Adding extra files for testing multiline, globbing, etc.

These two heaps conflict with each other, so that if any function uses
the dlmalloc heap implementation it will eventually result in memory
corruption.

This commit fixes this by implementing all heap-related functions. This
overrides the functions that are implemented in wasi-libc. That's why
all of them are implemented (even if they just panic): to make sure no
program accidentally uses the wrong one.

.circleci/config.yml

@@ -157,7 +157,7 @@ commands:
       - llvm-source-linux
       - restore_cache:
           keys:
-            - llvm-build-11-linux-v3-assert
+            - llvm-build-11-linux-v4-assert
       - run:
           name: "Build LLVM"
           command: |
@@ -176,7 +176,7 @@ commands:
               find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
             fi
       - save_cache:
-          key: llvm-build-11-linux-v3-assert
+          key: llvm-build-11-linux-v4-assert
           paths:
             llvm-build
       - run: make ASSERT=1
@@ -225,7 +225,7 @@ commands:
       - llvm-source-linux
       - restore_cache:
           keys:
-            - llvm-build-11-linux-v3-noassert
+            - llvm-build-11-linux-v4-noassert
       - run:
           name: "Build LLVM"
           command: |
@@ -244,7 +244,7 @@ commands:
               find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
             fi
       - save_cache:
-          key: llvm-build-11-linux-v3-noassert
+          key: llvm-build-11-linux-v4-noassert
           paths:
             llvm-build
       - build-wasi-libc
@@ -311,7 +311,7 @@ commands:
             - llvm-project/llvm/include
       - restore_cache:
           keys:
-            - llvm-build-11-macos-v4
+            - llvm-build-11-macos-v5
       - run:
           name: "Build LLVM"
           command: |
@@ -327,7 +327,7 @@ commands:
               find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
             fi
       - save_cache:
-          key: llvm-build-11-macos-v4
+          key: llvm-build-11-macos-v5
           paths:
             llvm-build
       - restore_cache:

.github/workflows/build-tinygo-dev-docker.yml

@@ -0,0 +1,45 @@
+name: CI for tinygo-dev docker container
+on:
+  push:
+    branches: [ dev ]
+
+jobs:
+  push_to_registry:
+    name: Push Docker image to GHCR/Docker Hub
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+        with:
+          submodules: recursive
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: |
+            tinygo/tinygo-dev
+            ghcr.io/${{ github.repository }}/tinygo-dev
+          tags: |
+            type=sha,format=long
+            type=raw,value=latest
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_HUB_USERNAME }}
+          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
+      - name: Log in to Github Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

.gitignore

@@ -16,6 +16,8 @@ src/device/stm32/*.go
 src/device/stm32/*.s
 src/device/kendryte/*.go
 src/device/kendryte/*.s
+src/device/rp/*.go
+src/device/rp/*.s
 vendor
 llvm-build
 llvm-project

CHANGELOG.md

@@ -1,3 +1,69 @@
+0.19.0
+---
+
+* **command line**
+  - don't consider compile-only tests as failing
+  - add -test flag for `tinygo list`
+  - escape commands while printing them with the -x flag
+  - make flash-command portable and safer to use
+  - use `extended-remote` instead of `remote` in GDB
+  - detect specific serial port IDs based on USB vid/pid
+  - add a flag to the command line to select the serial implementation
+* **compiler**
+  - `cgo`: improve constant parser
+  - `compiler`: support chained interrupt handlers
+  - `compiler`: add support for running a builtin in a goroutine
+  - `compiler`: do not emit nil checks for loading closure variables
+  - `compiler`: skip context parameter when starting regular goroutine
+  - `compiler`: refactor method names
+  - `compiler`: add function and global section pragmas
+  - `compiler`: implement `syscall.rawSyscallNoError` in inline assembly
+  - `interp`: ignore inline assembly in markExternal
+  - `interp`: fix a bug in pointer cast workaround
+  - `loader`: fix testing a main package
+* **standard library**
+  - `crypto/rand`: replace this package with a TinyGo version
+  - `machine`: make USBCDC global a pointer
+  - `machine`: make UART objects pointer receivers
+  - `machine`: define Serial as the default output
+  - `net`: add initial support for net.IP
+  - `net`: add more net compatibility
+  - `os`: add stub for os.ReadDir
+  - `os`: add FileMode constants from Go 1.16
+  - `os`: add stubs required for net/http
+  - `os`: implement process related functions
+  - `reflect`: implement AppendSlice
+  - `reflect`: add stubs required for net/http
+  - `runtime`: make task.Data a 64-bit integer to avoid overflow
+  - `runtime`: expose memory stats
+  - `sync`: implement NewCond
+  - `syscall`: fix int type in libc version
+* **targets**
+  - `cortexm`: do not disable interrupts on abort
+  - `cortexm`: bump default stack size to 2048 bytes
+  - `nrf`: avoid heap allocation in waitForEvent
+  - `nrf`: don't trigger a heap allocation in SPI.Transfer
+  - `nrf52840`: add support for flashing with the BOSSA tool
+  - `rp2040`: add support for GPIO input
+  - `rp2040`: add basic support for ADC
+  - `rp2040`: gpio and adc pin definitions
+  - `rp2040`: implement UART
+  - `rp2040`: patch elf to checksum 2nd stage boot
+  - `stm32`: add PWM for most chips
+  - `stm32`: add support for pin interrupts
+  - `stm32f103`: add support for PinInputPullup / PinInputPulldown
+  - `wasi`: remove wasm build tag
+* **boards**
+  - `feather-rp2040`: add support for this board
+  - `feather-nrf52840-sense`: add board definition for this board
+  - `pca10059`: support flashing from Windows
+  - `nano-rp2040`: add this board
+  - `nano-33-ble`: add support for this board
+  - `pico`: add the Raspberry Pi Pico board with the new RP2040 chip
+  - `qtpy`: add pin for neopixels
+  - all: add definition for ws2812 for supported boards
+
+
 0.18.0
 ---
 

Dockerfile

@@ -1,5 +1,5 @@
-# TinyGo base stage installs the most recent Go 1.15.x, LLVM 11 and the TinyGo compiler itself.
+# TinyGo base stage installs the most recent Go 1.16.x, LLVM 11 and the TinyGo compiler itself.
-FROM golang:1.15 AS tinygo-base
+FROM golang:1.16 AS tinygo-base
 
 RUN wget -O- https://apt.llvm.org/llvm-snapshot.gpg.key| apt-key add - && \
     echo "deb http://apt.llvm.org/buster/ llvm-toolchain-buster-11 main" >> /etc/apt/sources.list && \

Makefile

@@ -36,7 +36,7 @@ else
     LLVM_OPTION += '-DLLVM_ENABLE_ASSERTIONS=OFF'
 endif
 
-.PHONY: all tinygo test $(LLVM_BUILDDIR) llvm-source clean fmt gen-device gen-device-nrf gen-device-nxp gen-device-avr
+.PHONY: all tinygo test $(LLVM_BUILDDIR) llvm-source clean fmt gen-device gen-device-nrf gen-device-nxp gen-device-avr gen-device-rp
 
 LLVM_COMPONENTS = all-targets analysis asmparser asmprinter bitreader bitwriter codegen core coroutines coverage debuginfodwarf executionengine frontendopenmp instrumentation interpreter ipo irreader linker lto mc mcjit objcarcopts option profiledata scalaropts support target
 
@@ -71,7 +71,7 @@ else
 endif
 
 # Libraries that should be linked in for the statically linked Clang.
-CLANG_LIB_NAMES = clangAnalysis clangARCMigrate clangAST clangASTMatchers clangBasic clangCodeGen clangCrossTU clangDriver clangDynamicASTMatchers clangEdit clangFormat clangFrontend clangFrontendTool clangHandleCXX clangHandleLLVM clangIndex clangLex clangParse clangRewrite clangRewriteFrontend clangSema clangSerialization clangStaticAnalyzerCheckers clangStaticAnalyzerCore clangStaticAnalyzerFrontend clangTooling clangToolingASTDiff clangToolingCore clangToolingInclusions
+CLANG_LIB_NAMES = clangAnalysis clangAST clangASTMatchers clangBasic clangCodeGen clangCrossTU clangDriver clangDynamicASTMatchers clangEdit clangFormat clangFrontend clangFrontendTool clangHandleCXX clangHandleLLVM clangIndex clangLex clangParse clangRewrite clangRewriteFrontend clangSema clangSerialization clangTooling clangToolingASTDiff clangToolingCore clangToolingInclusions
 CLANG_LIBS = $(START_GROUP) $(addprefix -l,$(CLANG_LIB_NAMES)) $(END_GROUP) -lstdc++
 
 # Libraries that should be linked in for the statically linked LLD.
@@ -107,7 +107,7 @@ fmt-check:
 	@unformatted=$$(gofmt -l $(FMT_PATHS)); [ -z "$$unformatted" ] && exit 0; echo "Unformatted:"; for fn in $$unformatted; do echo "  $$fn"; done; exit 1
 
 
-gen-device: gen-device-avr gen-device-esp gen-device-nrf gen-device-sam gen-device-sifive gen-device-kendryte gen-device-nxp
+gen-device: gen-device-avr gen-device-esp gen-device-nrf gen-device-sam gen-device-sifive gen-device-kendryte gen-device-nxp gen-device-rp
 ifneq ($(STM32), 0)
 gen-device: gen-device-stm32
 endif
@@ -150,6 +150,9 @@ gen-device-stm32: build/gen-device-svd
 	./build/gen-device-svd -source=https://github.com/tinygo-org/stm32-svd lib/stm32-svd/svd src/device/stm32/
 	GO111MODULE=off $(GO) fmt ./src/device/stm32
 
+gen-device-rp: build/gen-device-svd
+	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/RaspberryPi lib/cmsis-svd/data/RaspberryPi/ src/device/rp/
+	GO111MODULE=off $(GO) fmt ./src/device/rp
 
 # Get LLVM sources.
 $(LLVM_PROJECTDIR)/llvm:
@@ -159,7 +162,7 @@ llvm-source: $(LLVM_PROJECTDIR)/llvm
 # Configure LLVM.
 TINYGO_SOURCE_DIR=$(shell pwd)
 $(LLVM_BUILDDIR)/build.ninja: llvm-source
-	mkdir -p $(LLVM_BUILDDIR); cd $(LLVM_BUILDDIR); cmake -G Ninja $(TINYGO_SOURCE_DIR)/$(LLVM_PROJECTDIR)/llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;RISCV;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR;Xtensa" -DCMAKE_BUILD_TYPE=Release -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_LIBEDIT=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_LIBXML2=OFF -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF $(LLVM_OPTION)
+	mkdir -p $(LLVM_BUILDDIR); cd $(LLVM_BUILDDIR); cmake -G Ninja $(TINYGO_SOURCE_DIR)/$(LLVM_PROJECTDIR)/llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;RISCV;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR;Xtensa" -DCMAKE_BUILD_TYPE=Release -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_LIBEDIT=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_LIBXML2=OFF -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF -DCLANG_ENABLE_STATIC_ANALYZER=OFF -DCLANG_ENABLE_ARCMT=OFF $(LLVM_OPTION)
 
 # Build LLVM.
 $(LLVM_BUILDDIR): $(LLVM_BUILDDIR)/build.ninja
@@ -227,6 +230,8 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/mcp3008
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/memstats
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=microbit            examples/microbit-blink
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/pininterrupt
@@ -331,9 +336,11 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-nrf52840  	examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=feather-nrf52840-sense examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-nrf52840  examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=qtpy  				examples/blinky1
+	$(TINYGO) build -size short -o test.hex -target=qtpy                examples/serial
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=teensy40            examples/blinky1
 	@$(MD5SUM) test.hex
@@ -349,6 +356,16 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-m4-can      examples/caninterrupt
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=arduino-nano33      examples/blinky1
+	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pico                examples/blinky1
+	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=nano-33-ble         examples/blinky1
+	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=nano-rp2040         examples/blinky1
+	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=feather-rp2040 		examples/blinky1
+	@$(MD5SUM) test.hex
 	# test pwm
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/pwm
 	@$(MD5SUM) test.hex
@@ -379,6 +396,8 @@ ifneq ($(STM32), 0)
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=stm32f4disco-1      examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=stm32f4disco-1      examples/pwm
+	@$(MD5SUM) test.hex
 endif
 ifneq ($(AVR), 0)
 	$(TINYGO) build -size short -o test.hex -target=atmega1284p         examples/serial
@@ -419,6 +438,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=1     examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pca10040 -serial=none examples/echo
+	@$(MD5SUM) test.hex
 	$(TINYGO) build             -o test.nro -target=nintendoswitch      examples/serial
 	@$(MD5SUM) test.nro
 	$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=0     ./testdata/stdlib.go

README.md

@@ -43,7 +43,7 @@ See the [getting started instructions](https://tinygo.org/getting-started/) for
 
 You can compile TinyGo programs for microcontrollers, WebAssembly and Linux.
 
-The following 62 microcontroller boards are currently supported:
+The following 68 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)
@@ -52,6 +52,8 @@ The following 62 microcontroller boards are currently supported:
 * [Adafruit Feather M4](https://www.adafruit.com/product/3857)
 * [Adafruit Feather M4 CAN](https://www.adafruit.com/product/4759)
 * [Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062)
+* [Adafruit Feather nRF52840 Sense](https://www.adafruit.com/product/4516)
+* [Adafruit Feather RP2040](https://www.adafruit.com/product/4884)
 * [Adafruit Feather STM32F405 Express](https://www.adafruit.com/product/4382)
 * [Adafruit Grand Central M4](https://www.adafruit.com/product/4064)
 * [Adafruit ItsyBitsy M0](https://www.adafruit.com/product/3727)
@@ -68,7 +70,10 @@ The following 62 microcontroller boards are currently supported:
 * [Arduino Mega 2560](https://store.arduino.cc/arduino-mega-2560-rev3)
 * [Arduino MKR1000](https://store.arduino.cc/arduino-mkr1000-wifi)
 * [Arduino Nano](https://store.arduino.cc/arduino-nano)
-* [Arduino Nano33 IoT](https://store.arduino.cc/nano-33-iot)
+* [Arduino Nano 33 BLE](https://store.arduino.cc/nano-33-ble)
+* [Arduino Nano 33 BLE Sense](https://store.arduino.cc/nano-33-ble-sense)
+* [Arduino Nano 33 IoT](https://store.arduino.cc/nano-33-iot)
+* [Arduino Nano RP2040 Connect](https://store.arduino.cc/nano-rp2040-connect)
 * [Arduino Uno](https://store.arduino.cc/arduino-uno-rev3)
 * [Arduino Zero](https://store.arduino.cc/usa/arduino-zero)
 * [BBC micro:bit](https://microbit.org/)
@@ -95,6 +100,7 @@ The following 62 microcontroller boards are currently supported:
 * [PJRC Teensy 3.6](https://www.pjrc.com/store/teensy36.html)
 * [PJRC Teensy 4.0](https://www.pjrc.com/store/teensy40.html)
 * [ProductivityOpen P1AM-100](https://facts-engineering.github.io/modules/P1AM-100/P1AM-100.html)
+* [Raspberry Pi Pico](https://www.raspberrypi.org/products/raspberry-pi-pico/)
 * [Seeed Wio Terminal](https://www.seeedstudio.com/Wio-Terminal-p-4509.html)
 * [Seeed Seeeduino XIAO](https://www.seeedstudio.com/Seeeduino-XIAO-Arduino-Microcontroller-SAMD21-Cortex-M0+-p-4426.html)
 * [Seeed Sipeed MAix BiT](https://www.seeedstudio.com/Sipeed-MAix-BiT-for-RISC-V-AI-IoT-p-2872.html)

azure-pipelines.yml

@@ -28,7 +28,7 @@ jobs:
     - task: CacheBeta@0
       displayName: Cache LLVM build
       inputs:
-        key: llvm-build-11-windows-v4
+        key: llvm-build-11-windows-v5
         path: llvm-build
     - task: Bash@3
       displayName: Build LLVM

builder/build.go

@@ -12,7 +12,9 @@ import (
 	"errors"
 	"fmt"
 	"go/types"
+	"hash/crc32"
 	"io/ioutil"
+	"math/bits"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -468,33 +470,10 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		linkerDependencies = append(linkerDependencies, job)
 	}
 
-	// Add libc dependency if needed.
-	root := goenv.Get("TINYGOROOT")
-	switch config.Target.Libc {
-	case "picolibc":
-		job, err := Picolibc.load(config.Triple(), config.CPU(), dir)
-		if err != nil {
-			return err
-		}
-		// The library needs to be compiled (cache miss).
-		jobs = append(jobs, job.dependencies...)
-		jobs = append(jobs, job)
-		linkerDependencies = append(linkerDependencies, job)
-	case "wasi-libc":
-		path := filepath.Join(root, "lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a")
-		if _, err := os.Stat(path); os.IsNotExist(err) {
-			return errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
-		}
-		ldflags = append(ldflags, path)
-	case "":
-		// no library specified, so nothing to do
-	default:
-		return fmt.Errorf("unknown libc: %s", config.Target.Libc)
-	}
-
 	// Add jobs to compile extra files. These files are in C or assembly and
 	// contain things like the interrupt vector table and low level operations
 	// such as stack switching.
+	root := goenv.Get("TINYGOROOT")
 	for _, path := range config.ExtraFiles() {
 		abspath := filepath.Join(root, path)
 		job := &compileJob{
@@ -535,6 +514,31 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		ldflags = append(ldflags, lprogram.LDFlags...)
 	}
 
+	// Add libc dependency if needed.
+	switch config.Target.Libc {
+	case "picolibc":
+		job, err := Picolibc.load(config.Triple(), config.CPU(), dir)
+		if err != nil {
+			return err
+		}
+		// The library needs to be compiled (cache miss).
+		jobs = append(jobs, job.dependencies...)
+		jobs = append(jobs, job)
+		linkerDependencies = append(linkerDependencies, job)
+	case "wasi-libc":
+		path := filepath.Join(root, "lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a")
+		if _, err := os.Stat(path); os.IsNotExist(err) {
+			return errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
+		}
+		job := dummyCompileJob(path)
+		jobs = append(jobs, job)
+		linkerDependencies = append(linkerDependencies, job)
+	case "":
+		// no library specified, so nothing to do
+	default:
+		return fmt.Errorf("unknown libc: %s", config.Target.Libc)
+	}
+
 	// Create a linker job, which links all object files together and does some
 	// extra stuff that can only be done after linking.
 	jobs = append(jobs, &compileJob{
@@ -547,8 +551,8 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 				}
 				ldflags = append(ldflags, dependency.result)
 			}
-			if config.Options.PrintCommands {
+			if config.Options.PrintCommands != nil {
-				fmt.Printf("%s %s\n", config.Target.Linker, strings.Join(ldflags, " "))
+				config.Options.PrintCommands(config.Target.Linker, ldflags...)
 			}
 			err = link(config.Target.Linker, ldflags...)
 			if err != nil {
@@ -566,6 +570,8 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 					return err
 				}
 			}
+
+			// Apply ELF patches
 			if config.AutomaticStackSize() {
 				// Modify the .tinygo_stacksizes section that contains a stack size
 				// for each goroutine.
@@ -574,6 +580,13 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 					return fmt.Errorf("could not modify stack sizes: %w", err)
 				}
 			}
+			if config.RP2040BootPatch() {
+				// Patch the second stage bootloader CRC into the .boot2 section
+				err = patchRP2040BootCRC(executable)
+				if err != nil {
+					return fmt.Errorf("could not patch RP2040 second stage boot loader: %w", err)
+				}
+			}
 
 			if config.Options.PrintSizes == "short" || config.Options.PrintSizes == "full" {
 				sizes, err := loadProgramSize(executable)
@@ -639,6 +652,18 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		if err != nil {
 			return err
 		}
+	case "nrf-dfu":
+		// special format for nrfutil for Nordic chips
+		tmphexpath := filepath.Join(dir, "main.hex")
+		err := objcopy(executable, tmphexpath, "hex")
+		if err != nil {
+			return err
+		}
+		tmppath = filepath.Join(dir, "main"+outext)
+		err = makeDFUFirmwareImage(config.Options, tmphexpath, tmppath)
+		if err != nil {
+			return err
+		}
 	default:
 		return fmt.Errorf("unknown output binary format: %s", outputBinaryFormat)
 	}
@@ -908,30 +933,7 @@ func determineStackSizes(mod llvm.Module, executable string) ([]string, map[stri
 // stack size information. Before this modification, all stack sizes in the
 // section assume the default stack size (which is relatively big).
 func modifyStackSizes(executable string, stackSizeLoads []string, stackSizes map[string]functionStackSize) error {
-	fp, err := os.OpenFile(executable, os.O_RDWR, 0)
+	data, fileHeader, err := getElfSectionData(executable, ".tinygo_stacksizes")
-	if err != nil {
-		return err
-	}
-	defer fp.Close()
-
-	elfFile, err := elf.NewFile(fp)
-	if err != nil {
-		return err
-	}
-
-	section := elfFile.Section(".tinygo_stacksizes")
-	if section == nil {
-		return errors.New("could not find .tinygo_stacksizes section")
-	}
-
-	if section.Size != section.FileSize {
-		// Sanity check.
-		return fmt.Errorf("expected .tinygo_stacksizes to have identical size and file size, got %d and %d", section.Size, section.FileSize)
-	}
-
-	// Read all goroutine stack sizes.
-	data := make([]byte, section.Size)
-	_, err = fp.ReadAt(data, int64(section.Offset))
 	if err != nil {
 		return err
 	}
@@ -953,15 +955,19 @@ func modifyStackSizes(executable string, stackSizeLoads []string, stackSizes map
 		if fn.stackSizeType == stacksize.Bounded {
 			stackSize := uint32(fn.stackSize)
 
