machine/dummy: add hooks to override peripheral methods

These two dependencies are optional but enabled by default when
available. Disable them in the Makefile so that the tinygo binary is
portable to systems that don't have them or have a different version
(for example, Arch has a newer version of libcurses and thus libtinfo).

.circleci/config.yml

@@ -47,6 +47,18 @@ commands:
           command: |
             curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
             dep ensure --vendor-only
+  llvm-source-linux:
+    steps:
+      - restore_cache:
+          keys:
+            - llvm-source-8-v2
+      - run:
+          name: "Fetch LLVM source"
+          command: make llvm-source
+      - save_cache:
+          key: llvm-source-8-v2
+          paths:
+            - llvm
   smoketest:
     steps:
       - smoketest-no-avr
@@ -86,6 +98,7 @@ commands:
           keys:
             - go-cache-{{ checksum "Gopkg.lock" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
             - go-cache-{{ checksum "Gopkg.lock" }}
+      - llvm-source-linux
       - dep
       - run: go install .
       - run: go test -v
@@ -105,7 +118,6 @@ commands:
           name: "Install apt dependencies"
           command: |
             sudo apt-get install \
-                libtinfo-dev \
                 python3 \
                 gcc-arm-linux-gnueabihf \
                 binutils-arm-none-eabi \
@@ -121,19 +133,10 @@ commands:
           keys:
             - go-cache-{{ checksum "Gopkg.lock" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
             - go-cache-{{ checksum "Gopkg.lock" }}
+      - llvm-source-linux
       - restore_cache:
           keys:
-            - llvm-source-8-v2
+            - llvm-build-8-linux-v4
-      - run:
-          name: "Fetch LLVM source"
-          command: make llvm-source
-      - save_cache:
-          key: llvm-source-8-v2
-          paths:
-            - llvm
-      - restore_cache:
-          keys:
-            - llvm-build-8-v2
       - run:
           name: "Build LLVM"
           command: |
@@ -151,7 +154,7 @@ commands:
               make llvm-build
             fi
       - save_cache:
-          key: llvm-build-8-v2
+          key: llvm-build-8-linux-v4
           paths:
             llvm-build
       - run:
@@ -204,7 +207,7 @@ commands:
             - llvm
       - restore_cache:
           keys:
-            - llvm-build-8-macos-v2
+            - llvm-build-8-macos-v3
       - run:
           name: "Build LLVM"
           command: |
@@ -216,7 +219,7 @@ commands:
               make llvm-build
             fi
       - save_cache:
-          key: llvm-build-8-macos-v2
+          key: llvm-build-8-macos-v3
           paths:
             llvm-build
       - run:

.gitignore

@@ -10,3 +10,5 @@ src/device/stm32/*.s
 src/device/sam/*.go
 src/device/sam/*.s
 vendor
+llvm
+llvm-build

Dockerfile

@@ -10,8 +10,11 @@ RUN wget -O- https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
 
 COPY . /go/src/github.com/tinygo-org/tinygo
 
+# remove submodules directories and re-init them to fix any hard-coded paths
+# after copying the tinygo directory in the previous step.
 RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
-    git submodule update --init
+    rm -rf ./lib/* && \
+    git submodule update --init --recursive --force
 
 RUN cd /go/src/github.com/tinygo-org/tinygo/ && \
     dep ensure --vendor-only && \

LICENSE

@@ -1,5 +1,8 @@
 Copyright (c) 2018-2019 TinyGo Authors. All rights reserved.
 
+TinyGo includes portions of the Go standard library.
+Copyright (c) 2009-2019 The Go Authors. All rights reserved.
+
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
 met:

Makefile

@@ -69,7 +69,7 @@ llvm-source: llvm/README.txt llvm/tools/clang/README.txt llvm/tools/lld/README.m
 
 # Configure LLVM.
 llvm-build/build.ninja: llvm-source
-	mkdir -p llvm-build; cd llvm-build; cmake -G Ninja ../llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR" -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=OFF -DLIBCLANG_BUILD_STATIC=ON
+	mkdir -p llvm-build; cd llvm-build; cmake -G Ninja ../llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR" -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=OFF -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF
 
 # Build LLVM.
 llvm-build: llvm-build/build.ninja
@@ -86,13 +86,16 @@ test:
 
 release: build/tinygo gen-device
 	@mkdir -p build/release/tinygo/bin
+	@mkdir -p build/release/tinygo/lib/clang/include
 	@mkdir -p build/release/tinygo/lib/CMSIS/CMSIS
 	@mkdir -p build/release/tinygo/lib/compiler-rt/lib
 	@mkdir -p build/release/tinygo/lib/nrfx
 	@mkdir -p build/release/tinygo/pkg/armv6m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7m-none-eabi
 	@mkdir -p build/release/tinygo/pkg/armv7em-none-eabi
+	@echo copying source files
 	@cp -p  build/tinygo                 build/release/tinygo/bin
+	@cp -p $(abspath $(CLANG_SRC))/lib/Headers/*.h build/release/tinygo/lib/clang/include
 	@cp -rp lib/CMSIS/CMSIS/Include      build/release/tinygo/lib/CMSIS/CMSIS
 	@cp -rp lib/CMSIS/README.md          build/release/tinygo/lib/CMSIS
 	@cp -rp lib/compiler-rt/lib/builtins build/release/tinygo/lib/compiler-rt/lib

buildcache.go

@@ -9,9 +9,11 @@ import (
 
 // Get the cache directory, usually ~/.cache/tinygo
 func cacheDir() string {
-	home := getHomeDir()
+	dir, err := os.UserCacheDir()
-	dir := filepath.Join(home, ".cache", "tinygo")
+	if err != nil {
-	return dir
+		panic("could not find cache dir: " + err.Error())
+	}
+	return filepath.Join(dir, "tinygo")
 }
 
 // Return the newest timestamp of all the file paths passed in. Used to check

builtins.go

@@ -5,7 +5,6 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"strings"
 	"time"
@@ -192,13 +191,13 @@ func loadBuiltins(target string) (path string, err error) {
 		srcs[i] = filepath.Join(builtinsDir, name)
 	}
 
-	if path, err := cacheLoad(outfile, commands["clang"], srcs); path != "" || err != nil {
+	if path, err := cacheLoad(outfile, commands["clang"][0], srcs); path != "" || err != nil {
 		return path, err
 	}
 
 	var cachepath string
 	err = compileBuiltins(target, func(path string) error {
-		path, err := cacheStore(path, outfile, commands["clang"], srcs)
+		path, err := cacheStore(path, outfile, commands["clang"][0], srcs)
 		cachepath = path
 		return err
 	})
@@ -240,11 +239,7 @@ func compileBuiltins(target string, callback func(path string) error) error {
 		// Note: -fdebug-prefix-map is necessary to make the output archive
 		// reproducible. Otherwise the temporary directory is stored in the
 		// archive itself, which varies each run.
-		cmd := exec.Command(commands["clang"], "-c", "-Oz", "-g", "-Werror", "-Wall", "-std=c11", "-fshort-enums", "-nostdlibinc", "-ffunction-sections", "-fdata-sections", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir, "-o", objpath, srcpath)
+		err := execCommand(commands["clang"], "-c", "-Oz", "-g", "-Werror", "-Wall", "-std=c11", "-fshort-enums", "-nostdlibinc", "-ffunction-sections", "-fdata-sections", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir, "-o", objpath, srcpath)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		cmd.Dir = dir
-		err = cmd.Run()
 		if err != nil {
 			return &commandError{"failed to build", srcpath, err}
 		}
@@ -294,5 +289,6 @@ func compileBuiltins(target string, callback func(path string) error) error {
 
 	// Give the caller the resulting file. The callback must copy the file,
 	// because after it returns the temporary directory will be removed.
+	arfile.Close()
 	return callback(arpath)
 }

commands.go

@@ -1,10 +1,33 @@
-// +build !darwin
-
 package main
 
-// commands used by the compilation process might have different file names on Linux than those used on macOS.
+import (
-var commands = map[string]string{
+	"errors"
-	"clang":   "clang-8",
+	"os"
-	"ld.lld":  "ld.lld-8",
+	"os/exec"
-	"wasm-ld": "wasm-ld-8",
+	"strings"
+)
+
+// Commands used by the compilation process might have different file names
+// across operating systems and distributions.
+var commands = map[string][]string{
+	"clang":   {"clang-8"},
+	"ld.lld":  {"ld.lld-8", "ld.lld"},
+	"wasm-ld": {"wasm-ld-8", "wasm-ld"},
+}
+
+func execCommand(cmdNames []string, args ...string) error {
+	for _, cmdName := range cmdNames {
+		cmd := exec.Command(cmdName, args...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		err := cmd.Run()
+		if err != nil {
+			if err, ok := err.(*exec.Error); ok && err.Err == exec.ErrNotFound {
+				// this command was not found, try the next
+				continue
+			}
+		}
+		return nil
+	}
+	return errors.New("none of these commands were found in your $PATH: " + strings.Join(cmdNames, " "))
 }

commands_macos.go

@@ -1,10 +0,0 @@
-// +build darwin
-
-package main
-
-// commands used by the compilation process might have different file names on macOS than those used on Linux.
-var commands = map[string]string{
-	"clang":   "clang-8",
-	"ld.lld":  "ld.lld",
-	"wasm-ld": "wasm-ld",
-}

compiler/calls.go

@@ -123,10 +123,7 @@ func (c *Compiler) collapseFormalParamInternal(t llvm.Type, fields []llvm.Value)
 	switch t.TypeKind() {
 	case llvm.StructTypeKind:
 		if len(c.flattenAggregateType(t)) <= MaxFieldsPerParam {
-			value, err := c.getZeroValue(t)
+			value := c.getZeroValue(t)
-			if err != nil {
-				panic("could not get zero value of struct: " + err.Error())
-			}
 			for i, subtyp := range t.StructElementTypes() {
 				structField, remaining := c.collapseFormalParamInternal(subtyp, fields)
 				fields = remaining

compiler/channel.go

@@ -12,16 +12,6 @@ import (
 
 // emitMakeChan returns a new channel value for the given channel type.
 func (c *Compiler) emitMakeChan(expr *ssa.MakeChan) (llvm.Value, error) {
-	valueType, err := c.getLLVMType(expr.Type().(*types.Chan).Elem())
-	if err != nil {
-		return llvm.Value{}, err
-	}
-	if c.targetData.TypeAllocSize(valueType) > c.targetData.TypeAllocSize(c.intType) {
-		// Values bigger than int overflow the data part of the coroutine.
-		// TODO: make the coroutine data part big enough to hold these bigger
-		// values.
-		return llvm.Value{}, c.makeError(expr.Pos(), "todo: channel with values bigger than int")
-	}
 	chanType := c.mod.GetTypeByName("runtime.channel")
 	size := c.targetData.TypeAllocSize(chanType)
 	sizeValue := llvm.ConstInt(c.uintptrType, size, false)
@@ -32,66 +22,64 @@ func (c *Compiler) emitMakeChan(expr *ssa.MakeChan) (llvm.Value, error) {
 
 // emitChanSend emits a pseudo chan send operation. It is lowered to the actual
 // channel send operation during goroutine lowering.
-func (c *Compiler) emitChanSend(frame *Frame, instr *ssa.Send) error {
+func (c *Compiler) emitChanSend(frame *Frame, instr *ssa.Send) {
-	valueType, err := c.getLLVMType(instr.Chan.Type().(*types.Chan).Elem())
+	valueType := c.getLLVMType(instr.X.Type())
-	if err != nil {
+	ch := c.getValue(frame, instr.Chan)
-		return err
+	chanValue := c.getValue(frame, instr.X)
-	}
-	ch, err := c.parseExpr(frame, instr.Chan)
-	if err != nil {
-		return err
-	}
-	chanValue, err := c.parseExpr(frame, instr.X)
-	if err != nil {
-		return err
-	}
 	valueSize := llvm.ConstInt(c.uintptrType, c.targetData.TypeAllocSize(chanValue.Type()), false)
+	coroutine := c.createRuntimeCall("getCoroutine", nil, "")
+
+	// store value-to-send
+	c.builder.SetInsertPointBefore(coroutine.InstructionParent().Parent().EntryBasicBlock().FirstInstruction())
 	valueAlloca := c.builder.CreateAlloca(valueType, "chan.value")
+	c.builder.SetInsertPointBefore(coroutine)
+	c.builder.SetInsertPointAtEnd(coroutine.InstructionParent())
 	c.builder.CreateStore(chanValue, valueAlloca)
 	valueAllocaCast := c.builder.CreateBitCast(valueAlloca, c.i8ptrType, "chan.value.i8ptr")
-	c.createRuntimeCall("chanSendStub", []llvm.Value{llvm.Undef(c.i8ptrType), ch, valueAllocaCast, valueSize}, "")
+
-	return nil
+	// Do the send.
+	c.createRuntimeCall("chanSend", []llvm.Value{coroutine, ch, valueAllocaCast, valueSize}, "")
+
+	// Make sure CoroSplit includes the alloca in the coroutine frame.
+	// This is a bit dirty, but it works (at least in LLVM 8).
+	valueSizeI64 := llvm.ConstInt(c.ctx.Int64Type(), c.targetData.TypeAllocSize(chanValue.Type()), false)
+	c.builder.CreateCall(c.getLifetimeEndFunc(), []llvm.Value{valueSizeI64, valueAllocaCast}, "")
 }
 
 // emitChanRecv emits a pseudo chan receive operation. It is lowered to the
 // actual channel receive operation during goroutine lowering.
-func (c *Compiler) emitChanRecv(frame *Frame, unop *ssa.UnOp) (llvm.Value, error) {
+func (c *Compiler) emitChanRecv(frame *Frame, unop *ssa.UnOp) llvm.Value {
-	valueType, err := c.getLLVMType(unop.X.Type().(*types.Chan).Elem())
+	valueType := c.getLLVMType(unop.X.Type().(*types.Chan).Elem())
-	if err != nil {
-		return llvm.Value{}, err
-	}
 	valueSize := llvm.ConstInt(c.uintptrType, c.targetData.TypeAllocSize(valueType), false)
-	ch, err := c.parseExpr(frame, unop.X)
+	ch := c.getValue(frame, unop.X)
-	if err != nil {
+	coroutine := c.createRuntimeCall("getCoroutine", nil, "")
-		return llvm.Value{}, err
+
-	}
+	// Allocate memory to receive into.
+	c.builder.SetInsertPointBefore(coroutine.InstructionParent().Parent().EntryBasicBlock().FirstInstruction())
 	valueAlloca := c.builder.CreateAlloca(valueType, "chan.value")
+	c.builder.SetInsertPointBefore(coroutine)
+	c.builder.SetInsertPointAtEnd(coroutine.InstructionParent())
 	valueAllocaCast := c.builder.CreateBitCast(valueAlloca, c.i8ptrType, "chan.value.i8ptr")
-	valueOk := c.builder.CreateAlloca(c.ctx.Int1Type(), "chan.comma-ok.alloca")
+
-	c.createRuntimeCall("chanRecvStub", []llvm.Value{llvm.Undef(c.i8ptrType), ch, valueAllocaCast, valueOk, valueSize}, "")
+	// Do the receive.
+	c.createRuntimeCall("chanRecv", []llvm.Value{coroutine, ch, valueAllocaCast, valueSize}, "")
 	received := c.builder.CreateLoad(valueAlloca, "chan.received")
 	if unop.CommaOk {
-		commaOk := c.builder.CreateLoad(valueOk, "chan.comma-ok")
+		commaOk := c.createRuntimeCall("getTaskPromiseData", []llvm.Value{coroutine}, "chan.commaOk.wide")
+		commaOk = c.builder.CreateTrunc(commaOk, c.ctx.Int1Type(), "chan.commaOk")
 		tuple := llvm.Undef(c.ctx.StructType([]llvm.Type{valueType, c.ctx.Int1Type()}, false))
 		tuple = c.builder.CreateInsertValue(tuple, received, 0, "")
 		tuple = c.builder.CreateInsertValue(tuple, commaOk, 1, "")
-		return tuple, nil
+		return tuple
 	} else {
-		return received, nil
+		return received
 	}
 }
 
 // emitChanClose closes the given channel.
-func (c *Compiler) emitChanClose(frame *Frame, param ssa.Value) error {
+func (c *Compiler) emitChanClose(frame *Frame, param ssa.Value) {
-	valueType, err := c.getLLVMType(param.Type().(*types.Chan).Elem())
+	valueType := c.getLLVMType(param.Type().(*types.Chan).Elem())
 	valueSize := llvm.ConstInt(c.uintptrType, c.targetData.TypeAllocSize(valueType), false)
-	if err != nil {
+	ch := c.getValue(frame, param)
-		return err
-	}
-	ch, err := c.parseExpr(frame, param)
-	if err != nil {
-		return err
-	}
 	c.createRuntimeCall("chanClose", []llvm.Value{ch, valueSize}, "")
-	return nil
 }

compiler/defer.go

@@ -36,7 +36,7 @@ func (c *Compiler) deferInitFunc(frame *Frame) {
 
 // emitDefer emits a single defer instruction, to be run when this function
 // returns.
-func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
+func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) {
 	// The pointer to the previous defer struct, which we will replace to
 	// make a linked list.
 	next := c.builder.CreateLoad(frame.deferPtr, "defer.next")
@@ -56,18 +56,12 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
 
