-monitoring event selector 27.
+	MHPMEVENT28 CSR = 0x33C // Machine performance-monitoring event selector 28.
+	MHPMEVENT29 CSR = 0x33D // Machine performance-monitoring event selector 29.
+	MHPMEVENT30 CSR = 0x33E // Machine performance-monitoring event selector 30.
+	MHPMEVENT31 CSR = 0x33F // Machine performance-monitoring event selector 31.
+
+	// Debug/Trace Registers (shared with Debug Mode)
+	TSELECT CSR = 0x7A0 // Debug/Trace trigger register select.
+	TDATA1  CSR = 0x7A1 // First Debug/Trace trigger data register.
+	TDATA2  CSR = 0x7A2 // Second Debug/Trace trigger data register.
+	TDATA3  CSR = 0x7A3 // Third Debug/Trace trigger data register.
+
+	// Debug Mode Registers
+	DCSR     CSR = 0x7B0 // Debug control and status register.
+	DPC      CSR = 0x7B1 // Debug PC.
+	DSCRATCH CSR = 0x7B2 // Debug scratch register.
+)

src/device/riscv/start.S

@@ -3,11 +3,58 @@
 .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$
+
+    // Jump to runtime.main
     call main
+
+.section .text.handleInterruptASM
+.global handleInterruptASM
+.type handleInterruptASM,@function
+handleInterruptASM:
+    // Save and restore all registers, because the hardware only saves/restores
+    // the pc.
+    // Note: we have to do this in assembly because the "interrupt"="machine"
+    // attribute is broken in LLVM: https://bugs.llvm.org/show_bug.cgi?id=42984
+    addi    sp, sp, -64
+    sw      ra, 60(sp)
+    sw      t0, 56(sp)
+    sw      t1, 52(sp)
+    sw      t2, 48(sp)
+    sw      a0, 44(sp)
+    sw      a1, 40(sp)
+    sw      a2, 36(sp)
+    sw      a3, 32(sp)
+    sw      a4, 28(sp)
+    sw      a5, 24(sp)
+    sw      a6, 20(sp)
+    sw      a7, 16(sp)
+    sw      t3, 12(sp)
+    sw      t4, 8(sp)
+    sw      t5, 4(sp)
+    sw      t6, 0(sp)
+    call    handleInterrupt
+    lw      t6, 0(sp)
+    lw      t5, 4(sp)
+    lw      t4, 8(sp)
+    lw      t3, 12(sp)
+    lw      a7, 16(sp)
+    lw      a6, 20(sp)
+    lw      a5, 24(sp)
+    lw      a4, 28(sp)
+    lw      a3, 32(sp)
+    lw      a2, 36(sp)
+    lw      a1, 40(sp)
+    lw      a0, 44(sp)
+    lw      t2, 48(sp)
+    lw      t1, 52(sp)
+    lw      t0, 56(sp)
+    lw      ra, 60(sp)
+    addi    sp, sp, 64
+    mret

src/device/stm32/stm32f103xx-bitfields.go

@@ -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
 

src/examples/systick/systick.go

@@ -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 {
 	}

src/machine/board_arduino.go

@@ -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

src/machine/board_arduino_nano.go

@@ -0,0 +1,27 @@
+// +build arduino_nano
+
+package machine
+
+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 16000000
+}
+
+// LED on the Arduino
+const LED Pin = 13
+
+// ADC on the Arduino
+const (
+	ADC0 Pin = 0
+	ADC1 Pin = 1
+	ADC2 Pin = 2
+	ADC3 Pin = 3
+	ADC4 Pin = 4 // Used by TWI for SDA
+	ADC5 Pin = 5 // Used by TWI for SCL
+)
+
+// UART pins
+const (
+	UART_TX_PIN Pin = 1
+	UART_RX_PIN Pin = 0
+)

src/machine/board_arduino_nano33.go

@@ -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}
-)

src/machine/board_arduino_nano33_baremetal.go

@@ -0,0 +1,61 @@
+// +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() {
+	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}
+)

src/machine/board_atsamd21.go

@@ -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
+)

src/machine/board_bluepill.go

@@ -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

src/machine/board_circuitplay_bluefruit.go

@@ -0,0 +1,73 @@
+// +build circuitplay_bluefruit
+
+package machine
+
+const HasLowFrequencyCrystal = true
+
+// GPIO Pins
+const (
+	D0  = P0_30
+	D1  = P0_14
+	D2  = P0_05
+	D3  = P0_04
+	D4  = P1_02
+	D5  = P1_15
+	D6  = P0_02
+	D7  = P1_06
+	D8  = P0_13
+	D9  = P0_29
+	D10 = P0_03
+	D11 = P1_04
+	D12 = P0_26
+	D13 = P1_14
+)
+
+// Analog Pins
+const (
+	A1 = P0_02
+	A2 = P0_29
+	A3 = P0_03
+	A4 = P0_04
+	A5 = P0_05
+	A6 = P0_30
+	A7 = P0_14
+	A8 = P0_28
+	A9 = P0_31
+)
+
+const (
+	LED       = D13
+	NEOPIXELS = D8
+
+	BUTTONA = D4
+	BUTTONB = D5
+	SLIDER  = D7 // built-in slide switch
+
+	BUTTON  = BUTTONA
+	BUTTON1 = BUTTONB
+
+	LIGHTSENSOR = A8
+	TEMPSENSOR  = A9
+)
+
+// UART0 pins (logical UART1)
+const (
+	UART_TX_PIN = P0_14 // PORTB
+	UART_RX_PIN = P0_30 // PORTB
+)
+
+// I2C pins
+const (
+	SDA_PIN = P0_05 // I2C0 external
+	SCL_PIN = P0_04 // I2C0 external
+
+	SDA1_PIN = P0_00 // I2C1 internal
+	SCL1_PIN = P0_01 // I2C1 internal
+)
+
+// SPI pins (internal flash)
+const (
+	SPI0_SCK_PIN  = P0_19 // SCK
+	SPI0_MOSI_PIN = P0_21 // MOSI
+	SPI0_MISO_PIN = P0_23 // MISO
+)

src/machine/board_circuitplay_express.go

@@ -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}
-)

src/machine/board_circuitplay_express_baremetal.go

@@ -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}
+)

src/machine/board_digispark.go

@@ -2,6 +2,18 @@
 
 package machine
 
+// Return the current CPU frequency in hertz.
+func CPUFrequency() uint32 {
+	return 16000000
+}
+
 const (
-	LED Pin = 1
+	P0 Pin = 0
+	P1 Pin = 1
+	P2 Pin = 2
+	P3 Pin = 3
+	P4 Pin = 4
+	P5 Pin = 5
+
+	LED = P1
 )

src/machine/board_feather-m0.go

@@ -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

src/machine/board_feather-m4.go

@@ -67,10 +67,10 @@ const (
 
 // I2C on the Feather M4.
 var (
-	I2C0 = I2C{Bus: sam.SERCOM2_I2CM,
-		SDA:     SDA_PIN,
-		SCL:     SCL_PIN,
-		PinMode: PinSERCOM}
+	I2C0 = I2C{
+		Bus:    sam.SERCOM2_I2CM,
+		SERCOM: 2,
+	}
 )
 
 // SPI pins
@@ -82,14 +82,8 @@ const (
 
 // SPI on the Feather M4.
 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,
+	SPI0 = SPI{
+		Bus:    sam.SERCOM1_SPIM,
+		SERCOM: 1,
 	}
 )

src/machine/board_itsybitsy-m0.go

@@ -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

src/machine/board_itsybitsy-m4.go

@@ -69,10 +69,10 @@ const (
 
 // I2C on the ItsyBitsy M4.
 var (
-	I2C0 = I2C{Bus: sam.SERCOM2_I2CM,
-		SDA:     SDA_PIN,
-		SCL:     SCL_PIN,
-		PinMode: PinSERCOM}
+	I2C0 = I2C{
+		Bus:    sam.SERCOM2_I2CM,
+		SERCOM: 2,
+	}
 )
 