-			// Adding 4 for the stack canary. Even though the size may be
-			// automatically determined, stack overflow checking is still
-			// important as the stack size cannot be determined for all
-			// goroutines.
-			stackSize += 4
-
 			// Add stack size used by interrupts.
-			switch elfFile.Machine {
+			switch fileHeader.Machine {
 			case elf.EM_ARM:
+				if stackSize%8 != 0 {
+					// If the stack isn't a multiple of 8, it means the leaf
+					// function with the biggest stack depth doesn't have an aligned
+					// stack. If the STKALIGN flag is set (which it is by default)
+					// the interrupt controller will forcibly align the stack before
+					// storing in-use registers. This will thus overwrite one word
+					// past the end of the stack (off-by-one).
+					stackSize += 4
+				}
+
 				// On Cortex-M (assumed here), this stack size is 8 words or 32
 				// bytes. This is only to store the registers that the interrupt
 				// may modify, the interrupt will switch to the interrupt stack
@@ -969,6 +975,14 @@ func modifyStackSizes(executable string, stackSizeLoads []string, stackSizes map
 				// Some background:
 				// https://interrupt.memfault.com/blog/cortex-m-rtos-context-switching
 				stackSize += 32
+
+				// Adding 4 for the stack canary, and another 4 to keep the
+				// stack aligned. Even though the size may be automatically
+				// determined, stack overflow checking is still important as the
+				// stack size cannot be determined for all goroutines.
+				stackSize += 8
+			default:
+				return fmt.Errorf("unknown architecture: %s", fileHeader.Machine.String())
 			}
 
 			// Finally write the stack size to the binary.
@@ -976,13 +990,7 @@ func modifyStackSizes(executable string, stackSizeLoads []string, stackSizes map
 		}
 	}
 
-	// Write back the modified stack sizes.
+	return replaceElfSection(executable, ".tinygo_stacksizes", data)
-	_, err = fp.WriteAt(data, int64(section.Offset))
-	if err != nil {
-		return err
-	}
-
-	return nil
 }
 
 // printStacks prints the maximum stack depth for functions that are started as
@@ -1014,3 +1022,41 @@ func printStacks(calculatedStacks []string, stackSizes map[string]functionStackS
 		}
 	}
 }
+
+// RP2040 second stage bootloader CRC32 calculation
+//
+// Spec: https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf
+// Section: 2.8.1.3.1. Checksum
+func patchRP2040BootCRC(executable string) error {
+	bytes, _, err := getElfSectionData(executable, ".boot2")
+	if err != nil {
+		return err
+	}
+
+	if len(bytes) != 256 {
+		return fmt.Errorf("rp2040 .boot2 section must be exactly 256 bytes")
+	}
+
+	// From the 'official' RP2040 checksum script:
+	//
+	//  Our bootrom CRC32 is slightly bass-ackward but it's
+	//  best to work around for now (FIXME)
+	//  100% worth it to save two Thumb instructions
+	revBytes := make([]byte, len(bytes))
+	for i := range bytes {
+		revBytes[i] = bits.Reverse8(bytes[i])
+	}
+
+	// crc32.Update does an initial negate and negates the
+	// result, so to meet RP2040 spec, pass 0x0 as initial
+	// hash and negate returned value.
+	//
+	// Note: checksum is over 252 bytes (256 - 4)
+	hash := bits.Reverse32(crc32.Update(0x0, crc32.IEEETable, revBytes[:252]) ^ 0xFFFFFFFF)
+
+	// Write the CRC to the end of the bootloader.
+	binary.LittleEndian.PutUint32(bytes[252:], hash)
+
+	// Update the .boot2 section to included the CRC
+	return replaceElfSection(executable, ".boot2", bytes)
+}

builder/cc.go

@@ -56,7 +56,7 @@ import (
 //   depfile but without invalidating its name. For this reason, the depfile is
 //   written on each new compilation (even when it seems unnecessary). However, it
 //   could in rare cases lead to a stale file fetched from the cache.
-func compileAndCacheCFile(abspath, tmpdir string, cflags []string, printCommands bool) (string, error) {
+func compileAndCacheCFile(abspath, tmpdir string, cflags []string, printCommands func(string, ...string)) (string, error) {
 	// Hash input file.
 	fileHash, err := hashFile(abspath)
 	if err != nil {
@@ -128,8 +128,8 @@ func compileAndCacheCFile(abspath, tmpdir string, cflags []string, printCommands
 		// flags (for the assembler) is a compiler error.
 		flags = append(flags, "-Qunused-arguments")
 	}
-	if printCommands {
+	if printCommands != nil {
-		fmt.Printf("clang %s\n", strings.Join(flags, " "))
+		printCommands("clang", flags...)
 	}
 	err = runCCompiler(flags...)
 	if err != nil {

builder/elfpatch.go

@@ -0,0 +1,57 @@
+package builder
+
+import (
+	"debug/elf"
+	"fmt"
+	"os"
+)
+
+func getElfSectionData(executable string, sectionName string) ([]byte, elf.FileHeader, error) {
+	elfFile, err := elf.Open(executable)
+	if err != nil {
+		return nil, elf.FileHeader{}, err
+	}
+	defer elfFile.Close()
+
+	section := elfFile.Section(sectionName)
+	if section == nil {
+		return nil, elf.FileHeader{}, fmt.Errorf("could not find %s section", sectionName)
+	}
+
+	data, err := section.Data()
+
+	return data, elfFile.FileHeader, err
+}
+
+func replaceElfSection(executable string, sectionName string, data []byte) error {
+	fp, err := os.OpenFile(executable, os.O_RDWR, 0)
+	if err != nil {
+		return err
+	}
+	defer fp.Close()
+
+	elfFile, err := elf.Open(executable)
+	if err != nil {
+		return err
+	}
+	defer elfFile.Close()
+
+	section := elfFile.Section(sectionName)
+	if section == nil {
+		return fmt.Errorf("could not find %s section", sectionName)
+	}
+
+	// Implicitly check for compressed sections
+	if section.Size != section.FileSize {
+		return fmt.Errorf("expected section %s to have identical size and file size, got %d and %d", sectionName, section.Size, section.FileSize)
+	}
+
+	// Only permit complete replacement of section
+	if section.Size != uint64(len(data)) {
+		return fmt.Errorf("expected section %s to have size %d, was actually %d", sectionName, len(data), section.Size)
+	}
+
+	// Write the replacement section data
+	_, err = fp.WriteAt(data, int64(section.Offset))
+	return err
+}

builder/nrfutil.go

@@ -0,0 +1,27 @@
+package builder
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os/exec"
+
+	"github.com/tinygo-org/tinygo/compileopts"
+)
+
+// https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrfutil%2FUG%2Fnrfutil%2Fnrfutil_intro.html
+
+func makeDFUFirmwareImage(options *compileopts.Options, infile, outfile string) error {
+	cmdLine := []string{"nrfutil", "pkg", "generate", "--hw-version", "52", "--sd-req", "0x0", "--debug-mode", "--application", infile, outfile}
+
+	if options.PrintCommands != nil {
+		options.PrintCommands(cmdLine[0], cmdLine[1:]...)
+	}
+
+	cmd := exec.Command(cmdLine[0], cmdLine[1:]...)
+	cmd.Stdout = ioutil.Discard
+	err := cmd.Run()
+	if err != nil {
+		return fmt.Errorf("could not run nrfutil pkg generate: %w", err)
+	}
+	return nil
+}

cgo/const.go

@@ -11,105 +11,184 @@ import (
 	"strings"
 )
 
+var (
+	prefixParseFns map[token.Token]func(*tokenizer) (ast.Expr, *scanner.Error)
+	precedences    = map[token.Token]int{
+		token.ADD: precedenceAdd,
+		token.SUB: precedenceAdd,
+		token.MUL: precedenceMul,
+		token.QUO: precedenceMul,
+		token.REM: precedenceMul,
+	}
+)
+
+const (
+	precedenceLowest = iota + 1
+	precedenceAdd
+	precedenceMul
+	precedencePrefix
+)
+
+func init() {
+	// This must be done in an init function to avoid an initialization order
+	// failure.
+	prefixParseFns = map[token.Token]func(*tokenizer) (ast.Expr, *scanner.Error){
+		token.IDENT:  parseIdent,
+		token.INT:    parseBasicLit,
+		token.FLOAT:  parseBasicLit,
+		token.STRING: parseBasicLit,
+		token.CHAR:   parseBasicLit,
+		token.LPAREN: parseParenExpr,
+		token.SUB:    parseUnaryExpr,
+	}
+}
+
 // parseConst parses the given string as a C constant.
 func parseConst(pos token.Pos, fset *token.FileSet, value string) (ast.Expr, *scanner.Error) {
 	t := newTokenizer(pos, fset, value)
-	expr, err := parseConstExpr(t)
+	expr, err := parseConstExpr(t, precedenceLowest)
-	if t.token != token.EOF {
+	t.Next()
+	if t.curToken != token.EOF {
 		return nil, &scanner.Error{
-			Pos: t.fset.Position(t.pos),
+			Pos: t.fset.Position(t.curPos),
-			Msg: "unexpected token " + t.token.String(),
+			Msg: "unexpected token " + t.curToken.String() + ", expected end of expression",
 		}
 	}
 	return expr, err
 }
 
 // parseConstExpr parses a stream of C tokens to a Go expression.
-func parseConstExpr(t *tokenizer) (ast.Expr, *scanner.Error) {
+func parseConstExpr(t *tokenizer, precedence int) (ast.Expr, *scanner.Error) {
-	switch t.token {
+	if t.curToken == token.EOF {
-	case token.LPAREN:
-		lparen := t.pos
-		t.Next()
-		x, err := parseConstExpr(t)
-		if err != nil {
-			return nil, err
-		}
-		if t.token != token.RPAREN {
-			return nil, unexpectedToken(t, token.RPAREN)
-		}
-		expr := &ast.ParenExpr{
-			Lparen: lparen,
-			X:      x,
-			Rparen: t.pos,
-		}
-		t.Next()
-		return expr, nil
-	case token.INT, token.FLOAT, token.STRING, token.CHAR:
-		expr := &ast.BasicLit{
-			ValuePos: t.pos,
-			Kind:     t.token,
-			Value:    t.value,
-		}
-		t.Next()
-		return expr, nil
-	case token.IDENT:
-		expr := &ast.Ident{
-			NamePos: t.pos,
-			Name:    "C." + t.value,
-		}
-		t.Next()
-		return expr, nil
-	case token.EOF:
 		return nil, &scanner.Error{
-			Pos: t.fset.Position(t.pos),
+			Pos: t.fset.Position(t.curPos),
 			Msg: "empty constant",
 		}
-	default:
+	}
+	prefix := prefixParseFns[t.curToken]
+	if prefix == nil {
 		return nil, &scanner.Error{
-			Pos: t.fset.Position(t.pos),
+			Pos: t.fset.Position(t.curPos),
-			Msg: fmt.Sprintf("unexpected token %s", t.token),
+			Msg: fmt.Sprintf("unexpected token %s", t.curToken),
 		}
 	}
+	leftExpr, err := prefix(t)
+
+	for t.peekToken != token.EOF && precedence < precedences[t.peekToken] {
+		switch t.peekToken {
+		case token.ADD, token.SUB, token.MUL, token.QUO, token.REM:
+			t.Next()
+			leftExpr, err = parseBinaryExpr(t, leftExpr)
+		}
+	}
+
+	return leftExpr, err
+}
+
+func parseIdent(t *tokenizer) (ast.Expr, *scanner.Error) {
+	return &ast.Ident{
+		NamePos: t.curPos,
+		Name:    "C." + t.curValue,
+	}, nil
+}
+
+func parseBasicLit(t *tokenizer) (ast.Expr, *scanner.Error) {
+	return &ast.BasicLit{
+		ValuePos: t.curPos,
+		Kind:     t.curToken,
+		Value:    t.curValue,
+	}, nil
+}
+
+func parseParenExpr(t *tokenizer) (ast.Expr, *scanner.Error) {
+	lparen := t.curPos
+	t.Next()
+	x, err := parseConstExpr(t, precedenceLowest)
+	if err != nil {
+		return nil, err
+	}
+	t.Next()
+	if t.curToken != token.RPAREN {
+		return nil, unexpectedToken(t, token.RPAREN)
+	}
+	expr := &ast.ParenExpr{
+		Lparen: lparen,
+		X:      x,
+		Rparen: t.curPos,
+	}
+	return expr, nil
+}
+
+func parseBinaryExpr(t *tokenizer, left ast.Expr) (ast.Expr, *scanner.Error) {
+	expression := &ast.BinaryExpr{
+		X:     left,
+		Op:    t.curToken,
+		OpPos: t.curPos,
+	}
+	precedence := precedences[t.curToken]
+	t.Next()
+	right, err := parseConstExpr(t, precedence)
+	expression.Y = right
+	return expression, err
+}
+
+func parseUnaryExpr(t *tokenizer) (ast.Expr, *scanner.Error) {
+	expression := &ast.UnaryExpr{
+		OpPos: t.curPos,
+		Op:    t.curToken,
+	}
+	t.Next()
+	x, err := parseConstExpr(t, precedencePrefix)
+	expression.X = x
+	return expression, err
 }
 
 // unexpectedToken returns an error of the form "unexpected token FOO, expected
 // BAR".
 func unexpectedToken(t *tokenizer, expected token.Token) *scanner.Error {
 	return &scanner.Error{
-		Pos: t.fset.Position(t.pos),
+		Pos: t.fset.Position(t.curPos),
-		Msg: fmt.Sprintf("unexpected token %s, expected %s", t.token, expected),
+		Msg: fmt.Sprintf("unexpected token %s, expected %s", t.curToken, expected),
 	}
 }
 
 // tokenizer reads C source code and converts it to Go tokens.
 type tokenizer struct {
-	pos   token.Pos
+	curPos, peekPos     token.Pos
-	fset  *token.FileSet
+	fset                *token.FileSet
-	token token.Token
+	curToken, peekToken token.Token
-	value string
+	curValue, peekValue string
-	buf   string
+	buf                 string
 }
 
 // newTokenizer initializes a new tokenizer, positioned at the first token in
 // the string.
 func newTokenizer(start token.Pos, fset *token.FileSet, buf string) *tokenizer {
 	t := &tokenizer{
-		pos:   start,
+		peekPos:   start,
-		fset:  fset,
+		fset:      fset,
-		buf:   buf,
+		buf:       buf,
-		token: token.ILLEGAL,
+		peekToken: token.ILLEGAL,
 	}
-	t.Next() // Parse the first token.
+	// Parse the first two tokens (cur and peek).
+	t.Next()
+	t.Next()
 	return t
 }
 
 // Next consumes the next token in the stream. There is no return value, read
 // the next token from the pos, token and value properties.
 func (t *tokenizer) Next() {
-	t.pos += token.Pos(len(t.value))
+	// The previous peek is now the current token.
+	t.curPos = t.peekPos
+	t.curToken = t.peekToken
+	t.curValue = t.peekValue
+
+	// Parse the next peek token.
+	t.peekPos += token.Pos(len(t.curValue))
 	for {
 		if len(t.buf) == 0 {
-			t.token = token.EOF
+			t.peekToken = token.EOF
 			return
 		}
 		c := t.buf[0]
@@ -118,17 +197,28 @@ func (t *tokenizer) Next() {
 			// Skip whitespace.
 			// Based on this source, not sure whether it represents C whitespace:
 			// https://en.cppreference.com/w/cpp/string/byte/isspace
-			t.pos++
+			t.peekPos++
 			t.buf = t.buf[1:]
-		case c == '(' || c == ')':
+		case c == '(' || c == ')' || c == '+' || c == '-' || c == '*' || c == '/' || c == '%':
 			// Single-character tokens.
+			// TODO: ++ (increment) and -- (decrement) operators.
 			switch c {
 			case '(':
-				t.token = token.LPAREN
+				t.peekToken = token.LPAREN
 			case ')':
-				t.token = token.RPAREN
+				t.peekToken = token.RPAREN
+			case '+':
+				t.peekToken = token.ADD
+			case '-':
+				t.peekToken = token.SUB
+			case '*':
+				t.peekToken = token.MUL
+			case '/':
+				t.peekToken = token.QUO
+			case '%':
+				t.peekToken = token.REM
 			}
-			t.value = t.buf[:1]
+			t.peekValue = t.buf[:1]
 			t.buf = t.buf[1:]
 			return
 		case c >= '0' && c <= '9':
@@ -146,17 +236,17 @@ func (t *tokenizer) Next() {
 					break
 				}
 			}
-			t.value = t.buf[:tokenLen]
+			t.peekValue = t.buf[:tokenLen]
 			t.buf = t.buf[tokenLen:]
 			if hasDot {
 				// Integer constants are more complicated than this but this is
 				// a close approximation.
 				// https://en.cppreference.com/w/cpp/language/integer_literal
-				t.token = token.FLOAT
+				t.peekToken = token.FLOAT
-				t.value = strings.TrimRight(t.value, "f")
+				t.peekValue = strings.TrimRight(t.peekValue, "f")
 			} else {
-				t.token = token.INT
+				t.peekToken = token.INT
-				t.value = strings.TrimRight(t.value, "uUlL")
+				t.peekValue = strings.TrimRight(t.peekValue, "uUlL")
 			}
 			return
 		case c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c == '_':
@@ -170,9 +260,9 @@ func (t *tokenizer) Next() {
 					break
 				}
 			}
-			t.value = t.buf[:tokenLen]
+			t.peekValue = t.buf[:tokenLen]
 			t.buf = t.buf[tokenLen:]
-			t.token = token.IDENT
+			t.peekToken = token.IDENT
 			return
 		case c == '"':
 			// String constant. Find the first '"' character that is not
@@ -188,8 +278,8 @@ func (t *tokenizer) Next() {
 					escape = c == '\\'
 				}
 			}
-			t.token = token.STRING
+			t.peekToken = token.STRING
-			t.value = t.buf[:tokenLen]
+			t.peekValue = t.buf[:tokenLen]
 			t.buf = t.buf[tokenLen:]
 			return
 		case c == '\'':
@@ -206,12 +296,12 @@ func (t *tokenizer) Next() {
 					escape = c == '\\'
 				}
 			}
-			t.token = token.CHAR
+			t.peekToken = token.CHAR
-			t.value = t.buf[:tokenLen]
+			t.peekValue = t.buf[:tokenLen]
 			t.buf = t.buf[tokenLen:]
 			return
 		default:
-			t.token = token.ILLEGAL
+			t.peekToken = token.ILLEGAL
 			return
 		}
 	}

cgo/const_test.go

@@ -18,7 +18,7 @@ func TestParseConst(t *testing.T) {
 		{`(5)`, `(5)`},
 		{`(((5)))`, `(5)`},
 		{`)`, `error: 1:1: unexpected token )`},
-		{`5)`, `error: 1:2: unexpected token )`},
+		{`5)`, `error: 1:2: unexpected token ), expected end of expression`},
 		{"  \t)", `error: 1:4: unexpected token )`},
 		{`5.8f`, `5.8`},
 		{`foo`, `C.foo`},
@@ -30,7 +30,24 @@ 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
+		{`5 5`, `error: 1:3: unexpected token INT, expected end of expression`}, // test for a bugfix
+		// Binary operators.
+		{`5+5`, `5 + 5`},
+		{`5-5`, `5 - 5`},
+		{`5*5`, `5 * 5`},
+		{`5/5`, `5 / 5`},
+		{`5%5`, `5 % 5`},
+		{`(5/5)`, `(5 / 5)`},
+		{`1 - 2`, `1 - 2`},
+		{`1 - 2 + 3`, `1 - 2 + 3`},
+		{`1 - 2 * 3`, `1 - 2*3`},
+		{`(1 - 2) * 3`, `(1 - 2) * 3`},
+		{`1 * 2 - 3`, `1*2 - 3`},
+		{`1 * (2 - 3)`, `1 * (2 - 3)`},
+		// Unary operators.
+		{`-5`, `-5`},
+		{`-5-2`, `-5 - 2`},
+		{`5 - - 2`, `5 - -2`},
 	} {
 		fset := token.NewFileSet()
 		startPos := fset.AddFile("", -1, 1000).Pos(0)

cgo/testdata/errors.out.go

@@ -1,7 +1,7 @@
 // CGo errors:
 //     testdata/errors.go:4:2: warning: some warning
 //     testdata/errors.go:11:9: error: unknown type name 'someType'
-//     testdata/errors.go:13:23: unexpected token )
+//     testdata/errors.go:13:23: unexpected token ), expected end of expression
 