 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields, followed by the call parameters).
-		itf, err := c.parseExpr(frame, instr.Call.Value) // interface
+		itf := c.getValue(frame, instr.Call.Value) // interface
-		if err != nil {
-			return err
-		}
 		receiverValue := c.builder.CreateExtractValue(itf, 1, "invoke.func.receiver")
 		values = []llvm.Value{callback, next, receiverValue}
 		valueTypes = append(valueTypes, c.i8ptrType)
 		for _, arg := range instr.Call.Args {
-			val, err := c.parseExpr(frame, arg)
+			val := c.getValue(frame, arg)
-			if err != nil {
-				return err
-			}
 			values = append(values, val)
 			valueTypes = append(valueTypes, val.Type())
 		}
@@ -86,10 +80,7 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
 		// runtime._defer fields).
 		values = []llvm.Value{callback, next}
 		for _, param := range instr.Call.Args {
-			llvmParam, err := c.parseExpr(frame, param)
+			llvmParam := c.getValue(frame, param)
-			if err != nil {
-				return err
-			}
 			values = append(values, llvmParam)
 			valueTypes = append(valueTypes, llvmParam.Type())
 		}
@@ -101,10 +92,7 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
 		// pointer.
 		// TODO: ignore this closure entirely and put pointers to the free
 		// variables directly in the defer struct, avoiding a memory allocation.
-		closure, err := c.parseExpr(frame, instr.Call.Value)
+		closure := c.getValue(frame, instr.Call.Value)
-		if err != nil {
-			return err
-		}
 		context := c.builder.CreateExtractValue(closure, 0, "")
 
 		// Get the callback number.
@@ -120,10 +108,7 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
 		// context pointer).
 		values = []llvm.Value{callback, next}
 		for _, param := range instr.Call.Args {
-			llvmParam, err := c.parseExpr(frame, param)
+			llvmParam := c.getValue(frame, param)
-			if err != nil {
-				return err
-			}
 			values = append(values, llvmParam)
 			valueTypes = append(valueTypes, llvmParam.Type())
 		}
@@ -131,15 +116,13 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
 		valueTypes = append(valueTypes, context.Type())
 
 	} else {
-		return c.makeError(instr.Pos(), "todo: defer on uncommon function call type")
+		c.addError(instr.Pos(), "todo: defer on uncommon function call type")
+		return
 	}
 
 	// Make a struct out of the collected values to put in the defer frame.
 	deferFrameType := c.ctx.StructType(valueTypes, false)
-	deferFrame, err := c.getZeroValue(deferFrameType)
+	deferFrame := c.getZeroValue(deferFrameType)
-	if err != nil {
-		return err
-	}
 	for i, value := range values {
 		deferFrame = c.builder.CreateInsertValue(deferFrame, value, i, "")
 	}
@@ -151,11 +134,10 @@ func (c *Compiler) emitDefer(frame *Frame, instr *ssa.Defer) error {
 	// Push it on top of the linked list by replacing deferPtr.
 	allocaCast := c.builder.CreateBitCast(alloca, next.Type(), "defer.alloca.cast")
 	c.builder.CreateStore(allocaCast, frame.deferPtr)
-	return nil
 }
 
 // emitRunDefers emits code to run all deferred functions.
-func (c *Compiler) emitRunDefers(frame *Frame) error {
+func (c *Compiler) emitRunDefers(frame *Frame) {
 	// Add a loop like the following:
 	//     for stack != nil {
 	//         _stack := stack
@@ -190,13 +172,13 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 	//     stack = stack.next
 	//     switch stack.callback {
 	c.builder.SetInsertPointAtEnd(loop)
-	nextStackGEP := c.builder.CreateGEP(deferData, []llvm.Value{
+	nextStackGEP := c.builder.CreateInBoundsGEP(deferData, []llvm.Value{
 		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
 		llvm.ConstInt(c.ctx.Int32Type(), 1, false), // .next field
 	}, "stack.next.gep")
 	nextStack := c.builder.CreateLoad(nextStackGEP, "stack.next")
 	c.builder.CreateStore(nextStack, frame.deferPtr)
-	gep := c.builder.CreateGEP(deferData, []llvm.Value{
+	gep := c.builder.CreateInBoundsGEP(deferData, []llvm.Value{
 		llvm.ConstInt(c.ctx.Int32Type(), 0, false),
 		llvm.ConstInt(c.ctx.Int32Type(), 0, false), // .callback field
 	}, "callback.gep")
@@ -220,11 +202,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			// Get the real defer struct type and cast to it.
 			valueTypes := []llvm.Type{c.uintptrType, llvm.PointerType(c.mod.GetTypeByName("runtime._defer"), 0), c.i8ptrType}
 			for _, arg := range callback.Args {
-				llvmType, err := c.getLLVMType(arg.Type())
+				valueTypes = append(valueTypes, c.getLLVMType(arg.Type()))
-				if err != nil {
-					return err
-				}
-				valueTypes = append(valueTypes, llvmType)
 			}
 			deferFrameType := c.ctx.StructType(valueTypes, false)
 			deferFramePtr := c.builder.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")
@@ -233,7 +211,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			forwardParams := []llvm.Value{}
 			zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 			for i := 2; i < len(valueTypes); i++ {
-				gep := c.builder.CreateGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false)}, "gep")
+				gep := c.builder.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false)}, "gep")
 				forwardParam := c.builder.CreateLoad(gep, "param")
 				forwardParams = append(forwardParams, forwardParam)
 			}
@@ -246,10 +224,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			// Parent coroutine handle.
 			forwardParams = append(forwardParams, llvm.Undef(c.i8ptrType))
 
-			fnPtr, _, err := c.getInvokeCall(frame, callback)
+			fnPtr, _ := c.getInvokeCall(frame, callback)
-			if err != nil {
-				return err
-			}
 			c.createCall(fnPtr, forwardParams, "")
 
 		case *ir.Function:
@@ -258,11 +233,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			// Get the real defer struct type and cast to it.
 			valueTypes := []llvm.Type{c.uintptrType, llvm.PointerType(c.mod.GetTypeByName("runtime._defer"), 0)}
 			for _, param := range callback.Params {
-				llvmType, err := c.getLLVMType(param.Type())
+				valueTypes = append(valueTypes, c.getLLVMType(param.Type()))
-				if err != nil {
-					return err
-				}
-				valueTypes = append(valueTypes, llvmType)
 			}
 			deferFrameType := c.ctx.StructType(valueTypes, false)
 			deferFramePtr := c.builder.CreateBitCast(deferData, llvm.PointerType(deferFrameType, 0), "deferFrame")
@@ -271,7 +242,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			forwardParams := []llvm.Value{}
 			zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 			for i := range callback.Params {
-				gep := c.builder.CreateGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i+2), false)}, "gep")
+				gep := c.builder.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i+2), false)}, "gep")
 				forwardParam := c.builder.CreateLoad(gep, "param")
 				forwardParams = append(forwardParams, forwardParam)
 			}
@@ -292,11 +263,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			valueTypes := []llvm.Type{c.uintptrType, llvm.PointerType(c.mod.GetTypeByName("runtime._defer"), 0)}
 			params := fn.Signature.Params()
 			for i := 0; i < params.Len(); i++ {
-				llvmType, err := c.getLLVMType(params.At(i).Type())
+				valueTypes = append(valueTypes, c.getLLVMType(params.At(i).Type()))
-				if err != nil {
-					return err
-				}
-				valueTypes = append(valueTypes, llvmType)
 			}
 			valueTypes = append(valueTypes, c.i8ptrType) // closure
 			deferFrameType := c.ctx.StructType(valueTypes, false)
@@ -306,7 +273,7 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 			forwardParams := []llvm.Value{}
 			zero := llvm.ConstInt(c.ctx.Int32Type(), 0, false)
 			for i := 2; i < len(valueTypes); i++ {
-				gep := c.builder.CreateGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false)}, "")
+				gep := c.builder.CreateInBoundsGEP(deferFramePtr, []llvm.Value{zero, llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false)}, "")
 				forwardParam := c.builder.CreateLoad(gep, "param")
 				forwardParams = append(forwardParams, forwardParam)
 			}
@@ -334,5 +301,4 @@ func (c *Compiler) emitRunDefers(frame *Frame) error {
 
 	// End of loop.
 	c.builder.SetInsertPointAtEnd(end)
-	return nil
 }

compiler/errors.go

@@ -12,3 +12,7 @@ func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
 		Msg:  msg,
 	}
 }
+
+func (c *Compiler) addError(pos token.Pos, msg string) {
+	c.diagnostics = append(c.diagnostics, c.makeError(pos, msg))
+}

compiler/func.go

@@ -41,7 +41,7 @@ func (c *Compiler) funcImplementation() funcValueImplementation {
 
 // createFuncValue creates a function value from a raw function pointer with no
 // context.
-func (c *Compiler) createFuncValue(funcPtr, context llvm.Value, sig *types.Signature) (llvm.Value, error) {
+func (c *Compiler) createFuncValue(funcPtr, context llvm.Value, sig *types.Signature) llvm.Value {
 	var funcValueScalar llvm.Value
 	switch c.funcImplementation() {
 	case funcValueDoubleword:
@@ -66,14 +66,11 @@ func (c *Compiler) createFuncValue(funcPtr, context llvm.Value, sig *types.Signa
 	default:
 		panic("unimplemented func value variant")
 	}
-	funcValueType, err := c.getFuncType(sig)
+	funcValueType := c.getFuncType(sig)
-	if err != nil {
-		return llvm.Value{}, err
-	}
 	funcValue := llvm.Undef(funcValueType)
 	funcValue = c.builder.CreateInsertValue(funcValue, context, 0, "")
 	funcValue = c.builder.CreateInsertValue(funcValue, funcValueScalar, 1, "")
-	return funcValue, nil
+	return funcValue
 }
 
 // getFuncSignature returns a global for identification of a particular function
@@ -112,10 +109,7 @@ func (c *Compiler) decodeFuncValue(funcValue llvm.Value, sig *types.Signature) (
 	case funcValueDoubleword:
 		funcPtr = c.builder.CreateExtractValue(funcValue, 1, "")
 	case funcValueSwitch:
-		llvmSig, err := c.getRawFuncType(sig)
+		llvmSig := c.getRawFuncType(sig)
-		if err != nil {
-			return llvm.Value{}, llvm.Value{}, err
-		}
 		sigGlobal := c.getFuncSignature(sig)
 		funcPtr = c.createRuntimeCall("getFuncPtr", []llvm.Value{funcValue, sigGlobal}, "")
 		funcPtr = c.builder.CreateIntToPtr(funcPtr, llvmSig, "")
@@ -126,25 +120,21 @@ func (c *Compiler) decodeFuncValue(funcValue llvm.Value, sig *types.Signature) (
 }
 
 // getFuncType returns the type of a func value given a signature.
-func (c *Compiler) getFuncType(typ *types.Signature) (llvm.Type, error) {
+func (c *Compiler) getFuncType(typ *types.Signature) llvm.Type {
 	switch c.funcImplementation() {
 	case funcValueDoubleword:
-		rawPtr, err := c.getRawFuncType(typ)
+		rawPtr := c.getRawFuncType(typ)
-		if err != nil {
+		return c.ctx.StructType([]llvm.Type{c.i8ptrType, rawPtr}, false)
-			return llvm.Type{}, err
-		}
-		return c.ctx.StructType([]llvm.Type{c.i8ptrType, rawPtr}, false), nil
 	case funcValueSwitch:
-		return c.mod.GetTypeByName("runtime.funcValue"), nil
+		return c.mod.GetTypeByName("runtime.funcValue")
 	default:
 		panic("unimplemented func value variant")
 	}
 }
 
 // getRawFuncType returns a LLVM function pointer type for a given signature.
-func (c *Compiler) getRawFuncType(typ *types.Signature) (llvm.Type, error) {
+func (c *Compiler) getRawFuncType(typ *types.Signature) llvm.Type {
 	// Get the return type.
-	var err error
 	var returnType llvm.Type
 	switch typ.Results().Len() {
 	case 0:
@@ -152,21 +142,14 @@ func (c *Compiler) getRawFuncType(typ *types.Signature) (llvm.Type, error) {
 		returnType = c.ctx.VoidType()
 	case 1:
 		// Just one return value.
-		returnType, err = c.getLLVMType(typ.Results().At(0).Type())
+		returnType = c.getLLVMType(typ.Results().At(0).Type())
-		if err != nil {
-			return llvm.Type{}, err
-		}
 	default:
 		// Multiple return values. Put them together in a struct.
 		// This appears to be the common way to handle multiple return values in
 		// LLVM.
 		members := make([]llvm.Type, typ.Results().Len())
 		for i := 0; i < typ.Results().Len(); i++ {
-			returnType, err := c.getLLVMType(typ.Results().At(i).Type())
+			members[i] = c.getLLVMType(typ.Results().At(i).Type())
-			if err != nil {
-				return llvm.Type{}, err
-			}
-			members[i] = returnType
 		}
 		returnType = c.ctx.StructType(members, false)
 	}
@@ -174,10 +157,7 @@ func (c *Compiler) getRawFuncType(typ *types.Signature) (llvm.Type, error) {
 	// Get the parameter types.
 	var paramTypes []llvm.Type
 	if typ.Recv() != nil {
-		recv, err := c.getLLVMType(typ.Recv().Type())
+		recv := c.getLLVMType(typ.Recv().Type())
-		if err != nil {
-			return llvm.Type{}, err
-		}
 		if recv.StructName() == "runtime._interface" {
 			// This is a call on an interface, not a concrete type.
 			// The receiver is not an interface, but a i8* type.
@@ -186,10 +166,7 @@ func (c *Compiler) getRawFuncType(typ *types.Signature) (llvm.Type, error) {
 		paramTypes = append(paramTypes, c.expandFormalParamType(recv)...)
 	}
 	for i := 0; i < typ.Params().Len(); i++ {
-		subType, err := c.getLLVMType(typ.Params().At(i).Type())
+		subType := c.getLLVMType(typ.Params().At(i).Type())
-		if err != nil {
-			return llvm.Type{}, err
-		}
 		paramTypes = append(paramTypes, c.expandFormalParamType(subType)...)
 	}
 	// All functions take these parameters at the end.
@@ -197,7 +174,7 @@ func (c *Compiler) getRawFuncType(typ *types.Signature) (llvm.Type, error) {
 	paramTypes = append(paramTypes, c.i8ptrType) // parent coroutine
 
 	// Make a func type out of the signature.
-	return llvm.PointerType(llvm.FunctionType(returnType, paramTypes, false), c.funcPtrAddrSpace), nil
+	return llvm.PointerType(llvm.FunctionType(returnType, paramTypes, false), c.funcPtrAddrSpace)
 }
 
 // parseMakeClosure makes a function value (with context) from the given
@@ -209,57 +186,17 @@ func (c *Compiler) parseMakeClosure(frame *Frame, expr *ssa.MakeClosure) (llvm.V
 	f := c.ir.GetFunction(expr.Fn.(*ssa.Function))
 
 	// Collect all bound variables.
-	boundVars := make([]llvm.Value, 0, len(expr.Bindings))
+	boundVars := make([]llvm.Value, len(expr.Bindings))
-	boundVarTypes := make([]llvm.Type, 0, len(expr.Bindings))
+	for i, binding := range expr.Bindings {
-	for _, binding := range expr.Bindings {
 		// The context stores the bound variables.
-		llvmBoundVar, err := c.parseExpr(frame, binding)
+		llvmBoundVar := c.getValue(frame, binding)
-		if err != nil {
+		boundVars[i] = llvmBoundVar
-			return llvm.Value{}, err
-		}
-		boundVars = append(boundVars, llvmBoundVar)
-		boundVarTypes = append(boundVarTypes, llvmBoundVar.Type())
-	}
-	contextType := c.ctx.StructType(boundVarTypes, false)
-
-	// Allocate memory for the context.
-	contextAlloc := llvm.Value{}
-	contextHeapAlloc := llvm.Value{}
-	if c.targetData.TypeAllocSize(contextType) <= c.targetData.TypeAllocSize(c.i8ptrType) {
-		// Context fits in a pointer - e.g. when it is a pointer. Store it
-		// directly in the stack after a convert.
-		// Because contextType is a struct and we have to cast it to a *i8,
-		// store it in an alloca first for bitcasting (store+bitcast+load).
-		contextAlloc = c.builder.CreateAlloca(contextType, "")
-	} else {
-		// Context is bigger than a pointer, so allocate it on the heap.
-		size := c.targetData.TypeAllocSize(contextType)
-		sizeValue := llvm.ConstInt(c.uintptrType, size, false)
-		contextHeapAlloc = c.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "")
-		contextAlloc = c.builder.CreateBitCast(contextHeapAlloc, llvm.PointerType(contextType, 0), "")
 	}
 
-	// Store all bound variables in the alloca or heap pointer.
+	// Store the bound variables in a single object, allocating it on the heap
-	for i, boundVar := range boundVars {
+	// if necessary.
-		indices := []llvm.Value{
+	context := c.emitPointerPack(boundVars)
-			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
-		}
-		gep := c.builder.CreateInBoundsGEP(contextAlloc, indices, "")
-		c.builder.CreateStore(boundVar, gep)
-	}
-
-	context := llvm.Value{}
-	if c.targetData.TypeAllocSize(contextType) <= c.targetData.TypeAllocSize(c.i8ptrType) {
-		// Load value (as *i8) from the alloca.
-		contextAlloc = c.builder.CreateBitCast(contextAlloc, llvm.PointerType(c.i8ptrType, 0), "")
-		context = c.builder.CreateLoad(contextAlloc, "")
-	} else {
-		// Get the original heap allocation pointer, which already is an
-		// *i8.
-		context = contextHeapAlloc
-	}
 