 // SPI pins
@@ -84,12 +84,8 @@ const (
 
 // SPI on the ItsyBitsy M4.
 var (
-	SPI0 = SPI{Bus: sam.SERCOM1_SPIM,
-		SCK:         SPI0_SCK_PIN,
-		MOSI:        SPI0_MOSI_PIN,
-		MISO:        SPI0_MISO_PIN,
-		DOpad:       spiTXPad2SCK3,
-		DIpad:       sercomRXPad3,
-		MISOPinMode: PinSERCOM,
+	SPI0 = SPI{
+		Bus:    sam.SERCOM1_SPIM,
+		SERCOM: 1,
 	}
 )

src/machine/board_metro-m4-airlift.go

@@ -77,10 +77,10 @@ const (
 
 // I2C on the Metro M4.
 var (
-	I2C0 = I2C{Bus: sam.SERCOM5_I2CM,
-		SDA:     SDA_PIN,
-		SCL:     SCL_PIN,
-		PinMode: PinSERCOMAlt}
+	I2C0 = I2C{
+		Bus:    sam.SERCOM5_I2CM,
+		SERCOM: 5,
+	}
 )
 
 // SPI pins
@@ -97,15 +97,8 @@ const (
 // SPI on the Metro M4.
 var (
 	SPI0 = SPI{
-		Bus:         sam.SERCOM2_SPIM,
-		SCK:         SPI0_SCK_PIN,
-		MOSI:        SPI0_MOSI_PIN,
-		MISO:        SPI0_MISO_PIN,
-		DOpad:       spiTXPad0SCK1,
-		DIpad:       sercomRXPad2,
-		MISOPinMode: PinSERCOM,
-		MOSIPinMode: PinSERCOM,
-		SCKPinMode:  PinSERCOM,
+		Bus:    sam.SERCOM2_SPIM,
+		SERCOM: 2,
 	}
 	NINA_SPI = SPI0
 )
@@ -119,14 +112,7 @@ const (
 // SPI1 on the Metro M4 on pins 11,12,13
 var (
 	SPI1 = SPI{
-		Bus:         sam.SERCOM1_SPIM,
-		SCK:         SPI1_SCK_PIN,
-		MOSI:        SPI1_MOSI_PIN,
-		MISO:        SPI1_MISO_PIN,
-		DOpad:       spiTXPad3SCK1,
-		DIpad:       sercomRXPad0,
-		MISOPinMode: PinSERCOM,
-		MOSIPinMode: PinSERCOM,
-		SCKPinMode:  PinSERCOM,
+		Bus:    sam.SERCOM1_SPIM,
+		SERCOM: 1,
 	}
 )

src/machine/board_nucleof103rb.go

@@ -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

src/machine/board_pybadge.go

@@ -0,0 +1,142 @@
+// +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,
+		SERCOM: 2,
+	}
+)
+
+// 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,
+		SERCOM: 1,
+	}
+)
+
+// TFT SPI pins
+const (
+	SPI1_SCK_PIN  = PB13 // SCK: SERCOM4/PAD[1]
+	SPI1_MOSI_PIN = PB15 // MOSI: SERCOM4/PAD[3]
+	SPI1_MISO_PIN = NoPin
+)
+
+// TFT SPI on the PyBadge.
+var (
+	SPI1 = SPI{
+		Bus:    sam.SERCOM4_SPIM,
+		SERCOM: 4,
+	}
+)

src/machine/board_pyportal.go

@@ -0,0 +1,145 @@
+// +build sam,atsamd51,pyportal
+
+package machine
+
+import (
+	"device/sam"
+)
+
+// used to reset into bootloader
+const RESET_MAGIC_VALUE = 0xf01669ef
+
+// GPIO Pins
+const (
+	D0  = PB13 // NINA_RX
+	D1  = PB12 // NINA_TX
+	D2  = PB22 // built-in neopixel
+	D3  = PA04 // PWM available
+	D4  = PA05 // PWM available
+	D5  = PB16 // NINA_ACK
+	D6  = PB15 // NINA_GPIO0
+	D7  = PB17 // NINA_RESETN
+	D8  = PB14 // NINA_CS
+	D9  = PB04 // TFT_RD
+	D10 = PB05 // TFT_DC
+	D11 = PB06 // TFT_CS
+	D12 = PB07 // TFT_TE
+	D13 = PB23 // built-in LED
+	D24 = PA00 // TFT_RESET
+	D25 = PB31 // TFT_BACKLIGHT
+	D26 = PB09 // TFT_WR
+	D27 = PB02 // SDA
+	D28 = PB03 // SCL
+	D29 = PA12 // MOSI
+	D30 = PA13 // SCK
+	D31 = PA14 // MISO
+	D32 = PB30 // SD_CS
+	D33 = PA01 // SD_CARD_DETECT
+	D34 = PA16 // LCD_DATA0
+	D35 = PA17 // LCD_DATA1
+	D36 = PA18 // LCD_DATA2
+	D37 = PA19 // LCD_DATA3
+	D38 = PA20 // LCD_DATA4
+	D39 = PA21 // LCD_DATA5
+	D40 = PA22 // LCD_DATA6
+	D41 = PA23 // LCD_DATA7
+	D42 = PB10 // QSPI
+	D43 = PB11 // QSPI
+	D44 = PA08 // QSPI
+	D45 = PA09 // QSPI
+	D46 = PA10 // QSPI
+	D47 = PA11 // QSPI
+	D50 = PA02 // speaker amplifier shutdown
+	D51 = PA15 // NINA_RTS
+
+	NINA_CS     = D8
+	NINA_ACK    = D5
+	NINA_GPIO0  = D6
+	NINA_RESETN = D7
+
+	NINA_TX  = D1
+	NINA_RX  = D0
+	NINA_RTS = D51
+
+	LCD_DATA0 = D34
+
+	TFT_RD        = D9
+	TFT_DC        = D10
+	TFT_CS        = D11
+	TFT_TE        = D12
+	TFT_RESET     = D24
+	TFT_BACKLIGHT = D25
+	TFT_WR        = D26
+
+	NEOPIXEL = D2
+	SPK_SD   = D50
+)
+
+// Analog pins
+const (
+	A0 = PA02 // ADC0/AIN[0]
+	A1 = D3   // ADC0/AIN[4]
+	A2 = PA07 // ADC0/AIN[7]
+	A3 = D4   // ADC0/AIN[5]
+	A4 = PB00 // ADC0/AIN[12]
+	A5 = PB01 // ADC0/AIN[13]
+	A6 = PA06 // ADC0/AIN[6]
+	A7 = PB08 // ADC1/AIN[0]
+
+	AUDIO_OUT = A0
+	LIGHT     = A2
+	TOUCH_YD  = A4
+	TOUCH_XL  = A5
+	TOUCH_YU  = A6
+	TOUCH_XR  = A7
+)
+
+const (
+	LED = D13
+)
+
+// UART0 aka USBCDC pins
+const (
+	USBCDC_DM_PIN = PA24
+	USBCDC_DP_PIN = PA25
+)
+
+// TODO: add configuration for UART on SERCOM4 that is connected to TX/RX of ESP32
+const (
+	UART_TX_PIN = NoPin
+	UART_RX_PIN = NoPin
+)
+
+// I2C pins
+const (
+	SDA_PIN = PB02 // SDA: SERCOM2/PAD[0]
+	SCL_PIN = PB03 // SCL: SERCOM2/PAD[1]
+)
+
+// I2C on the PyPortal.
+var (
+	I2C0 = I2C{
+		Bus:    sam.SERCOM5_I2CM,
+		SERCOM: 5,
+	}
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN  = PA13 // SCK: SERCOM1/PAD[1]
+	SPI0_MOSI_PIN = PA12 // MOSI: SERCOM1/PAD[3]
+	SPI0_MISO_PIN = PA14 // MISO: SERCOM1/PAD[2]
+
+	NINA_MOSI = SPI0_MOSI_PIN
+	NINA_MISO = SPI0_MISO_PIN
+	NINA_SCK  = SPI0_SCK_PIN
+)
+
+// SPI on the PyPortal.
+var (
+	SPI0 = SPI{
+		Bus:    sam.SERCOM2_SPIM,
+		SERCOM: 2,
+	}
+	NINA_SPI = SPI0
+)

src/machine/board_trinket.go

@@ -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

src/machine/machine_atmega.go

@@ -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))
-	}
-}

src/machine/machine_atsamd21.go

@@ -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)

src/machine/machine_atsamd51.go

@@ -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
 
@@ -110,6 +113,162 @@ const (
 	PB31 Pin = 63
 )
 