 // Type checking errors after CGo processing:
 //     testdata/errors.go:102: cannot use 2 << 10 (untyped int constant 2048) as uint8 value in variable declaration (overflows)

compileopts/config.go

@@ -55,7 +55,7 @@ func (c *Config) GOARCH() string {
 
 // BuildTags returns the complete list of build tags used during this build.
 func (c *Config) BuildTags() []string {
-	tags := append(c.Target.BuildTags, []string{"tinygo", "gc." + c.GC(), "scheduler." + c.Scheduler()}...)
+	tags := append(c.Target.BuildTags, []string{"tinygo", "gc." + c.GC(), "scheduler." + c.Scheduler(), "serial." + c.Serial()}...)
 	for i := 1; i <= c.GoMinorVersion; i++ {
 		tags = append(tags, fmt.Sprintf("go1.%d", i))
 	}
@@ -89,7 +89,7 @@ func (c *Config) NeedsStackObjects() bool {
 	switch c.GC() {
 	case "conservative", "extalloc":
 		for _, tag := range c.BuildTags() {
-			if tag == "wasm" {
+			if tag == "tinygo.wasm" {
 				return true
 			}
 		}
@@ -113,6 +113,18 @@ func (c *Config) Scheduler() string {
 	return "coroutines"
 }
 
+// Serial returns the serial implementation for this build configuration: uart,
+// usb (meaning USB-CDC), or none.
+func (c *Config) Serial() string {
+	if c.Options.Serial != "" {
+		return c.Options.Serial
+	}
+	if c.Target.Serial != "" {
+		return c.Target.Serial
+	}
+	return "none"
+}
+
 // OptLevels returns the optimization level (0-2), size level (0-2), and inliner
 // threshold as used in the LLVM optimization pipeline.
 func (c *Config) OptLevels() (optLevel, sizeLevel int, inlinerThreshold uint) {
@@ -176,6 +188,15 @@ func (c *Config) AutomaticStackSize() bool {
 	return false
 }
 
+// RP2040BootPatch returns whether the RP2040 boot patch should be applied that
+// calculates and patches in the checksum for the 2nd stage bootloader.
+func (c *Config) RP2040BootPatch() bool {
+	if c.Target.RP2040BootPatch != nil {
+		return *c.Target.RP2040BootPatch
+	}
+	return false
+}
+
 // CFlags returns the flags to pass to the C compiler. This is necessary for CGo
 // preprocessing.
 func (c *Config) CFlags() []string {
@@ -254,6 +275,11 @@ func (c *Config) BinaryFormat(ext string) string {
 		// More information:
 		// https://github.com/Microsoft/uf2
 		return "uf2"
+	case ".zip":
+		if c.Target.BinaryFormat != "" {
+			return c.Target.BinaryFormat
+		}
+		return "zip"
 	default:
 		// Use the ELF format for unrecognized file formats.
 		return "elf"

compileopts/options.go

@@ -9,6 +9,7 @@ import (
 var (
 	validGCOptions            = []string{"none", "leaking", "extalloc", "conservative"}
 	validSchedulerOptions     = []string{"none", "tasks", "coroutines"}
+	validSerialOptions        = []string{"none", "uart", "usb"}
 	validPrintSizeOptions     = []string{"none", "short", "full"}
 	validPanicStrategyOptions = []string{"print", "trap"}
 	validOptOptions           = []string{"none", "0", "1", "2", "s", "z"}
@@ -22,10 +23,11 @@ type Options struct {
 	GC              string
 	PanicStrategy   string
 	Scheduler       string
+	Serial          string
 	PrintIR         bool
 	DumpSSA         bool
 	VerifyIR        bool
-	PrintCommands   bool
+	PrintCommands   func(cmd string, args ...string)
 	Debug           bool
 	PrintSizes      string
 	PrintAllocs     *regexp.Regexp // regexp string
@@ -59,6 +61,15 @@ func (o *Options) Verify() error {
 		}
 	}
 
+	if o.Serial != "" {
+		valid := isInArray(validSerialOptions, o.Serial)
+		if !valid {
+			return fmt.Errorf(`invalid serial option '%s': valid values are %s`,
+				o.Serial,
+				strings.Join(validSerialOptions, ", "))
+		}
+	}
+
 	if o.PrintSizes != "" {
 		valid := isInArray(validPrintSizeOptions, o.PrintSizes)
 		if !valid {

compileopts/target.go

@@ -31,6 +31,7 @@ type TargetSpec struct {
 	BuildTags        []string `json:"build-tags"`
 	GC               string   `json:"gc"`
 	Scheduler        string   `json:"scheduler"`
+	Serial           string   `json:"serial"` // which serial output to use (uart, usb, none)
 	Linker           string   `json:"linker"`
 	RTLib            string   `json:"rtlib"` // compiler runtime library (libgcc, compiler-rt)
 	Libc             string   `json:"libc"`
@@ -40,10 +41,12 @@ type TargetSpec struct {
 	LDFlags          []string `json:"ldflags"`
 	LinkerScript     string   `json:"linkerscript"`
 	ExtraFiles       []string `json:"extra-files"`
+	RP2040BootPatch  *bool    `json:"rp2040-boot-patch"`        // Patch RP2040 2nd stage bootloader checksum
 	Emulator         []string `json:"emulator" override:"copy"` // inherited Emulator must not be append
 	FlashCommand     string   `json:"flash-command"`
 	GDB              []string `json:"gdb"`
 	PortReset        string   `json:"flash-1200-bps-reset"`
+	SerialPort       []string `json:"serial-port"` // serial port IDs in the form "acm:vid:pid" or "usb:vid:pid"
 	FlashMethod      string   `json:"flash-method"`
 	FlashVolume      string   `json:"msd-volume-name"`
 	FlashFilename    string   `json:"msd-firmware-name"`

compiler/asserts.go

@@ -162,6 +162,10 @@ func (b *builder) createNilCheck(inst ssa.Value, ptr llvm.Value, blockPrefix str
 	case *ssa.Alloc:
 		// An alloc is never nil.
 		return
+	case *ssa.FreeVar:
+		// A free variable is allocated in a parent function and is thus never
+		// nil.
+		return
 	case *ssa.IndexAddr:
 		// This pointer is the result of an index operation into a slice or
 		// array. Such slices/arrays are already bounds checked so the pointer

compiler/compiler.go

@@ -23,7 +23,7 @@ import (
 // Version of the compiler pacakge. Must be incremented each time the compiler
 // package changes in a way that affects the generated LLVM module.
 // This version is independent of the TinyGo version number.
-const Version = 9 // last change: implement reflect.New()
+const Version = 12 // last change: implement syscall.rawSyscallNoError
 
 func init() {
 	llvm.InitializeAllTargets()
@@ -693,6 +693,7 @@ func (c *compilerContext) getDIFile(filename string) llvm.Metadata {
 // createPackage builds the LLVM IR for all types, methods, and global variables
 // in the given package.
 func (c *compilerContext) createPackage(irbuilder llvm.Builder, pkg *ssa.Package) {
+	println("called create package:", pkg.Pkg.Name())
 	// Sort by position, so that the order of the functions in the IR matches
 	// the order of functions in the source file. This is useful for testing,
 	// for example.
@@ -715,11 +716,11 @@ func (c *compilerContext) createPackage(irbuilder llvm.Builder, pkg *ssa.Package
 		member := pkg.Members[name]
 		switch member := member.(type) {
 		case *ssa.Function:
+			// Create the function definition.
+			b := newBuilder(c, irbuilder, member)
 			if member.Blocks == nil {
 				continue // external function
 			}
-			// Create the function definition.
-			b := newBuilder(c, irbuilder, member)
 			b.createFunction()
 		case *ssa.Type:
 			if types.IsInterface(member.Type()) {
@@ -758,11 +759,44 @@ func (c *compilerContext) createPackage(irbuilder llvm.Builder, pkg *ssa.Package
 		case *ssa.Global:
 			// Global variable.
 			info := c.getGlobalInfo(member)
+			// process go:embed pragmas
+			// TODO: skip this if not Go 1.16 or higher
+			if strings.TrimSpace(info.embeds) != "" {
+				embeds, err := parseGoEmbed(info.embeds)
+				if err != nil {
+					c.addError(member.Pos(), `invalid go:embed pragma: `+err.Error())
+					goto getGlobal
+				}
+				importsEmbedPkg := false
+				for _, imprt := range pkg.Pkg.Imports() {
+					if imprt.Name() == "embed" {
+						importsEmbedPkg = true
+						break
+					}
+				}
+				if !importsEmbedPkg {
+					// FIXME: technically the "embed" package needs to be imported in every
+					// *source file* that has a //go:embed pragma... that will always be the
+					// case when referencing embed.FS but not necessarily when a go:embed
+					// pragma is added to a string or []byte.  For now, as long as the embed
+					// package is imported in at least one source file, TinyGo will process
+					// any go:embed pragmas in the entire package.
+					c.addError(member.Pos(), `//go:embed only allowed in Go files that import "embed"`)
+					goto getGlobal
+				}
+				fmt.Printf("file embed found at %v (import: %v): %v\n", info.linkName, importsEmbedPkg, embeds)
+			}
+
+		getGlobal:
+			global := c.getGlobal(member)
 			if !info.extern {
-				global := c.getGlobal(member)
 				global.SetInitializer(llvm.ConstNull(global.Type().ElementType()))
 				global.SetVisibility(llvm.HiddenVisibility)
+				if info.section != "" {
+					global.SetSection(info.section)
+				}
 			}
+
 		}
 	}
 }
@@ -787,6 +821,9 @@ func (b *builder) createFunction() {
 		b.llvmFn.SetVisibility(llvm.HiddenVisibility)
 		b.llvmFn.SetUnnamedAddr(true)
 	}
+	if b.info.section != "" {
+		b.llvmFn.SetSection(b.info.section)
+	}
 	if b.info.exported && strings.HasPrefix(b.Triple, "wasm") {
 		// Set the exported name. This is necessary for WebAssembly because
 		// otherwise the function is not exported.
@@ -994,6 +1031,8 @@ func getPos(val posser) token.Pos {
 	switch val := val.(type) {
 	case *ssa.MakeInterface:
 		return getPos(val.X)
+	case *ssa.MakeClosure:
+		return val.Fn.(*ssa.Function).Pos()
 	case *ssa.Return:
 		syntax := val.Parent().Syntax()
 		if syntax != nil {
@@ -1048,52 +1087,8 @@ func (b *builder) createInstruction(instr ssa.Instruction) {
 	case *ssa.Defer:
 		b.createDefer(instr)
 	case *ssa.Go:
-		// Get all function parameters to pass to the goroutine.
-		var params []llvm.Value
-		for _, param := range instr.Call.Args {
-			params = append(params, b.getValue(param))
-		}
-
 		// Start a new goroutine.
-		if callee := instr.Call.StaticCallee(); callee != nil {
+		b.createGo(instr)
-			// Static callee is known. This makes it easier to start a new
-			// goroutine.
-			var context llvm.Value
-			switch value := instr.Call.Value.(type) {
-			case *ssa.Function:
-				// Goroutine call is regular function call. No context is necessary.
-				context = llvm.Undef(b.i8ptrType)
-			case *ssa.MakeClosure:
-				// A goroutine call on a func value, but the callee is trivial to find. For
-				// example: immediately applied functions.
-				funcValue := b.getValue(value)
-				context = b.extractFuncContext(funcValue)
-			default:
-				panic("StaticCallee returned an unexpected value")
-			}
-			params = append(params, context) // context parameter
-			b.createGoInstruction(b.getFunction(callee), params, "", callee.Pos())
-		} else if !instr.Call.IsInvoke() {
-			// This is a function pointer.
-			// At the moment, two extra params are passed to the newly started
-			// goroutine:
-			//   * The function context, for closures.
-			//   * The function pointer (for tasks).
-			funcPtr, context := b.decodeFuncValue(b.getValue(instr.Call.Value), instr.Call.Value.Type().Underlying().(*types.Signature))
-			params = append(params, context) // context parameter
-			switch b.Scheduler {
-			case "none", "coroutines":
-				// There are no additional parameters needed for the goroutine start operation.
-			case "tasks":
-				// Add the function pointer as a parameter to start the goroutine.
-				params = append(params, funcPtr)
-			default:
-				panic("unknown scheduler type")
-			}
-			b.createGoInstruction(funcPtr, params, b.fn.RelString(nil), instr.Pos())
-		} else {
-			b.addError(instr.Pos(), "todo: go on interface call")
-		}
 	case *ssa.If:
 		cond := b.getValue(instr.Cond)
 		block := instr.Block()
@@ -1346,6 +1341,8 @@ func (b *builder) createFunctionCall(instr *ssa.CallCommon) (llvm.Value, error)
 			return b.emitCSROperation(instr)
 		case strings.HasPrefix(name, "syscall.Syscall"):
 			return b.createSyscall(instr)
+		case strings.HasPrefix(name, "syscall.rawSyscallNoError"):
+			return b.createRawSyscallNoError(instr)
 		case strings.HasPrefix(name, "runtime/volatile.Load"):
 			return b.createVolatileLoad(instr)
 		case strings.HasPrefix(name, "runtime/volatile.Store"):

compiler/compiler_test.go

@@ -19,6 +19,8 @@ var flagUpdate = flag.Bool("update", false, "update tests based on test output")
 // Basic tests for the compiler. Build some Go files and compare the output with
 // the expected LLVM IR for regression testing.
 func TestCompiler(t *testing.T) {
+	t.Parallel()
+
 	// Check LLVM version.
 	llvmMajor, err := strconv.Atoi(strings.SplitN(llvm.Version, ".", 2)[0])
 	if err != nil {
@@ -32,43 +34,56 @@ func TestCompiler(t *testing.T) {
 		t.Skip("compiler tests require LLVM 11 or above, got LLVM ", llvm.Version)
 	}
 
-	target, err := compileopts.LoadTarget("wasm")
+	tests := []struct {
-	if err != nil {
+		file   string
-		t.Fatal("failed to load target:", err)
+		target string
-	}
+	}{
-	config := &compileopts.Config{
+		{"basic.go", ""},
-		Options: &compileopts.Options{},
+		{"pointer.go", ""},
-		Target:  target,
+		{"slice.go", ""},
-	}
+		{"string.go", ""},
-	compilerConfig := &Config{
+		{"float.go", ""},
-		Triple:             config.Triple(),
+		{"interface.go", ""},
-		GOOS:               config.GOOS(),
+		{"func.go", ""},
-		GOARCH:             config.GOARCH(),
+		{"pragma.go", ""},
-		CodeModel:          config.CodeModel(),
+		{"goroutine.go", "wasm"},
-		RelocationModel:    config.RelocationModel(),
+		{"goroutine.go", "cortex-m-qemu"},
-		Scheduler:          config.Scheduler(),
-		FuncImplementation: config.FuncImplementation(),
-		AutomaticStackSize: config.AutomaticStackSize(),
-	}
-	machine, err := NewTargetMachine(compilerConfig)
-	if err != nil {
-		t.Fatal("failed to create target machine:", err)
 	}
 
-	tests := []string{
+	for _, tc := range tests {
-		"basic.go",
+		name := tc.file
-		"pointer.go",
+		targetString := "wasm"
-		"slice.go",
+		if tc.target != "" {
-		"string.go",
+			targetString = tc.target
-		"float.go",
+			name = tc.file + "-" + tc.target
-		"interface.go",
+		}
-		"func.go",
+
-	}
+		t.Run(name, func(t *testing.T) {
+			target, err := compileopts.LoadTarget(targetString)
+			if err != nil {
+				t.Fatal("failed to load target:", err)
+			}
+			config := &compileopts.Config{
+				Options: &compileopts.Options{},
+				Target:  target,
+			}
+			compilerConfig := &Config{
+				Triple:             config.Triple(),
+				GOOS:               config.GOOS(),
+				GOARCH:             config.GOARCH(),
+				CodeModel:          config.CodeModel(),
+				RelocationModel:    config.RelocationModel(),
+				Scheduler:          config.Scheduler(),
+				FuncImplementation: config.FuncImplementation(),
+				AutomaticStackSize: config.AutomaticStackSize(),
+			}
+			machine, err := NewTargetMachine(compilerConfig)
+			if err != nil {
+				t.Fatal("failed to create target machine:", err)
+			}
 
-	for _, testCase := range tests {
-		t.Run(testCase, func(t *testing.T) {
 			// Load entire program AST into memory.
-			lprogram, err := loader.Load(config, []string{"./testdata/" + testCase}, config.ClangHeaders, types.Config{
+			lprogram, err := loader.Load(config, []string{"./testdata/" + tc.file}, config.ClangHeaders, types.Config{
 				Sizes: Sizes(machine),
 			})
 			if err != nil {
@@ -76,13 +91,13 @@ func TestCompiler(t *testing.T) {
 			}
 			err = lprogram.Parse()
 			if err != nil {
-				t.Fatalf("could not parse test case %s: %s", testCase, err)
+				t.Fatalf("could not parse test case %s: %s", tc.file, err)
 			}
 