 	// Create the closure.
-	return c.createFuncValue(f.LLVMFn, context, f.Signature)
+	return c.createFuncValue(f.LLVMFn, context, f.Signature), nil
 }

compiler/goroutine-lowering.go

@@ -10,8 +10,8 @@ package compiler
 //         go foo()
 //         time.Sleep(2 * time.Second)
 //         println("some other operation")
-//         bar()
+//         i := bar()
-//         println("done")
+//         println("done", *i)
 //     }
 //
 //     func foo() {
@@ -21,9 +21,10 @@ package compiler
 //         }
 //     }
 //
-//     func bar() {
+//     func bar() *int {
 //         time.Sleep(time.Second)
 //         println("blocking operation completed)
+//         return new(int)
 //     }
 //
 // It is transformed by the IR generator in compiler.go into the following
@@ -34,8 +35,8 @@ package compiler
 //         fn()
 //         time.Sleep(2 * time.Second)
 //         println("some other operation")
-//         bar() // imagine an 'await' keyword in front of this call
+//         i := bar() // imagine an 'await' keyword in front of this call
-//         println("done")
+//         println("done", *i)
 //     }
 //
 //     func foo() {
@@ -45,9 +46,10 @@ package compiler
 //         }
 //     }
 //
-//     func bar() {
+//     func bar() *int {
 //         time.Sleep(time.Second)
 //         println("blocking operation completed)
+//         return new(int)
 //     }
 //
 // The pass in this file transforms this code even further, to the following
@@ -59,9 +61,11 @@ package compiler
 //         runtime.sleepTask(hdl, 2 * time.Second) // ask the scheduler to re-activate this coroutine at the right time
 //         llvm.suspend(hdl)                       // suspend point
 //         println("some other operation")
+//         var i *int                              // allocate space on the stack for the return value
+//         runtime.setTaskPromisePtr(hdl, &i)      // store return value alloca in our coroutine promise
 //         bar(hdl)                                // await, pass a continuation (hdl) to bar
 //         llvm.suspend(hdl)                       // suspend point, wait for the callee to re-activate
-//         println("done")
+//         println("done", *i)
 //         runtime.activateTask(parent)            // re-activate the parent (nop, there is no parent)
 //     }
 //
@@ -142,10 +146,9 @@ func (c *Compiler) LowerGoroutines() error {
 	realMain.SetLinkage(llvm.InternalLinkage)
 	c.mod.NamedFunction("runtime.alloc").SetLinkage(llvm.InternalLinkage)
 	c.mod.NamedFunction("runtime.free").SetLinkage(llvm.InternalLinkage)
-	c.mod.NamedFunction("runtime.chanSend").SetLinkage(llvm.InternalLinkage)
-	c.mod.NamedFunction("runtime.chanRecv").SetLinkage(llvm.InternalLinkage)
 	c.mod.NamedFunction("runtime.sleepTask").SetLinkage(llvm.InternalLinkage)
-	c.mod.NamedFunction("runtime.activateTask").SetLinkage(llvm.InternalLinkage)
+	c.mod.NamedFunction("runtime.setTaskPromisePtr").SetLinkage(llvm.InternalLinkage)
+	c.mod.NamedFunction("runtime.getTaskPromisePtr").SetLinkage(llvm.InternalLinkage)
 	c.mod.NamedFunction("runtime.scheduler").SetLinkage(llvm.InternalLinkage)
 
 	return nil
@@ -174,13 +177,13 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 	if !deadlockStub.IsNil() {
 		worklist = append(worklist, deadlockStub)
 	}
-	chanSendStub := c.mod.NamedFunction("runtime.chanSendStub")
+	chanSend := c.mod.NamedFunction("runtime.chanSend")
-	if !chanSendStub.IsNil() {
+	if !chanSend.IsNil() {
-		worklist = append(worklist, chanSendStub)
+		worklist = append(worklist, chanSend)
 	}
-	chanRecvStub := c.mod.NamedFunction("runtime.chanRecvStub")
+	chanRecv := c.mod.NamedFunction("runtime.chanRecv")
-	if !chanRecvStub.IsNil() {
+	if !chanRecv.IsNil() {
-		worklist = append(worklist, chanRecvStub)
+		worklist = append(worklist, chanRecv)
 	}
 
 	if len(worklist) == 0 {
@@ -278,9 +281,6 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 	coroBeginType := llvm.FunctionType(c.i8ptrType, []llvm.Type{c.ctx.TokenType(), c.i8ptrType}, false)
 	coroBeginFunc := llvm.AddFunction(c.mod, "llvm.coro.begin", coroBeginType)
 
-	coroPromiseType := llvm.FunctionType(c.i8ptrType, []llvm.Type{c.i8ptrType, c.ctx.Int32Type(), c.ctx.Int1Type()}, false)
-	coroPromiseFunc := llvm.AddFunction(c.mod, "llvm.coro.promise", coroPromiseType)
-
 	coroSuspendType := llvm.FunctionType(c.ctx.Int8Type(), []llvm.Type{c.ctx.TokenType(), c.ctx.Int1Type()}, false)
 	coroSuspendFunc := llvm.AddFunction(c.mod, "llvm.coro.suspend", coroSuspendType)
 
@@ -292,7 +292,7 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 
 	// Transform all async functions into coroutines.
 	for _, f := range asyncList {
-		if f == sleep || f == deadlockStub || f == chanSendStub || f == chanRecvStub {
+		if f == sleep || f == deadlockStub || f == chanSend || f == chanRecv {
 			continue
 		}
 
@@ -309,7 +309,7 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 			for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
 				if !inst.IsACallInst().IsNil() {
 					callee := inst.CalledValue()
-					if _, ok := asyncFuncs[callee]; !ok || callee == sleep || callee == deadlockStub || callee == chanSendStub || callee == chanRecvStub {
+					if _, ok := asyncFuncs[callee]; !ok || callee == sleep || callee == deadlockStub || callee == chanSend || callee == chanRecv {
 						continue
 					}
 					asyncCalls = append(asyncCalls, inst)
@@ -347,10 +347,18 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 			// Split this basic block.
 			await := c.splitBasicBlock(inst, llvm.NextBasicBlock(c.builder.GetInsertBlock()), "task.await")
 
-			// Set task state to TASK_STATE_CALL.
+			// Allocate space for the return value.
-			c.builder.SetInsertPointAtEnd(inst.InstructionParent())
+			var retvalAlloca llvm.Value
+			if inst.Type().TypeKind() != llvm.VoidTypeKind {
+				c.builder.SetInsertPointBefore(inst.InstructionParent().Parent().EntryBasicBlock().FirstInstruction())
+				retvalAlloca = c.builder.CreateAlloca(inst.Type(), "coro.retvalAlloca")
+				c.builder.SetInsertPointBefore(inst)
+				data := c.builder.CreateBitCast(retvalAlloca, c.i8ptrType, "")
+				c.createRuntimeCall("setTaskPromisePtr", []llvm.Value{frame.taskHandle, data}, "")
+			}
 
 			// Suspend.
+			c.builder.SetInsertPointAtEnd(inst.InstructionParent())
 			continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
 				llvm.ConstNull(c.ctx.TokenType()),
 				llvm.ConstInt(c.ctx.Int1Type(), 0, false),
@@ -358,44 +366,63 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 			sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
 			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), await)
 			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+
+			if inst.Type().TypeKind() != llvm.VoidTypeKind {
+				// Load the return value from the alloca. The callee has
+				// written the return value to it.
+				c.builder.SetInsertPointBefore(await.FirstInstruction())
+				retval := c.builder.CreateLoad(retvalAlloca, "coro.retval")
+				inst.ReplaceAllUsesWith(retval)
+			}
 		}
 
 		// Replace return instructions with suspend points that should
 		// reactivate the parent coroutine.
 		for _, inst := range returns {
-			if inst.OperandsCount() == 0 {
+			// These properties were added by the functionattrs pass. Remove
-				// These properties were added by the functionattrs pass.
+			// them, because now we start using the parameter.
-				// Remove them, because now we start using the parameter.
+			// https://llvm.org/docs/Passes.html#functionattrs-deduce-function-attributes
-				// https://llvm.org/docs/Passes.html#functionattrs-deduce-function-attributes
+			for _, kind := range []string{"nocapture", "readnone"} {
-				for _, kind := range []string{"nocapture", "readnone"} {
+				kindID := llvm.AttributeKindID(kind)
-					kindID := llvm.AttributeKindID(kind)
+				f.RemoveEnumAttributeAtIndex(f.ParamsCount(), kindID)
-					f.RemoveEnumAttributeAtIndex(f.ParamsCount(), kindID)
-				}
-
-				// Reactivate the parent coroutine. This adds it back to
-				// the run queue, so it is started again by the
-				// scheduler when possible (possibly right after the
-				// following suspend).
-				c.builder.SetInsertPointBefore(inst)
-
-				parentHandle := f.LastParam()
-				c.createRuntimeCall("activateTask", []llvm.Value{parentHandle}, "")
-
-				// Suspend this coroutine.
-				// It would look like this is unnecessary, but if this
-				// suspend point is left out, it leads to undefined
-				// behavior somehow (with the unreachable instruction).
-				continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
-					llvm.ConstNull(c.ctx.TokenType()),
-					llvm.ConstInt(c.ctx.Int1Type(), 1, false),
-				}, "ret")
-				sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
-				sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), frame.unreachableBlock)
-				sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
-				inst.EraseFromParentAsInstruction()
-			} else {
-				panic("todo: return value from coroutine")
 			}
+
+			c.builder.SetInsertPointBefore(inst)
+
+			parentHandle := f.LastParam()
+
+			// Store return values.
+			switch inst.OperandsCount() {
+			case 0:
+				// Nothing to return.
+			case 1:
+				// Return this value by writing to the pointer stored in the
+				// parent handle. The parent coroutine has made an alloca that
+				// we can write to to store our return value.
+				returnValuePtr := c.createRuntimeCall("getTaskPromisePtr", []llvm.Value{parentHandle}, "coro.parentData")
+				alloca := c.builder.CreateBitCast(returnValuePtr, llvm.PointerType(inst.Operand(0).Type(), 0), "coro.parentAlloca")
+				c.builder.CreateStore(inst.Operand(0), alloca)
+			default:
+				panic("unreachable")
+			}
+
+			// Reactivate the parent coroutine. This adds it back to the run
+			// queue, so it is started again by the scheduler when possible
+			// (possibly right after the following suspend).
+			c.createRuntimeCall("activateTask", []llvm.Value{parentHandle}, "")
+
+			// Suspend this coroutine.
+			// It would look like this is unnecessary, but if this
+			// suspend point is left out, it leads to undefined
+			// behavior somehow (with the unreachable instruction).
+			continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
+				llvm.ConstNull(c.ctx.TokenType()),
+				llvm.ConstInt(c.ctx.Int1Type(), 1, false),
+			}, "ret")
+			sw := c.builder.CreateSwitch(continuePoint, frame.suspendBlock, 2)
+			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), frame.unreachableBlock)
+			sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
+			inst.EraseFromParentAsInstruction()
 		}
 
 		// Coroutine cleanup. Free resources associated with this coroutine.
@@ -420,6 +447,14 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 		c.builder.CreateUnreachable()
 	}
 
+	// Replace calls to runtime.getCoroutineCall with the coroutine of this
+	// frame.
+	for _, getCoroutineCall := range getUses(c.mod.NamedFunction("runtime.getCoroutine")) {
+		frame := asyncFuncs[getCoroutineCall.InstructionParent().Parent()]
+		getCoroutineCall.ReplaceAllUsesWith(frame.taskHandle)
+		getCoroutineCall.EraseFromParentAsInstruction()
+	}
+
 	// Transform calls to time.Sleep() into coroutine suspend points.
 	for _, sleepCall := range getUses(sleep) {
 		// sleepCall must be a call instruction.
@@ -463,37 +498,11 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 		deadlockCall.EraseFromParentAsInstruction()
 	}
 
-	// Transform calls to runtime.chanSendStub into channel send operations.
+	// Transform calls to runtime.chanSend into channel send operations.
-	for _, sendOp := range getUses(chanSendStub) {
+	for _, sendOp := range getUses(chanSend) {
 		// sendOp must be a call instruction.
 		frame := asyncFuncs[sendOp.InstructionParent().Parent()]
 
-		// Send the value over the channel, or block.
-		sendOp.SetOperand(0, frame.taskHandle)
-		sendOp.SetOperand(sendOp.OperandsCount()-1, c.mod.NamedFunction("runtime.chanSend"))
-
-		// Use taskState.data to store the value to send:
-		//     *(*valueType)(&coroutine.promise().data) = valueToSend
-		//     runtime.chanSend(coroutine, ch)
-		bitcast := sendOp.Operand(2)
-		valueAlloca := bitcast.Operand(0)
-		c.builder.SetInsertPointBefore(valueAlloca)
-		promiseType := c.mod.GetTypeByName("runtime.taskState")
-		promiseRaw := c.builder.CreateCall(coroPromiseFunc, []llvm.Value{
-			frame.taskHandle,
-			llvm.ConstInt(c.ctx.Int32Type(), uint64(c.targetData.PrefTypeAlignment(promiseType)), false),
-			llvm.ConstInt(c.ctx.Int1Type(), 0, false),
-		}, "task.promise.raw")
-		promise := c.builder.CreateBitCast(promiseRaw, llvm.PointerType(promiseType, 0), "task.promise")
-		dataPtr := c.builder.CreateGEP(promise, []llvm.Value{
-			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(c.ctx.Int32Type(), 2, false),
-		}, "task.promise.data")
-		sendOp.SetOperand(2, llvm.Undef(c.i8ptrType))
-		valueAlloca.ReplaceAllUsesWith(c.builder.CreateBitCast(dataPtr, valueAlloca.Type(), ""))
-		bitcast.EraseFromParentAsInstruction()
-		valueAlloca.EraseFromParentAsInstruction()
-
 		// Yield to scheduler.
 		c.builder.SetInsertPointBefore(llvm.NextInstruction(sendOp))
 		continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
@@ -506,21 +515,11 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
 	}
 
-	// Transform calls to runtime.chanRecvStub into channel receive operations.
+	// Transform calls to runtime.chanRecv into channel receive operations.
-	for _, recvOp := range getUses(chanRecvStub) {
+	for _, recvOp := range getUses(chanRecv) {
 		// recvOp must be a call instruction.
 		frame := asyncFuncs[recvOp.InstructionParent().Parent()]
 
-		bitcast := recvOp.Operand(2)
-		commaOk := recvOp.Operand(3)
-		valueAlloca := bitcast.Operand(0)
-
-		// Receive the value over the channel, or block.
-		recvOp.SetOperand(0, frame.taskHandle)
-		recvOp.SetOperand(recvOp.OperandsCount()-1, c.mod.NamedFunction("runtime.chanRecv"))
-		recvOp.SetOperand(2, llvm.Undef(c.i8ptrType))
-		bitcast.EraseFromParentAsInstruction()
-
 		// Yield to scheduler.
 		c.builder.SetInsertPointBefore(llvm.NextInstruction(recvOp))
 		continuePoint := c.builder.CreateCall(coroSuspendFunc, []llvm.Value{
@@ -532,32 +531,6 @@ func (c *Compiler) markAsyncFunctions() (needsScheduler bool, err error) {
 		c.builder.SetInsertPointAtEnd(recvOp.InstructionParent())
 		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 0, false), wakeup)
 		sw.AddCase(llvm.ConstInt(c.ctx.Int8Type(), 1, false), frame.cleanupBlock)
-
-		// The value to receive is stored in taskState.data:
-		//     runtime.chanRecv(coroutine, ch)
-		//     promise := coroutine.promise()
-		//     valueReceived := *(*valueType)(&promise.data)
-		//     ok := promise.commaOk
-		c.builder.SetInsertPointBefore(wakeup.FirstInstruction())
-		promiseType := c.mod.GetTypeByName("runtime.taskState")
-		promiseRaw := c.builder.CreateCall(coroPromiseFunc, []llvm.Value{
-			frame.taskHandle,
-			llvm.ConstInt(c.ctx.Int32Type(), uint64(c.targetData.PrefTypeAlignment(promiseType)), false),
-			llvm.ConstInt(c.ctx.Int1Type(), 0, false),
-		}, "task.promise.raw")
-		promise := c.builder.CreateBitCast(promiseRaw, llvm.PointerType(promiseType, 0), "task.promise")
-		dataPtr := c.builder.CreateGEP(promise, []llvm.Value{
-			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(c.ctx.Int32Type(), 2, false),
-		}, "task.promise.data")
-		valueAlloca.ReplaceAllUsesWith(c.builder.CreateBitCast(dataPtr, valueAlloca.Type(), ""))
-		valueAlloca.EraseFromParentAsInstruction()
-		commaOkPtr := c.builder.CreateGEP(promise, []llvm.Value{
-			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
-			llvm.ConstInt(c.ctx.Int32Type(), 1, false),
-		}, "task.promise.comma-ok")
-		commaOk.ReplaceAllUsesWith(commaOkPtr)
-		recvOp.SetOperand(3, llvm.Undef(commaOk.Type()))
 	}
 
 	return true, c.lowerMakeGoroutineCalls()

compiler/inlineasm.go

@@ -68,11 +68,7 @@ func (c *Compiler) emitAsmFull(frame *Frame, instr *ssa.CallCommon) (llvm.Value,
 			}
 			key := constant.StringVal(r.Key.(*ssa.Const).Value)
 			//println("value:", r.Value.(*ssa.MakeInterface).X.String())
-			value, err := c.parseExpr(frame, r.Value.(*ssa.MakeInterface).X)
+			registers[key] = c.getValue(frame, r.Value.(*ssa.MakeInterface).X)
-			if err != nil {
-				return llvm.Value{}, err
-			}
-			registers[key] = value
 		case *ssa.Call:
 			if r.Common() == instr {
 				break
@@ -145,10 +141,7 @@ func (c *Compiler) emitSVCall(frame *Frame, args []ssa.Value) (llvm.Value, error
 		} else {
 			constraints += ",{r" + strconv.Itoa(i) + "}"
 		}
-		llvmValue, err := c.parseExpr(frame, arg)
+		llvmValue := c.getValue(frame, arg)
-		if err != nil {
-			return llvm.Value{}, err
-		}
 		llvmArgs = append(llvmArgs, llvmValue)
 		argTypes = append(argTypes, llvmValue.Type())
 	}