+const (
+	pinPadMapSERCOM0Pad0 uint16 = 0x1000
+	pinPadMapSERCOM1Pad0 uint16 = 0x2000
+	pinPadMapSERCOM2Pad0 uint16 = 0x3000
+	pinPadMapSERCOM3Pad0 uint16 = 0x4000
+	pinPadMapSERCOM4Pad0 uint16 = 0x5000
+	pinPadMapSERCOM5Pad0 uint16 = 0x6000
+	pinPadMapSERCOM6Pad0 uint16 = 0x7000
+	pinPadMapSERCOM7Pad0 uint16 = 0x8000
+	pinPadMapSERCOM0Pad2 uint16 = 0x1200
+	pinPadMapSERCOM1Pad2 uint16 = 0x2200
+	pinPadMapSERCOM2Pad2 uint16 = 0x3200
+	pinPadMapSERCOM3Pad2 uint16 = 0x4200
+	pinPadMapSERCOM4Pad2 uint16 = 0x5200
+	pinPadMapSERCOM5Pad2 uint16 = 0x6200
+	pinPadMapSERCOM6Pad2 uint16 = 0x7200
+	pinPadMapSERCOM7Pad2 uint16 = 0x8200
+
+	pinPadMapSERCOM0AltPad0 uint16 = 0x0010
+	pinPadMapSERCOM1AltPad0 uint16 = 0x0020
+	pinPadMapSERCOM2AltPad0 uint16 = 0x0030
+	pinPadMapSERCOM3AltPad0 uint16 = 0x0040
+	pinPadMapSERCOM4AltPad0 uint16 = 0x0050
+	pinPadMapSERCOM5AltPad0 uint16 = 0x0060
+	pinPadMapSERCOM6AltPad0 uint16 = 0x0070
+	pinPadMapSERCOM7AltPad0 uint16 = 0x0080
+	pinPadMapSERCOM0AltPad1 uint16 = 0x0011
+	pinPadMapSERCOM1AltPad1 uint16 = 0x0021
+	pinPadMapSERCOM2AltPad1 uint16 = 0x0031
+	pinPadMapSERCOM3AltPad1 uint16 = 0x0041
+	pinPadMapSERCOM4AltPad1 uint16 = 0x0051
+	pinPadMapSERCOM5AltPad1 uint16 = 0x0061
+	pinPadMapSERCOM6AltPad1 uint16 = 0x0071
+	pinPadMapSERCOM7AltPad1 uint16 = 0x0081
+	pinPadMapSERCOM0AltPad2 uint16 = 0x0012
+	pinPadMapSERCOM1AltPad2 uint16 = 0x0022
+	pinPadMapSERCOM2AltPad2 uint16 = 0x0032
+	pinPadMapSERCOM3AltPad2 uint16 = 0x0042
+	pinPadMapSERCOM4AltPad2 uint16 = 0x0052
+	pinPadMapSERCOM5AltPad2 uint16 = 0x0062
+	pinPadMapSERCOM6AltPad2 uint16 = 0x0072
+	pinPadMapSERCOM7AltPad2 uint16 = 0x0082
+)
+
+// pinPadMapping lists which pins have which SERCOMs attached to them.
+// The encoding is rather dense, with each uint16 encoding two pins and both
+// SERCOM and SERCOM-ALT.
+//
+// Observations:
+//   * There are eight SERCOMs. Those SERCOM numbers can be encoded in 4 bits.
+//   * Even pad numbers are usually on even pins, and odd pad numbers are usually
+//     on odd pins. The exception is SERCOM-ALT, which sometimes swaps pad 0 and 1.
+//     With that, there is still an invariant that the pad number for an odd pin is
+//     the pad number for the corresponding even pin with the low bit toggled.
+//   * Pin pads come in pairs. If PA00 has pad 0, then PA01 has pad 1.
+// With this information, we can encode SERCOM pin/pad numbers much more
+// efficiently. Due to pads coming in pairs, we can ignore half the pins: the
+// information for an odd pin can be calculated easily from the preceding even
+// pin.
+//
+// Each word below is split in two bytes. The 8 high bytes are for SERCOM and
+// the 8 low bits are for SERCOM-ALT. Of each byte, the 4 high bits encode the
+// SERCOM + 1 while the two low bits encodes the pad number (the pad number for
+// the odd pin can be trivially calculated by toggling the low bit of the pad
+// number). It encodes SERCOM + 1 instead of just the SERCOM number, to make it
+// easy to check whether a nibble is set at all.
+//
+// Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/60001507E.pdf
+var pinPadMapping = [32]uint16{
+	// page 32
+	PA00 / 2: 0 | pinPadMapSERCOM1AltPad0,
+
+	// page 33
+	PB08 / 2: 0 | pinPadMapSERCOM4AltPad0,
+	PA04 / 2: 0 | pinPadMapSERCOM0AltPad0,
+	PA06 / 2: 0 | pinPadMapSERCOM0AltPad2,
+	//PC04 / 2: pinPadMapSERCOM6Pad0 | 0,
+	//PC06 / 2: pinPadMapSERCOM6Pad2 | 0,
+	PA08 / 2: pinPadMapSERCOM0Pad0 | pinPadMapSERCOM2AltPad1,
+	PA10 / 2: pinPadMapSERCOM0Pad2 | pinPadMapSERCOM2AltPad2,
+	PB10 / 2: 0 | pinPadMapSERCOM4AltPad2,
+	PB12 / 2: pinPadMapSERCOM4Pad0 | 0,
+	PB14 / 2: pinPadMapSERCOM4Pad2 | 0,
+	//PD08 / 2: pinPadMapSERCOM7Pad0 | pinPadMapSERCOM6AltPad1,
+	//PD10 / 2: pinPadMapSERCOM7Pad2 | pinPadMapSERCOM6AltPad2,
+	//PC10 / 2: pinPadMapSERCOM6Pad2 | pinPadMapSERCOM7AltPad2,
+
+	// page 34
+	//PC12 / 2: pinPadMapSERCOM7Pad0 | pinPadMapSERCOM6AltPad1,
+	//PC14 / 2: pinPadMapSERCOM7Pad2 | pinPadMapSERCOM6AltPad2,
+	PA12 / 2: pinPadMapSERCOM2Pad0 | pinPadMapSERCOM4AltPad1,
+	PA14 / 2: pinPadMapSERCOM2Pad2 | pinPadMapSERCOM4AltPad2,
+	PA16 / 2: pinPadMapSERCOM1Pad0 | pinPadMapSERCOM3AltPad1,
+	PA18 / 2: pinPadMapSERCOM1Pad2 | pinPadMapSERCOM3AltPad2,
+	//PC16 / 2: pinPadMapSERCOM6Pad0 | pinPadMapSERCOM0AltPad1,
+	//PC18 / 2: pinPadMapSERCOM6Pad2 | pinPadMapSERCOM0AltPad2,
+	//PC22 / 2: pinPadMapSERCOM1Pad0 | pinPadMapSERCOM3AltPad1,
+	//PD20 / 2: pinPadMapSERCOM1Pad2 | pinPadMapSERCOM3AltPad2,
+	PB16 / 2: pinPadMapSERCOM5Pad0 | 0,
+	PB18 / 2: pinPadMapSERCOM5Pad2 | pinPadMapSERCOM7AltPad2,
+
+	// page 35
+	PB20 / 2: pinPadMapSERCOM3Pad0 | pinPadMapSERCOM7AltPad1,
+	PA20 / 2: pinPadMapSERCOM5Pad2 | pinPadMapSERCOM3AltPad2,
+	PA22 / 2: pinPadMapSERCOM3Pad0 | pinPadMapSERCOM5AltPad1,
+	PA24 / 2: pinPadMapSERCOM3Pad2 | pinPadMapSERCOM5AltPad2,
+	PB22 / 2: pinPadMapSERCOM1Pad2 | pinPadMapSERCOM5AltPad2,
+	PB24 / 2: pinPadMapSERCOM0Pad0 | pinPadMapSERCOM2AltPad1,
+	PB26 / 2: pinPadMapSERCOM2Pad0 | pinPadMapSERCOM4AltPad1,
+	PB28 / 2: pinPadMapSERCOM2Pad2 | pinPadMapSERCOM4AltPad2,
+	//PC24 / 2: pinPadMapSERCOM0Pad2 | pinPadMapSERCOM2AltPad2,
+	//PC26 / 2: pinPadMapSERCOM1Pad1 | 0, // note: PC26 doesn't support SERCOM, but PC27 does
+	//PC28 / 2: pinPadMapSERCOM1Pad1 | 0, // note: PC29 doesn't exist in the datasheet?
+	PA30 / 2: 0 | pinPadMapSERCOM1AltPad2,
+
+	// page 36
+	PB30 / 2: 0 | pinPadMapSERCOM5AltPad1,
+	PB00 / 2: 0 | pinPadMapSERCOM5AltPad2,
+	PB02 / 2: 0 | pinPadMapSERCOM5AltPad0,
+}
+
+// findPinPadMapping looks up the pad number and the pinmode for a given pin and
+// SERCOM number. The result can either be SERCOM, SERCOM-ALT, or "not found"
+// (indicated by returning ok=false). The pad number is returned to calculate
+// the DOPO/DIPO bitfields of the various serial peripherals.
+func findPinPadMapping(sercom uint8, pin Pin) (pinMode PinMode, pad uint32, ok bool) {
+	bytes := pinPadMapping[pin/2]
+	upper := byte(bytes >> 8)
+	lower := byte(bytes & 0xff)
+
+	if upper != 0 {
+		// SERCOM
+		if (upper>>4)-1 == sercom {
+			pinMode = PinSERCOM
+			pad |= uint32(upper % 4)
+			ok = true
+		}
+	}
+	if lower != 0 {
+		// SERCOM-ALT
+		if (lower>>4)-1 == sercom {
+			pinMode = PinSERCOMAlt
+			pad |= uint32(lower % 4)
+			ok = true
+		}
+	}
+
+	if ok {
+		// If the pin is uneven, toggle the lowest bit of the pad number.
+		if pin&1 != 0 {
+			pad ^= 1
+		}
+	}
+	return
+}
+
 // Return the register and mask to enable a given GPIO pin. This can be used to
 // implement bit-banged drivers.
 func (p Pin) PortMaskSet() (*uint32, uint32) {
@@ -319,7 +478,7 @@ func InitADC() {
 