 			// Compile AST to IR.
 			program := lprogram.LoadSSA()
 			pkg := lprogram.MainPkg()
-			mod, errs := CompilePackage(testCase, pkg, program.Package(pkg.Pkg), machine, compilerConfig, false)
+			mod, errs := CompilePackage(tc.file, pkg, program.Package(pkg.Pkg), machine, compilerConfig, false)
 			if errs != nil {
 				for _, err := range errs {
 					t.Error(err)
@@ -105,18 +120,22 @@ func TestCompiler(t *testing.T) {
 			}
 			funcPasses.FinalizeFunc()
 
-			outfile := "./testdata/" + testCase[:len(testCase)-3] + ".ll"
+			outFilePrefix := tc.file[:len(tc.file)-3]
+			if tc.target != "" {
+				outFilePrefix += "-" + tc.target
+			}
+			outPath := "./testdata/" + outFilePrefix + ".ll"
 
 			// Update test if needed. Do not check the result.
 			if *flagUpdate {
-				err := ioutil.WriteFile(outfile, []byte(mod.String()), 0666)
+				err := ioutil.WriteFile(outPath, []byte(mod.String()), 0666)
 				if err != nil {
 					t.Error("failed to write updated output file:", err)
 				}
 				return
 			}
 
-			expected, err := ioutil.ReadFile(outfile)
+			expected, err := ioutil.ReadFile(outPath)
 			if err != nil {
 				t.Fatal("failed to read golden file:", err)
 			}

compiler/embed.go

@@ -0,0 +1,70 @@
+package compiler
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// parseGoEmbed parses the text following "//go:embed" to extract the glob patterns.
+// It accepts unquoted space-separated patterns as well as double-quoted and back-quoted Go strings.
+// Copied from https://github.com/golang/go/blob/219fe9d547d09d3de1b024c6c8b8314dd0bf12e4/src/cmd/compile/internal/noder/noder.go#L1717-L1776
+func parseGoEmbed(args string) ([]string, error) {
+	var list []string
+	for args = strings.TrimSpace(args); args != ""; args = strings.TrimSpace(args) {
+		var path string
+	Switch:
+		switch args[0] {
+		default:
+			i := len(args)
+			for j, c := range args {
+				if unicode.IsSpace(c) {
+					i = j
+					break
+				}
+			}
+			path = args[:i]
+			args = args[i:]
+
+		case '`':
+			i := strings.Index(args[1:], "`")
+			if i < 0 {
+				return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
+			}
+			path = args[1 : 1+i]
+			args = args[1+i+1:]
+
+		case '"':
+			i := 1
+			for ; i < len(args); i++ {
+				if args[i] == '\\' {
+					i++
+					continue
+				}
+				if args[i] == '"' {
+					q, err := strconv.Unquote(args[:i+1])
+					if err != nil {
+						return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args[:i+1])
+					}
+					path = q
+					args = args[i+1:]
+					break Switch
+				}
+			}
+			if i >= len(args) {
+				return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
+			}
+		}
+
+		if args != "" {
+			r, _ := utf8.DecodeRuneInString(args)
+			if !unicode.IsSpace(r) {
+				return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
+			}
+		}
+		list = append(list, path)
+	}
+	return list, nil
+}

compiler/goroutine.go

@@ -5,25 +5,110 @@ package compiler
 
 import (
 	"go/token"
+	"go/types"
 
 	"github.com/tinygo-org/tinygo/compiler/llvmutil"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
 )
 
-// createGoInstruction starts a new goroutine with the provided function pointer
+// createGo emits code to start a new goroutine.
-// and parameters.
+func (b *builder) createGo(instr *ssa.Go) {
-// In general, you should pass all regular parameters plus the context parameter.
+	// Get all function parameters to pass to the goroutine.
-// There is one exception: the task-based scheduler needs to have the function
+	var params []llvm.Value
-// pointer passed in as a parameter too in addition to the context.
+	for _, param := range instr.Call.Args {
-//
+		params = append(params, b.getValue(param))
-// Because a go statement doesn't return anything, return undef.
+	}
-func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, prefix string, pos token.Pos) llvm.Value {
+
+	var prefix string
+	var funcPtr llvm.Value
+	hasContext := false
+	if callee := instr.Call.StaticCallee(); callee != nil {
+		// Static callee is known. This makes it easier to start a new
+		// goroutine.
+		var context llvm.Value
+		switch value := instr.Call.Value.(type) {
+		case *ssa.Function:
+			// Goroutine call is regular function call. No context is necessary.
+			if b.Scheduler == "coroutines" {
+				// The context parameter is assumed to be always present in the
+				// coroutines scheduler.
+				context = llvm.Undef(b.i8ptrType)
+			}
+		case *ssa.MakeClosure:
+			// A goroutine call on a func value, but the callee is trivial to find. For
+			// example: immediately applied functions.
+			funcValue := b.getValue(value)
+			context = b.extractFuncContext(funcValue)
+		default:
+			panic("StaticCallee returned an unexpected value")
+		}
+		if !context.IsNil() {
+			params = append(params, context) // context parameter
+			hasContext = true
+		}
+		funcPtr = b.getFunction(callee)
+	} else if builtin, ok := instr.Call.Value.(*ssa.Builtin); ok {
+		// We cheat. None of the builtins do any long or blocking operation, so
+		// we might as well run these builtins right away without the program
+		// noticing the difference.
+		// Possible exceptions:
+		//   - copy: this is a possibly long operation, but not a blocking
+		//     operation. Semantically it makes no difference to run it right
+		//     away (not in a goroutine). However, in practice it makes no sense
+		//     to run copy in a goroutine as there is no way to (safely) know
+		//     when it is finished.
+		//   - panic: the error message would appear in the parent goroutine.
+		//     But because `go panic("err")` would halt the program anyway
+		//     (there is no recover), panicking right away would give the same
+		//     behavior as creating a goroutine, switching the scheduler to that
+		//     goroutine, and panicking there. So this optimization seems
+		//     correct.
+		//   - recover: because it runs in a new goroutine, it is never a
+		//     deferred function. Thus this is a no-op.
+		if builtin.Name() == "recover" {
+			// This is a no-op, even in a deferred function:
+			//   go recover()
+			return
+		}
+		var argTypes []types.Type
+		var argValues []llvm.Value
+		for _, arg := range instr.Call.Args {
+			argTypes = append(argTypes, arg.Type())
+			argValues = append(argValues, b.getValue(arg))
+		}
+		b.createBuiltin(argTypes, argValues, builtin.Name(), instr.Pos())
+		return
+	} else if !instr.Call.IsInvoke() {
+		// This is a function pointer.
+		// At the moment, two extra params are passed to the newly started
+		// goroutine:
+		//   * The function context, for closures.
+		//   * The function pointer (for tasks).
+		var context llvm.Value
+		funcPtr, context = b.decodeFuncValue(b.getValue(instr.Call.Value), instr.Call.Value.Type().Underlying().(*types.Signature))
+		params = append(params, context) // context parameter
+		hasContext = true
+		switch b.Scheduler {
+		case "none", "coroutines":
+			// There are no additional parameters needed for the goroutine start operation.
+		case "tasks":
+			// Add the function pointer as a parameter to start the goroutine.
+			params = append(params, funcPtr)
+		default:
+			panic("unknown scheduler type")
+		}
+		prefix = b.fn.RelString(nil)
+	} else {
+		b.addError(instr.Pos(), "todo: go on interface call")
+		return
+	}
+
 	paramBundle := b.emitPointerPack(params)
 	var callee, stackSize llvm.Value
 	switch b.Scheduler {
 	case "none", "tasks":
-		callee = b.createGoroutineStartWrapper(funcPtr, prefix, pos)
+		callee = b.createGoroutineStartWrapper(funcPtr, prefix, hasContext, instr.Pos())
 		if b.AutomaticStackSize {
 			// The stack size is not known until after linking. Call a dummy
 			// function that will be replaced with a load from a special ELF
@@ -35,7 +120,7 @@ func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, p
 			// The stack size is fixed at compile time. By emitting it here as a
 			// constant, it can be optimized.
 			if b.Scheduler == "tasks" && b.DefaultStackSize == 0 {
-				b.addError(pos, "default stack size for goroutines is not set")
+				b.addError(instr.Pos(), "default stack size for goroutines is not set")
 			}
 			stackSize = llvm.ConstInt(b.uintptrType, b.DefaultStackSize, false)
 		}
@@ -49,7 +134,6 @@ func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, p
 	}
 	start := b.getFunction(b.program.ImportedPackage("internal/task").Members["start"].(*ssa.Function))
 	b.createCall(start, []llvm.Value{callee, paramBundle, stackSize, llvm.Undef(b.i8ptrType), llvm.ConstPointerNull(b.i8ptrType)}, "")
-	return llvm.Undef(funcPtr.Type().ElementType().ReturnType())
 }
 
 // createGoroutineStartWrapper creates a wrapper for the task-based
@@ -70,7 +154,12 @@ func (b *builder) createGoInstruction(funcPtr llvm.Value, params []llvm.Value, p
 // allows a single (pointer) argument to the newly started goroutine. Also, it
 // ignores the return value because newly started goroutines do not have a
 // return value.
-func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix string, pos token.Pos) llvm.Value {
+//
+// The hasContext parameter indicates whether the context parameter (the second
+// to last parameter of the function) is used for this wrapper. If hasContext is
+// false, the parameter bundle is assumed to have no context parameter and undef
+// is passed instead.
+func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix string, hasContext bool, pos token.Pos) llvm.Value {
 	var wrapper llvm.Value
 
 	builder := c.ctx.NewBuilder()
@@ -117,8 +206,15 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 
 		// Create the list of params for the call.
 		paramTypes := fn.Type().ElementType().ParamTypes()
-		params := llvmutil.EmitPointerUnpack(builder, c.mod, wrapper.Param(0), paramTypes[:len(paramTypes)-1])
+		paramTypes = paramTypes[:len(paramTypes)-1] // strip parentHandle parameter
-		params = append(params, llvm.Undef(c.i8ptrType))
+		if !hasContext {
+			paramTypes = paramTypes[:len(paramTypes)-1] // strip context parameter
+		}
+		params := llvmutil.EmitPointerUnpack(builder, c.mod, wrapper.Param(0), paramTypes)
+		if !hasContext {
+			params = append(params, llvm.Undef(c.i8ptrType)) // add dummy context parameter
+		}
+		params = append(params, llvm.Undef(c.i8ptrType)) // add dummy parentHandle parameter
 
 		// Create the call.
 		builder.CreateCall(fn, params, "")
@@ -180,8 +276,11 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		// Get the function pointer.
 		fnPtr := params[len(params)-1]
 
-		// Ignore the last param, which isn't used anymore.
+		// The last parameter in the packed object has somewhat of a dual role.
-		// TODO: avoid this extra "parent handle" parameter in most functions.
+		// Inside the parameter bundle it's the function pointer, stored right
+		// after the context pointer. But in the IR call instruction, it's the
+		// parentHandle function that's always undef outside of the coroutines
+		// scheduler. Thus, make the parameter undef here.
 		params[len(params)-1] = llvm.Undef(c.i8ptrType)
 
 		// Create the call.

compiler/interface.go

@@ -311,10 +311,21 @@ func (c *compilerContext) getInterfaceMethodSet(typ types.Type) llvm.Value {
 // used during the interface lowering pass.
 func (c *compilerContext) getMethodSignature(method *types.Func) llvm.Value {
 	signature := methodSignature(method)
-	signatureGlobal := c.mod.NamedGlobal("func " + signature)
+	var globalName string
+	if token.IsExported(method.Name()) {
+		globalName = "reflect/methods." + signature
+	} else {
+		globalName = method.Type().(*types.Signature).Recv().Pkg().Path() + ".$methods." + signature
+	}
+	signatureGlobal := c.mod.NamedGlobal(globalName)
 	if signatureGlobal.IsNil() {
-		signatureGlobal = llvm.AddGlobal(c.mod, c.ctx.Int8Type(), "func "+signature)
+		// TODO: put something useful in these globals, such as the method
+		// signature. Useful to one day implement reflect.Value.Method(n).
+		signatureGlobal = llvm.AddGlobal(c.mod, c.ctx.Int8Type(), globalName)
+		signatureGlobal.SetInitializer(llvm.ConstInt(c.ctx.Int8Type(), 0, false))
+		signatureGlobal.SetLinkage(llvm.LinkOnceODRLinkage)
 		signatureGlobal.SetGlobalConstant(true)
+		signatureGlobal.SetAlignment(1)
 	}
 	return signatureGlobal
 }

compiler/interrupt.go

@@ -41,10 +41,7 @@ func (b *builder) createInterruptGlobal(instr *ssa.CallCommon) (llvm.Value, erro
 	// type are lowered in the interrupt lowering pass.
 	globalType := b.program.ImportedPackage("runtime/interrupt").Type("handle").Type()
 	globalLLVMType := b.getLLVMType(globalType)
-	globalName := "runtime/interrupt.$interrupt" + strconv.FormatInt(id.Int64(), 10)
+	globalName := b.fn.Package().Pkg.Path() + "$interrupt" + strconv.FormatInt(id.Int64(), 10)
-	if global := b.mod.NamedGlobal(globalName); !global.IsNil() {
-		return llvm.Value{}, b.makeError(instr.Pos(), "interrupt redeclared in this program")
-	}
 	global := llvm.AddGlobal(b.mod, globalLLVMType, globalName)
 	global.SetVisibility(llvm.HiddenVisibility)
 	global.SetGlobalConstant(true)

compiler/symbol.go

@@ -24,6 +24,7 @@ type functionInfo struct {
 	module     string     // go:wasm-module
 	importName string     // go:linkname, go:export - The name the developer assigns
 	linkName   string     // go:linkname, go:export - The name that we map for the particular module -> importName
+	section    string     // go:section - object file section name
 	exported   bool       // go:export, CGo
 	nobounds   bool       // go:nobounds
 	variadic   bool       // go:variadic (CGo only)
@@ -270,6 +271,10 @@ func (info *functionInfo) parsePragmas(f *ssa.Function) {
 				if hasUnsafeImport(f.Pkg.Pkg) {
 					info.linkName = parts[2]
 				}
+			case "//go:section":
+				if len(parts) == 2 && hasUnsafeImport(f.Pkg.Pkg) {
+					info.section = parts[1]
+				}
 			case "//go:nobounds":
 				// Skip bounds checking in this function. Useful for some
 				// runtime functions.
@@ -325,6 +330,8 @@ type globalInfo struct {
 	linkName string // go:extern
 	extern   bool   // go:extern
 	align    int    // go:align
+	section  string // go:section
+	embeds   string // go:embed
 }
 
 // loadASTComments loads comments on globals from the AST, for use later in the
@@ -438,6 +445,13 @@ func (info *globalInfo) parsePragmas(doc *ast.CommentGroup) {
 			if err == nil {
 				info.align = align
 			}
+		case "//go:section":
+			if len(parts) == 2 {
+				info.section = parts[1]
+			}
+		case "//go:embed":
+			raw := strings.TrimPrefix(comment.Text, "//go:embed")
+			info.embeds += " " + raw
 		}
 	}
 }

compiler/syscall.go

@@ -10,11 +10,11 @@ import (
 	"tinygo.org/x/go-llvm"
 )
 
-// createSyscall emits an inline system call instruction, depending on the
+// createRawSyscall creates a system call with the provided system call number
-// target OS/arch.
+// and returns the result as a single integer (the system call result). The
-func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
+// result is not further interpreted.
+func (b *builder) createRawSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 	num := b.getValue(call.Args[0])
-	var syscallResult llvm.Value
 	switch {
 	case b.GOARCH == "amd64":
 		if b.GOOS == "darwin" {
@@ -57,7 +57,7 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		constraints += ",~{rcx},~{r11}"
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "syscall", constraints, true, false, llvm.InlineAsmDialectIntel)
-		syscallResult = b.CreateCall(target, args, "")
+		return b.CreateCall(target, args, ""), nil
 	case b.GOARCH == "386" && b.GOOS == "linux":
 		// Sources:
 		//   syscall(2) man page
@@ -83,7 +83,7 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		}
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "int 0x80", constraints, true, false, llvm.InlineAsmDialectIntel)
-		syscallResult = b.CreateCall(target, args, "")
+		return b.CreateCall(target, args, ""), nil
 	case b.GOARCH == "arm" && b.GOOS == "linux":
 		// Implement the EABI system call convention for Linux.
 		// Source: syscall(2) man page.
@@ -115,7 +115,7 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		}
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
-		syscallResult = b.CreateCall(target, args, "")
+		return b.CreateCall(target, args, ""), nil
 	case b.GOARCH == "arm64" && b.GOOS == "linux":
 		// Source: syscall(2) man page.
 		args := []llvm.Value{}
@@ -147,10 +147,19 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		constraints += ",~{x16},~{x17}" // scratch registers
 		fnType := llvm.FunctionType(b.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
-		syscallResult = b.CreateCall(target, args, "")
+		return b.CreateCall(target, args, ""), nil
 	default:
 		return llvm.Value{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS+"/"+b.GOARCH)
 	}
+}
+
+// createSyscall emits instructions for the syscall.Syscall* family of
+// functions, depending on the target OS/arch.
+func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
+	syscallResult, err := b.createRawSyscall(call)
+	if err != nil {
+		return syscallResult, err
+	}
 	switch b.GOOS {
 	case "linux", "freebsd":
 		// Return values: r0, r1 uintptr, err Errno
@@ -190,3 +199,16 @@ func (b *builder) createSyscall(call *ssa.CallCommon) (llvm.Value, error) {
 		return llvm.Value{}, b.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+b.GOOS+"/"+b.GOARCH)
 	}
 }
+
+// createRawSyscallNoError emits instructions for the Linux-specific
+// syscall.rawSyscallNoError function.
+func (b *builder) createRawSyscallNoError(call *ssa.CallCommon) (llvm.Value, error) {
+	syscallResult, err := b.createRawSyscall(call)
+	if err != nil {
+		return syscallResult, err
+	}
+	retval := llvm.ConstNull(b.ctx.StructType([]llvm.Type{b.uintptrType, b.uintptrType}, false))
+	retval = b.CreateInsertValue(retval, syscallResult, 0, "")
+	retval = b.CreateInsertValue(retval, llvm.ConstInt(b.uintptrType, 0, false), 1, "")
+	return retval, nil
+}