compiler/interface-lowering.go

@@ -527,11 +527,40 @@ func (p *lowerInterfacesPass) replaceInvokeWithCall(use llvm.Value, typ *typeInf
 	}
 	inttoptr := inttoptrs[0]
 	function := typ.getMethod(signature).function
-	if inttoptr.Type() != function.Type() {
+	if inttoptr.Type() == function.Type() {
-		p.builder.SetInsertPointBefore(use)
+		// Easy case: the types are the same. Simply replace the inttoptr
-		function = p.builder.CreateBitCast(function, inttoptr.Type(), "")
+		// result (which is directly called) with the actual function.
+		inttoptr.ReplaceAllUsesWith(function)
+	} else {
+		// Harder case: the type is not actually the same. Go through each call
+		// (of which there should be only one), extract the receiver params for
+		// this call and replace the call with a direct call to the target
+		// function.
+		for _, call := range getUses(inttoptr) {
+			if call.IsACallInst().IsNil() || call.CalledValue() != inttoptr {
+				panic("expected the inttoptr to be called as a method, this is not a method call")
+			}
+			operands := make([]llvm.Value, call.OperandsCount()-1)
+			for i := range operands {
+				operands[i] = call.Operand(i)
+			}
+			paramTypes := function.Type().ElementType().ParamTypes()
+			receiverParamTypes := paramTypes[:len(paramTypes)-(len(operands)-1)]
+			methodParamTypes := paramTypes[len(paramTypes)-(len(operands)-1):]
+			for i, methodParamType := range methodParamTypes {
+				if methodParamType != operands[i+1].Type() {
+					panic("expected method call param type and function param type to be the same")
+				}
+			}
+			p.builder.SetInsertPointBefore(call)
+			receiverParams := p.emitPointerUnpack(operands[0], receiverParamTypes)
+			result := p.builder.CreateCall(function, append(receiverParams, operands[1:]...), "")
+			if result.Type().TypeKind() != llvm.VoidTypeKind {
+				call.ReplaceAllUsesWith(result)
+			}
+			call.EraseFromParentAsInstruction()
+		}
 	}
-	inttoptr.ReplaceAllUsesWith(function)
 	inttoptr.EraseFromParentAsInstruction()
 	use.EraseFromParentAsInstruction()
 }

compiler/interface.go

@@ -23,37 +23,7 @@ import (
 //
 // An interface value is a {typecode, value} tuple, or {i16, i8*} to be exact.
 func (c *Compiler) parseMakeInterface(val llvm.Value, typ types.Type, pos token.Pos) (llvm.Value, error) {
-	var itfValue llvm.Value
+	itfValue := c.emitPointerPack([]llvm.Value{val})
-	size := c.targetData.TypeAllocSize(val.Type())
-	if size > c.targetData.TypeAllocSize(c.i8ptrType) {
-		// Allocate on the heap and put a pointer in the interface.
-		// TODO: escape analysis.
-		sizeValue := llvm.ConstInt(c.uintptrType, size, false)
-		alloc := c.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "makeinterface.alloc")
-		itfValueCast := c.builder.CreateBitCast(alloc, llvm.PointerType(val.Type(), 0), "makeinterface.cast.value")
-		c.builder.CreateStore(val, itfValueCast)
-		itfValue = c.builder.CreateBitCast(itfValueCast, c.i8ptrType, "makeinterface.cast.i8ptr")
-	} else if size == 0 {
-		itfValue = llvm.ConstPointerNull(c.i8ptrType)
-	} else {
-		// Directly place the value in the interface.
-		switch val.Type().TypeKind() {
-		case llvm.IntegerTypeKind:
-			itfValue = c.builder.CreateIntToPtr(val, c.i8ptrType, "makeinterface.cast.int")
-		case llvm.PointerTypeKind:
-			itfValue = c.builder.CreateBitCast(val, c.i8ptrType, "makeinterface.cast.ptr")
-		case llvm.StructTypeKind, llvm.FloatTypeKind, llvm.DoubleTypeKind:
-			// A bitcast would be useful here, but bitcast doesn't allow
-			// aggregate types. So we'll bitcast it using an alloca.
-			// Hopefully this will get optimized away.
-			mem := c.builder.CreateAlloca(c.i8ptrType, "makeinterface.cast.struct")
-			memStructPtr := c.builder.CreateBitCast(mem, llvm.PointerType(val.Type(), 0), "makeinterface.cast.struct.cast")
-			c.builder.CreateStore(val, memStructPtr)
-			itfValue = c.builder.CreateLoad(mem, "makeinterface.cast.load")
-		default:
-			return llvm.Value{}, c.makeError(pos, "todo: makeinterface: cast small type to i8*")
-		}
-	}
 	itfTypeCodeGlobal := c.getTypeCode(typ)
 	itfMethodSetGlobal, err := c.getTypeMethodSet(typ)
 	if err != nil {
@@ -274,19 +244,9 @@ func (c *Compiler) getMethodSignature(method *types.Func) llvm.Value {
 //
 // Type asserts on concrete types are trivial: just compare type numbers. Type
 // asserts on interfaces are more difficult, see the comments in the function.
-func (c *Compiler) parseTypeAssert(frame *Frame, expr *ssa.TypeAssert) (llvm.Value, error) {
+func (c *Compiler) parseTypeAssert(frame *Frame, expr *ssa.TypeAssert) llvm.Value {
-	itf, err := c.parseExpr(frame, expr.X)
+	itf := c.getValue(frame, expr.X)
-	if err != nil {
+	assertedType := c.getLLVMType(expr.AssertedType)
-		return llvm.Value{}, err
-	}
-	assertedType, err := c.getLLVMType(expr.AssertedType)
-	if err != nil {
-		return llvm.Value{}, err
-	}
-	valueNil, err := c.getZeroValue(assertedType)
-	if err != nil {
-		return llvm.Value{}, err
-	}
 
 	actualTypeNum := c.builder.CreateExtractValue(itf, 0, "interface.type")
 	commaOk := llvm.Value{}
@@ -339,67 +299,35 @@ func (c *Compiler) parseTypeAssert(frame *Frame, expr *ssa.TypeAssert) (llvm.Val
 		// Type assert on concrete type. Extract the underlying type from
 		// the interface (but only after checking it matches).
 		valuePtr := c.builder.CreateExtractValue(itf, 1, "typeassert.value.ptr")
-		size := c.targetData.TypeAllocSize(assertedType)
+		valueOk = c.emitPointerUnpack(valuePtr, []llvm.Type{assertedType})[0]
-		if size > c.targetData.TypeAllocSize(c.i8ptrType) {
-			// Value was stored in an allocated buffer, load it from there.
-			valuePtrCast := c.builder.CreateBitCast(valuePtr, llvm.PointerType(assertedType, 0), "")
-			valueOk = c.builder.CreateLoad(valuePtrCast, "typeassert.value.ok")
-		} else if size == 0 {
-			valueOk, err = c.getZeroValue(assertedType)
-			if err != nil {
-				return llvm.Value{}, err
-			}
-		} else {
-			// Value was stored directly in the interface.
-			switch assertedType.TypeKind() {
-			case llvm.IntegerTypeKind:
-				valueOk = c.builder.CreatePtrToInt(valuePtr, assertedType, "typeassert.value.ok")
-			case llvm.PointerTypeKind:
-				valueOk = c.builder.CreateBitCast(valuePtr, assertedType, "typeassert.value.ok")
-			default: // struct, float, etc.
-				// A bitcast would be useful here, but bitcast doesn't allow
-				// aggregate types. So we'll bitcast it using an alloca.
-				// Hopefully this will get optimized away.
-				mem := c.builder.CreateAlloca(c.i8ptrType, "")
-				c.builder.CreateStore(valuePtr, mem)
-				memCast := c.builder.CreateBitCast(mem, llvm.PointerType(assertedType, 0), "")
-				valueOk = c.builder.CreateLoad(memCast, "typeassert.value.ok")
-			}
-		}
 	}
 	c.builder.CreateBr(nextBlock)
 
 	// Continue after the if statement.
 	c.builder.SetInsertPointAtEnd(nextBlock)
 	phi := c.builder.CreatePHI(assertedType, "typeassert.value")
-	phi.AddIncoming([]llvm.Value{valueNil, valueOk}, []llvm.BasicBlock{prevBlock, okBlock})
+	phi.AddIncoming([]llvm.Value{c.getZeroValue(assertedType), valueOk}, []llvm.BasicBlock{prevBlock, okBlock})
 
 	if expr.CommaOk {
 		tuple := c.ctx.ConstStruct([]llvm.Value{llvm.Undef(assertedType), llvm.Undef(c.ctx.Int1Type())}, false) // create empty tuple
 		tuple = c.builder.CreateInsertValue(tuple, phi, 0, "")                                                  // insert value
 		tuple = c.builder.CreateInsertValue(tuple, commaOk, 1, "")                                              // insert 'comma ok' boolean
-		return tuple, nil
+		return tuple
 	} else {
 		// This is kind of dirty as the branch above becomes mostly useless,
 		// but hopefully this gets optimized away.
 		c.createRuntimeCall("interfaceTypeAssert", []llvm.Value{commaOk}, "")
-		return phi, nil
+		return phi
 	}
 }
 
 // getInvokeCall creates and returns the function pointer and parameters of an
 // interface call. It can be used in a call or defer instruction.
-func (c *Compiler) getInvokeCall(frame *Frame, instr *ssa.CallCommon) (llvm.Value, []llvm.Value, error) {
+func (c *Compiler) getInvokeCall(frame *Frame, instr *ssa.CallCommon) (llvm.Value, []llvm.Value) {
 	// Call an interface method with dynamic dispatch.
-	itf, err := c.parseExpr(frame, instr.Value) // interface
+	itf := c.getValue(frame, instr.Value) // interface
-	if err != nil {
-		return llvm.Value{}, nil, err
-	}
 
-	llvmFnType, err := c.getRawFuncType(instr.Method.Type().(*types.Signature))
+	llvmFnType := c.getRawFuncType(instr.Method.Type().(*types.Signature))
-	if err != nil {
-		return llvm.Value{}, nil, err
-	}
 
 	typecode := c.builder.CreateExtractValue(itf, 0, "invoke.typecode")
 	values := []llvm.Value{
@@ -413,11 +341,7 @@ func (c *Compiler) getInvokeCall(frame *Frame, instr *ssa.CallCommon) (llvm.Valu
 
 	args := []llvm.Value{receiverValue}
 	for _, arg := range instr.Args {
-		val, err := c.parseExpr(frame, arg)
+		args = append(args, c.getValue(frame, arg))
-		if err != nil {
-			return llvm.Value{}, nil, err
-		}
-		args = append(args, val)
 	}
 	// Add the context parameter. An interface call never takes a context but we
 	// have to supply the parameter anyway.
@@ -425,7 +349,7 @@ func (c *Compiler) getInvokeCall(frame *Frame, instr *ssa.CallCommon) (llvm.Valu
 	// Add the parent goroutine handle.
 	args = append(args, llvm.Undef(c.i8ptrType))
 
-	return fnCast, args, nil
+	return fnCast, args
 }
 
 // interfaceInvokeWrapper keeps some state between getInterfaceInvokeWrapper and
@@ -450,10 +374,7 @@ func (c *Compiler) getInterfaceInvokeWrapper(f *ir.Function) (llvm.Value, error)
 	}
 
 	// Get the expanded receiver type.
-	receiverType, err := c.getLLVMType(f.Params[0].Type())
+	receiverType := c.getLLVMType(f.Params[0].Type())
-	if err != nil {
-		return llvm.Value{}, err
-	}
 	expandedReceiverType := c.expandFormalParamType(receiverType)
 
 	// Does this method even need any wrapping?
@@ -480,7 +401,7 @@ func (c *Compiler) getInterfaceInvokeWrapper(f *ir.Function) (llvm.Value, error)
 
 // createInterfaceInvokeWrapper finishes the work of getInterfaceInvokeWrapper,
 // see that function for details.
-func (c *Compiler) createInterfaceInvokeWrapper(state interfaceInvokeWrapper) error {
+func (c *Compiler) createInterfaceInvokeWrapper(state interfaceInvokeWrapper) {
 	wrapper := state.wrapper
 	fn := state.fn
 	receiverType := state.receiverType
@@ -490,10 +411,7 @@ func (c *Compiler) createInterfaceInvokeWrapper(state interfaceInvokeWrapper) er
 	// add debug info if needed
 	if c.Debug {
 		pos := c.ir.Program.Fset.Position(fn.Pos())
-		difunc, err := c.attachDebugInfoRaw(fn, wrapper, "$invoke", pos.Filename, pos.Line)
+		difunc := c.attachDebugInfoRaw(fn, wrapper, "$invoke", pos.Filename, pos.Line)
-		if err != nil {
-			return err
-		}
 		c.builder.SetCurrentDebugLocation(uint(pos.Line), uint(pos.Column), difunc, llvm.Metadata{})
 	}
 
@@ -501,28 +419,7 @@ func (c *Compiler) createInterfaceInvokeWrapper(state interfaceInvokeWrapper) er
 	block := c.ctx.AddBasicBlock(wrapper, "entry")
 	c.builder.SetInsertPointAtEnd(block)
 
-	var receiverPtr llvm.Value
+	receiverValue := c.emitPointerUnpack(wrapper.Param(0), []llvm.Type{receiverType})[0]
-	if c.targetData.TypeAllocSize(receiverType) > c.targetData.TypeAllocSize(c.i8ptrType) {
-		// The receiver is passed in using a pointer. We have to load it here
-		// and pass it by value to the real function.
-
-		// Load the underlying value.
-		receiverPtrType := llvm.PointerType(receiverType, 0)
-		receiverPtr = c.builder.CreateBitCast(wrapper.Param(0), receiverPtrType, "receiver.ptr")
-	} else {
-		// The value is stored in the interface, but it is of type struct which
-		// is expanded to multiple parameters (e.g. {i8, i8}). So we have to
-		// receive the struct as parameter, expand it, and pass it on to the
-		// real function.
-
-		// Cast the passed-in i8* to the struct value (using an alloca) and
-		// extract its values.
-		alloca := c.builder.CreateAlloca(c.i8ptrType, "receiver.alloca")
-		c.builder.CreateStore(wrapper.Param(0), alloca)
-		receiverPtr = c.builder.CreateBitCast(alloca, llvm.PointerType(receiverType, 0), "receiver.ptr")
-	}
-
-	receiverValue := c.builder.CreateLoad(receiverPtr, "receiver")
 	params := append(c.expandFormalParam(receiverValue), wrapper.Params()[1:]...)
 	if fn.LLVMFn.Type().ElementType().ReturnType().TypeKind() == llvm.VoidTypeKind {
 		c.builder.CreateCall(fn.LLVMFn, params, "")
@@ -531,6 +428,4 @@ func (c *Compiler) createInterfaceInvokeWrapper(state interfaceInvokeWrapper) er
 		ret := c.builder.CreateCall(fn.LLVMFn, params, "ret")
 		c.builder.CreateRet(ret)
 	}
-
-	return nil
 }

compiler/llvm.go

@@ -22,6 +22,17 @@ func getUses(value llvm.Value) []llvm.Value {
 	return uses
 }
 
+// getLifetimeEndFunc returns the llvm.lifetime.end intrinsic and creates it
+// first if it doesn't exist yet.
+func (c *Compiler) getLifetimeEndFunc() llvm.Value {
+	fn := c.mod.NamedFunction("llvm.lifetime.end.p0i8")
+	if fn.IsNil() {
+		fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.ctx.Int64Type(), c.i8ptrType}, false)
+		fn = llvm.AddFunction(c.mod, "llvm.lifetime.end.p0i8", fnType)
+	}
+	return fn
+}
+
 // splitBasicBlock splits a LLVM basic block into two parts. All instructions
 // after afterInst are moved into a new basic block (created right after the
 // current one) with the given name.

compiler/map.go

@@ -10,10 +10,7 @@ import (
 )
 
 func (c *Compiler) emitMapLookup(keyType, valueType types.Type, m, key llvm.Value, commaOk bool, pos token.Pos) (llvm.Value, error) {
-	llvmValueType, err := c.getLLVMType(valueType)
+	llvmValueType := c.getLLVMType(valueType)
-	if err != nil {
-		return llvm.Value{}, err
-	}
 	mapValueAlloca := c.builder.CreateAlloca(llvmValueType, "hashmap.value")
 	mapValuePtr := c.builder.CreateBitCast(mapValueAlloca, c.i8ptrType, "hashmap.valueptr")
 	var commaOkValue llvm.Value
@@ -42,7 +39,7 @@ func (c *Compiler) emitMapLookup(keyType, valueType types.Type, m, key llvm.Valu
 	}
 }
 