 	sam.ADC0.CTRLA.SetBits(sam.ADC_CTRLA_PRESCALER_DIV32 << sam.ADC_CTRLA_PRESCALER_Pos)
 	// adcs[i]->CTRLB.bit.RESSEL = ADC_CTRLB_RESSEL_10BIT_Val;
-	sam.ADC0.CTRLB.SetBits(sam.ADC_CTRLB_RESSEL_10BIT << sam.ADC_CTRLB_RESSEL_Pos)
+	sam.ADC0.CTRLB.SetBits(sam.ADC_CTRLB_RESSEL_12BIT << sam.ADC_CTRLB_RESSEL_Pos)
 
 	// wait for sync
 	for sam.ADC0.SYNCBUSY.HasBits(sam.ADC_SYNCBUSY_CTRLB) {
@@ -349,7 +508,7 @@ func InitADC() {
 
 	// same for ADC1, as for ADC0
 	sam.ADC1.CTRLA.SetBits(sam.ADC_CTRLA_PRESCALER_DIV32 << sam.ADC_CTRLA_PRESCALER_Pos)
-	sam.ADC1.CTRLB.SetBits(sam.ADC_CTRLB_RESSEL_10BIT << sam.ADC_CTRLB_RESSEL_Pos)
+	sam.ADC1.CTRLB.SetBits(sam.ADC_CTRLB_RESSEL_12BIT << sam.ADC_CTRLB_RESSEL_Pos)
 	for sam.ADC1.SYNCBUSY.HasBits(sam.ADC_SYNCBUSY_CTRLB) {
 	}
 	sam.ADC1.SAMPCTRL.Set(5)
@@ -387,6 +546,9 @@ func (a ADC) Get() uint16 {
 	}
 
 	// Selection for the positive ADC input channel
+	bus.INPUTCTRL.ClearBits(sam.ADC_INPUTCTRL_MUXPOS_Msk)
+	for bus.SYNCBUSY.HasBits(sam.ADC_SYNCBUSY_ENABLE) {
+	}
 	bus.INPUTCTRL.SetBits((uint16(ch) & sam.ADC_INPUTCTRL_MUXPOS_Msk) << sam.ADC_INPUTCTRL_MUXPOS_Pos)
 	for bus.SYNCBUSY.HasBits(sam.ADC_SYNCBUSY_ENABLE) {
 	}
@@ -402,7 +564,7 @@ func (a ADC) Get() uint16 {
 	}
 
 	// Clear the Data Ready flag
-	bus.INTFLAG.SetBits(sam.ADC_INTFLAG_RESRDY)
+	bus.INTFLAG.ClearBits(sam.ADC_INTFLAG_RESRDY)
 	for bus.SYNCBUSY.HasBits(sam.ADC_SYNCBUSY_ENABLE) {
 	}
 
@@ -444,16 +606,20 @@ func (a ADC) getADCChannel() uint8 {
 		return 6
 	case PA07:
 		return 7
+	case PB00:
+		return 12
+	case PB01:
+		return 13
 	case PB02:
-		return 10
+		return 14
 	case PB03:
-		return 11
+		return 15
 	case PA09:
 		return 17
 	case PA11:
 		return 19
 	default:
-		return 0
+		panic("Invalid ADC pin")
 	}
 }
 
@@ -461,7 +627,8 @@ func (a ADC) getADCChannel() uint8 {
 type UART struct {
 	Buffer *RingBuffer
 	Bus    *sam.SERCOM_USART_INT_Type
-	Mode   PinMode
+	SERCOM uint8
+	IRQVal uint32 // RXC interrupt
 }
 
 var (
@@ -469,89 +636,71 @@ var (
 	UART0 = USBCDC{Buffer: NewRingBuffer()}
 
 	// The first hardware serial port on the SAMD51. Uses the SERCOM3 interface.
-	UART1 = UART{Bus: sam.SERCOM3_USART_INT,
+	UART1 = UART{
 		Buffer: NewRingBuffer(),
-		Mode:   PinSERCOMAlt,
+		Bus:    sam.SERCOM3_USART_INT,
+		SERCOM: 3,
+		IRQVal: sam.IRQ_SERCOM3_2, // RXC interrupt
 	}
 
 	// The second hardware serial port on the SAMD51. Uses the SERCOM0 interface.
 	UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
-		Mode:   PinSERCOMAlt,
+		SERCOM: 0,
+		IRQVal: sam.IRQ_SERCOM0_2, // RXC interrupt
 	}
 )
 
 const (
-	sampleRate16X  = 16
-	lsbFirst       = 1
-	sercomRXPad0   = 0
-	sercomRXPad1   = 1
-	sercomRXPad2   = 2
-	sercomRXPad3   = 3
-	sercomTXPad0   = 0 // Only for UART
-	sercomTXPad2   = 1 // Only for UART
-	sercomTXPad023 = 2 // Only for UART with TX on PAD0, RTS on PAD2 and CTS on PAD3
-
-	spiTXPad0SCK1 = 0
-	spiTXPad2SCK3 = 1
-	spiTXPad3SCK1 = 2
-	spiTXPad0SCK3 = 3
+	sampleRate16X = 16
+	lsbFirst      = 1
 )
 