compiler/testdata/goroutine-cortex-m-qemu.ll

@@ -0,0 +1,150 @@
+; ModuleID = 'goroutine.go'
+source_filename = "goroutine.go"
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv7m-none-eabi"
+
+%runtime.channel = type { i32, i32, i8, %runtime.channelBlockedList*, i32, i32, i32, i8* }
+%runtime.channelBlockedList = type { %runtime.channelBlockedList*, %"internal/task.Task"*, %runtime.chanSelectState*, { %runtime.channelBlockedList*, i32, i32 } }
+%"internal/task.Task" = type { %"internal/task.Task"*, i8*, i64, %"internal/task.state" }
+%"internal/task.state" = type { i32, i32* }
+%runtime.chanSelectState = type { %runtime.channel*, i8* }
+
+declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
+
+define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define hidden void @main.regularFunctionGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %stacksize = call i32 @"internal/task.getGoroutineStackSize"(i32 ptrtoint (void (i8*)* @"main.regularFunction$gowrapper" to i32), i8* undef, i8* undef)
+  call void @"internal/task.start"(i32 ptrtoint (void (i8*)* @"main.regularFunction$gowrapper" to i32), i8* nonnull inttoptr (i32 5 to i8*), i32 %stacksize, i8* undef, i8* null)
+  ret void
+}
+
+declare void @main.regularFunction(i32, i8*, i8*)
+
+define linkonce_odr void @"main.regularFunction$gowrapper"(i8* %0) unnamed_addr #0 {
+entry:
+  %unpack.int = ptrtoint i8* %0 to i32
+  call void @main.regularFunction(i32 %unpack.int, i8* undef, i8* undef)
+  ret void
+}
+
+declare i32 @"internal/task.getGoroutineStackSize"(i32, i8*, i8*)
+
+declare void @"internal/task.start"(i32, i8*, i32, i8*, i8*)
+
+define hidden void @main.inlineFunctionGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %stacksize = call i32 @"internal/task.getGoroutineStackSize"(i32 ptrtoint (void (i8*)* @"main.inlineFunctionGoroutine$1$gowrapper" to i32), i8* undef, i8* undef)
+  call void @"internal/task.start"(i32 ptrtoint (void (i8*)* @"main.inlineFunctionGoroutine$1$gowrapper" to i32), i8* nonnull inttoptr (i32 5 to i8*), i32 %stacksize, i8* undef, i8* null)
+  ret void
+}
+
+define hidden void @"main.inlineFunctionGoroutine$1"(i32 %x, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define linkonce_odr void @"main.inlineFunctionGoroutine$1$gowrapper"(i8* %0) unnamed_addr #1 {
+entry:
+  %unpack.int = ptrtoint i8* %0 to i32
+  call void @"main.inlineFunctionGoroutine$1"(i32 %unpack.int, i8* undef, i8* undef)
+  ret void
+}
+
+define hidden void @main.closureFunctionGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %n = call i8* @runtime.alloc(i32 4, i8* undef, i8* null)
+  %0 = bitcast i8* %n to i32*
+  store i32 3, i32* %0, align 4
+  %1 = call i8* @runtime.alloc(i32 8, i8* undef, i8* null)
+  %2 = bitcast i8* %1 to i32*
+  store i32 5, i32* %2, align 4
+  %3 = getelementptr inbounds i8, i8* %1, i32 4
+  %4 = bitcast i8* %3 to i8**
+  store i8* %n, i8** %4, align 4
+  %stacksize = call i32 @"internal/task.getGoroutineStackSize"(i32 ptrtoint (void (i8*)* @"main.closureFunctionGoroutine$1$gowrapper" to i32), i8* undef, i8* undef)
+  call void @"internal/task.start"(i32 ptrtoint (void (i8*)* @"main.closureFunctionGoroutine$1$gowrapper" to i32), i8* nonnull %1, i32 %stacksize, i8* undef, i8* null)
+  %5 = load i32, i32* %0, align 4
+  call void @runtime.printint32(i32 %5, i8* undef, i8* null)
+  ret void
+}
+
+define hidden void @"main.closureFunctionGoroutine$1"(i32 %x, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %unpack.ptr = bitcast i8* %context to i32*
+  store i32 7, i32* %unpack.ptr, align 4
+  ret void
+}
+
+define linkonce_odr void @"main.closureFunctionGoroutine$1$gowrapper"(i8* %0) unnamed_addr #2 {
+entry:
+  %1 = bitcast i8* %0 to i32*
+  %2 = load i32, i32* %1, align 4
+  %3 = getelementptr inbounds i8, i8* %0, i32 4
+  %4 = bitcast i8* %3 to i8**
+  %5 = load i8*, i8** %4, align 4
+  call void @"main.closureFunctionGoroutine$1"(i32 %2, i8* %5, i8* undef)
+  ret void
+}
+
+declare void @runtime.printint32(i32, i8*, i8*)
+
+define hidden void @main.funcGoroutine(i8* %fn.context, void (i32, i8*, i8*)* %fn.funcptr, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %0 = call i8* @runtime.alloc(i32 12, i8* undef, i8* null)
+  %1 = bitcast i8* %0 to i32*
+  store i32 5, i32* %1, align 4
+  %2 = getelementptr inbounds i8, i8* %0, i32 4
+  %3 = bitcast i8* %2 to i8**
+  store i8* %fn.context, i8** %3, align 4
+  %4 = getelementptr inbounds i8, i8* %0, i32 8
+  %5 = bitcast i8* %4 to void (i32, i8*, i8*)**
+  store void (i32, i8*, i8*)* %fn.funcptr, void (i32, i8*, i8*)** %5, align 4
+  %stacksize = call i32 @"internal/task.getGoroutineStackSize"(i32 ptrtoint (void (i8*)* @main.funcGoroutine.gowrapper to i32), i8* undef, i8* undef)
+  call void @"internal/task.start"(i32 ptrtoint (void (i8*)* @main.funcGoroutine.gowrapper to i32), i8* nonnull %0, i32 %stacksize, i8* undef, i8* null)
+  ret void
+}
+
+define linkonce_odr void @main.funcGoroutine.gowrapper(i8* %0) unnamed_addr #3 {
+entry:
+  %1 = bitcast i8* %0 to i32*
+  %2 = load i32, i32* %1, align 4
+  %3 = getelementptr inbounds i8, i8* %0, i32 4
+  %4 = bitcast i8* %3 to i8**
+  %5 = load i8*, i8** %4, align 4
+  %6 = getelementptr inbounds i8, i8* %0, i32 8
+  %7 = bitcast i8* %6 to void (i32, i8*, i8*)**
+  %8 = load void (i32, i8*, i8*)*, void (i32, i8*, i8*)** %7, align 4
+  call void %8(i32 %2, i8* %5, i8* undef)
+  ret void
+}
+
+define hidden void @main.recoverBuiltinGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define hidden void @main.copyBuiltinGoroutine(i8* %dst.data, i32 %dst.len, i32 %dst.cap, i8* %src.data, i32 %src.len, i32 %src.cap, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %copy.n = call i32 @runtime.sliceCopy(i8* %dst.data, i8* %src.data, i32 %dst.len, i32 %src.len, i32 1, i8* undef, i8* null)
+  ret void
+}
+
+declare i32 @runtime.sliceCopy(i8* nocapture writeonly, i8* nocapture readonly, i32, i32, i32, i8*, i8*)
+
+define hidden void @main.closeBuiltinGoroutine(%runtime.channel* dereferenceable_or_null(32) %ch, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  call void @runtime.chanClose(%runtime.channel* %ch, i8* undef, i8* null)
+  ret void
+}
+
+declare void @runtime.chanClose(%runtime.channel* dereferenceable_or_null(32), i8*, i8*)
+
+attributes #0 = { "tinygo-gowrapper"="main.regularFunction" }
+attributes #1 = { "tinygo-gowrapper"="main.inlineFunctionGoroutine$1" }
+attributes #2 = { "tinygo-gowrapper"="main.closureFunctionGoroutine$1" }
+attributes #3 = { "tinygo-gowrapper" }

compiler/testdata/goroutine-wasm.ll

@@ -0,0 +1,106 @@
+; ModuleID = 'goroutine.go'
+source_filename = "goroutine.go"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32--wasi"
+
+%runtime.funcValueWithSignature = type { i32, i8* }
+%runtime.channel = type { i32, i32, i8, %runtime.channelBlockedList*, i32, i32, i32, i8* }
+%runtime.channelBlockedList = type { %runtime.channelBlockedList*, %"internal/task.Task"*, %runtime.chanSelectState*, { %runtime.channelBlockedList*, i32, i32 } }
+%"internal/task.Task" = type { %"internal/task.Task"*, i8*, i64, %"internal/task.state" }
+%"internal/task.state" = type { i8* }
+%runtime.chanSelectState = type { %runtime.channel*, i8* }
+
+@"main.regularFunctionGoroutine$pack" = private unnamed_addr constant { i32, i8* } { i32 5, i8* undef }
+@"main.inlineFunctionGoroutine$pack" = private unnamed_addr constant { i32, i8* } { i32 5, i8* undef }
+@"reflect/types.funcid:func:{basic:int}{}" = external constant i8
+@"main.closureFunctionGoroutine$1$withSignature" = linkonce_odr constant %runtime.funcValueWithSignature { i32 ptrtoint (void (i32, i8*, i8*)* @"main.closureFunctionGoroutine$1" to i32), i8* @"reflect/types.funcid:func:{basic:int}{}" }
+
+declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
+
+define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define hidden void @main.regularFunctionGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  call void @"internal/task.start"(i32 ptrtoint (void (i32, i8*, i8*)* @main.regularFunction to i32), i8* bitcast ({ i32, i8* }* @"main.regularFunctionGoroutine$pack" to i8*), i32 undef, i8* undef, i8* null)
+  ret void
+}
+
+declare void @main.regularFunction(i32, i8*, i8*)
+
+declare void @"internal/task.start"(i32, i8*, i32, i8*, i8*)
+
+define hidden void @main.inlineFunctionGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  call void @"internal/task.start"(i32 ptrtoint (void (i32, i8*, i8*)* @"main.inlineFunctionGoroutine$1" to i32), i8* bitcast ({ i32, i8* }* @"main.inlineFunctionGoroutine$pack" to i8*), i32 undef, i8* undef, i8* null)
+  ret void
+}
+
+define hidden void @"main.inlineFunctionGoroutine$1"(i32 %x, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define hidden void @main.closureFunctionGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %n = call i8* @runtime.alloc(i32 4, i8* undef, i8* null)
+  %0 = bitcast i8* %n to i32*
+  store i32 3, i32* %0, align 4
+  %1 = call i8* @runtime.alloc(i32 8, i8* undef, i8* null)
+  %2 = bitcast i8* %1 to i32*
+  store i32 5, i32* %2, align 4
+  %3 = getelementptr inbounds i8, i8* %1, i32 4
+  %4 = bitcast i8* %3 to i8**
+  store i8* %n, i8** %4, align 4
+  call void @"internal/task.start"(i32 ptrtoint (void (i32, i8*, i8*)* @"main.closureFunctionGoroutine$1" to i32), i8* nonnull %1, i32 undef, i8* undef, i8* null)
+  %5 = load i32, i32* %0, align 4
+  call void @runtime.printint32(i32 %5, i8* undef, i8* null)
+  ret void
+}
+
+define hidden void @"main.closureFunctionGoroutine$1"(i32 %x, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %unpack.ptr = bitcast i8* %context to i32*
+  store i32 7, i32* %unpack.ptr, align 4
+  ret void
+}
+
+declare void @runtime.printint32(i32, i8*, i8*)
+
+define hidden void @main.funcGoroutine(i8* %fn.context, i32 %fn.funcptr, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %0 = call i32 @runtime.getFuncPtr(i8* %fn.context, i32 %fn.funcptr, i8* nonnull @"reflect/types.funcid:func:{basic:int}{}", i8* undef, i8* null)
+  %1 = call i8* @runtime.alloc(i32 8, i8* undef, i8* null)
+  %2 = bitcast i8* %1 to i32*
+  store i32 5, i32* %2, align 4
+  %3 = getelementptr inbounds i8, i8* %1, i32 4
+  %4 = bitcast i8* %3 to i8**
+  store i8* %fn.context, i8** %4, align 4
+  call void @"internal/task.start"(i32 %0, i8* nonnull %1, i32 undef, i8* undef, i8* null)
+  ret void
+}
+
+declare i32 @runtime.getFuncPtr(i8*, i32, i8* dereferenceable_or_null(1), i8*, i8*)
+
+define hidden void @main.recoverBuiltinGoroutine(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define hidden void @main.copyBuiltinGoroutine(i8* %dst.data, i32 %dst.len, i32 %dst.cap, i8* %src.data, i32 %src.len, i32 %src.cap, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %copy.n = call i32 @runtime.sliceCopy(i8* %dst.data, i8* %src.data, i32 %dst.len, i32 %src.len, i32 1, i8* undef, i8* null)
+  ret void
+}
+
+declare i32 @runtime.sliceCopy(i8* nocapture writeonly, i8* nocapture readonly, i32, i32, i32, i8*, i8*)
+
+define hidden void @main.closeBuiltinGoroutine(%runtime.channel* dereferenceable_or_null(32) %ch, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  call void @runtime.chanClose(%runtime.channel* %ch, i8* undef, i8* null)
+  ret void
+}
+
+declare void @runtime.chanClose(%runtime.channel* dereferenceable_or_null(32), i8*, i8*)

compiler/testdata/goroutine.go

@@ -0,0 +1,43 @@
+package main
+
+func regularFunctionGoroutine() {
+	go regularFunction(5)
+}
+
+func inlineFunctionGoroutine() {
+	go func(x int) {
+	}(5)
+}
+
+func closureFunctionGoroutine() {
+	n := 3
+	go func(x int) {
+		n = 7
+	}(5)
+	print(n) // note: this is racy (but good enough for this test)
+}
+
+func funcGoroutine(fn func(x int)) {
+	go fn(5)
+}
+
+func recoverBuiltinGoroutine() {
+	// This is a no-op.
+	go recover()
+}
+
+func copyBuiltinGoroutine(dst, src []byte) {
+	// This is not run in a goroutine. While this copy operation can indeed take
+	// some time (if there is a lot of data to copy), there is no race-free way
+	// to make use of the result so it's unlikely applications will make use of
+	// it. And doing it this way should be just within the Go specification.
+	go copy(dst, src)
+}
+
+func closeBuiltinGoroutine(ch chan int) {
+	// This builtin is executed directly, not in a goroutine.
+	// The observed behavior is the same.
+	go close(ch)
+}
+
+func regularFunction(x int)

compiler/testdata/interface.ll

@@ -13,15 +13,15 @@ target triple = "wasm32--wasi"
 @"reflect/types.type:pointer:named:error" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:named:error", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* null }
 @"reflect/types.type:named:error" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{Error:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* @"reflect/types.type:pointer:named:error" }
 @"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* bitcast ([1 x i8*]* @"reflect/types.interface:interface{Error() string}$interface" to %runtime.typecodeID*), i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" }
-@"func Error() string" = external constant i8
+@"reflect/methods.Error() string" = linkonce_odr constant i8 0, align 1
-@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"func Error() string"]
+@"reflect/types.interface:interface{Error() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.Error() string"]
 @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{Error:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* null }
 @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* @"reflect/types.type:interface:{String:func:{}{basic:string}}", i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* null }
 @"reflect/types.type:interface:{String:func:{}{basic:string}}" = linkonce_odr constant %runtime.typecodeID { %runtime.typecodeID* bitcast ([1 x i8*]* @"reflect/types.interface:interface{String() string}$interface" to %runtime.typecodeID*), i32 0, %runtime.interfaceMethodInfo* null, %runtime.typecodeID* @"reflect/types.type:pointer:interface:{String:func:{}{basic:string}}" }
-@"func String() string" = external constant i8
+@"reflect/methods.String() string" = linkonce_odr constant i8 0, align 1
-@"reflect/types.interface:interface{String() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"func String() string"]
+@"reflect/types.interface:interface{String() string}$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.String() string"]
 @"reflect/types.typeid:basic:int" = external constant i8
-@"error$interface" = linkonce_odr constant [1 x i8*] [i8* @"func Error() string"]
+@"error$interface" = linkonce_odr constant [1 x i8*] [i8* @"reflect/methods.Error() string"]
 
 declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
 
@@ -92,7 +92,7 @@ typeassert.next:                                  ; preds = %typeassert.ok, %ent
 
 define hidden %runtime._string @main.callErrorMethod(i32 %itf.typecode, i8* %itf.value, i8* %context, i8* %parentHandle) unnamed_addr {
 entry:
-  %invoke.func = call i32 @runtime.interfaceMethod(i32 %itf.typecode, i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"error$interface", i32 0, i32 0), i8* nonnull @"func Error() string", i8* undef, i8* null)
+  %invoke.func = call i32 @runtime.interfaceMethod(i32 %itf.typecode, i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"error$interface", i32 0, i32 0), i8* nonnull @"reflect/methods.Error() string", i8* undef, i8* null)
   %invoke.func.cast = inttoptr i32 %invoke.func to %runtime._string (i8*, i8*, i8*)*
   %0 = call %runtime._string %invoke.func.cast(i8* %itf.value, i8* undef, i8* undef)
   ret %runtime._string %0

compiler/testdata/pragma.go

@@ -0,0 +1,66 @@
+package main
+
+import _ "unsafe"
+
+// Creates an external global with name extern_global.
+//go:extern extern_global
+var externGlobal [0]byte
+
+// Creates a
+//go:align 32
+var alignedGlobal [4]uint32
+
+// Test conflicting pragmas (the last one counts).
+//go:align 64
+//go:align 16
+var alignedGlobal16 [4]uint32
+
+// Test exported functions.
+//export extern_func
+func externFunc() {
+}
+
+// Define a function in a different package using go:linkname.
+//go:linkname withLinkageName1 somepkg.someFunction1
+func withLinkageName1() {
+}
+
+// Import a function from a different package using go:linkname.
+//go:linkname withLinkageName2 somepkg.someFunction2
+func withLinkageName2()
+
+// Function has an 'inline hint', similar to the inline keyword in C.
+//go:inline
+func inlineFunc() {
+}
+
+// Function should never be inlined, equivalent to GCC
+// __attribute__((noinline)).
+//go:noinline
+func noinlineFunc() {
+}
+
+// This function should have the specified section.
+//go:section .special_function_section
+func functionInSection() {
+}
+
+//export exportedFunctionInSection
+//go:section .special_function_section
+func exportedFunctionInSection() {
+}
+
+// This function should not: it's only a declaration and not a definition.
+//go:section .special_function_section
+func undefinedFunctionNotInSection()
+
+//go:section .special_global_section
+var globalInSection uint32
+
+//go:section .special_global_section
+//go:extern undefinedGlobalNotInSection
+var undefinedGlobalNotInSection uint32
+
+//go:align 1024
+//go:section .global_section
+var multipleGlobalPragmas uint32

compiler/testdata/pragma.ll

@@ -0,0 +1,59 @@
+; ModuleID = 'pragma.go'
+source_filename = "pragma.go"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32--wasi"
+
+@extern_global = external global [0 x i8], align 1
+@main.alignedGlobal = hidden global [4 x i32] zeroinitializer, align 32
+@main.alignedGlobal16 = hidden global [4 x i32] zeroinitializer, align 16
+@main.globalInSection = hidden global i32 0, section ".special_global_section", align 4
+@undefinedGlobalNotInSection = external global i32, align 4
+@main.multipleGlobalPragmas = hidden global i32 0, section ".global_section", align 1024
+
+declare noalias nonnull i8* @runtime.alloc(i32, i8*, i8*)
+
+define hidden void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define void @extern_func() #0 {
+entry:
+  ret void
+}
+
+define hidden void @somepkg.someFunction1(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+declare void @somepkg.someFunction2(i8*, i8*)
+
+; Function Attrs: inlinehint
+define hidden void @main.inlineFunc(i8* %context, i8* %parentHandle) unnamed_addr #1 {
+entry:
+  ret void
+}
+
+; Function Attrs: noinline
+define hidden void @main.noinlineFunc(i8* %context, i8* %parentHandle) unnamed_addr #2 {
+entry:
+  ret void
+}
+
+define hidden void @main.functionInSection(i8* %context, i8* %parentHandle) unnamed_addr section ".special_function_section" {
+entry:
+  ret void
+}
+
+define void @exportedFunctionInSection() #3 section ".special_function_section" {
+entry:
+  ret void
+}
+
+declare void @main.undefinedFunctionNotInSection(i8*, i8*)
+
+attributes #0 = { "wasm-export-name"="extern_func" }
+attributes #1 = { inlinehint }
+attributes #2 = { noinline }
+attributes #3 = { "wasm-export-name"="exportedFunctionInSection" }

go.mod

@@ -1,6 +1,6 @@
 module github.com/tinygo-org/tinygo
 
-go 1.13
+go 1.16
 
 require (
 	github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2

goenv/version.go

@@ -12,7 +12,7 @@ import (
 
 // Version of TinyGo.
 // Update this value before release of new version of software.
-const Version = "0.18.0"
+const Version = "0.20.0-dev"
 
 // GetGorootVersion returns the major and minor version for a given GOROOT path.
 // If the goroot cannot be determined, (0, 0) is returned.