-func (c *Compiler) emitMapUpdate(keyType types.Type, m, key, value llvm.Value, pos token.Pos) error {
+func (c *Compiler) emitMapUpdate(keyType types.Type, m, key, value llvm.Value, pos token.Pos) {
 	valueAlloca := c.builder.CreateAlloca(value.Type(), "hashmap.value")
 	c.builder.CreateStore(value, valueAlloca)
 	valuePtr := c.builder.CreateBitCast(valueAlloca, c.i8ptrType, "hashmap.valueptr")
@@ -51,7 +48,6 @@ func (c *Compiler) emitMapUpdate(keyType types.Type, m, key, value llvm.Value, p
 		// key is a string
 		params := []llvm.Value{m, key, valuePtr}
 		c.createRuntimeCall("hashmapStringSet", params, "")
-		return nil
 	} else if hashmapIsBinaryKey(keyType) {
 		// key can be compared with runtime.memequal
 		keyAlloca := c.builder.CreateAlloca(key.Type(), "hashmap.key")
@@ -59,9 +55,8 @@ func (c *Compiler) emitMapUpdate(keyType types.Type, m, key, value llvm.Value, p
 		keyPtr := c.builder.CreateBitCast(keyAlloca, c.i8ptrType, "hashmap.keyptr")
 		params := []llvm.Value{m, keyPtr, valuePtr}
 		c.createRuntimeCall("hashmapBinarySet", params, "")
-		return nil
 	} else {
-		return c.makeError(pos, "only strings, bools, ints or structs of bools/ints are supported as map keys, but got: "+keyType.String())
+		c.addError(pos, "only strings, bools, ints or structs of bools/ints are supported as map keys, but got: "+keyType.String())
 	}
 }
 

compiler/optimizer.go

@@ -18,6 +18,10 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro
 	}
 	builder.AddCoroutinePassesToExtensionPoints()
 
+	if c.PanicStrategy == "trap" {
+		c.replacePanicsWithTrap() // -panic=trap
+	}
+
 	// Run function passes for each function.
 	funcPasses := llvm.NewFunctionPassManagerForModule(c.mod)
 	defer funcPasses.Dispose()
@@ -113,6 +117,25 @@ func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) erro
 	return nil
 }
 
+// Replace panic calls with calls to llvm.trap, to reduce code size. This is the
+// -panic=trap intrinsic.
+func (c *Compiler) replacePanicsWithTrap() {
+	trap := c.mod.NamedFunction("llvm.trap")
+	for _, name := range []string{"runtime._panic", "runtime.runtimePanic"} {
+		fn := c.mod.NamedFunction(name)
+		if fn.IsNil() {
+			continue
+		}
+		for _, use := range getUses(fn) {
+			if use.IsACallInst().IsNil() || use.CalledValue() != fn {
+				panic("expected use of a panic function to be a call")
+			}
+			c.builder.SetInsertPointBefore(use)
+			c.builder.CreateCall(trap, nil, "")
+		}
+	}
+}
+
 // Eliminate created but not used maps.
 //
 // In the future, this should statically allocate created but never modified
@@ -249,7 +272,7 @@ func (c *Compiler) OptimizeAllocs() {
 			sizeInWords := (size + uint64(alignment) - 1) / uint64(alignment)
 			allocaType := llvm.ArrayType(c.ctx.IntType(alignment*8), int(sizeInWords))
 			alloca := c.builder.CreateAlloca(allocaType, "stackalloc.alloca")
-			zero, _ := c.getZeroValue(alloca.Type().ElementType())
+			zero := c.getZeroValue(alloca.Type().ElementType())
 			c.builder.CreateStore(zero, alloca)
 			stackalloc := c.builder.CreateBitCast(alloca, bitcast.Type(), "stackalloc")
 			bitcast.ReplaceAllUsesWith(stackalloc)
@@ -284,18 +307,6 @@ func (c *Compiler) doesEscape(value llvm.Value) bool {
 				return true
 			}
 		} else if use.IsACallInst() != nilValue {
-			// Call only escapes when the (pointer) parameter is not marked
-			// "nocapture". This flag means that the parameter does not escape
-			// the give function.
-			if use.CalledValue().IsAFunction() != nilValue {
-				if use.CalledValue().IsDeclaration() {
-					// Kind of dirty: assume external functions don't let
-					// pointers escape.
-					// TODO: introduce //go:noescape that sets the 'nocapture'
-					// flag on each input parameter.
-					continue
-				}
-			}
 			if !c.hasFlag(use, value, "nocapture") {
 				return true
 			}

compiler/sizes.go

@@ -113,6 +113,9 @@ func (s *StdSizes) Sizeof(T types.Type) int64 {
 		if k == types.Uintptr {
 			return s.PtrSize
 		}
+		if k == types.UnsafePointer {
+			return s.PtrSize
+		}
 		panic("unknown basic type: " + t.String())
 	case *types.Array:
 		n := t.Len()

compiler/syscall.go

@@ -51,10 +51,7 @@ func (c *Compiler) emitSyscall(frame *Frame, call *ssa.CallCommon) (llvm.Value,
 				"{r12}",
 				"{r13}",
 			}[i]
-			llvmValue, err := c.parseExpr(frame, arg)
+			llvmValue := c.getValue(frame, arg)
-			if err != nil {
-				return llvm.Value{}, err
-			}
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
@@ -80,10 +77,7 @@ func (c *Compiler) emitSyscall(frame *Frame, call *ssa.CallCommon) (llvm.Value,
 				"{r5}",
 				"{r6}",
 			}[i]
-			llvmValue, err := c.parseExpr(frame, arg)
+			llvmValue := c.getValue(frame, arg)
-			if err != nil {
-				return llvm.Value{}, err
-			}
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}
@@ -113,10 +107,7 @@ func (c *Compiler) emitSyscall(frame *Frame, call *ssa.CallCommon) (llvm.Value,
 				"{x4}",
 				"{x5}",
 			}[i]
-			llvmValue, err := c.parseExpr(frame, arg)
+			llvmValue := c.getValue(frame, arg)
-			if err != nil {
-				return llvm.Value{}, err
-			}
 			args = append(args, llvmValue)
 			argTypes = append(argTypes, llvmValue.Type())
 		}

compiler/wordpack.go

@@ -0,0 +1,108 @@
+package compiler
+
+// This file contains utility functions to pack and unpack sets of values. It
+// can take in a list of values and tries to store it efficiently in the pointer
+// itself if possible and legal.
+
+import (
+	"tinygo.org/x/go-llvm"
+)
+
+// emitPointerPack packs the list of values into a single pointer value using
+// bitcasts, or else allocates a value on the heap if it cannot be packed in the
+// pointer value directly. It returns the pointer with the packed data.
+func (c *Compiler) emitPointerPack(values []llvm.Value) llvm.Value {
+	valueTypes := make([]llvm.Type, len(values))
+	for i, value := range values {
+		valueTypes[i] = value.Type()
+	}
+	packedType := c.ctx.StructType(valueTypes, false)
+
+	// Allocate memory for the packed data.
+	var packedAlloc, packedHeapAlloc llvm.Value
+	size := c.targetData.TypeAllocSize(packedType)
+	if size == 0 {
+		return llvm.ConstPointerNull(c.i8ptrType)
+	} else if len(values) == 1 && values[0].Type().TypeKind() == llvm.PointerTypeKind {
+		return c.builder.CreateBitCast(values[0], c.i8ptrType, "pack.ptr")
+	} else if size <= c.targetData.TypeAllocSize(c.i8ptrType) {
+		// Packed data fits in a pointer, so store it directly inside the
+		// pointer.
+		if len(values) == 1 && values[0].Type().TypeKind() == llvm.IntegerTypeKind {
+			// Try to keep this cast in SSA form.
+			return c.builder.CreateIntToPtr(values[0], c.i8ptrType, "pack.int")
+		}
+		// Because packedType is a struct and we have to cast it to a *i8, store
+		// it in an alloca first for bitcasting (store+bitcast+load).
+		packedAlloc = c.builder.CreateAlloca(packedType, "")
+	} else {
+		// Packed data is bigger than a pointer, so allocate it on the heap.
+		sizeValue := llvm.ConstInt(c.uintptrType, size, false)
+		packedHeapAlloc = c.createRuntimeCall("alloc", []llvm.Value{sizeValue}, "")
+		packedAlloc = c.builder.CreateBitCast(packedHeapAlloc, llvm.PointerType(packedType, 0), "")
+	}
+	// Store all values in the alloca or heap pointer.
+	for i, value := range values {
+		indices := []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
+		}
+		gep := c.builder.CreateInBoundsGEP(packedAlloc, indices, "")
+		c.builder.CreateStore(value, gep)
+	}
+
+	if packedHeapAlloc.IsNil() {
+		// Load value (as *i8) from the alloca.
+		packedAlloc = c.builder.CreateBitCast(packedAlloc, llvm.PointerType(c.i8ptrType, 0), "")
+		return c.builder.CreateLoad(packedAlloc, "")
+	} else {
+		// Get the original heap allocation pointer, which already is an *i8.
+		return packedHeapAlloc
+	}
+}
+
+// emitPointerUnpack extracts a list of values packed using emitPointerPack.
+func (c *Compiler) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
+	packedType := c.ctx.StructType(valueTypes, false)
+
+	// Get a correctly-typed pointer to the packed data.
+	var packedAlloc llvm.Value
+	size := c.targetData.TypeAllocSize(packedType)
+	if size == 0 {
+		// No data to unpack.
+	} else if len(valueTypes) == 1 && valueTypes[0].TypeKind() == llvm.PointerTypeKind {
+		// A single pointer is always stored directly.
+		return []llvm.Value{c.builder.CreateBitCast(ptr, valueTypes[0], "unpack.ptr")}
+	} else if size <= c.targetData.TypeAllocSize(c.i8ptrType) {
+		// Packed data stored directly in pointer.
+		if len(valueTypes) == 1 && valueTypes[0].TypeKind() == llvm.IntegerTypeKind {
+			// Keep this cast in SSA form.
+			return []llvm.Value{c.builder.CreatePtrToInt(ptr, valueTypes[0], "unpack.int")}
+		}
+		// Fallback: load it using an alloca.
+		packedRawAlloc := c.builder.CreateAlloca(llvm.PointerType(c.i8ptrType, 0), "unpack.raw.alloc")
+		packedRawValue := c.builder.CreateBitCast(ptr, llvm.PointerType(c.i8ptrType, 0), "unpack.raw.value")
+		c.builder.CreateStore(packedRawValue, packedRawAlloc)
+		packedAlloc = c.builder.CreateBitCast(packedRawAlloc, llvm.PointerType(packedType, 0), "unpack.alloc")
+	} else {
+		// Packed data stored on the heap. Bitcast the passed-in pointer to the
+		// correct pointer type.
+		packedAlloc = c.builder.CreateBitCast(ptr, llvm.PointerType(packedType, 0), "unpack.raw.ptr")
+	}
+	// Load each value from the packed data.
+	values := make([]llvm.Value, len(valueTypes))
+	for i, valueType := range valueTypes {
+		if c.targetData.TypeAllocSize(valueType) == 0 {
+			// This value has length zero, so there's nothing to load.
+			values[i] = c.getZeroValue(valueType)
+			continue
+		}
+		indices := []llvm.Value{
+			llvm.ConstInt(c.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(c.ctx.Int32Type(), uint64(i), false),
+		}
+		gep := c.builder.CreateInBoundsGEP(packedAlloc, indices, "")
+		values[i] = c.builder.CreateLoad(gep, "")
+	}
+	return values
+}

linker-builtin.go

@@ -24,7 +24,7 @@ import "C"
 // This version uses the built-in linker when trying to use lld.
 func Link(linker string, flags ...string) error {
 	switch linker {
-	case "ld.lld", commands["ld.lld"]:
+	case "ld.lld":
 		flags = append([]string{"tinygo:" + linker}, flags...)
 		var cflag *C.char
 		buf := C.calloc(C.size_t(len(flags)), C.size_t(unsafe.Sizeof(cflag)))
@@ -39,7 +39,7 @@ func Link(linker string, flags ...string) error {
 			return errors.New("failed to link using built-in ld.lld")
 		}
 		return nil
-	case "wasm-ld", commands["wasm-ld"]:
+	case "wasm-ld":
 		flags = append([]string{"tinygo:" + linker}, flags...)
 		var cflag *C.char
 		buf := C.calloc(C.size_t(len(flags)), C.size_t(unsafe.Sizeof(cflag)))
@@ -57,6 +57,9 @@ func Link(linker string, flags ...string) error {
 		return nil
 	default:
 		// Fall back to external command.
+		if cmdNames, ok := commands[linker]; ok {
+			return execCommand(cmdNames, flags...)
+		}
 		cmd := exec.Command(linker, flags...)
 		cmd.Stdout = os.Stdout
 		cmd.Stderr = os.Stderr

linker-external.go

@@ -14,6 +14,9 @@ import (
 //
 // This version always runs the linker as an external command.
 func Link(linker string, flags ...string) error {
+	if cmdNames, ok := commands[linker]; ok {
+		return execCommand(cmdNames, flags...)
+	}
 	cmd := exec.Command(linker, flags...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr

loader/cgo.go

@@ -23,6 +23,7 @@ type fileInfo struct {
 	typedefs        map[string]*typedefInfo
 	elaboratedTypes map[string]ast.Expr
 	importCPos      token.Pos
+	missingSymbols  map[string]struct{}
 }
 
 // functionInfo stores some information about a Cgo function found by libclang
@@ -62,10 +63,27 @@ var cgoAliases = map[string]string{
 	"C.uintptr_t": "uintptr",
 }
 
+// cgoBuiltinAliases are handled specially because they only exist on the Go
+// side of CGo, not on the CGo (they're prefixed with "_Cgo_" there).
+var cgoBuiltinAliases = map[string]struct{}{
+	"char":      struct{}{},
+	"schar":     struct{}{},
+	"uchar":     struct{}{},
+	"short":     struct{}{},
+	"ushort":    struct{}{},
+	"int":       struct{}{},
+	"uint":      struct{}{},
+	"long":      struct{}{},
+	"ulong":     struct{}{},
+	"longlong":  struct{}{},
+	"ulonglong": struct{}{},
+}
+
 // cgoTypes lists some C types with ambiguous sizes that must be retrieved
 // somehow from C. This is done by adding some typedefs to get the size of each
 // type.
 const cgoTypes = `
+typedef char                _Cgo_char;
 typedef signed char         _Cgo_schar;
 typedef unsigned char       _Cgo_uchar;
 typedef short               _Cgo_short;
@@ -89,6 +107,13 @@ func (p *Package) processCgo(filename string, f *ast.File, cflags []string) []er
 		globals:         map[string]*globalInfo{},
 		typedefs:        map[string]*typedefInfo{},
 		elaboratedTypes: map[string]ast.Expr{},
+		missingSymbols:  map[string]struct{}{},
+	}
+
+	// Find all C.* symbols.
+	f = astutil.Apply(f, info.findMissingCGoNames, nil).(*ast.File)
+	for name := range cgoBuiltinAliases {
+		info.missingSymbols["_Cgo_"+name] = struct{}{}
 	}
 
 	// Find `import "C"` statements in the file.
@@ -220,6 +245,9 @@ func (info *fileInfo) addFuncDecls() {
 //         // ...
 //     )
 func (info *fileInfo) addFuncPtrDecls() {
+	if len(info.functions) == 0 {
+		return
+	}
 	gen := &ast.GenDecl{
 		TokPos: info.importCPos,
 		Tok:    token.VAR,
@@ -268,6 +296,9 @@ func (info *fileInfo) addFuncPtrDecls() {
 //         // ...
 //     )
 func (info *fileInfo) addVarDecls() {
+	if len(info.globals) == 0 {
+		return
+	}
 	gen := &ast.GenDecl{
 		TokPos: info.importCPos,
 		Tok:    token.VAR,
@@ -344,6 +375,9 @@ func (info *fileInfo) addTypeAliases() {
 }
 
 func (info *fileInfo) addTypedefs() {
+	if len(info.typedefs) == 0 {
+		return
+	}
 	gen := &ast.GenDecl{
 		TokPos: info.importCPos,
 		Tok:    token.TYPE,
@@ -356,8 +390,10 @@ func (info *fileInfo) addTypedefs() {
 	for _, name := range names {
 		typedef := info.typedefs[name]
 		typeName := "C." + name
+		isAlias := true
 		if strings.HasPrefix(name, "_Cgo_") {
 			typeName = "C." + name[len("_Cgo_"):]
+			isAlias = false // C.short etc. should not be aliased to the equivalent Go type (not portable)
 		}
 		if _, ok := cgoAliases[typeName]; ok {
 			// This is a type that also exists in Go (defined in stdint.h).
@@ -375,6 +411,9 @@ func (info *fileInfo) addTypedefs() {
 			},
 			Type: typedef.typeExpr,
 		}
+		if isAlias {
+			typeSpec.Assign = info.importCPos
+		}
 		obj.Decl = typeSpec
 		gen.Specs = append(gen.Specs, typeSpec)
 	}
@@ -387,6 +426,9 @@ func (info *fileInfo) addTypedefs() {
 // See also:
 // https://en.cppreference.com/w/cpp/language/elaborated_type_specifier
 func (info *fileInfo) addElaboratedTypes() {
+	if len(info.elaboratedTypes) == 0 {
+		return
+	}
 	gen := &ast.GenDecl{
 		TokPos: info.importCPos,
 		Tok:    token.TYPE,
@@ -398,7 +440,7 @@ func (info *fileInfo) addElaboratedTypes() {
 	sort.Strings(names)
 	for _, name := range names {
 		typ := info.elaboratedTypes[name]
-		typeName := "C.struct_" + name
+		typeName := "C." + name
 		obj := &ast.Object{
 			Kind: ast.Typ,
 			Name: typeName,
@@ -417,6 +459,27 @@ func (info *fileInfo) addElaboratedTypes() {
 	info.Decls = append(info.Decls, gen)
 }
 