 // Configure the UART.
-func (uart UART) Configure(config UARTConfig) {
+func (uart UART) Configure(config UARTConfig) error {
 	// Default baud rate to 115200.
 	if config.BaudRate == 0 {
 		config.BaudRate = 115200
 	}
 
 	// determine pins
-	if config.TX == 0 {
+	if config.TX == 0 && config.RX == 0 {
 		// use default pins
 		config.TX = UART_TX_PIN
 		config.RX = UART_RX_PIN
 	}
 
-	// determine pads
-	var txpad, rxpad int
-	switch config.TX {
-	case PA04:
-		txpad = sercomTXPad0
-	case PA10:
-		txpad = sercomTXPad2
-	case PA18:
-		txpad = sercomTXPad2
-	case PA16:
-		txpad = sercomTXPad0
+	// Determine transmit pinout.
+	txPinMode, txPad, ok := findPinPadMapping(uart.SERCOM, config.TX)
+	if !ok {
+		return ErrInvalidOutputPin
+	}
+	var txPinOut uint32
+	// See CTRLA.RXPO bits of the SERCOM USART peripheral (page 945-946) for how
+	// pads are mapped to pinout values.
+	switch txPad {
+	case 0:
+		txPinOut = 0
 	default:
-		panic("Invalid TX pin for UART")
+		// TODO: flow control (RTS/CTS)
+		return ErrInvalidOutputPin
 	}
 
-	switch config.RX {
-	case PA06:
-		rxpad = sercomRXPad2
-	case PA07:
-		rxpad = sercomRXPad3
-	case PA11:
-		rxpad = sercomRXPad3
-	case PA18:
-		rxpad = sercomRXPad2
-	case PA16:
-		rxpad = sercomRXPad0
-	case PA19:
-		rxpad = sercomRXPad3
-	case PA17:
-		rxpad = sercomRXPad1
-	default:
-		panic("Invalid RX pin for UART")
+	// Determine receive pinout.
+	rxPinMode, rxPad, ok := findPinPadMapping(uart.SERCOM, config.RX)
+	if !ok {
+		return ErrInvalidInputPin
 	}
+	// As you can see in the CTRLA.RXPO bits of the SERCOM USART peripheral
+	// (page 945), input pins are mapped directly.
+	rxPinOut := rxPad
 
 	// configure pins
-	config.TX.Configure(PinConfig{Mode: uart.Mode})
-	config.RX.Configure(PinConfig{Mode: uart.Mode})
+	config.TX.Configure(PinConfig{Mode: txPinMode})
+	config.RX.Configure(PinConfig{Mode: rxPinMode})
 
-	// reset SERCOM0
+	// reset SERCOM
 	uart.Bus.CTRLA.SetBits(sam.SERCOM_USART_INT_CTRLA_SWRST)
 	for uart.Bus.CTRLA.HasBits(sam.SERCOM_USART_INT_CTRLA_SWRST) ||
 		uart.Bus.SYNCBUSY.HasBits(sam.SERCOM_USART_INT_SYNCBUSY_SWRST) {
@@ -584,8 +733,8 @@ func (uart UART) Configure(config UARTConfig) {
 	// set UART pads. This is not same as pins...
 	//  SERCOM_USART_CTRLA_TXPO(txPad) |
 	//   SERCOM_USART_CTRLA_RXPO(rxPad);
-	uart.Bus.CTRLA.SetBits(uint32((txpad << sam.SERCOM_USART_INT_CTRLA_TXPO_Pos) |
-		(rxpad << sam.SERCOM_USART_INT_CTRLA_RXPO_Pos)))
+	uart.Bus.CTRLA.SetBits((txPinOut << sam.SERCOM_USART_INT_CTRLA_TXPO_Pos) |
+		(rxPinOut << sam.SERCOM_USART_INT_CTRLA_RXPO_Pos))
 
 	// Enable Transceiver and Receiver
 	//sercom->USART.CTRLB.reg |= SERCOM_USART_CTRLB_TXEN | SERCOM_USART_CTRLB_RXEN ;
@@ -601,19 +750,14 @@ func (uart UART) Configure(config UARTConfig) {
 	uart.Bus.INTENSET.Set(sam.SERCOM_USART_INT_INTENSET_RXC)
 
 	// Enable RX IRQ.
-	switch uart.Bus {
-	case sam.SERCOM0_USART_INT:
-		arm.EnableIRQ(sam.IRQ_SERCOM0_0)
-		arm.EnableIRQ(sam.IRQ_SERCOM0_1)
-		arm.EnableIRQ(sam.IRQ_SERCOM0_2)
-		arm.EnableIRQ(sam.IRQ_SERCOM0_OTHER)
-	default:
-		// Currently assumes SERCOM3
-		arm.EnableIRQ(sam.IRQ_SERCOM3_0)
-		arm.EnableIRQ(sam.IRQ_SERCOM3_1)
-		arm.EnableIRQ(sam.IRQ_SERCOM3_2)
-		arm.EnableIRQ(sam.IRQ_SERCOM3_OTHER)
-	}
+	// This is a small note at the bottom of the NVIC section of the datasheet:
+	// > The integer number specified in the source refers to the respective bit
+	// > position in the INTFLAG register of respective peripheral.
+	// Therefore, if we only need to listen to the RXC interrupt source (in bit
+	// position 2), we only need interrupt source 2 for this SERCOM device.
+	arm.EnableIRQ(uart.IRQVal)
+
+	return nil
 }
 
 // SetBaudRate sets the communication speed for the UART.
@@ -639,53 +783,15 @@ func (uart UART) WriteByte(c byte) error {
 	return nil
 }
 
-//go:export SERCOM3_0_IRQHandler
-func handleSERCOM3_0() {
-	handleUART1()
-}
-
-//go:export SERCOM3_1_IRQHandler
-func handleSERCOM3_1() {
-	handleUART1()
-}
-
 //go:export SERCOM3_2_IRQHandler
 func handleSERCOM3_2() {
-	handleUART1()
-}
-
-//go:export SERCOM3_OTHER_IRQHandler
-func handleSERCOM3_OTHER() {
-	handleUART1()
-}
-
-func handleUART1() {
 	// should reset IRQ
 	UART1.Receive(byte((UART1.Bus.DATA.Get() & 0xFF)))
 	UART1.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
 }
 
-//go:export SERCOM0_0_IRQHandler
-func handleSERCOM0_0() {
-	handleUART2()
-}
-
-//go:export SERCOM0_1_IRQHandler
-func handleSERCOM0_1() {
-	handleUART2()
-}
-
 //go:export SERCOM0_2_IRQHandler
 func handleSERCOM0_2() {
-	handleUART2()
-}
-
-//go:export SERCOM0_OTHER_IRQHandler
-func handleSERCOM0_OTHER() {
-	handleUART2()
-}
-
-func handleUART2() {
 	// should reset IRQ
 	UART2.Receive(byte((UART2.Bus.DATA.Get() & 0xFF)))
 	UART2.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
@@ -693,10 +799,8 @@ func handleUART2() {
 
 // I2C on the SAMD51.
 type I2C struct {
-	Bus     *sam.SERCOM_I2CM_Type
-	SCL     Pin
-	SDA     Pin
-	PinMode PinMode
+	Bus    *sam.SERCOM_I2CM_Type
+	SERCOM uint8
 }
 
 // I2CConfig is used to store config info for I2C.
@@ -729,12 +833,33 @@ const (
 const i2cTimeout = 1000
 
 // Configure is intended to setup the I2C interface.
-func (i2c I2C) Configure(config I2CConfig) {
+func (i2c I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
 		config.Frequency = TWI_FREQ_100KHZ
 	}
 