interp/errors.go

@@ -57,6 +57,7 @@ func (r *runner) errorAt(inst instruction, err error) *Error {
 	pos := getPosition(inst.llvmInst)
 	return &Error{
 		ImportPath: r.pkgName,
+		Inst:       inst.llvmInst,
 		Pos:        pos,
 		Err:        err,
 		Traceback:  []ErrorLine{{pos, inst.llvmInst}},

interp/interp.go

@@ -15,7 +15,7 @@ import (
 // package is changed in a way that affects the output so that cached package
 // builds will be invalidated.
 // This version is independent of the TinyGo version number.
-const Version = 1
+const Version = 2 // last change: fix GEP on untyped pointers
 
 // Enable extra checks, which should be disabled by default.
 // This may help track down bugs by adding a few more sanity checks.
@@ -110,17 +110,26 @@ func Run(mod llvm.Module, debug bool) error {
 			fmt.Fprintln(os.Stderr, "call:", fn.Name())
 		}
 		_, mem, callErr := r.run(r.getFunction(fn), nil, nil, "    ")
+		call.EraseFromParentAsInstruction()
 		if callErr != nil {
 			if isRecoverableError(callErr.Err) {
 				if r.debug {
 					fmt.Fprintln(os.Stderr, "not interpreting", r.pkgName, "because of error:", callErr.Error())
 				}
+				// Remove instructions that were created as part of interpreting
+				// the package.
 				mem.revert()
+				// Create a call to the package initializer (which was
+				// previously deleted).
+				i8undef := llvm.Undef(r.i8ptrType)
+				r.builder.CreateCall(fn, []llvm.Value{i8undef, i8undef}, "")
+				// Make sure that any globals touched by the package
+				// initializer, won't be accessed by later package initializers.
+				r.markExternalLoad(fn)
 				continue
 			}
 			return callErr
 		}
-		call.EraseFromParentAsInstruction()
 		for index, obj := range mem.objects {
 			r.objects[index] = obj
 		}
@@ -129,7 +138,7 @@ func Run(mod llvm.Module, debug bool) error {
 
 	// Update all global variables in the LLVM module.
 	mem := memoryView{r: r}
-	for _, obj := range r.objects {
+	for i, obj := range r.objects {
 		if obj.llvmGlobal.IsNil() {
 			continue
 		}
@@ -159,6 +168,12 @@ func Run(mod llvm.Module, debug bool) error {
 			name := obj.llvmGlobal.Name()
 			obj.llvmGlobal.EraseFromParentAsGlobal()
 			newGlobal.SetName(name)
+
+			// Update interp-internal references.
+			delete(r.globals, obj.llvmGlobal)
+			obj.llvmGlobal = newGlobal
+			r.globals[newGlobal] = i
+			r.objects[i] = obj
 			continue
 		}
 		if err != nil {
@@ -264,3 +279,19 @@ func (r *runner) getFunction(llvmFn llvm.Value) *function {
 	r.functionCache[llvmFn] = fn
 	return fn
 }
+
+// markExternalLoad marks the given llvmValue as being loaded externally. This
+// is primarily used to mark package initializers that could not be run at
+// compile time. As an example, a package initialize might store to a global
+// variable. Another package initializer might read from the same global
+// variable. By marking this function as being run at runtime, that load
+// instruction will need to be run at runtime instead of at compile time.
+func (r *runner) markExternalLoad(llvmValue llvm.Value) {
+	mem := memoryView{r: r}
+	mem.markExternalLoad(llvmValue)
+	for index, obj := range mem.objects {
+		if obj.marked > r.objects[index].marked {
+			r.objects[index].marked = obj.marked
+		}
+	}
+}

interp/interp_test.go

@@ -17,6 +17,7 @@ func TestInterp(t *testing.T) {
 		"slice-copy",
 		"consteval",
 		"interface",
+		"revert",
 	} {
 		name := name // make tc local to this closure
 		t.Run(name, func(t *testing.T) {

interp/memory.go

@@ -178,6 +178,9 @@ func (mv *memoryView) markExternal(llvmValue llvm.Value, mark uint8) {
 		default:
 			panic("interp: unknown constant expression")
 		}
+	} else if !llvmValue.IsAInlineAsm().IsNil() {
+		// Inline assembly can modify globals but only exported globals. Let's
+		// hope the author knows what they're doing.
 	} else {
 		llvmType := llvmValue.Type()
 		switch llvmType.TypeKind() {
@@ -569,6 +572,17 @@ func (v pointerValue) toLLVMValue(llvmType llvm.Type, mem *memoryView) (llvm.Val
 	}
 
 	if llvmType.IsNil() {
+		if v.offset() != 0 {
+			// If there is an offset, make sure to use a GEP to index into the
+			// pointer. Because there is no expected type, we use whatever is
+			// most convenient: an *i8 type. It is trivial to index byte-wise.
+			if llvmValue.Type() != mem.r.i8ptrType {
+				llvmValue = llvm.ConstBitCast(llvmValue, mem.r.i8ptrType)
+			}
+			llvmValue = llvm.ConstInBoundsGEP(llvmValue, []llvm.Value{
+				llvm.ConstInt(llvmValue.Type().Context().Int32Type(), uint64(v.offset()), false),
+			})
+		}
 		return llvmValue, nil
 	}
 

interp/testdata/basic.ll

@@ -66,6 +66,9 @@ entry:
   call void @modifyExternal(i32* bitcast (void ()* @willModifyGlobal to i32*))
   store i16 7, i16* @main.exposedValue2
 
+  ; Test that inline assembly is ignored.
+  call void @modifyExternal(i32* bitcast (void ()* @hasInlineAsm to i32*))
+
   ; Test switch statement.
   %switch1 = call i64 @testSwitch(i64 1) ; 1 returns 6
   %switch2 = call i64 @testSwitch(i64 9) ; 9 returns the default value -1
@@ -102,6 +105,15 @@ entry:
   ret void
 }
 
+; Inline assembly should be ignored in the interp package. While it is possible
+; to modify other globals that way, usually that's not the case and there is no
+; real way to check.
+define void @hasInlineAsm() {
+entry:
+  call void asm sideeffect "", ""()
+  ret void
+}
+
 define i64 @testSwitch(i64 %val) {
 entry:
   ; Test switch statement.

interp/testdata/basic.out.ll

@@ -26,6 +26,7 @@ entry:
   store i16 5, i16* @main.exposedValue1
   call void @modifyExternal(i32* bitcast (void ()* @willModifyGlobal to i32*))
   store i16 7, i16* @main.exposedValue2
+  call void @modifyExternal(i32* bitcast (void ()* @hasInlineAsm to i32*))
   call void @runtime.printint64(i64 6)
   call void @runtime.printint64(i64 -1)
   %agg = call { i8, i32, { float, { i64, i16 } } } @nestedStruct()
@@ -59,6 +60,12 @@ entry:
   ret void
 }
 
+define void @hasInlineAsm() {
+entry:
+  call void asm sideeffect "", ""()
+  ret void
+}
+
 define i64 @testSwitch(i64 %val) local_unnamed_addr {
 entry:
   switch i64 %val, label %otherwise [

interp/testdata/revert.ll

@@ -0,0 +1,32 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+declare void @externalCall(i64)
+
+@foo.knownAtRuntime = global i64 0
+@bar.knownAtRuntime = global i64 0
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  call void @foo.init(i8* undef, i8* undef)
+  call void @bar.init(i8* undef, i8* undef)
+  call void @main.init(i8* undef, i8* undef)
+  ret void
+}
+
+define internal void @foo.init(i8* %context, i8* %parentHandle) unnamed_addr {
+  store i64 5, i64* @foo.knownAtRuntime
+  unreachable ; this triggers a revert of @foo.init.
+}
+
+define internal void @bar.init(i8* %context, i8* %parentHandle) unnamed_addr {
+  %val = load i64, i64* @foo.knownAtRuntime
+  store i64 %val, i64* @bar.knownAtRuntime
+  ret void
+}
+
+define internal void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  call void @externalCall(i64 3)
+  ret void
+}

interp/testdata/revert.out.ll

@@ -0,0 +1,21 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+@foo.knownAtRuntime = local_unnamed_addr global i64 0
+@bar.knownAtRuntime = local_unnamed_addr global i64 0
+
+declare void @externalCall(i64) local_unnamed_addr
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  call fastcc void @foo.init(i8* undef, i8* undef)
+  %val = load i64, i64* @foo.knownAtRuntime, align 8
+  store i64 %val, i64* @bar.knownAtRuntime, align 8
+  call void @externalCall(i64 3)
+  ret void
+}
+
+define internal fastcc void @foo.init(i8* %context, i8* %parentHandle) unnamed_addr {
+  store i64 5, i64* @foo.knownAtRuntime, align 8
+  unreachable
+}

loader/goroot.go

@@ -2,6 +2,14 @@ package loader
 
 // This file constructs a new temporary GOROOT directory by merging both the
 // standard Go GOROOT and the GOROOT from TinyGo using symlinks.
+//
+// The goal is to replace specific packages from Go with a TinyGo version. It's
+// never a partial replacement, either a package is fully replaced or it is not.
+// This is important because if we did allow to merge packages (e.g. by adding
+// files to a package), it would lead to a dependency on implementation details
+// with all the maintenance burden that results in. Only allowing to replace
+// packages as a whole avoids this as packages are already designed to have a
+// public (backwards-compatible) API.
 
 import (
 	"crypto/sha512"
@@ -139,6 +147,7 @@ func mergeDirectory(goroot, tinygoroot, tmpgoroot, importPath string, overrides
 		if err != nil {
 			return err
 		}
+		hasTinyGoFiles := false
 		for _, e := range tinygoEntries {
 			if e.IsDir() {
 				// A directory, so merge this thing.
@@ -154,6 +163,7 @@ func mergeDirectory(goroot, tinygoroot, tmpgoroot, importPath string, overrides
 				if err != nil {
 					return err
 				}
+				hasTinyGoFiles = true
 			}
 		}
 
@@ -164,21 +174,30 @@ func mergeDirectory(goroot, tinygoroot, tmpgoroot, importPath string, overrides
 			return err
 		}
 		for _, e := range gorootEntries {
-			if !e.IsDir() {
+			if e.IsDir() {
-				// Don't merge in files from Go. Otherwise we'd end up with a
+				if _, ok := overrides[path.Join(importPath, e.Name())+"/"]; ok {
-				// weird syscall package with files from both roots.
+					// Already included above, so don't bother trying to create this
-				continue
+					// symlink.
-			}
+					continue
-			if _, ok := overrides[path.Join(importPath, e.Name())+"/"]; ok {
+				}
-				// Already included above, so don't bother trying to create this
+				newname := filepath.Join(tmpgoroot, "src", importPath, e.Name())
-				// symlink.
+				oldname := filepath.Join(goroot, "src", importPath, e.Name())
-				continue
+				err := symlink(oldname, newname)
-			}
+				if err != nil {
-			newname := filepath.Join(tmpgoroot, "src", importPath, e.Name())
+					return err
-			oldname := filepath.Join(goroot, "src", importPath, e.Name())
+				}
-			err := symlink(oldname, newname)
+			} else {
-			if err != nil {
+				// Only merge files from Go if TinyGo does not have any files.
-				return err
+				// Otherwise we'd end up with a weird mix from both Go
+				// implementations.
+				if !hasTinyGoFiles {
+					newname := filepath.Join(tmpgoroot, "src", importPath, e.Name())
+					oldname := filepath.Join(goroot, "src", importPath, e.Name())
+					err := symlink(oldname, newname)
+					if err != nil {
+						return err
+					}
+				}
 			}
 		}
 	}
@@ -201,6 +220,8 @@ func needsSyscallPackage(buildTags []string) bool {
 func pathsToOverride(needsSyscallPackage bool) map[string]bool {
 	paths := map[string]bool{
 		"/":                     true,
+		"crypto/":               true,
+		"crypto/rand/":          false,
 		"device/":               false,
 		"examples/":             false,
 		"internal/":             true,
@@ -208,6 +229,7 @@ func pathsToOverride(needsSyscallPackage bool) map[string]bool {
 		"internal/reflectlite/": false,
 		"internal/task/":        false,
 		"machine/":              false,
+		"net/":                  true,
 		"os/":                   true,
 		"reflect/":              false,
 		"runtime/":              false,

loader/loader.go

@@ -343,12 +343,11 @@ func (p *Package) Check() error {
 	checker.Importer = p
 
 	packageName := p.ImportPath
-	if p.Name == "main" {
+	if p == p.program.MainPkg() {
-		// The main package normally has a different import path, such as
+		if p.Name != "main" {
-		// "command-line-arguments" or "./testdata/cgo". Therefore, use the name
+			// Sanity check. Should not ever trigger.
-		// "main" in such a case: this package isn't imported from anywhere.
+			panic("expected main package to have name 'main'")
-		// This is safe as it isn't possible to import a package with the name
+		}
-		// "main".
 		packageName = "main"
 	}
 	typesPkg, err := checker.Check(packageName, p.program.fset, p.Files, &p.info)

main.go

@@ -15,6 +15,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strconv"
 	"strings"
 	"sync/atomic"
 	"time"
@@ -95,12 +96,31 @@ func copyFile(src, dst string) error {
 
 // executeCommand is a simple wrapper to exec.Cmd
 func executeCommand(options *compileopts.Options, name string, arg ...string) *exec.Cmd {
-	if options.PrintCommands {
+	if options.PrintCommands != nil {
-		fmt.Printf("%s %s\n", name, strings.Join(arg, " "))
+		options.PrintCommands(name, arg...)
 	}
 	return exec.Command(name, arg...)
 }
 
+// printCommand prints a command to stdout while formatting it like a real
+// command (escaping characters etc). The resulting command should be easy to
+// run directly in a shell, although it is not guaranteed to be a safe shell
+// escape. That's not a problem as the primary use case is printing the command,
+// not running it.
+func printCommand(cmd string, args ...string) {
+	command := append([]string{cmd}, args...)
+	for i, arg := range command {
+		// Source: https://www.oreilly.com/library/view/learning-the-bash/1565923472/ch01s09.html
+		const specialChars = "~`#$&*()\\|[]{};'\"<>?! "
+		if strings.ContainsAny(arg, specialChars) {
+			// See: https://stackoverflow.com/questions/15783701/which-characters-need-to-be-escaped-when-using-bash
+			arg = "'" + strings.ReplaceAll(arg, `'`, `'\''`) + "'"
+			command[i] = arg
+		}
+	}
+	fmt.Fprintln(os.Stderr, strings.Join(command, " "))
+}
+
 // Build compiles and links the given package and writes it to outpath.
 func Build(pkgName, outpath string, options *compileopts.Options) error {
 	config, err := builder.NewConfig(options)
@@ -145,7 +165,7 @@ func Test(pkgName string, options *compileopts.Options, testCompileOnly bool, ou
 		return false, err
 	}
 
-	var passed bool
+	passed := true
 	err = builder.Build(pkgName, outpath, config, func(result builder.BuildResult) error {
 		if testCompileOnly || outpath != "" {
 			// Write test binary to the specified file name.
@@ -256,6 +276,8 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			fileExt = ".bin"
 		case strings.Contains(config.Target.FlashCommand, "{uf2}"):
 			fileExt = ".uf2"
+		case strings.Contains(config.Target.FlashCommand, "{zip}"):
+			fileExt = ".zip"
 		default:
 			return errors.New("invalid target file - did you forget the {hex} token in the 'flash-command' section?")
 		}
@@ -275,7 +297,7 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 	return builder.Build(pkgName, fileExt, config, func(result builder.BuildResult) error {
 		// do we need port reset to put MCU into bootloader mode?
 		if config.Target.PortReset == "true" && flashMethod != "openocd" {
-			port, err := getDefaultPort(strings.FieldsFunc(port, func(c rune) bool { return c == ',' }))
+			port, err := getDefaultPort(port, config.Target.SerialPort)
 			if err != nil {
 				return err
 			}
@@ -293,36 +315,36 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 		case "", "command":
 			// Create the command.
 			flashCmd := config.Target.FlashCommand
-			fileToken := "{" + fileExt[1:] + "}"
+			flashCmdList, err := shlex.Split(flashCmd)
-			flashCmd = strings.ReplaceAll(flashCmd, fileToken, result.Binary)
+			if err != nil {
+				return fmt.Errorf("could not parse flash command %#v: %w", flashCmd, err)
+			}
 
 			if strings.Contains(flashCmd, "{port}") {
 				var err error
-				port, err = getDefaultPort(strings.FieldsFunc(port, func(c rune) bool { return c == ',' }))
+				port, err = getDefaultPort(port, config.Target.SerialPort)
 				if err != nil {
 					return err
 				}
 			}
 
-			flashCmd = strings.ReplaceAll(flashCmd, "{port}", port)
+			// Fill in fields in the command template.
-
+			fileToken := "{" + fileExt[1:] + "}"
-			// Execute the command.
+			for i, arg := range flashCmdList {
-			var cmd *exec.Cmd
+				arg = strings.ReplaceAll(arg, fileToken, result.Binary)
-			switch runtime.GOOS {
+				arg = strings.ReplaceAll(arg, "{port}", port)
-			case "windows":
+				flashCmdList[i] = arg
-				command := strings.Split(flashCmd, " ")
-				if len(command) < 2 {
-					return errors.New("invalid flash command")
-				}
-				cmd = executeCommand(config.Options, command[0], command[1:]...)
-			default:
-				cmd = executeCommand(config.Options, "/bin/sh", "-c", flashCmd)
 			}
 
+			// Execute the command.
+			if len(flashCmdList) < 2 {
+				return fmt.Errorf("invalid flash command: %#v", flashCmd)
+			}
+			cmd := executeCommand(config.Options, flashCmdList[0], flashCmdList[1:]...)
 			cmd.Stdout = os.Stdout
 			cmd.Stderr = os.Stderr
 			cmd.Dir = goenv.Get("TINYGOROOT")
-			err := cmd.Run()
+			err = cmd.Run()
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
@@ -413,7 +435,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 		case "native":
 			// Run GDB directly.
 		case "openocd":
-			gdbCommands = append(gdbCommands, "target remote :3333", "monitor halt", "load", "monitor reset halt")
+			gdbCommands = append(gdbCommands, "target extended-remote :3333", "monitor halt", "load", "monitor reset halt")
 
 			// We need a separate debugging daemon for on-chip debugging.
 			args, err := config.OpenOCDConfiguration()
@@ -432,7 +454,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 				daemon.Stderr = w
 			}
 		case "jlink":
-			gdbCommands = append(gdbCommands, "target remote :2331", "load", "monitor reset halt")
+			gdbCommands = append(gdbCommands, "target extended-remote :2331", "load", "monitor reset halt")
 
 			// We need a separate debugging daemon for on-chip debugging.
 			daemon = executeCommand(config.Options, "JLinkGDBServer", "-device", config.Target.JLinkDevice)
@@ -447,7 +469,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 				daemon.Stderr = w
 			}
 		case "qemu":
-			gdbCommands = append(gdbCommands, "target remote :1234")
+			gdbCommands = append(gdbCommands, "target extended-remote :1234")
 
 			// Run in an emulator.
 			args := append(config.Target.Emulator[1:], result.Binary, "-s", "-S")
@@ -455,7 +477,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "qemu-user":
-			gdbCommands = append(gdbCommands, "target remote :1234")
+			gdbCommands = append(gdbCommands, "target extended-remote :1234")
 
 			// Run in an emulator.
 			args := append(config.Target.Emulator[1:], "-g", "1234", result.Binary)
@@ -463,7 +485,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "mgba":
-			gdbCommands = append(gdbCommands, "target remote :2345")
+			gdbCommands = append(gdbCommands, "target extended-remote :2345")
 
 			// Run in an emulator.
 			args := append(config.Target.Emulator[1:], result.Binary, "-g")
@@ -471,7 +493,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
 		case "simavr":
-			gdbCommands = append(gdbCommands, "target remote :1234")
+			gdbCommands = append(gdbCommands, "target extended-remote :1234")
 
 			// Run in an emulator.
 			args := append(config.Target.Emulator[1:], "-g", result.Binary)
@@ -697,7 +719,8 @@ func windowsFindUSBDrive(volume string, options *compileopts.Options) (string, e
 }
 