+// findMissingCGoNames traverses the AST and finds all C.something names. Only
+// these symbols are extracted from the parsed C AST and converted to the Go
+// equivalent.
+func (info *fileInfo) findMissingCGoNames(cursor *astutil.Cursor) bool {
+	switch node := cursor.Node().(type) {
+	case *ast.SelectorExpr:
+		x, ok := node.X.(*ast.Ident)
+		if !ok {
+			return true
+		}
+		if x.Name == "C" {
+			name := node.Sel.Name
+			if _, ok := cgoBuiltinAliases[name]; ok {
+				name = "_Cgo_" + name
+			}
+			info.missingSymbols[name] = struct{}{}
+		}
+	}
+	return true
+}
+
 // walker replaces all "C".<something> expressions to literal "C.<something>"
 // expressions. Such expressions are impossible to write in Go (a dot cannot be
 // used in the middle of a name) so in practice all C identifiers live in a

loader/libclang.go

@@ -4,6 +4,7 @@ package loader
 // modification. It does not touch the AST itself.
 
 import (
+	"fmt"
 	"go/ast"
 	"go/scanner"
 	"go/token"
@@ -45,6 +46,8 @@ CXType tinygo_clang_getTypedefDeclUnderlyingType(GoCXCursor c);
 CXType tinygo_clang_getCursorResultType(GoCXCursor c);
 int tinygo_clang_Cursor_getNumArguments(GoCXCursor c);
 GoCXCursor tinygo_clang_Cursor_getArgument(GoCXCursor c, unsigned i);
+CXSourceLocation tinygo_clang_getCursorLocation(GoCXCursor c);
+CXTranslationUnit tinygo_clang_Cursor_getTranslationUnit(GoCXCursor c);
 
 int tinygo_clang_globals_visitor(GoCXCursor c, GoCXCursor parent, CXClientData client_data);
 int tinygo_clang_struct_visitor(GoCXCursor c, GoCXCursor parent, CXClientData client_data);
@@ -66,9 +69,13 @@ func (info *fileInfo) parseFragment(fragment string, cflags []string, posFilenam
 	index := C.clang_createIndex(0, 0)
 	defer C.clang_disposeIndex(index)
 
+	// pretend to be a .c file
 	filenameC := C.CString(posFilename + "!cgo.c")
 	defer C.free(unsafe.Pointer(filenameC))
 
+	// fix up error locations
+	fragment = fmt.Sprintf("# %d %#v\n", posLine+1, posFilename) + fragment
+
 	fragmentC := C.CString(fragment)
 	defer C.free(unsafe.Pointer(fragmentC))
 
@@ -107,20 +114,12 @@ func (info *fileInfo) parseFragment(fragment string, cflags []string, posFilenam
 			spelling := getString(C.clang_getDiagnosticSpelling(diagnostic))
 			severity := diagnosticSeverity[C.clang_getDiagnosticSeverity(diagnostic)]
 			location := C.clang_getDiagnosticLocation(diagnostic)
-			var file C.CXFile
+			var libclangFilename C.CXString
 			var line C.unsigned
 			var column C.unsigned
-			var offset C.unsigned
+			C.clang_getPresumedLocation(location, &libclangFilename, &line, &column)
-			C.clang_getExpansionLocation(location, &file, &line, &column, &offset)
+			filename := getString(libclangFilename)
-			filename := getString(C.clang_getFileName(file))
+			if filepath.IsAbs(filename) {
-			if filename == posFilename+"!cgo.c" {
-				// Adjust errors from the `import "C"` snippet.
-				// Note: doesn't adjust filenames inside the error message
-				// itself.
-				filename = posFilename
-				line += C.uint(posLine)
-				offset = 0 // hard to calculate
-			} else if filepath.IsAbs(filename) {
 				// Relative paths for readability, like other Go parser errors.
 				relpath, err := filepath.Rel(info.Program.Dir, filename)
 				if err == nil {
@@ -130,7 +129,7 @@ func (info *fileInfo) parseFragment(fragment string, cflags []string, posFilenam
 			errs = append(errs, &scanner.Error{
 				Pos: token.Position{
 					Filename: filename,
-					Offset:   int(offset),
+					Offset:   0, // not provided by clang_getPresumedLocation
 					Line:     int(line),
 					Column:   int(column),
 				},
@@ -162,9 +161,13 @@ func (info *fileInfo) parseFragment(fragment string, cflags []string, posFilenam
 func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClientData) C.int {
 	info := refMap.Get(unsafe.Pointer(client_data)).(*fileInfo)
 	kind := C.tinygo_clang_getCursorKind(c)
+	pos := info.getCursorPosition(c)
 	switch kind {
 	case C.CXCursor_FunctionDecl:
 		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		if _, required := info.missingSymbols[name]; !required {
+			return C.CXChildVisit_Continue
+		}
 		cursorType := C.tinygo_clang_getCursorType(c)
 		if C.clang_isFunctionTypeVariadic(cursorType) != 0 {
 			return C.CXChildVisit_Continue // not supported
@@ -181,7 +184,7 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 			}
 			fn.args = append(fn.args, paramInfo{
 				name:     argName,
-				typeExpr: info.makeASTType(argType),
+				typeExpr: info.makeASTType(argType, pos),
 			})
 		}
 		resultType := C.tinygo_clang_getCursorResultType(c)
@@ -189,53 +192,33 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 			fn.results = &ast.FieldList{
 				List: []*ast.Field{
 					&ast.Field{
-						Type: info.makeASTType(resultType),
+						Type: info.makeASTType(resultType, pos),
 					},
 				},
 			}
 		}
+	case C.CXCursor_StructDecl:
+		typ := C.tinygo_clang_getCursorType(c)
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		if _, required := info.missingSymbols["struct_"+name]; !required {
+			return C.CXChildVisit_Continue
+		}
+		info.makeASTType(typ, pos)
 	case C.CXCursor_TypedefDecl:
 		typedefType := C.tinygo_clang_getCursorType(c)
 		name := getString(C.clang_getTypedefName(typedefType))
-		underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
+		if _, required := info.missingSymbols[name]; !required {
-		expr := info.makeASTType(underlyingType)
+			return C.CXChildVisit_Continue
-		if strings.HasPrefix(name, "_Cgo_") {
-			expr := expr.(*ast.Ident)
-			typeSize := C.clang_Type_getSizeOf(underlyingType)
-			switch expr.Name {
-			// TODO: plain char (may be signed or unsigned)
-			case "C.schar", "C.short", "C.int", "C.long", "C.longlong":
-				switch typeSize {
-				case 1:
-					expr.Name = "int8"
-				case 2:
-					expr.Name = "int16"
-				case 4:
-					expr.Name = "int32"
-				case 8:
-					expr.Name = "int64"
-				}
-			case "C.uchar", "C.ushort", "C.uint", "C.ulong", "C.ulonglong":
-				switch typeSize {
-				case 1:
-					expr.Name = "uint8"
-				case 2:
-					expr.Name = "uint16"
-				case 4:
-					expr.Name = "uint32"
-				case 8:
-					expr.Name = "uint64"
-				}
-			}
-		}
-		info.typedefs[name] = &typedefInfo{
-			typeExpr: expr,
 		}
+		info.makeASTType(typedefType, pos)
 	case C.CXCursor_VarDecl:
 		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		if _, required := info.missingSymbols[name]; !required {
+			return C.CXChildVisit_Continue
+		}
 		cursorType := C.tinygo_clang_getCursorType(c)
 		info.globals[name] = &globalInfo{
-			typeExpr: info.makeASTType(cursorType),
+			typeExpr: info.makeASTType(cursorType, pos),
 		}
 	}
 	return C.CXChildVisit_Continue
@@ -248,11 +231,48 @@ func getString(clangString C.CXString) (s string) {
 	return
 }
 
+// getCursorPosition returns a usable token.Pos from a libclang cursor. If the
+// file for this cursor has not been seen before, it is read from libclang
+// (which already has the file in memory) and added to the token.FileSet.
+func (info *fileInfo) getCursorPosition(cursor C.GoCXCursor) token.Pos {
+	location := C.tinygo_clang_getCursorLocation(cursor)
+	var file C.CXFile
+	var line C.unsigned
+	var column C.unsigned
+	var offset C.unsigned
+	C.clang_getExpansionLocation(location, &file, &line, &column, &offset)
+	if line == 0 || file == nil {
+		// Invalid token.
+		return token.NoPos
+	}
+	filename := getString(C.clang_getFileName(file))
+	if _, ok := info.tokenFiles[filename]; !ok {
+		// File has not been seen before in this package, add line information
+		// now by reading the file from libclang.
+		tu := C.tinygo_clang_Cursor_getTranslationUnit(cursor)
+		var size C.size_t
+		sourcePtr := C.clang_getFileContents(tu, file, &size)
+		source := ((*[1 << 28]byte)(unsafe.Pointer(sourcePtr)))[:size:size]
+		lines := []int{0}
+		for i := 0; i < len(source)-1; i++ {
+			if source[i] == '\n' {
+				lines = append(lines, i+1)
+			}
+		}
+		f := info.fset.AddFile(filename, -1, int(size))
+		f.SetLines(lines)
+		info.tokenFiles[filename] = f
+	}
+	return info.tokenFiles[filename].Pos(int(offset))
+}
+
 // makeASTType return the ast.Expr for the given libclang type. In other words,
 // it converts a libclang type to a type in the Go AST.
-func (info *fileInfo) makeASTType(typ C.CXType) ast.Expr {
+func (info *fileInfo) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 	var typeName string
 	switch typ.kind {
+	case C.CXType_Char_S, C.CXType_Char_U:
+		typeName = "C.char"
 	case C.CXType_SChar:
 		typeName = "C.schar"
 	case C.CXType_UChar:
@@ -293,19 +313,33 @@ func (info *fileInfo) makeASTType(typ C.CXType) ast.Expr {
 			typeName = "complex128"
 		}
 	case C.CXType_Pointer:
+		pointeeType := C.clang_getPointeeType(typ)
+		if pointeeType.kind == C.CXType_Void {
+			// void* type is translated to Go as unsafe.Pointer
+			return &ast.SelectorExpr{
+				X: &ast.Ident{
+					NamePos: pos,
+					Name:    "unsafe",
+				},
+				Sel: &ast.Ident{
+					NamePos: pos,
+					Name:    "Pointer",
+				},
+			}
+		}
 		return &ast.StarExpr{
-			Star: info.importCPos,
+			Star: pos,
-			X:    info.makeASTType(C.clang_getPointeeType(typ)),
+			X:    info.makeASTType(pointeeType, pos),
 		}
 	case C.CXType_ConstantArray:
 		return &ast.ArrayType{
-			Lbrack: info.importCPos,
+			Lbrack: pos,
 			Len: &ast.BasicLit{
-				ValuePos: info.importCPos,
+				ValuePos: pos,
 				Kind:     token.INT,
 				Value:    strconv.FormatInt(int64(C.clang_getArraySize(typ)), 10),
 			},
-			Elt: info.makeASTType(C.clang_getElementType(typ)),
+			Elt: info.makeASTType(C.clang_getElementType(typ), pos),
 		}
 	case C.CXType_FunctionProto:
 		// Be compatible with gc, which uses the *[0]byte type for function
@@ -313,95 +347,151 @@ func (info *fileInfo) makeASTType(typ C.CXType) ast.Expr {
 		// Return type [0]byte because this is a function type, not a pointer to
 		// this function type.
 		return &ast.ArrayType{
-			Lbrack: info.importCPos,
+			Lbrack: pos,
 			Len: &ast.BasicLit{
-				ValuePos: info.importCPos,
+				ValuePos: pos,
 				Kind:     token.INT,
 				Value:    "0",
 			},
 			Elt: &ast.Ident{
-				NamePos: info.importCPos,
+				NamePos: pos,
 				Name:    "byte",
 			},
 		}
 	case C.CXType_Typedef:
-		typedefName := getString(C.clang_getTypedefName(typ))
+		name := getString(C.clang_getTypedefName(typ))
+		if _, ok := info.typedefs[name]; !ok {
+			info.typedefs[name] = nil // don't recurse
+			c := C.tinygo_clang_getTypeDeclaration(typ)
+			underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
+			expr := info.makeASTType(underlyingType, pos)
+			if strings.HasPrefix(name, "_Cgo_") {
+				expr := expr.(*ast.Ident)
+				typeSize := C.clang_Type_getSizeOf(underlyingType)
+				switch expr.Name {
+				case "C.char":
+					if typeSize != 1 {
+						// This happens for some very special purpose architectures
+						// (DSPs etc.) that are not currently targeted.
+						// https://www.embecosm.com/2017/04/18/non-8-bit-char-support-in-clang-and-llvm/
+						panic("unknown char width")
+					}
+					switch underlyingType.kind {
+					case C.CXType_Char_S:
+						expr.Name = "int8"
+					case C.CXType_Char_U:
+						expr.Name = "uint8"
+					}
+				case "C.schar", "C.short", "C.int", "C.long", "C.longlong":
+					switch typeSize {
+					case 1:
+						expr.Name = "int8"
+					case 2:
+						expr.Name = "int16"
+					case 4:
+						expr.Name = "int32"
+					case 8:
+						expr.Name = "int64"
+					}
+				case "C.uchar", "C.ushort", "C.uint", "C.ulong", "C.ulonglong":
+					switch typeSize {
+					case 1:
+						expr.Name = "uint8"
+					case 2:
+						expr.Name = "uint16"
+					case 4:
+						expr.Name = "uint32"
+					case 8:
+						expr.Name = "uint64"
+					}
+				}
+			}
+			info.typedefs[name] = &typedefInfo{
+				typeExpr: expr,
+			}
+		}
 		return &ast.Ident{
-			NamePos: info.importCPos,
+			NamePos: pos,
-			Name:    "C." + typedefName,
+			Name:    "C." + name,
 		}
 	case C.CXType_Elaborated:
 		underlying := C.clang_Type_getNamedType(typ)
 		switch underlying.kind {
 		case C.CXType_Record:
-			cursor := C.tinygo_clang_getTypeDeclaration(typ)
+			return info.makeASTType(underlying, pos)
-			name := getString(C.tinygo_clang_getCursorSpelling(cursor))
-			// It is possible that this is a recursive definition, for example
-			// in linked lists (structs contain a pointer to the next element
-			// of the same type). If the name exists in info.elaboratedTypes,
-			// it is being processed, although it may not be fully defined yet.
-			if _, ok := info.elaboratedTypes[name]; !ok {
-				info.elaboratedTypes[name] = nil // predeclare (to avoid endless recursion)
-				info.elaboratedTypes[name] = info.makeASTType(underlying)
-			}
-			return &ast.Ident{
-				NamePos: info.importCPos,
-				Name:    "C.struct_" + name,
-			}
 		default:
 			panic("unknown elaborated type")
 		}
 	case C.CXType_Record:
 		cursor := C.tinygo_clang_getTypeDeclaration(typ)
-		fieldList := &ast.FieldList{
+		name := getString(C.tinygo_clang_getCursorSpelling(cursor))
-			Opening: info.importCPos,
+		var cgoName string
-			Closing: info.importCPos,
-		}
-		ref := refMap.Put(struct {
-			fieldList *ast.FieldList
-			info      *fileInfo
-		}{fieldList, info})
-		defer refMap.Remove(ref)
-		C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_struct_visitor), C.CXClientData(ref))
 		switch C.tinygo_clang_getCursorKind(cursor) {
 		case C.CXCursor_StructDecl:
-			return &ast.StructType{
+			cgoName = "struct_" + name
-				Struct: info.importCPos,
-				Fields: fieldList,
-			}
 		case C.CXCursor_UnionDecl:
-			if len(fieldList.List) > 1 {
+			cgoName = "union_" + name
-				// Insert a special field at the front (of zero width) as a
+		default:
-				// marker that this is struct is actually a union. This is done
+			panic("unknown record declaration")
-				// by giving the field a name that cannot be expressed directly
+		}
-				// in Go.
+		if _, ok := info.elaboratedTypes[cgoName]; !ok {
-				// Other parts of the compiler look at the first element in a
+			info.elaboratedTypes[cgoName] = nil // predeclare (to avoid endless recursion)
-				// struct (of size > 2) to know whether this is a union.
+			fieldList := &ast.FieldList{
-				// Note that we don't have to insert it for single-element
+				Opening: pos,
-				// unions as they're basically equivalent to a struct.
+				Closing: pos,
-				unionMarker := &ast.Field{
+			}
-					Type: &ast.StructType{
+			ref := refMap.Put(struct {
-						Struct: info.importCPos,
+				fieldList *ast.FieldList
-					},
+				info      *fileInfo
+			}{fieldList, info})
+			defer refMap.Remove(ref)
+			C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_struct_visitor), C.CXClientData(ref))
+			switch C.tinygo_clang_getCursorKind(cursor) {
+			case C.CXCursor_StructDecl:
+				info.elaboratedTypes[cgoName] = &ast.StructType{
+					Struct: pos,
+					Fields: fieldList,
 				}
-				unionMarker.Names = []*ast.Ident{
+			case C.CXCursor_UnionDecl:
-					&ast.Ident{
+				if len(fieldList.List) > 1 {
-						NamePos: info.importCPos,
+					// Insert a special field at the front (of zero width) as a
-						Name:    "C union",
+					// marker that this is struct is actually a union. This is done
-						Obj: &ast.Object{
+					// by giving the field a name that cannot be expressed directly
-							Kind: ast.Var,
+					// in Go.
-							Name: "C union",
+					// Other parts of the compiler look at the first element in a
-							Decl: unionMarker,
+					// struct (of size > 2) to know whether this is a union.
+					// Note that we don't have to insert it for single-element
+					// unions as they're basically equivalent to a struct.
+					unionMarker := &ast.Field{
+						Type: &ast.StructType{
+							Struct: pos,
 						},
-					},
+					}
+					unionMarker.Names = []*ast.Ident{
+						&ast.Ident{
+							NamePos: pos,
+							Name:    "C union",
+							Obj: &ast.Object{
+								Kind: ast.Var,
+								Name: "C union",
+								Decl: unionMarker,
+							},
+						},
+					}
+					fieldList.List = append([]*ast.Field{unionMarker}, fieldList.List...)
 				}
-				fieldList.List = append([]*ast.Field{unionMarker}, fieldList.List...)
+				info.elaboratedTypes[cgoName] = &ast.StructType{
-			}
+					Struct: pos,
-			return &ast.StructType{
+					Fields: fieldList,
-				Struct: info.importCPos,
+				}
-				Fields: fieldList,
+			default:
+				panic("unreachable")
 			}
 		}
+		return &ast.Ident{
+			NamePos: pos,
+			Name:    "C." + cgoName,
+		}
 	}
 	if typeName == "" {
 		// Fallback, probably incorrect but at least the error points to an odd
@@ -409,7 +499,7 @@ func (info *fileInfo) makeASTType(typ C.CXType) ast.Expr {
 		typeName = "C." + getString(C.clang_getTypeSpelling(typ))
 	}
 	return &ast.Ident{
-		NamePos: info.importCPos,
+		NamePos: pos,
 		Name:    typeName,
 	}
 }
@@ -428,11 +518,11 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 	name := getString(C.tinygo_clang_getCursorSpelling(c))
 	typ := C.tinygo_clang_getCursorType(c)
 	field := &ast.Field{
-		Type: info.makeASTType(typ),
+		Type: info.makeASTType(typ, info.getCursorPosition(c)),
 	}
 	field.Names = []*ast.Ident{
 		&ast.Ident{
-			NamePos: info.importCPos,
+			NamePos: info.getCursorPosition(c),
 			Name:    name,
 			Obj: &ast.Object{
 				Kind: ast.Var,

loader/libclang_stubs.c

@@ -44,3 +44,11 @@ int tinygo_clang_Cursor_getNumArguments(CXCursor c) {
 CXCursor tinygo_clang_Cursor_getArgument(CXCursor c, unsigned i) {
 	return clang_Cursor_getArgument(c, i);
 }
+
+CXSourceLocation tinygo_clang_getCursorLocation(CXCursor c) {
+	return clang_getCursorLocation(c);
+}
+
+CXTranslationUnit tinygo_clang_Cursor_getTranslationUnit(CXCursor c) {
+	return clang_Cursor_getTranslationUnit(c);
+}

loader/loader.go

@@ -22,6 +22,7 @@ type Program struct {
 	fset          *token.FileSet
 	TypeChecker   types.Config
 	Dir           string // current working directory (for error reporting)
+	TINYGOROOT    string // root of the TinyGo installation or root of the source code
 	CFlags        []string
 }
 