+	// Use default I2C pins if not set.
+	if config.SDA == 0 && config.SCL == 0 {
+		config.SDA = SDA_PIN
+		config.SCL = SCL_PIN
+	}
+
+	sclPinMode, sclPad, ok := findPinPadMapping(i2c.SERCOM, config.SCL)
+	if !ok || sclPad != 1 {
+		// SCL must be on pad 1, according to section 36.4 of the datasheet.
+		// Note: this is not an exhaustive test for I2C support on the pin: not
+		// all pins support I2C.
+		return ErrInvalidClockPin
+	}
+	sdaPinMode, sdaPad, ok := findPinPadMapping(i2c.SERCOM, config.SDA)
+	if !ok || sdaPad != 0 {
+		// SDA must be on pad 0, according to section 36.4 of the datasheet.
+		// Note: this is not an exhaustive test for I2C support on the pin: not
+		// all pins support I2C.
+		return ErrInvalidDataPin
+	}
+
 	// reset SERCOM
 	i2c.Bus.CTRLA.SetBits(sam.SERCOM_I2CM_CTRLA_SWRST)
 	for i2c.Bus.CTRLA.HasBits(sam.SERCOM_I2CM_CTRLA_SWRST) ||
@@ -760,8 +885,10 @@ func (i2c I2C) Configure(config I2CConfig) {
 	}
 
 	// enable pins
-	i2c.SDA.Configure(PinConfig{Mode: i2c.PinMode})
-	i2c.SCL.Configure(PinConfig{Mode: i2c.PinMode})
+	config.SDA.Configure(PinConfig{Mode: sdaPinMode})
+	config.SCL.Configure(PinConfig{Mode: sclPinMode})
+
+	return nil
 }
 
 // SetBaudRate sets the communication speed for the I2C.
@@ -860,7 +987,7 @@ func (i2c I2C) WriteByte(data byte) error {
 	timeout := i2cTimeout
 	for !i2c.Bus.INTFLAG.HasBits(sam.SERCOM_I2CM_INTFLAG_MB) {
 		// check for bus error
-		if sam.SERCOM3_I2CM.STATUS.HasBits(sam.SERCOM_I2CM_STATUS_BUSERR) {
+		if i2c.Bus.STATUS.HasBits(sam.SERCOM_I2CM_STATUS_BUSERR) {
 			return errors.New("I2C bus error")
 		}
 		timeout--
@@ -929,15 +1056,8 @@ func (i2c I2C) readByte() byte {
 
 // SPI
 type SPI struct {
-	Bus         *sam.SERCOM_SPIM_Type
-	SCK         Pin
-	MOSI        Pin
-	MISO        Pin
-	DOpad       int
-	DIpad       int
-	SCKPinMode  PinMode
-	MOSIPinMode PinMode
-	MISOPinMode PinMode
+	Bus    *sam.SERCOM_SPIM_Type
+	SERCOM uint8
 }
 
 // SPIConfig is used to store config info for SPI.
@@ -951,34 +1071,61 @@ type SPIConfig struct {
 }
 
 // Configure is intended to setup the SPI interface.
-func (spi SPI) Configure(config SPIConfig) {
-	doPad := spi.DOpad
-	diPad := spi.DIpad
+func (spi SPI) Configure(config SPIConfig) error {
+	// Use default pins if not set.
+	if config.SCK == 0 && config.MOSI == 0 && config.MISO == 0 {
+		config.SCK = SPI0_SCK_PIN
+		config.MOSI = SPI0_MOSI_PIN
+		config.MISO = SPI0_MISO_PIN
+	}
 
 	// set default frequency
 	if config.Frequency == 0 {
 		config.Frequency = 4000000
 	}
 
+	// Determine the input pinout (for MISO).
+	var dataInPinout uint32
+	misoPinMode, misoPad, ok := findPinPadMapping(spi.SERCOM, config.MISO)
+	if config.MISO != NoPin {
+		if !ok {
+			return ErrInvalidInputPin
+		}
+		dataInPinout = misoPad // mapped directly
+	}
+
+	// Determine the output pinout (for MOSI/SCK).
+	// See DOPO field in the CTRLA register on page 986 of the datasheet.
+	var dataOutPinout uint32
+	sckPinMode, sckPad, ok := findPinPadMapping(spi.SERCOM, config.SCK)
+	if !ok || sckPad != 1 {
+		// SCK pad must always be 1
+		return ErrInvalidOutputPin
+	}
+	mosiPinMode, mosiPad, ok := findPinPadMapping(spi.SERCOM, config.MOSI)
+	if !ok {
+		return ErrInvalidOutputPin
+	}
+	switch mosiPad {
+	case 0:
+		dataOutPinout = 0x0
+	case 3:
+		dataOutPinout = 0x2
+	default:
+		return ErrInvalidOutputPin
+	}
+
 	// Disable SPI port.
 	spi.Bus.CTRLA.ClearBits(sam.SERCOM_SPIM_CTRLA_ENABLE)
 	for spi.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_ENABLE) {
 	}
 
 	// enable pins
-	if spi.SCKPinMode == 0 {
-		spi.SCKPinMode = PinSERCOMAlt
+	config.SCK.Configure(PinConfig{Mode: sckPinMode})
+	config.MOSI.Configure(PinConfig{Mode: mosiPinMode})
+	if config.MISO != NoPin {
+		config.MISO.Configure(PinConfig{Mode: misoPinMode})
 	}
-	if spi.MOSIPinMode == 0 {
-		spi.MOSIPinMode = PinSERCOMAlt
-	}
-	if spi.MISOPinMode == 0 {
-		spi.MISOPinMode = PinSERCOMAlt
-	}
-
-	spi.SCK.Configure(PinConfig{Mode: spi.SCKPinMode})
-	spi.MOSI.Configure(PinConfig{Mode: spi.MOSIPinMode})
-	spi.MISO.Configure(PinConfig{Mode: spi.MISOPinMode})
 
 	// reset SERCOM
 	spi.Bus.CTRLA.SetBits(sam.SERCOM_SPIM_CTRLA_SWRST)
@@ -987,17 +1134,17 @@ func (spi SPI) Configure(config SPIConfig) {
 	}
 
 	// set bit transfer order
-	dataOrder := 0
+	dataOrder := uint32(0)
 	if config.LSBFirst {
 		dataOrder = 1
 	}
 
 	// Set SPI master
 	// SERCOM_SPIM_CTRLA_MODE_SPI_MASTER = 3
-	spi.Bus.CTRLA.Set(uint32((3 << sam.SERCOM_SPIM_CTRLA_MODE_Pos) |
-		(doPad << sam.SERCOM_SPIM_CTRLA_DOPO_Pos) |
-		(diPad << sam.SERCOM_SPIM_CTRLA_DIPO_Pos) |
-		(dataOrder << sam.SERCOM_SPIM_CTRLA_DORD_Pos)))
+	spi.Bus.CTRLA.Set((3 << sam.SERCOM_SPIM_CTRLA_MODE_Pos) |
+		(dataOutPinout << sam.SERCOM_SPIM_CTRLA_DOPO_Pos) |
+		(dataInPinout << sam.SERCOM_SPIM_CTRLA_DIPO_Pos) |
+		(dataOrder << sam.SERCOM_SPIM_CTRLA_DORD_Pos))
 
 	spi.Bus.CTRLB.SetBits((0 << sam.SERCOM_SPIM_CTRLB_CHSIZE_Pos) | // 8bit char size
 		sam.SERCOM_SPIM_CTRLB_RXEN) // receive enable
@@ -1031,6 +1178,8 @@ func (spi SPI) Configure(config SPIConfig) {
 	spi.Bus.CTRLA.SetBits(sam.SERCOM_SPIM_CTRLA_ENABLE)
 	for spi.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_ENABLE) {
 	}
+
+	return nil
 }
 
 // Transfer writes/reads a single byte using the SPI interface.
@@ -1049,19 +1198,6 @@ func (spi SPI) Transfer(w byte) (byte, error) {
 // PWM
 const period = 0xFFFF
 