 // getDefaultPort returns the default serial port depending on the operating system.
-func getDefaultPort(portCandidates []string) (port string, err error) {
+func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err error) {
+	portCandidates := strings.FieldsFunc(portFlag, func(c rune) bool { return c == ',' })
 	if len(portCandidates) == 1 {
 		return portCandidates[0], nil
 	}
@@ -713,13 +736,70 @@ func getDefaultPort(portCandidates []string) (port string, err error) {
 			return "", err
 		}
 
-		for _, p := range portsList {
+		var preferredPortIDs [][2]uint16
-			if p.IsUSB {
+		for _, s := range usbInterfaces {
-				ports = append(ports, p.Name)
+			parts := strings.Split(s, ":")
+			if len(parts) != 3 || (parts[0] != "acm" && parts[0] == "usb") {
+				// acm and usb are the two types of serial ports recognized
+				// under Linux (ttyACM*, ttyUSB*). Other operating systems don't
+				// generally make this distinction. If this is not one of the
+				// given USB devices, don't try to parse the USB IDs.
+				continue
 			}
+			vid, err := strconv.ParseUint(parts[1], 16, 16)
+			if err != nil {
+				return "", fmt.Errorf("could not parse USB vendor ID %q: %w", parts[1], err)
+			}
+			pid, err := strconv.ParseUint(parts[2], 16, 16)
+			if err != nil {
+				return "", fmt.Errorf("could not parse USB product ID %q: %w", parts[1], err)
+			}
+			preferredPortIDs = append(preferredPortIDs, [2]uint16{uint16(vid), uint16(pid)})
 		}
 
-		if ports == nil || len(ports) == 0 {
+		var primaryPorts []string   // ports picked from preferred USB VID/PID
+		var secondaryPorts []string // other ports (as a fallback)
+		for _, p := range portsList {
+			if !p.IsUSB {
+				continue
+			}
+			if p.VID != "" && p.PID != "" {
+				foundPort := false
+				vid, vidErr := strconv.ParseUint(p.VID, 16, 16)
+				pid, pidErr := strconv.ParseUint(p.PID, 16, 16)
+				if vidErr == nil && pidErr == nil {
+					for _, id := range preferredPortIDs {
+						if uint16(vid) == id[0] && uint16(pid) == id[1] {
+							primaryPorts = append(primaryPorts, p.Name)
+							foundPort = true
+							continue
+						}
+					}
+				}
+				if foundPort {
+					continue
+				}
+			}
+
+			secondaryPorts = append(secondaryPorts, p.Name)
+		}
+		if len(primaryPorts) == 1 {
+			// There is exactly one match in the set of preferred ports. Use
+			// this port, even if there may be others available. This allows
+			// flashing a specific board even if there are multiple available.
+			return primaryPorts[0], nil
+		} else if len(primaryPorts) > 1 {
+			// There are multiple preferred ports, probably because more than
+			// one device of the same type are connected (e.g. two Arduino
+			// Unos).
+			ports = primaryPorts
+		} else {
+			// No preferred ports found. Fall back to other serial ports
+			// available in the system.
+			ports = secondaryPorts
+		}
+
+		if len(ports) == 0 {
 			// fallback
 			switch runtime.GOOS {
 			case "darwin":
@@ -929,6 +1009,7 @@ func main() {
 	gc := flag.String("gc", "", "garbage collector to use (none, leaking, extalloc, conservative)")
 	panicStrategy := flag.String("panic", "print", "panic strategy (print, trap)")
 	scheduler := flag.String("scheduler", "", "which scheduler to use (none, coroutines, tasks)")
+	serial := flag.String("serial", "", "which serial output to use (none, uart, usb)")
 	printIR := flag.Bool("printir", false, "print LLVM IR")
 	dumpSSA := flag.Bool("dumpssa", false, "dump internal Go SSA")
 	verifyIR := flag.Bool("verifyir", false, "run extra verification steps on LLVM IR")
@@ -947,10 +1028,11 @@ func main() {
 	wasmAbi := flag.String("wasm-abi", "", "WebAssembly ABI conventions: js (no i64 params) or generic")
 	llvmFeatures := flag.String("llvm-features", "", "comma separated LLVM features to enable")
 
-	var flagJSON, flagDeps *bool
+	var flagJSON, flagDeps, flagTest *bool
 	if command == "help" || command == "list" {
 		flagJSON = flag.Bool("json", false, "print data in JSON format")
-		flagDeps = flag.Bool("deps", false, "")
+		flagDeps = flag.Bool("deps", false, "supply -deps flag to go list")
+		flagTest = flag.Bool("test", false, "supply -test flag to go list")
 	}
 	var outpath string
 	if command == "help" || command == "build" || command == "build-library" || command == "test" {
@@ -1000,6 +1082,7 @@ func main() {
 		GC:              *gc,
 		PanicStrategy:   *panicStrategy,
 		Scheduler:       *scheduler,
+		Serial:          *serial,
 		PrintIR:         *printIR,
 		DumpSSA:         *dumpSSA,
 		VerifyIR:        *verifyIR,
@@ -1007,7 +1090,6 @@ func main() {
 		PrintSizes:      *printSize,
 		PrintStacks:     *printStacks,
 		PrintAllocs:     printAllocs,
-		PrintCommands:   *printCommands,
 		Tags:            *tags,
 		GlobalValues:    globalVarValues,
 		WasmAbi:         *wasmAbi,
@@ -1015,6 +1097,9 @@ func main() {
 		OpenOCDCommands: ocdCommands,
 		LLVMFeatures:    *llvmFeatures,
 	}
+	if *printCommands {
+		options.PrintCommands = printCommand
+	}
 
 	os.Setenv("CC", "clang -target="+*target)
 
@@ -1200,6 +1285,9 @@ func main() {
 		if *flagDeps {
 			extraArgs = append(extraArgs, "-deps")
 		}
+		if *flagTest {
+			extraArgs = append(extraArgs, "-test")
+		}
 		cmd, err := loader.List(config, extraArgs, flag.Args())
 		if err != nil {
 			fmt.Fprintln(os.Stderr, "failed to run `go list`:", err)

main_test.go

@@ -35,9 +35,9 @@ func TestCompiler(t *testing.T) {
 		"calls.go",
 		"cgo/",
 		"channel.go",
-		"coroutines.go",
 		"float.go",
 		"gc.go",
+		"goroutines.go",
 		"init.go",
 		"init_multi.go",
 		"interface.go",
@@ -125,7 +125,7 @@ func TestCompiler(t *testing.T) {
 		// Test with few optimizations enabled (no inlining, etc).
 		t.Run("opt=1", func(t *testing.T) {
 			t.Parallel()
-			runTestWithConfig("stdlib.go", "", t, &compileopts.Options{
+			runTestWithConfig("stdlib.go", "", t, compileopts.Options{
 				Opt: "1",
 			}, nil, nil)
 		})
@@ -134,15 +134,14 @@ func TestCompiler(t *testing.T) {
 		// TODO: fix this for stdlib.go, which currently fails.
 		t.Run("opt=0", func(t *testing.T) {
 			t.Parallel()
-			runTestWithConfig("print.go", "", t, &compileopts.Options{
+			runTestWithConfig("print.go", "", t, compileopts.Options{
 				Opt: "0",
 			}, nil, nil)
 		})
 
 		t.Run("ldflags", func(t *testing.T) {
 			t.Parallel()
-			runTestWithConfig("ldflags.go", "", t, &compileopts.Options{
+			runTestWithConfig("ldflags.go", "", t, compileopts.Options{
-				Opt: "z",
 				GlobalValues: map[string]map[string]string{
 					"main": {
 						"someGlobal": "foobar",
@@ -188,20 +187,20 @@ func runBuild(src, out string, opts *compileopts.Options) error {
 }
 
 func runTest(name, target string, t *testing.T, cmdArgs, environmentVars []string) {
-	options := &compileopts.Options{
+	options := compileopts.Options{
-		Target:     target,
+		Target: target,
-		Opt:        "z",
-		PrintIR:    false,
-		DumpSSA:    false,
-		VerifyIR:   true,
-		Debug:      true,
-		PrintSizes: "",
-		WasmAbi:    "",
 	}
 	runTestWithConfig(name, target, t, options, cmdArgs, environmentVars)
 }
 
-func runTestWithConfig(name, target string, t *testing.T, options *compileopts.Options, cmdArgs, environmentVars []string) {
+func runTestWithConfig(name, target string, t *testing.T, options compileopts.Options, cmdArgs, environmentVars []string) {
+	// Set default config.
+	options.Debug = true
+	options.VerifyIR = true
+	if options.Opt == "" {
+		options.Opt = "z"
+	}
+
 	// Get the expected output for this test.
 	// Note: not using filepath.Join as it strips the path separator at the end
 	// of the path.
@@ -230,7 +229,7 @@ func runTestWithConfig(name, target string, t *testing.T, options *compileopts.O
 
 	// Build the test binary.
 	binary := filepath.Join(tmpdir, "test")
-	err = runBuild("./"+path, binary, options)
+	err = runBuild("./"+path, binary, &options)
 	if err != nil {
 		printCompilerError(t.Log, err)
 		t.Fail()

src/crypto/rand/rand.go

@@ -0,0 +1,19 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package rand implements a cryptographically secure
+// random number generator.
+package rand
+
+import "io"
+
+// Reader is a global, shared instance of a cryptographically
+// secure random number generator.
+var Reader io.Reader
+
+// Read is a helper function that calls Reader.Read using io.ReadFull.
+// On return, n == len(b) if and only if err == nil.
+func Read(b []byte) (n int, err error) {
+	return io.ReadFull(Reader, b)
+}

src/crypto/rand/rand_getentropy.go

@@ -0,0 +1,38 @@
+// +build darwin freebsd wasi
+
+// This implementation of crypto/rand uses the getentropy system call (available
+// on both MacOS and WASI) to generate random numbers.
+
+package rand
+
+import (
+	"errors"
+	"unsafe"
+)
+
+var errReadFailed = errors.New("rand: could not read random bytes")
+
+func init() {
+	Reader = &reader{}
+}
+
+type reader struct {
+}
+
+func (r *reader) Read(b []byte) (n int, err error) {
+	if len(b) != 0 {
+		if len(b) > 256 {
+			b = b[:256]
+		}
+		result := libc_getentropy(unsafe.Pointer(&b[0]), len(b))
+		if result < 0 {
+			// Maybe we should return a syscall.Errno here?
+			return 0, errReadFailed
+		}
+	}
+	return len(b), nil
+}
+
+// int getentropy(void *buf, size_t buflen);
+//export getentropy
+func libc_getentropy(buf unsafe.Pointer, buflen int) int

src/crypto/rand/rand_urandom.go

@@ -0,0 +1,38 @@
+// +build linux,!baremetal,!wasi
+
+// This implementation of crypto/rand uses the /dev/urandom pseudo-file to
+// generate random numbers.
+// TODO: convert to the getentropy or getrandom libc function on Linux once it
+// is more widely supported.
+
+package rand
+
+import (
+	"syscall"
+)
+
+func init() {
+	Reader = &reader{}
+}
+
+type reader struct {
+	fd int
+}
+
+func (r *reader) Read(b []byte) (n int, err error) {
+	if len(b) == 0 {
+		return
+	}
+
+	// Open /dev/urandom first if needed.
+	if r.fd == 0 {
+		fd, err := syscall.Open("/dev/urandom", syscall.O_RDONLY, 0)
+		if err != nil {
+			return 0, err
+		}
+		r.fd = fd
+	}
+
+	// Read from the file.
+	return syscall.Read(r.fd, b)
+}

src/crypto/rand/util.go

@@ -0,0 +1,143 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package rand
+
+import (
+	"errors"
+	"io"
+	"math/big"
+)
+
+// smallPrimes is a list of small, prime numbers that allows us to rapidly
+// exclude some fraction of composite candidates when searching for a random
+// prime. This list is truncated at the point where smallPrimesProduct exceeds
+// a uint64. It does not include two because we ensure that the candidates are
+// odd by construction.
+var smallPrimes = []uint8{
+	3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53,
+}
+
+// smallPrimesProduct is the product of the values in smallPrimes and allows us
+// to reduce a candidate prime by this number and then determine whether it's
+// coprime to all the elements of smallPrimes without further big.Int
+// operations.
+var smallPrimesProduct = new(big.Int).SetUint64(16294579238595022365)
+
+// Prime returns a number, p, of the given size, such that p is prime
+// with high probability.
+// Prime will return error for any error returned by rand.Read or if bits < 2.
+func Prime(rand io.Reader, bits int) (p *big.Int, err error) {
+	if bits < 2 {
+		err = errors.New("crypto/rand: prime size must be at least 2-bit")
+		return
+	}
+
+	b := uint(bits % 8)
+	if b == 0 {
+		b = 8
+	}
+
+	bytes := make([]byte, (bits+7)/8)
+	p = new(big.Int)
+
+	bigMod := new(big.Int)
+
+	for {
+		_, err = io.ReadFull(rand, bytes)
+		if err != nil {
+			return nil, err
+		}
+
+		// Clear bits in the first byte to make sure the candidate has a size <= bits.
+		bytes[0] &= uint8(int(1<<b) - 1)
+		// Don't let the value be too small, i.e, set the most significant two bits.
+		// Setting the top two bits, rather than just the top bit,
+		// means that when two of these values are multiplied together,
+		// the result isn't ever one bit short.
+		if b >= 2 {
+			bytes[0] |= 3 << (b - 2)
+		} else {
+			// Here b==1, because b cannot be zero.
+			bytes[0] |= 1
+			if len(bytes) > 1 {
+				bytes[1] |= 0x80
+			}
+		}
+		// Make the value odd since an even number this large certainly isn't prime.
+		bytes[len(bytes)-1] |= 1
+
+		p.SetBytes(bytes)
+
+		// Calculate the value mod the product of smallPrimes. If it's
+		// a multiple of any of these primes we add two until it isn't.
+		// The probability of overflowing is minimal and can be ignored
+		// because we still perform Miller-Rabin tests on the result.
+		bigMod.Mod(p, smallPrimesProduct)
+		mod := bigMod.Uint64()
+
+	NextDelta:
+		for delta := uint64(0); delta < 1<<20; delta += 2 {
+			m := mod + delta
+			for _, prime := range smallPrimes {
+				if m%uint64(prime) == 0 && (bits > 6 || m != uint64(prime)) {
+					continue NextDelta
+				}
+			}
+
+			if delta > 0 {
+				bigMod.SetUint64(delta)
+				p.Add(p, bigMod)
+			}
+			break
+		}
+
+		// There is a tiny possibility that, by adding delta, we caused
+		// the number to be one bit too long. Thus we check BitLen
+		// here.
+		if p.ProbablyPrime(20) && p.BitLen() == bits {
+			return
+		}
+	}
+}
+
+// Int returns a uniform random value in [0, max). It panics if max <= 0.
+func Int(rand io.Reader, max *big.Int) (n *big.Int, err error) {
+	if max.Sign() <= 0 {
+		panic("crypto/rand: argument to Int is <= 0")
+	}
+	n = new(big.Int)
+	n.Sub(max, n.SetUint64(1))
+	// bitLen is the maximum bit length needed to encode a value < max.
+	bitLen := n.BitLen()
+	if bitLen == 0 {
+		// the only valid result is 0
+		return
+	}
+	// k is the maximum byte length needed to encode a value < max.
+	k := (bitLen + 7) / 8
+	// b is the number of bits in the most significant byte of max-1.
+	b := uint(bitLen % 8)
+	if b == 0 {
+		b = 8
+	}
+
+	bytes := make([]byte, k)
+
+	for {
+		_, err = io.ReadFull(rand, bytes)
+		if err != nil {
+			return nil, err
+		}
+
+		// Clear bits in the first byte to increase the probability
+		// that the candidate is < max.
+		bytes[0] &= uint8(int(1<<b) - 1)
+
+		n.SetBytes(bytes)
+		if n.Cmp(max) < 0 {
+			return
+		}
+	}
+}

src/examples/echo/echo.go

@@ -9,7 +9,7 @@ import (
 
 // change these to test a different UART or pins if available
 var (
-	uart = machine.UART0
+	uart = machine.Serial
 	tx   = machine.UART_TX_PIN
 	rx   = machine.UART_RX_PIN
 )

src/examples/embed/embed.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"embed"
+	"log"
+)
+
+//go:embed file*.txt
+//go:embed index.html styles.css
+var files embed.FS
+
+func main() {
+	println(".....")
+	println(msg)
+	contents, err := files.ReadDir(".")
+	if err != nil {
+		log.Fatal(err)
+	}
+	for _, c := range contents {
+		println("file:", c.Name())
+	}
+}

src/examples/embed/file1.txt

@@ -0,0 +1 @@
+file 1

src/examples/embed/file2.txt

@@ -0,0 +1 @@
+file 2

src/examples/embed/file3.txt

@@ -0,0 +1 @@
+file 3

src/examples/embed/message.txt

@@ -0,0 +1 @@
+hello world!

src/examples/embed/test.go

@@ -0,0 +1,6 @@
+package main
+
+import _ "embed"
+
+//go:embed message.txt
+var msg string

src/examples/memstats/memstats.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"math/rand"
+	"runtime"
+	"time"
+)
+
+func main() {
+
+	ms := runtime.MemStats{}
+
+	for {
+		escapesToHeap()
+		runtime.ReadMemStats(&ms)
+		println("Heap before GC. Used: ", ms.HeapInuse, " Free: ", ms.HeapIdle, " Meta: ", ms.GCSys)
+		runtime.GC()
+		runtime.ReadMemStats(&ms)
+		println("Heap after  GC. Used: ", ms.HeapInuse, " Free: ", ms.HeapIdle, " Meta: ", ms.GCSys)
+		time.Sleep(5 * time.Second)
+	}
+
+}
+
+func escapesToHeap() {
+	n := rand.Intn(100)
+	println("Doing ", n, " iterations")
+	for i := 0; i < n; i++ {
+		s := make([]byte, i)
+		_ = append(s, 42)
+	}
+}

src/examples/pininterrupt/stm32.go

@@ -0,0 +1,10 @@
+// +build stm32
+
+package main
+
+import "machine"
+
+const (
+	buttonMode      = machine.PinInputPulldown
+	buttonPinChange = machine.PinRising | machine.PinFalling
+)

src/examples/pwm/bluepill.go

@@ -0,0 +1,11 @@
+// +build bluepill
+
+package main
+
+import "machine"
+
+var (
+	pwm  = &machine.TIM2
+	pinA = machine.PA0
+	pinB = machine.PA1
+)

src/examples/pwm/nucleo-f722ze.go

@@ -0,0 +1,11 @@
+// +build stm32f7
+
+package main
+
+import "machine"
+
+var (
+	pwm  = &machine.TIM1
+	pinA = machine.PA8
+	pinB = machine.PA9
+)

src/examples/pwm/nucleo-l031k6.go

@@ -0,0 +1,11 @@
+// +build stm32l0
+
+package main
+
+import "machine"
+
+var (
+	pwm  = &machine.TIM2
+	pinA = machine.PA0
+	pinB = machine.PB3
+)

src/examples/pwm/nucleo-l432kc.go

@@ -0,0 +1,11 @@
+// +build stm32l4
+
+package main
+
+import "machine"
+
+var (
+	pwm  = &machine.TIM2
+	pinA = machine.PA0
+	pinB = machine.PB3
+)

src/examples/pwm/nucleo-l552ze.go

@@ -0,0 +1,11 @@
+// +build stm32l5
+
+package main
+
+import "machine"
+
+var (
+	pwm  = &machine.TIM1
+	pinA = machine.PA8
+	pinB = machine.PA9
+)

src/examples/pwm/stm32f4disco.go

@@ -0,0 +1,13 @@
+// +build stm32f4disco
+
+package main
+
+import "machine"
+
+var (
+	// These pins correspond to LEDs on the discovery
+	// board
+	pwm  = &machine.TIM4
+	pinA = machine.PD12
+	pinB = machine.PD13
+)

src/internal/task/task.go

@@ -13,7 +13,7 @@ type Task struct {
 	Ptr unsafe.Pointer
 
 	// Data is a field which can be used for storing state information.
-	Data uint
+	Data uint64
 