@@ -29,10 +30,11 @@ type Program struct {
 type Package struct {
 	*Program
 	*build.Package
-	Imports   map[string]*Package
+	Imports    map[string]*Package
-	Importing bool
+	Importing  bool
-	Files     []*ast.File
+	Files      []*ast.File
-	Pkg       *types.Package
+	tokenFiles map[string]*token.File
+	Pkg        *types.Package
 	types.Info
 }
 
@@ -105,6 +107,7 @@ func (p *Program) newPackage(pkg *build.Package) *Package {
 			Scopes:     make(map[ast.Node]*types.Scope),
 			Selections: make(map[*ast.SelectorExpr]*types.Selection),
 		},
+		tokenFiles: map[string]*token.File{},
 	}
 }
 
@@ -292,6 +295,16 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 		}
 		files = append(files, f)
 	}
+	clangIncludes := ""
+	if len(p.CgoFiles) != 0 {
+		if _, err := os.Stat(filepath.Join(p.TINYGOROOT, "llvm", "tools", "clang", "lib", "Headers")); !os.IsNotExist(err) {
+			// Running from the source directory.
+			clangIncludes = filepath.Join(p.TINYGOROOT, "llvm", "tools", "clang", "lib", "Headers")
+		} else {
+			// Running from the installation directory.
+			clangIncludes = filepath.Join(p.TINYGOROOT, "lib", "clang", "include")
+		}
+	}
 	for _, file := range p.CgoFiles {
 		path := filepath.Join(p.Package.Dir, file)
 		f, err := p.parseFile(path, parser.ParseComments)
@@ -299,7 +312,7 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 			fileErrs = append(fileErrs, err)
 			continue
 		}
-		errs := p.processCgo(path, f, append(p.CFlags, "-I"+p.Package.Dir))
+		errs := p.processCgo(path, f, append(p.CFlags, "-I"+p.Package.Dir, "-I"+clangIncludes))
 		if errs != nil {
 			fileErrs = append(fileErrs, errs...)
 			continue

main.go

@@ -33,16 +33,27 @@ func (e *commandError) Error() string {
 	return e.Msg + " " + e.File + ": " + e.Err.Error()
 }
 
+// multiError is a list of multiple errors (actually: diagnostics) returned
+// during LLVM IR generation.
+type multiError struct {
+	Errs []error
+}
+
+func (e *multiError) Error() string {
+	return e.Errs[0].Error()
+}
+
 type BuildConfig struct {
-	opt        string
+	opt           string
-	gc         string
+	gc            string
-	printIR    bool
+	panicStrategy string
-	dumpSSA    bool
+	printIR       bool
-	debug      bool
+	dumpSSA       bool
-	printSizes string
+	debug         bool
-	cFlags     []string
+	printSizes    string
-	ldFlags    []string
+	cFlags        []string
-	wasmAbi    string
+	ldFlags       []string
+	wasmAbi       string
 }
 
 // Helper function for Compiler object.
@@ -51,23 +62,39 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 		config.gc = spec.GC
 	}
 
-	// Append command line passed CFlags and LDFlags
+	root := sourceDir()
-	spec.CFlags = append(spec.CFlags, config.cFlags...)
-	spec.LDFlags = append(spec.LDFlags, config.ldFlags...)
 
+	// Merge and adjust CFlags.
+	cflags := append([]string{}, config.cFlags...)
+	for _, flag := range spec.CFlags {
+		cflags = append(cflags, strings.Replace(flag, "{root}", root, -1))
+	}
+
+	// Merge and adjust LDFlags.
+	ldflags := append([]string{}, config.ldFlags...)
+	for _, flag := range spec.LDFlags {
+		ldflags = append(ldflags, strings.Replace(flag, "{root}", root, -1))
+	}
+
+	goroot := getGoroot()
+	if goroot == "" {
+		return errors.New("cannot locate $GOROOT, please set it manually")
+	}
 	compilerConfig := compiler.Config{
-		Triple:    spec.Triple,
+		Triple:        spec.Triple,
-		CPU:       spec.CPU,
+		CPU:           spec.CPU,
-		GOOS:      spec.GOOS,
+		GOOS:          spec.GOOS,
-		GOARCH:    spec.GOARCH,
+		GOARCH:        spec.GOARCH,
-		GC:        config.gc,
+		GC:            config.gc,
-		CFlags:    spec.CFlags,
+		PanicStrategy: config.panicStrategy,
-		LDFlags:   spec.LDFlags,
+		CFlags:        cflags,
-		Debug:     config.debug,
+		LDFlags:       ldflags,
-		DumpSSA:   config.dumpSSA,
+		Debug:         config.debug,
-		RootDir:   sourceDir(),
+		DumpSSA:       config.dumpSSA,
-		GOPATH:    getGopath(),
+		TINYGOROOT:    root,
-		BuildTags: spec.BuildTags,
+		GOROOT:        goroot,
+		GOPATH:        getGopath(),
+		BuildTags:     spec.BuildTags,
 	}
 	c, err := compiler.NewCompiler(pkgName, compilerConfig)
 	if err != nil {
@@ -75,12 +102,15 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 	}
 
 	// Compile Go code to IR.
-	err = c.Compile(pkgName)
+	errs := c.Compile(pkgName)
-	if err != nil {
+	if len(errs) != 0 {
-		return err
+		if len(errs) == 1 {
+			return errs[0]
+		}
+		return &multiError{errs}
 	}
 	if config.printIR {
-		fmt.Println("Generated LLVM IR:")
+		fmt.Println("; Generated LLVM IR:")
 		fmt.Println(c.IR())
 	}
 	if err := c.Verify(); err != nil {
@@ -191,19 +221,20 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 		// Prepare link command.
 		executable := filepath.Join(dir, "main")
 		tmppath := executable // final file
-		ldflags := append(spec.LDFlags, "-o", executable, objfile, "-L", sourceDir())
+		ldflags := append(ldflags, "-o", executable, objfile, "-L", root)
 		if spec.RTLib == "compiler-rt" {
 			ldflags = append(ldflags, librt)
 		}
 
 		// Compile extra files.
 		for i, path := range spec.ExtraFiles {
+			abspath := filepath.Join(root, path)
 			outpath := filepath.Join(dir, "extra-"+strconv.Itoa(i)+"-"+filepath.Base(path)+".o")
-			cmd := exec.Command(spec.Compiler, append(spec.CFlags, "-c", "-o", outpath, path)...)
+			cmdNames := []string{spec.Compiler}
-			cmd.Stdout = os.Stdout
+			if names, ok := commands[spec.Compiler]; ok {
-			cmd.Stderr = os.Stderr
+				cmdNames = names
-			cmd.Dir = sourceDir()
+			}
-			err := cmd.Run()
+			err := execCommand(cmdNames, append(cflags, "-c", "-o", outpath, abspath)...)
 			if err != nil {
 				return &commandError{"failed to build", path, err}
 			}
@@ -215,11 +246,11 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 			for _, file := range pkg.CFiles {
 				path := filepath.Join(pkg.Package.Dir, file)
 				outpath := filepath.Join(dir, "pkg"+strconv.Itoa(i)+"-"+file+".o")
-				cmd := exec.Command(spec.Compiler, append(spec.CFlags, "-c", "-o", outpath, path)...)
+				cmdNames := []string{spec.Compiler}
-				cmd.Stdout = os.Stdout
+				if names, ok := commands[spec.Compiler]; ok {
-				cmd.Stderr = os.Stderr
+					cmdNames = names
-				cmd.Dir = sourceDir()
+				}
-				err := cmd.Run()
+				err := execCommand(cmdNames, append(cflags, "-c", "-o", outpath, path)...)
 				if err != nil {
 					return &commandError{"failed to build", path, err}
 				}
@@ -228,11 +259,7 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 		}
 
 		// Link the object files together.
-		if linker, ok := commands[spec.Linker]; ok {
+		err = Link(spec.Linker, ldflags...)
-			err = Link(linker, ldflags...)
-		} else {
-			err = Link(spec.Linker, ldflags...)
-		}
 		if err != nil {
 			return &commandError{"failed to link", executable, err}
 		}
@@ -496,6 +523,10 @@ func handleCompilerError(err error) {
 			for _, err := range errLoader.Errs {
 				fmt.Fprintln(os.Stderr, err)
 			}
+		} else if errMulti, ok := err.(*multiError); ok {
+			for _, err := range errMulti.Errs {
+				fmt.Fprintln(os.Stderr, err)
+			}
 		} else {
 			fmt.Fprintln(os.Stderr, "error:", err)
 		}
@@ -507,6 +538,7 @@ func main() {
 	outpath := flag.String("o", "", "output filename")
 	opt := flag.String("opt", "z", "optimization level: 0, 1, 2, s, z")
 	gc := flag.String("gc", "", "garbage collector to use (none, dumb, marksweep)")
+	panicStrategy := flag.String("panic", "print", "panic strategy (abort, trap)")
 	printIR := flag.Bool("printir", false, "print LLVM IR")
 	dumpSSA := flag.Bool("dumpssa", false, "dump internal Go SSA")
 	target := flag.String("target", "", "LLVM target")
@@ -527,13 +559,14 @@ func main() {
 
 	flag.CommandLine.Parse(os.Args[2:])
 	config := &BuildConfig{
-		opt:        *opt,
+		opt:           *opt,
-		gc:         *gc,
+		gc:            *gc,
-		printIR:    *printIR,
+		panicStrategy: *panicStrategy,
-		dumpSSA:    *dumpSSA,
+		printIR:       *printIR,
-		debug:      !*nodebug,
+		dumpSSA:       *dumpSSA,
-		printSizes: *printSize,
+		debug:         !*nodebug,
-		wasmAbi:    *wasmAbi,
+		printSizes:    *printSize,
+		wasmAbi:       *wasmAbi,
 	}
 
 	if *cFlags != "" {
@@ -544,6 +577,12 @@ func main() {
 		config.ldFlags = strings.Split(*ldFlags, " ")
 	}
 
+	if *panicStrategy != "print" && *panicStrategy != "trap" {
+		fmt.Fprintln(os.Stderr, "Panic strategy must be either print or trap.")
+		usage()
+		os.Exit(1)
+	}
+
 	os.Setenv("CC", "clang -target="+*target)
 
 	switch command {

main_test.go

@@ -13,17 +13,19 @@ import (
 	"runtime"
 	"sort"
 	"testing"
+
+	"github.com/tinygo-org/tinygo/loader"
 )
 
 const TESTDATA = "testdata"
 
 func TestCompiler(t *testing.T) {
-	matches, err := filepath.Glob(TESTDATA + "/*.go")
+	matches, err := filepath.Glob(filepath.Join(TESTDATA, "*.go"))
 	if err != nil {
 		t.Fatal("could not read test files:", err)
 	}
 
-	dirMatches, err := filepath.Glob(TESTDATA + "/*/main.go")
+	dirMatches, err := filepath.Glob(filepath.Join(TESTDATA, "*", "main.go"))
 	if err != nil {
 		t.Fatal("could not read test packages:", err)
 	}
@@ -64,7 +66,7 @@ func TestCompiler(t *testing.T) {
 	if runtime.GOOS == "linux" {
 		t.Log("running tests for linux/arm...")
 		for _, path := range matches {
-			if path == "testdata/cgo/" {
+			if path == filepath.Join("testdata", "cgo")+string(filepath.Separator) {
 				continue // TODO: improve CGo
 			}
 			t.Run(path, func(t *testing.T) {
@@ -74,7 +76,7 @@ func TestCompiler(t *testing.T) {
 
 		t.Log("running tests for linux/arm64...")
 		for _, path := range matches {
-			if path == "testdata/cgo/" {
+			if path == filepath.Join("testdata", "cgo")+string(filepath.Separator) {
 				continue // TODO: improve CGo
 			}
 			t.Run(path, func(t *testing.T) {
@@ -84,7 +86,7 @@ func TestCompiler(t *testing.T) {
 
 		t.Log("running tests for WebAssembly...")
 		for _, path := range matches {
-			if path == "testdata/gc.go" {
+			if path == filepath.Join("testdata", "gc.go") {
 				continue // known to fail
 			}
 			t.Run(path, func(t *testing.T) {
@@ -97,7 +99,7 @@ func TestCompiler(t *testing.T) {
 func runTest(path, tmpdir string, target string, t *testing.T) {
 	// Get the expected output for this test.
 	txtpath := path[:len(path)-3] + ".txt"
-	if path[len(path)-1] == '/' {
+	if path[len(path)-1] == os.PathSeparator {
 		txtpath = path + "out.txt"
 	}
 	f, err := os.Open(txtpath)
@@ -121,7 +123,13 @@ func runTest(path, tmpdir string, target string, t *testing.T) {
 	binary := filepath.Join(tmpdir, "test")
 	err = Build("./"+path, binary, target, config)
 	if err != nil {
-		t.Log("failed to build:", err)
+		if errLoader, ok := err.(loader.Errors); ok {
+			for _, err := range errLoader.Errs {
+				t.Log("failed to build:", err)
+			}
+		} else {
+			t.Log("failed to build:", err)
+		}
 		t.Fail()
 		return
 	}

src/examples/microbit-blink/microbit-blink.go

@@ -1,4 +1,4 @@
-// blink program for the BBC micro:bit that uses the entire LED matrix
+// blink program for the BBC micro:bit
 package main
 
 import (
@@ -6,14 +6,19 @@ import (
 	"time"
 )
 
+// The LED matrix in the micro:bit is a multiplexed display: https://en.wikipedia.org/wiki/Multiplexed_display
+// Driver for easier control: https://github.com/tinygo-org/drivers/tree/master/microbitmatrix
 func main() {
-	machine.InitLEDMatrix()
+	ledrow := machine.GPIO{machine.LED_ROW_1}
-
+	ledrow.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	ledcol := machine.GPIO{machine.LED_COL_1}
+	ledcol.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	ledcol.Low()
 	for {
-		machine.ClearLEDMatrix()
+		ledrow.Low()
 		time.Sleep(time.Millisecond * 500)
 
-		machine.SetEntireLEDMatrixOn()
+		ledrow.High()
 		time.Sleep(time.Millisecond * 500)
 	}
 }

src/examples/wasm/README.md

@@ -1,6 +1,6 @@
 # TinyGo WebAssembly examples
 
-The examples here show two different ways of using WebAssembly with TinyGo;
+The examples here show two different ways of using WebAssembly with TinyGo:
 
 1. Defining and exporting functions via the `//go:export <name>` directive. See
 [the export folder](./export) for an example of this.
@@ -31,23 +31,31 @@ $ make main
 
 ## Running
 
-Start the local webserver:
+Start the local web server:
 
 ```bash
 $ go run main.go
 Serving ./html on http://localhost:8080
 ```
 
-`fmt.Println` prints to the browser console.
+Use your web browser to visit http://localhost:8080.
+
+* The wasm "export" example displays a simple math equation using HTML, with
+the result calculated dynamically using WebAssembly.  Changing any of the
+values on the left hand side triggers the exported wasm `update` function to
+recalculate the result.
+* The wasm "main" example uses `println` to write to your browser JavaScript
+console. You may need to open the browser development tools console to see it.
 