-// InitPWM initializes the PWM interface.
-func InitPWM() {
-	// turn on timer clocks used for PWM
-	sam.MCLK.APBBMASK.SetBits(sam.MCLK_APBBMASK_TCC0_ | sam.MCLK_APBBMASK_TCC1_)
-	sam.MCLK.APBCMASK.SetBits(sam.MCLK_APBCMASK_TCC2_)
-
-	//use clock generator 0
-	sam.GCLK.PCHCTRL[25].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
-		sam.GCLK_PCHCTRL_CHEN)
-	sam.GCLK.PCHCTRL[29].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
-		sam.GCLK_PCHCTRL_CHEN)
-}
-
 // Configure configures a PWM pin for output.
 func (pwm PWM) Configure() {
 	// Set pin as output
@@ -1176,34 +1312,6 @@ func (pwm PWM) setPinCfg(val uint8) {
 	pwm.Pin.setPinCfg(val)
 }
 
-// getTimer returns the timer to be used for PWM on this pin
-func (pwm PWM) getTimer() *sam.TCC_Type {
-	switch pwm.Pin {
-	case PA16:
-		return sam.TCC1
-	case PA17:
-		return sam.TCC1
-	case PA14:
-		return sam.TCC2
-	case PA15:
-		return sam.TCC2
-	case PA18:
-		return sam.TCC1
-	case PA19:
-		return sam.TCC1
-	case PA20:
-		return sam.TCC0
-	case PA21:
-		return sam.TCC0
-	case PA23:
-		return sam.TCC0
-	case PA22:
-		return sam.TCC0
-	default:
-		return nil // not supported on this pin
-	}
-}
-
 // setChannel sets the value for the correct channel for PWM on this pin
 func (pwm PWM) setChannel(val uint32) {
 	switch pwm.Pin {
@@ -1227,6 +1335,8 @@ func (pwm PWM) setChannel(val uint32) {
 		pwm.getTimer().CC[3].Set(val)
 	case PA22:
 		pwm.getTimer().CC[2].Set(val)
+	case PB31:
+		pwm.getTimer().CC[1].Set(val)
 	default:
 		return // not supported on this pin
 	}
@@ -1255,6 +1365,8 @@ func (pwm PWM) setChannelBuffer(val uint32) {
 		pwm.getTimer().CCBUF[3].Set(val)
 	case PA22:
 		pwm.getTimer().CCBUF[2].Set(val)
+	case PB31:
+		pwm.getTimer().CCBUF[1].Set(val)
 	default:
 		return // not supported on this pin
 	}
@@ -1283,6 +1395,8 @@ func (pwm PWM) getMux() PinMode {
 		return PinPWMG
 	case PA22:
 		return PinPWMG
+	case PB31:
+		return PinPWMF
 	default:
 		return 0 // not supported on this pin
 	}
@@ -1400,11 +1514,11 @@ 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 +1564,7 @@ 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)
@@ -2044,14 +2138,14 @@ func setEPINTENSET(ep uint32, val uint8) {
 	sam.USB_DEVICE.DEVICE_ENDPOINT[ep].EPINTENSET.Set(val)
 }
 
-// ResetProcessor should perform a system reset in preperation
+// ResetProcessor should perform a system reset in preparation
 // to switch to the bootloader to flash new firmware.
 func ResetProcessor() {
 	arm.DisableInterrupts()
 
 	// Perform magic reset into bootloader, as mentioned in
 	// https://github.com/arduino/ArduinoCore-samd/issues/197
-	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + 0x00030000 - 4))) = RESET_MAGIC_VALUE
+	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + HSRAM_SIZE - 4))) = RESET_MAGIC_VALUE
 
 	arm.SystemReset()
 }

src/machine/machine_atsamd51g19.go

@@ -6,3 +6,48 @@
 // http://ww1.microchip.com/downloads/en/DeviceDoc/60001507C.pdf
 //
 package machine
+
+import "device/sam"
+
+const HSRAM_SIZE = 0x00030000
+
+// InitPWM initializes the PWM interface.
+func InitPWM() {
+	// turn on timer clocks used for PWM
+	sam.MCLK.APBBMASK.SetBits(sam.MCLK_APBBMASK_TCC0_ | sam.MCLK_APBBMASK_TCC1_)
+	sam.MCLK.APBCMASK.SetBits(sam.MCLK_APBCMASK_TCC2_)
+
+	//use clock generator 0
+	sam.GCLK.PCHCTRL[25].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+	sam.GCLK.PCHCTRL[29].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+}
+
+// getTimer returns the timer to be used for PWM on this pin
+func (pwm PWM) getTimer() *sam.TCC_Type {
+	switch pwm.Pin {
+	case PA16:
+		return sam.TCC1
+	case PA17:
+		return sam.TCC1
+	case PA14:
+		return sam.TCC2
+	case PA15:
+		return sam.TCC2
+	case PA18:
+		return sam.TCC1
+	case PA19:
+		return sam.TCC1
+	case PA20:
+		return sam.TCC0
+	case PA21:
+		return sam.TCC0
+	case PA23:
+		return sam.TCC0
+	case PA22:
+		return sam.TCC0
+	default:
+		return nil // not supported on this pin
+	}
+}

src/machine/machine_atsamd51j19.go

@@ -6,3 +6,53 @@
 // http://ww1.microchip.com/downloads/en/DeviceDoc/60001507C.pdf
 //
 package machine
+
+import "device/sam"
+
+const HSRAM_SIZE = 0x00030000
+
+// InitPWM initializes the PWM interface.
+func InitPWM() {
+	// turn on timer clocks used for PWM
+	sam.MCLK.APBBMASK.SetBits(sam.MCLK_APBBMASK_TCC0_ | sam.MCLK_APBBMASK_TCC1_)
+	sam.MCLK.APBCMASK.SetBits(sam.MCLK_APBCMASK_TCC2_)
+	sam.MCLK.APBDMASK.SetBits(sam.MCLK_APBDMASK_TCC4_)
+
+	//use clock generator 0
+	sam.GCLK.PCHCTRL[25].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+	sam.GCLK.PCHCTRL[29].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+	sam.GCLK.PCHCTRL[38].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+}
+
+// getTimer returns the timer to be used for PWM on this pin
+func (pwm PWM) getTimer() *sam.TCC_Type {
+	switch pwm.Pin {
+	case PA16:
+		return sam.TCC1
+	case PA17:
+		return sam.TCC1
+	case PA14:
+		return sam.TCC2
+	case PA15:
+		return sam.TCC2
+	case PA18:
+		return sam.TCC1
+	case PA19:
+		return sam.TCC1
+	case PA20:
+		return sam.TCC0
+	case PA21:
+		return sam.TCC0
+	case PA23:
+		return sam.TCC0
+	case PA22:
+		return sam.TCC0
+	case PB31:
+		return sam.TCC4
+	default:
+		return nil // not supported on this pin
+	}
+}

src/machine/machine_atsamd51j20.go

@@ -0,0 +1,58 @@
+// +build sam,atsamd51,atsamd51j20
+
+// Peripheral abstraction layer for the atsamd51.
+//
+// Datasheet:
+// http://ww1.microchip.com/downloads/en/DeviceDoc/60001507C.pdf
+//
+package machine
+
+import "device/sam"
+
+const HSRAM_SIZE = 0x00040000
+
+// InitPWM initializes the PWM interface.
+func InitPWM() {
+	// turn on timer clocks used for PWM
+	sam.MCLK.APBBMASK.SetBits(sam.MCLK_APBBMASK_TCC0_ | sam.MCLK_APBBMASK_TCC1_)
+	sam.MCLK.APBCMASK.SetBits(sam.MCLK_APBCMASK_TCC2_)
+	sam.MCLK.APBDMASK.SetBits(sam.MCLK_APBDMASK_TCC4_)
+
+	//use clock generator 0
+	sam.GCLK.PCHCTRL[25].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+	sam.GCLK.PCHCTRL[29].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+	sam.GCLK.PCHCTRL[38].Set((sam.GCLK_PCHCTRL_GEN_GCLK0 << sam.GCLK_PCHCTRL_GEN_Pos) |
+		sam.GCLK_PCHCTRL_CHEN)
+}
+
+// getTimer returns the timer to be used for PWM on this pin
+func (pwm PWM) getTimer() *sam.TCC_Type {
+	switch pwm.Pin {
+	case PA16:
+		return sam.TCC1
+	case PA17:
+		return sam.TCC1
+	case PA14:
+		return sam.TCC2
+	case PA15:
+		return sam.TCC2
+	case PA18:
+		return sam.TCC1
+	case PA19:
+		return sam.TCC1
+	case PA20:
+		return sam.TCC0
+	case PA21:
+		return sam.TCC0
+	case PA23:
+		return sam.TCC0
+	case PA22:
+		return sam.TCC0
+	case PB31:
+		return sam.TCC4
+	default:
+		return nil // not supported on this pin
+	}
+}

src/machine/machine_fe310.go

@@ -4,9 +4,12 @@ package machine
 
 import (
 	"device/sifive"
+	"runtime/interrupt"
 )
 