 	// state is the underlying running state of the task.
 	state state

src/machine/board_arduino_mkr1000.go

@@ -47,7 +47,7 @@ const (
 	LED = D6
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN Pin = PA24
 	USBCDC_DP_PIN Pin = PA25

src/machine/board_arduino_nano33.go

@@ -46,7 +46,7 @@ const (
 	LED = D13
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN Pin = PA24
 	USBCDC_DP_PIN Pin = PA25

src/machine/board_arduino_nano33_baremetal.go

@@ -9,7 +9,8 @@ import (
 
 // UART1 on the Arduino Nano 33 connects to the onboard NINA-W102 WiFi chip.
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM3_USART,
 		SERCOM: 3,
@@ -18,7 +19,8 @@ var (
 
 // UART2 on the Arduino Nano 33 connects to the normal TX/RX pins.
 var (
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM5_USART,
 		SERCOM: 5,
@@ -26,8 +28,8 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM3, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM3, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM5, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM5, _UART2.handleInterrupt)
 }
 
 // I2C on the Arduino Nano 33.

src/machine/board_atsame54-xpro.go

@@ -152,7 +152,7 @@ const (
 	PIN_USB_ID      = PC19
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25
@@ -240,28 +240,32 @@ var (
 // UART on the SAM E54 Xplained Pro
 var (
 	// Extension Header EXT1
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
 		SERCOM: 0,
 	}
 
 	// Extension Header EXT2
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM5_USART_INT,
 		SERCOM: 5,
 	}
 
 	// Extension Header EXT3
-	UART3 = UART{
+	UART3  = &_UART3
+	_UART3 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM1_USART_INT,
 		SERCOM: 1,
 	}
 
 	// EDBG Virtual COM Port
-	UART4 = UART{
+	UART4  = &_UART4
+	_UART4 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM2_USART_INT,
 		SERCOM: 2,
@@ -269,10 +273,10 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, _UART2.handleInterrupt)
-	UART3.Interrupt = interrupt.New(sam.IRQ_SERCOM1_2, UART3.handleInterrupt)
+	UART3.Interrupt = interrupt.New(sam.IRQ_SERCOM1_2, _UART3.handleInterrupt)
-	UART4.Interrupt = interrupt.New(sam.IRQ_SERCOM2_2, UART4.handleInterrupt)
+	UART4.Interrupt = interrupt.New(sam.IRQ_SERCOM2_2, _UART4.handleInterrupt)
 }
 
 // I2C on the SAM E54 Xplained Pro

src/machine/board_bluepill.go

@@ -7,49 +7,18 @@ import (
 	"runtime/interrupt"
 )
 
-// https://wiki.stm32duino.com/index.php?title=File:Bluepillpinout.gif
-const (
-	PA0  = portA + 0
-	PA1  = portA + 1
-	PA2  = portA + 2
-	PA3  = portA + 3
-	PA4  = portA + 4
-	PA5  = portA + 5
-	PA6  = portA + 6
-	PA7  = portA + 7
-	PA8  = portA + 8
-	PA9  = portA + 9
-	PA10 = portA + 10
-	PA11 = portA + 11
-	PA12 = portA + 12
-	PA13 = portA + 13
-	PA14 = portA + 14
-	PA15 = portA + 15
-	PB0  = portB + 0
-	PB1  = portB + 1
-	PB2  = portB + 2
-	PB3  = portB + 3
-	PB4  = portB + 4
-	PB5  = portB + 5
-	PB6  = portB + 6
-	PB7  = portB + 7
-	PB8  = portB + 8
-	PB9  = portB + 9
-	PB10 = portB + 10
-	PB11 = portB + 11
-	PB12 = portB + 12
-	PB13 = portB + 13
-	PB14 = portB + 14
-	PB15 = portB + 15
-	PC13 = portC + 13
-	PC14 = portC + 14
-	PC15 = portC + 15
-)
-
 const (
 	LED = PC13
 )
 
+const (
+	// This board does not have a user button, so
+	// use first GPIO pin by default
+	BUTTON = PA0
+)
+
+var DefaultUART = UART1
+
 // UART pins
 const (
 	UART_TX_PIN     = PA9
@@ -60,20 +29,21 @@ const (
 
 var (
 	// USART1 is the first hardware serial port on the STM32.
-	// Both UART0 and UART1 refer to USART1.
+	UART1  = &_UART1
-	UART0 = UART{
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    stm32.USART1,
 	}
-	UART1 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    stm32.USART2,
 	}
 )
 
 func init() {
-	UART0.Interrupt = interrupt.New(stm32.IRQ_USART1, UART0.handleInterrupt)
+	UART1.Interrupt = interrupt.New(stm32.IRQ_USART1, _UART1.handleInterrupt)
-	UART1.Interrupt = interrupt.New(stm32.IRQ_USART2, UART1.handleInterrupt)
+	UART2.Interrupt = interrupt.New(stm32.IRQ_USART2, _UART2.handleInterrupt)
 }
 
 // SPI pins

src/machine/board_circuitplay_bluefruit.go

@@ -38,6 +38,7 @@ const (
 const (
 	LED       = D13
 	NEOPIXELS = D8
+	WS2812    = D8
 
 	BUTTONA = D4
 	BUTTONB = D5
@@ -56,11 +57,6 @@ const (
 	UART_RX_PIN = P0_30 // PORTB
 )
 
-// UART0 is the USB device
-var (
-	UART0 = &USB
-)
-
 // I2C pins
 const (
 	SDA_PIN = P0_05 // I2C0 external

src/machine/board_circuitplay_express.go

@@ -41,6 +41,7 @@ const (
 const (
 	LED       = D13
 	NEOPIXELS = D8
+	WS2812    = D8
 
 	BUTTONA = D4
 	BUTTONB = D5

src/machine/board_circuitplay_express_baremetal.go

@@ -9,7 +9,8 @@ import (
 
 // UART1 on the Circuit Playground Express.
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM4_USART,
 		SERCOM: 4,
@@ -17,7 +18,7 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM4, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM4, _UART1.handleInterrupt)
 }
 
 // I2C on the Circuit Playground Express.

src/machine/board_clue_alpha.go

@@ -72,6 +72,7 @@ const (
 	LED1     = LED
 	LED2     = D43
 	NEOPIXEL = D18
+	WS2812   = D18
 
 	BUTTON_LEFT  = D5
 	BUTTON_RIGHT = D11
@@ -103,11 +104,6 @@ const (
 	UART_TX_PIN = D1
 )
 
-// UART0 is the USB device
-var (
-	UART0 = &USB
-)
-
 // I2C pins
 const (
 	SDA_PIN = D20 // I2C0 external

src/machine/board_feather-m0.go

@@ -42,7 +42,7 @@ const (
 	LED = D13
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25
@@ -56,7 +56,8 @@ const (
 
 // UART1 on the Feather M0.
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM1_USART,
 		SERCOM: 1,
@@ -64,7 +65,7 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM1, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM1, _UART1.handleInterrupt)
 }
 
 // I2C pins

src/machine/board_feather-m4-can.go

@@ -44,9 +44,10 @@ const (
 const (
 	LED       = D13
 	NEOPIXELS = D8
+	WS2812    = D8
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25
@@ -103,13 +104,15 @@ var (
 )
 
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM5_USART_INT,
 		SERCOM: 5,
 	}
 
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
 		SERCOM: 0,
@@ -117,8 +120,8 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, _UART2.handleInterrupt)
 
 	// turn on neopixel
 	D7.Configure(PinConfig{Mode: PinOutput})

src/machine/board_feather-m4.go

@@ -36,10 +36,11 @@ const (
 )
 
 const (
-	LED = D13
+	LED    = D13
+	WS2812 = D8
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25

src/machine/board_feather-m4_baremetal.go

@@ -8,13 +8,15 @@ import (
 )
 
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM5_USART_INT,
 		SERCOM: 5,
 	}
 
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
 		SERCOM: 0,
@@ -22,8 +24,8 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, _UART2.handleInterrupt)
 }
 
 // I2C on the Feather M4.

src/machine/board_feather-nrf52840-sense.go

@@ -0,0 +1,101 @@
+// +build feather_nrf52840_sense
+
+package machine
+
+const HasLowFrequencyCrystal = true
+
+// GPIO Pins
+const (
+	D0  = P0_25 // UART TX
+	D1  = P0_24 // UART RX
+	D2  = P0_10 // NFC2
+	D3  = P1_11
+	D4  = P1_10 // LED2
+	D5  = P1_08
+	D6  = P0_07
+	D7  = P1_02 // Button
+	D8  = P0_16 // NeoPixel
+	D9  = P0_26
+	D10 = P0_27
+	D11 = P0_06
+	D12 = P0_08
+	D13 = P1_09 // LED1
+	D14 = P0_04 // A0
+	D15 = P0_05 // A1
+	D16 = P0_30 // A2
+	D17 = P0_28 // A3
+	D18 = P0_02 // A4
+	D19 = P0_03 // A5
+	D20 = P0_29 // Battery
+	D21 = P0_31 // AREF
+	D22 = P0_12 // I2C SDA
+	D23 = P0_11 // I2C SCL
+	D24 = P0_15 // SPI MISO
+	D25 = P0_13 // SPI MOSI
+	D26 = P0_14 // SPI SCK
+	D27 = P0_19 // QSPI CLK
+	D28 = P0_20 // QSPI CS
+	D29 = P0_17 // QSPI Data 0
+	D30 = P0_22 // QSPI Data 1
+	D31 = P0_23 // QSPI Data 2
+	D32 = P0_21 // QSPI Data 3
+	D33 = P0_09 // NFC1 (test point on bottom of board)
+)
+
+// Analog Pins
+const (
+	A0 = D14
+	A1 = D15
+	A2 = D16
+	A3 = D17
+	A4 = D18
+	A5 = D19
+	A6 = D20 // Battery
+	A7 = D21 // ARef
+)
+
+const (
+	LED      = D13
+	LED1     = LED
+	LED2     = D4
+	NEOPIXEL = D8
+	WS2812   = D8
+	BUTTON   = D7
+
+	QSPI_SCK   = D27
+	QSPI_CS    = D28
+	QSPI_DATA0 = D29
+	QSPI_DATA1 = D30
+	QSPI_DATA2 = D31
+	QSPI_DATA3 = D32
+)
+
+// UART0 pins (logical UART1)
+const (
+	UART_RX_PIN = D0
+	UART_TX_PIN = D1
+)
+
+// I2C pins
+const (
+	SDA_PIN = D22 // I2C0 external
+	SCL_PIN = D23 // I2C0 external
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN = D26 // SCK
+	SPI0_SDO_PIN = D25 // SDO
+	SPI0_SDI_PIN = D24 // SDI
+)
+
+// USB CDC identifiers
+const (
+	usb_STRING_PRODUCT      = "Feather nRF52840 Express"
+	usb_STRING_MANUFACTURER = "Adafruit Industries LLC"
+)
+
+var (
+	usb_VID uint16 = 0x239A
+	usb_PID uint16 = 0x8088
+)

src/machine/board_feather-nrf52840.go

@@ -59,6 +59,7 @@ const (
 	LED1     = LED
 	LED2     = D4
 	NEOPIXEL = D8
+	WS2812   = D8
 	BUTTON   = D7
 
 	QSPI_SCK   = D27
@@ -75,11 +76,6 @@ const (
 	UART_TX_PIN = D1
 )
 
-// UART0 is the USB device
-var (
-	UART0 = &USB
-)
-
 // I2C pins
 const (
 	SDA_PIN = D22 // I2C0 external

src/machine/board_feather-stm32f405.go

@@ -84,6 +84,7 @@ const (
 	LED_NEOPIXEL = D8
 	LED_BUILTIN  = LED_RED
 	LED          = LED_BUILTIN
+	WS2812       = D8
 )
 
 func initLED() {}
@@ -119,31 +120,34 @@ const (
 )
 
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer:            NewRingBuffer(),
 		Bus:               stm32.USART3,
 		TxAltFuncSelector: AF7_USART1_2_3,
 		RxAltFuncSelector: AF7_USART1_2_3,
 	}
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer:            NewRingBuffer(),
 		Bus:               stm32.USART6,
 		TxAltFuncSelector: AF8_USART4_5_6,
 		RxAltFuncSelector: AF8_USART4_5_6,
 	}
-	UART3 = UART{
+	UART3  = &_UART3
+	_UART3 = UART{
 		Buffer:            NewRingBuffer(),
 		Bus:               stm32.USART1,
 		TxAltFuncSelector: AF7_USART1_2_3,
 		RxAltFuncSelector: AF7_USART1_2_3,
 	}
-	UART0 = UART1
+	DefaultUART = UART1
 )
 
 func initUART() {
-	UART1.Interrupt = interrupt.New(stm32.IRQ_USART3, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(stm32.IRQ_USART3, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(stm32.IRQ_USART6, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(stm32.IRQ_USART6, _UART2.handleInterrupt)
-	UART3.Interrupt = interrupt.New(stm32.IRQ_USART1, UART3.handleInterrupt)
+	UART3.Interrupt = interrupt.New(stm32.IRQ_USART1, _UART3.handleInterrupt)
 }
 
 // -- SPI ----------------------------------------------------------------------

src/machine/board_feather_rp2040.go

@@ -0,0 +1,10 @@
+// +build feather_rp2040
+
+package machine
+
+const (
+	LED = GPIO13
+
+	// Onboard crystal oscillator frequency, in MHz.
+	xoscFreq = 12 // MHz
+)

src/machine/board_grandcentral-m4.go

@@ -139,6 +139,7 @@ const (
 	LED_RX   = UART_RX_LED_PIN
 	LED_TX   = UART_TX_LED_PIN
 	NEOPIXEL = NEOPIXEL_PIN
+	WS2812   = NEOPIXEL_PIN
 )
 
 // UART pins

src/machine/board_grandcentral-m4_baremetal.go

@@ -8,30 +8,34 @@ import (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM4_2, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM4_2, _UART2.handleInterrupt)
-	UART3.Interrupt = interrupt.New(sam.IRQ_SERCOM1_2, UART3.handleInterrupt)
+	UART3.Interrupt = interrupt.New(sam.IRQ_SERCOM1_2, _UART3.handleInterrupt)
-	UART4.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, UART4.handleInterrupt)
+	UART4.Interrupt = interrupt.New(sam.IRQ_SERCOM5_2, _UART4.handleInterrupt)
 }
 
 // UART on the Grand Central M4
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
 		SERCOM: 0,
 	}
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM4_USART_INT,
 		SERCOM: 4,
 	}
-	UART3 = UART{
+	UART3  = &_UART3
+	_UART3 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM1_USART_INT,
 		SERCOM: 1,
 	}
-	UART4 = UART{
+	UART4  = &_UART4
+	_UART4 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM5_USART_INT,
 		SERCOM: 5,

src/machine/board_hifive1b.go

@@ -35,6 +35,8 @@ const (
 	LED_BLUE  = P21
 )
 
+var DefaultUART = UART0
+
 const (
 	// TODO: figure out the pin numbers for these.
 	UART_TX_PIN = D1

src/machine/board_itsybitsy-m0.go

@@ -42,7 +42,7 @@ const (
 	LED = D13
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25
@@ -56,7 +56,8 @@ const (
 
 // UART1 on the ItsyBitsy M0.
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM1_USART,
 		SERCOM: 1,
@@ -64,7 +65,7 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM1, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM1, _UART1.handleInterrupt)
 }
 
 // I2C pins

src/machine/board_itsybitsy-m4.go

@@ -37,7 +37,7 @@ const (
 	LED = D13
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25

src/machine/board_itsybitsy-m4_baremetal.go

@@ -8,13 +8,15 @@ import (
 )
 
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM3_USART_INT,
 		SERCOM: 3,
 	}
 
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
 		SERCOM: 0,
@@ -22,8 +24,8 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM3_2, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM3_2, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, _UART2.handleInterrupt)
 }
 
 // I2C on the ItsyBitsy M4.

src/machine/board_itsybitsy-nrf52840.go

@@ -70,11 +70,6 @@ const (
 	UART_TX_PIN = D1
 )
 
-// UART0 is the USB device
-var (
-	UART0 = &USB
-)
-
 // I2C pins
 const (
 	SDA_PIN = D21 // I2C0 external

src/machine/board_lgt92.go

@@ -54,10 +54,13 @@ const (
 	I2C0_SDA_PIN = PA10
 )
 
+var DefaultUART = UART0
+
 var (
 
 	// Console UART (LPUSART1)
-	UART0 = UART{
+	UART0  = &_UART0
+	_UART0 = UART{
 		Buffer:            NewRingBuffer(),
 		Bus:               stm32.LPUART1,
 		TxAltFuncSelector: 6,
@@ -65,7 +68,8 @@ var (
 	}
 
 	// Gps UART
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer:            NewRingBuffer(),
 		Bus:               stm32.USART1,
 		TxAltFuncSelector: 0,
@@ -88,6 +92,6 @@ var (
 
 func init() {
 	// Enable UARTs Interrupts
-	UART0.Interrupt = interrupt.New(stm32.IRQ_AES_RNG_LPUART1, UART0.handleInterrupt)
+	UART0.Interrupt = interrupt.New(stm32.IRQ_AES_RNG_LPUART1, _UART0.handleInterrupt)
-	UART1.Interrupt = interrupt.New(stm32.IRQ_USART1, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(stm32.IRQ_USART1, _UART1.handleInterrupt)
 }

src/machine/board_maixbit.go

@@ -52,6 +52,8 @@ const (
 	LED_BLUE  = D14
 )
 
+var DefaultUART = UART0
+
 // Default pins for UARTHS.
 const (
 	UART_TX_PIN = D5

src/machine/board_matrixportal-m4.go

@@ -75,6 +75,7 @@ const (
 const (
 	LED      = D13
 	NEOPIXEL = D4
+	WS2812   = D4
 )
 
 // Button pins

src/machine/board_matrixportal-m4_baremetal.go

@@ -9,13 +9,15 @@ import (
 
 // UART on the MatrixPortal M4
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM1_USART_INT,
 		SERCOM: 1,
 	}
 
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM4_USART_INT,
 		SERCOM: 4,
@@ -23,8 +25,8 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM1_1, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM1_1, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM4_1, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM4_1, _UART2.handleInterrupt)
 }
 
 // I2C on the MatrixPortal M4

src/machine/board_metro-m4-airlift.go

@@ -37,10 +37,11 @@ const (
 )
 
 const (
-	LED = D13
+	LED    = D13
+	WS2812 = D40
 )
 
-// UART0 aka USBCDC pins
+// USBCDC pins
 const (
 	USBCDC_DM_PIN = PA24
 	USBCDC_DP_PIN = PA25

src/machine/board_metro-m4-airlift_baremetal.go

@@ -8,13 +8,15 @@ import (
 )
 
 var (
-	UART1 = UART{
+	UART1  = &_UART1
+	_UART1 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM3_USART_INT,
 		SERCOM: 3,
 	}
 
-	UART2 = UART{
+	UART2  = &_UART2
+	_UART2 = UART{
 		Buffer: NewRingBuffer(),
 		Bus:    sam.SERCOM0_USART_INT,
 		SERCOM: 0,
@@ -22,8 +24,8 @@ var (
 )
 
 func init() {
-	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM3_2, UART1.handleInterrupt)
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM3_2, _UART1.handleInterrupt)
-	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, UART2.handleInterrupt)
+	UART2.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, _UART2.handleInterrupt)
 }
 
 // I2C on the Metro M4.