-const CPU_FREQUENCY = 16000000
+func CPUFrequency() uint32 {
+	return 16000000
+}
 
 type PinMode uint8
 
@@ -63,6 +66,23 @@ func (uart UART) Configure(config UARTConfig) {
 	// 115200 baud rate is 138.
 	sifive.UART0.DIV.Set(138)
 	sifive.UART0.TXCTRL.Set(sifive.UART_TXCTRL_ENABLE)
+	sifive.UART0.RXCTRL.Set(sifive.UART_RXCTRL_ENABLE)
+	sifive.UART0.IE.Set(sifive.UART_IE_RXWM) // enable the receive interrupt (only)
+	intr := interrupt.New(sifive.IRQ_UART0, UART0.handleInterrupt)
+	intr.SetPriority(5)
+	intr.Enable()
+}
+
+func (uart *UART) handleInterrupt(interrupt.Interrupt) {
+	rxdata := uart.Bus.RXDATA.Get()
+	c := byte(rxdata)
+	if uint32(c) != rxdata {
+		// The rxdata has other bits set than just the low 8 bits. This probably
+		// means that the 'empty' flag is set, which indicates there is no data
+		// to be read and the byte is garbage. Ignore this byte.
+		return
+	}
+	uart.Receive(c)
 }
 
 func (uart UART) WriteByte(c byte) {
@@ -108,7 +128,7 @@ 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

src/machine/machine_gameboyadvance.go

@@ -8,6 +8,25 @@ import (
 	"unsafe"
 )
 
+// Interrupt numbers as used on the GameBoy Advance. Register them with
+// runtime/interrupt.New.
+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
+)
+
 // Make it easier to directly write to I/O RAM.
 var ioram = (*[0x400]volatile.Register8)(unsafe.Pointer(uintptr(0x04000000)))
 

src/machine/machine_nrf.go

@@ -3,9 +3,9 @@
 package machine
 
 import (
-	"device/arm"
 	"device/nrf"
 	"errors"
+	"runtime/interrupt"
 )
 
 var (
@@ -88,8 +88,9 @@ 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, UART0.handleInterrupt)
+	intr.SetPriority(0xc0) // low priority
+	intr.Enable()
 }
 
 // SetBaudRate sets the communication speed for the UART.
@@ -116,7 +117,7 @@ func (uart UART) WriteByte(c byte) error {
 	return nil
 }
 
-func (uart UART) handleInterrupt() {
+func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	if nrf.UART0.EVENTS_RXDRDY.Get() != 0 {
 		uart.Receive(byte(nrf.UART0.RXD.Get()))
 		nrf.UART0.EVENTS_RXDRDY.Set(0x0)

src/machine/machine_nrf51.go

@@ -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))

src/machine/machine_nrf52.go

@@ -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))

src/machine/machine_nrf52840.go

@@ -7,7 +7,61 @@ import (
 	"unsafe"
 )
 
-const CPU_FREQUENCY = 64000000
+func CPUFrequency() uint32 {
+	return 64000000
+}
+
+// Hardware pins
+const (
+	P0_00 Pin = 0
+	P0_01 Pin = 1
+	P0_02 Pin = 2
+	P0_03 Pin = 3
+	P0_04 Pin = 4
+	P0_05 Pin = 5
+	P0_06 Pin = 6
+	P0_07 Pin = 7
+	P0_08 Pin = 8
+	P0_09 Pin = 9
+	P0_10 Pin = 10
+	P0_11 Pin = 11
+	P0_12 Pin = 12
+	P0_13 Pin = 13
+	P0_14 Pin = 14
+	P0_15 Pin = 15
+	P0_16 Pin = 16
+	P0_17 Pin = 17
+	P0_18 Pin = 18
+	P0_19 Pin = 19
+	P0_20 Pin = 20
+	P0_21 Pin = 21
+	P0_22 Pin = 22
+	P0_23 Pin = 23
+	P0_24 Pin = 24
+	P0_25 Pin = 25
+	P0_26 Pin = 26
+	P0_27 Pin = 27
+	P0_28 Pin = 28
+	P0_29 Pin = 29
+	P0_30 Pin = 30
+	P0_31 Pin = 31
+	P1_00 Pin = 32
+	P1_01 Pin = 33
+	P1_02 Pin = 34
+	P1_03 Pin = 35
+	P1_04 Pin = 36
+	P1_05 Pin = 37
+	P1_06 Pin = 38
+	P1_07 Pin = 39
+	P1_08 Pin = 40
+	P1_09 Pin = 41
+	P1_10 Pin = 42
+	P1_11 Pin = 43
+	P1_12 Pin = 44
+	P1_13 Pin = 45
+	P1_14 Pin = 46
+	P1_15 Pin = 47
+)
 
 // Get peripheral and pin number for this GPIO pin.
 func (p Pin) getPortPin() (*nrf.GPIO_Type, uint32) {
@@ -23,11 +77,6 @@ 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))

src/machine/machine_stm32f103xx.go

@@ -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

src/machine/machine_stm32f407.go

@@ -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)))
-}

src/machine/spi.go

@@ -1,4 +1,4 @@
-// +build sam stm32,!stm32f407 fe310
+// +build !baremetal sam stm32,!stm32f407 fe310
 
 package machine
 

src/machine/usb.go

@@ -3,7 +3,6 @@
 package machine
 
 import (
-	"bytes"
 	"errors"
 	"runtime/volatile"
 )
@@ -348,18 +347,18 @@ const cdcSize = iadDescriptorSize +
 
 // Bytes returns CDCDescriptor data.
 func (d CDCDescriptor) Bytes() []byte {
-	buf := bytes.NewBuffer(make([]byte, 0))
-	buf.Write(d.iad.Bytes())
-	buf.Write(d.cif.Bytes())
-	buf.Write(d.header.Bytes())
-	buf.Write(d.controlManagement.Bytes())
-	buf.Write(d.functionalDescriptor.Bytes())
-	buf.Write(d.callManagement.Bytes())
-	buf.Write(d.cifin.Bytes())
-	buf.Write(d.dif.Bytes())
-	buf.Write(d.out.Bytes())
-	buf.Write(d.in.Bytes())
-	return buf.Bytes()
+	var buf []byte
+	buf = append(buf, d.iad.Bytes()...)
+	buf = append(buf, d.cif.Bytes()...)
+	buf = append(buf, d.header.Bytes()...)
+	buf = append(buf, d.controlManagement.Bytes()...)
+	buf = append(buf, d.functionalDescriptor.Bytes()...)
+	buf = append(buf, d.callManagement.Bytes()...)
+	buf = append(buf, d.cifin.Bytes()...)
+	buf = append(buf, d.dif.Bytes()...)
+	buf = append(buf, d.out.Bytes()...)
+	buf = append(buf, d.in.Bytes()...)
+	return buf
 }
 
 // MSCDescriptor is not used yet.

src/os/file_unix.go

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

src/runtime/arch_wasm.go

@@ -12,7 +12,7 @@ const GOARCH = "wasm"
 const TargetBits = 32
 
 //go:extern __heap_base
-var heapStartSymbol unsafe.Pointer
+var heapStartSymbol [0]byte
 
 //go:export llvm.wasm.memory.size.i32
 func wasm_memory_size(index int32) int32