 ## How it works
 
-Execution of the contents require a few JS helper functions which are called
+Execution of the contents require a few JavaScript helper functions which are
-from WebAssembly. We have defined these in
+called from WebAssembly.
-[wasm_exec.js](../../../targets/wasm_exec.js). It is based on
+
-`$GOROOT/misc/wasm/wasm_exec.js` from the standard library, but is slightly
+We have defined these in [wasm_exec.js](../../../targets/wasm_exec.js).  It is
-different. Ensure you are using the same version of `wasm_exec.js` as the
+based on `$GOROOT/misc/wasm/wasm_exec.js` from the standard library, but is
-version of `tinygo` you are using to compile.
+slightly different. Ensure you are using the same version of `wasm_exec.js` as
+the version of `tinygo` you are using to compile.
 
 The general steps required to run the WebAssembly file in the browser includes
 loading it into JavaScript with `WebAssembly.instantiateStreaming`, or
@@ -80,8 +88,9 @@ If you have used explicit exports, you can call them by invoking them under the
 `wasm.exports` namespace. See the [`export`](./export/wasm.js) directory for an
 example of this.
 
-In addition to this piece of JavaScript, it is important that the file is served
+In addition to the JavaScript, it is important the wasm file is served with the
-with the correct `Content-Type` header set.
+[`Content-Type`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type)
+header set to `application/wasm`.  Without it, most browsers won't run it.
 
 ```go
 package main
@@ -98,14 +107,25 @@ func main() {
 	fs := http.FileServer(http.Dir(dir))
 	log.Print("Serving " + dir + " on http://localhost:8080")
 	http.ListenAndServe(":8080", http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
+		resp.Header().Add("Cache-Control", "no-cache")
 		if strings.HasSuffix(req.URL.Path, ".wasm") {
 			resp.Header().Set("content-type", "application/wasm")
 		}
-
 		fs.ServeHTTP(resp, req)
-	}))
+	}))}
-}
 ```
 
-This simple server serves anything inside the `./html` directory on port `8080`,
+This simple server serves anything inside the `./html` directory on port
-setting any `*.wasm` files `Content-Type` header appropriately.
+`8080`, setting any `*.wasm` files `Content-Type` header appropriately.
+
+For development purposes (**only!**), it also sets the `Cache-Control` header
+so your browser doesn't cache the files.  This is useful while developing, to
+ensure your browser displays the newest wasm when you recompile.
+
+In a production environment you **probably wouldn't** want to set the
+`Cache-Control` header like this.  Caching is generally beneficial for end
+users.
+
+Further information on the `Cache-Control` header can be found here:
+
+* https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control

src/examples/wasm/main/main.go

@@ -1,9 +1,5 @@
 package main
 
-import (
-	"fmt"
-)
-
 func main() {
-	fmt.Println("Hello world!")
+	println("Hello world!")
 }

src/examples/wasm/server.go

@@ -12,10 +12,10 @@ func main() {
 	fs := http.FileServer(http.Dir(dir))
 	log.Print("Serving " + dir + " on http://localhost:8080")
 	http.ListenAndServe(":8080", http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
+		resp.Header().Add("Cache-Control", "no-cache")
 		if strings.HasSuffix(req.URL.Path, ".wasm") {
 			resp.Header().Set("content-type", "application/wasm")
 		}
-
 		fs.ServeHTTP(resp, req)
 	}))
 }

src/machine/board_microbit.go

@@ -2,11 +2,6 @@
 
 package machine
 
-import (
-	"device/nrf"
-	"errors"
-)
-
 // The micro:bit does not have a 32kHz crystal on board.
 const HasLowFrequencyCrystal = false
 
@@ -79,65 +74,3 @@ const (
 	LED_ROW_2 = 14
 	LED_ROW_3 = 15
 )
-
-// matrixSettings has the legs of the LED grid in the form {row, column} for each LED position.
-var matrixSettings = [5][5][2]uint8{
-	{{LED_ROW_1, LED_COL_1}, {LED_ROW_2, LED_COL_4}, {LED_ROW_1, LED_COL_2}, {LED_ROW_2, LED_COL_5}, {LED_ROW_1, LED_COL_3}},
-	{{LED_ROW_3, LED_COL_4}, {LED_ROW_3, LED_COL_5}, {LED_ROW_3, LED_COL_6}, {LED_ROW_3, LED_COL_7}, {LED_ROW_3, LED_COL_8}},
-	{{LED_ROW_2, LED_COL_2}, {LED_ROW_1, LED_COL_9}, {LED_ROW_2, LED_COL_3}, {LED_ROW_3, LED_COL_9}, {LED_ROW_2, LED_COL_1}},
-	{{LED_ROW_1, LED_COL_8}, {LED_ROW_1, LED_COL_7}, {LED_ROW_1, LED_COL_6}, {LED_ROW_1, LED_COL_5}, {LED_ROW_1, LED_COL_4}},
-	{{LED_ROW_3, LED_COL_3}, {LED_ROW_2, LED_COL_7}, {LED_ROW_3, LED_COL_1}, {LED_ROW_2, LED_COL_6}, {LED_ROW_3, LED_COL_2}}}
-
-// InitLEDMatrix initializes the LED matrix, by setting all of the row/col pins to output
-// then calling ClearLEDMatrix.
-func InitLEDMatrix() {
-	set := 0
-	for i := LED_COL_1; i <= LED_ROW_3; i++ {
-		set |= 1 << uint8(i)
-	}
-	nrf.GPIO.DIRSET = nrf.RegValue(set)
-	ClearLEDMatrix()
-}
-
-// ClearLEDMatrix clears the entire LED matrix.
-func ClearLEDMatrix() {
-	set := 0
-	for i := LED_COL_1; i <= LED_COL_9; i++ {
-		set |= 1 << uint8(i)
-	}
-	nrf.GPIO.OUTSET = nrf.RegValue(set)
-	nrf.GPIO.OUTCLR = (1 << LED_ROW_1) | (1 << LED_ROW_2) | (1 << LED_ROW_3)
-}
-
-// SetLEDMatrix turns on a single LED on the LED matrix.
-// Currently limited to a single LED at a time, it will clear the matrix before setting it.
-func SetLEDMatrix(x, y uint8) error {
-	if x > 4 || y > 4 {
-		return errors.New("Invalid LED matrix row or column")
-	}
-
-	// Clear matrix
-	ClearLEDMatrix()
-
-	nrf.GPIO.OUTSET = (1 << matrixSettings[y][x][0])
-	nrf.GPIO.OUTCLR = (1 << matrixSettings[y][x][1])
-
-	return nil
-}
-
-// SetEntireLEDMatrixOn turns on all of the LEDs on the LED matrix.
-func SetEntireLEDMatrixOn() error {
-	set := 0
-	for i := LED_ROW_1; i <= LED_ROW_3; i++ {
-		set |= 1 << uint8(i)
-	}
-	nrf.GPIO.OUTSET = nrf.RegValue(set)
-
-	set = 0
-	for i := LED_COL_1; i <= LED_COL_9; i++ {
-		set |= 1 << uint8(i)
-	}
-	nrf.GPIO.OUTCLR = nrf.RegValue(set)
-
-	return nil
-}

src/machine/machine_atsamd21.go

@@ -343,6 +343,12 @@ func (a ADC) Get() uint16 {
 	sam.ADC.INPUTCTRL |= sam.RegValue(ch << sam.ADC_INPUTCTRL_MUXPOS_Pos)
 	waitADCSync()
 
+	// Select internal ground for ADC input
+	sam.ADC.INPUTCTRL &^= sam.ADC_INPUTCTRL_MUXNEG_Msk
+	waitADCSync()
+	sam.ADC.INPUTCTRL |= sam.RegValue(sam.ADC_INPUTCTRL_MUXNEG_GND << sam.ADC_INPUTCTRL_MUXNEG_Pos)
+	waitADCSync()
+
 	// Enable ADC
 	sam.ADC.CTRLA |= sam.ADC_CTRLA_ENABLE
 	waitADCSync()
@@ -368,7 +374,7 @@ func (a ADC) Get() uint16 {
 	sam.ADC.CTRLA &^= sam.ADC_CTRLA_ENABLE
 	waitADCSync()
 
-	return uint16(val)
+	return uint16(val) << 4 // scales from 12 to 16-bit result
 }
 
 func (a ADC) getADCChannel() uint8 {

src/machine/machine_dummy.go

@@ -12,29 +12,77 @@ const (
 )
 
 // Fake LED numbers, for testing.
-const (
+var (
-	LED  = LED1
+	LED  uint8 = LED1
-	LED1 = 0
+	LED1 uint8 = 0
-	LED2 = 0
+	LED2 uint8 = 0
-	LED3 = 0
+	LED3 uint8 = 0
-	LED4 = 0
+	LED4 uint8 = 0
 )
 
 // Fake button numbers, for testing.
-const (
+var (
-	BUTTON  = BUTTON1
+	BUTTON  uint8 = BUTTON1
-	BUTTON1 = 0
+	BUTTON1 uint8 = 5
-	BUTTON2 = 0
+	BUTTON2 uint8 = 6
-	BUTTON3 = 0
+	BUTTON3 uint8 = 7
-	BUTTON4 = 0
+	BUTTON4 uint8 = 8
+)
+
+// Fake SPI interfaces, for testing.
+var (
+	SPI0 = SPI{0}
+)
+
+var (
+	GPIOConfigure func(pin uint8, config GPIOConfig)
+	GPIOSet       func(pin uint8, value bool)
+	GPIOGet       func(pin uint8) bool
+	SPIConfigure  func(bus uint8, sck uint8, mosi uint8, miso uint8)
+	SPITransfer   func(bus uint8, w uint8) uint8
 )
 
 func (p GPIO) Configure(config GPIOConfig) {
+	if GPIOConfigure != nil {
+		GPIOConfigure(p.Pin, config)
+	}
 }
 
 func (p GPIO) Set(value bool) {
+	if GPIOSet != nil {
+		GPIOSet(p.Pin, value)
+	}
 }
 
 func (p GPIO) Get() bool {
+	if GPIOGet != nil {
+		return GPIOGet(p.Pin)
+	}
 	return false
 }
+
+type SPI struct {
+	Bus uint8
+}
+
+type SPIConfig struct {
+	Frequency uint32
+	SCK       uint8
+	MOSI      uint8
+	MISO      uint8
+	Mode      uint8
+}
+
+func (spi SPI) Configure(config SPIConfig) {
+	if SPIConfigure != nil {
+		SPIConfigure(spi.Bus, config.SCK, config.MOSI, config.MISO)
+	}
+}
+
+// Transfer writes/reads a single byte using the SPI interface.
+func (spi SPI) Transfer(w byte) (byte, error) {
+	if SPITransfer != nil {
+		return SPITransfer(spi.Bus, w), nil
+	}
+	return 0, nil
+}

src/machine/spi.go

@@ -1,4 +1,4 @@
-// +build nrf stm32f103xx atsamd21g18a
+// +build js,wasm nrf stm32f103xx atsamd21g18a
 
 package machine
 

src/runtime/chan.go

@@ -39,33 +39,27 @@ const (
 	chanStateClosed
 )
 
-func chanSendStub(caller *coroutine, ch *channel, _ unsafe.Pointer, size uintptr)
-func chanRecvStub(caller *coroutine, ch *channel, _ unsafe.Pointer, _ *bool, size uintptr)
 func deadlockStub()
 
 // chanSend sends a single value over the channel. If this operation can
 // complete immediately (there is a goroutine waiting for a value), it sends the
 // value and re-activates both goroutines. If not, it sets itself as waiting on
 // a value.
-//
+func chanSend(sender *coroutine, ch *channel, value unsafe.Pointer, size uintptr) {
-// The unsafe.Pointer value is used during lowering. During IR generation, it
-// points to the to-be-received value. During coroutine lowering, this value is
-// replaced with a read from the coroutine promise.
-func chanSend(sender *coroutine, ch *channel, _ unsafe.Pointer, size uintptr) {
 	if ch == nil {
 		// A nil channel blocks forever. Do not scheduler this goroutine again.
 		return
 	}
 	switch ch.state {
 	case chanStateEmpty:
+		sender.promise().ptr = value
 		ch.state = chanStateSend
 		ch.blocked = sender
 	case chanStateRecv:
 		receiver := ch.blocked
 		receiverPromise := receiver.promise()
-		senderPromise := sender.promise()
+		memcpy(receiverPromise.ptr, value, size)
-		memcpy(unsafe.Pointer(&receiverPromise.data), unsafe.Pointer(&senderPromise.data), size)
+		receiverPromise.data = 1 // commaOk = true
-		receiverPromise.commaOk = true
 		ch.blocked = receiverPromise.next
 		receiverPromise.next = nil
 		activateTask(receiver)
@@ -76,6 +70,7 @@ func chanSend(sender *coroutine, ch *channel, _ unsafe.Pointer, size uintptr) {
 	case chanStateClosed:
 		runtimePanic("send on closed channel")
 	case chanStateSend:
+		sender.promise().ptr = value
 		sender.promise().next = ch.blocked
 		ch.blocked = sender
 	}
@@ -85,11 +80,7 @@ func chanSend(sender *coroutine, ch *channel, _ unsafe.Pointer, size uintptr) {
 // sender, it receives the value immediately and re-activates both coroutines.
 // If not, it sets itself as available for receiving. If the channel is closed,
 // it immediately activates itself with a zero value as the result.
-//
+func chanRecv(receiver *coroutine, ch *channel, value unsafe.Pointer, size uintptr) {
-// The two unnamed values exist to help during lowering. The unsafe.Pointer
-// points to the value, and the *bool points to the comma-ok value. Both are
-// replaced by reads from the coroutine promise.
-func chanRecv(receiver *coroutine, ch *channel, _ unsafe.Pointer, _ *bool, size uintptr) {
 	if ch == nil {
 		// A nil channel blocks forever. Do not scheduler this goroutine again.
 		return
@@ -97,10 +88,9 @@ func chanRecv(receiver *coroutine, ch *channel, _ unsafe.Pointer, _ *bool, size
 	switch ch.state {
 	case chanStateSend:
 		sender := ch.blocked
-		receiverPromise := receiver.promise()
 		senderPromise := sender.promise()
-		memcpy(unsafe.Pointer(&receiverPromise.data), unsafe.Pointer(&senderPromise.data), size)
+		memcpy(value, senderPromise.ptr, size)
-		receiverPromise.commaOk = true
+		receiver.promise().data = 1 // commaOk = true
 		ch.blocked = senderPromise.next
 		senderPromise.next = nil
 		activateTask(receiver)
@@ -109,14 +99,15 @@ func chanRecv(receiver *coroutine, ch *channel, _ unsafe.Pointer, _ *bool, size
 			ch.state = chanStateEmpty
 		}
 	case chanStateEmpty:
+		receiver.promise().ptr = value
 		ch.state = chanStateRecv
 		ch.blocked = receiver
 	case chanStateClosed:
-		receiverPromise := receiver.promise()
+		memzero(value, size)
-		memzero(unsafe.Pointer(&receiverPromise.data), size)
+		receiver.promise().data = 0 // commaOk = false
-		receiverPromise.commaOk = false
 		activateTask(receiver)
 	case chanStateRecv:
+		receiver.promise().ptr = value
 		receiver.promise().next = ch.blocked
 		ch.blocked = receiver
 	}
@@ -142,8 +133,8 @@ func chanClose(ch *channel, size uintptr) {
 	case chanStateRecv:
 		// The receiver must be re-activated with a zero value.
 		receiverPromise := ch.blocked.promise()
-		memzero(unsafe.Pointer(&receiverPromise.data), size)
+		memzero(receiverPromise.ptr, size)
-		receiverPromise.commaOk = false
+		receiverPromise.data = 0 // commaOk = false
 		activateTask(ch.blocked)
 		ch.state = chanStateClosed
 		ch.blocked = nil

src/runtime/complex.go

@@ -0,0 +1,65 @@
+// 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 runtime
+
+// inf2one returns a signed 1 if f is an infinity and a signed 0 otherwise.
+// The sign of the result is the sign of f.
+func inf2one(f float64) float64 {
+	g := 0.0
+	if isInf(f) {
+		g = 1.0
+	}
+	return copysign(g, f)
+}
+
+func complex64div(n complex64, m complex64) complex64 {
+	return complex64(complex128div(complex128(n), complex128(m)))
+}
+
+func complex128div(n complex128, m complex128) complex128 {
+	var e, f float64 // complex(e, f) = n/m
+
+	// Algorithm for robust complex division as described in
+	// Robert L. Smith: Algorithm 116: Complex division. Commun. ACM 5(8): 435 (1962).
+	if abs(real(m)) >= abs(imag(m)) {
+		ratio := imag(m) / real(m)
+		denom := real(m) + ratio*imag(m)
+		e = (real(n) + imag(n)*ratio) / denom
+		f = (imag(n) - real(n)*ratio) / denom
+	} else {
+		ratio := real(m) / imag(m)
+		denom := imag(m) + ratio*real(m)
+		e = (real(n)*ratio + imag(n)) / denom
+		f = (imag(n)*ratio - real(n)) / denom
+	}
+
+	if isNaN(e) && isNaN(f) {
+		// Correct final result to infinities and zeros if applicable.
+		// Matches C99: ISO/IEC 9899:1999 - G.5.1  Multiplicative operators.
+
+		a, b := real(n), imag(n)
+		c, d := real(m), imag(m)
+
+		switch {
+		case m == 0 && (!isNaN(a) || !isNaN(b)):
+			e = copysign(inf, c) * a
+			f = copysign(inf, c) * b
+
+		case (isInf(a) || isInf(b)) && isFinite(c) && isFinite(d):
+			a = inf2one(a)
+			b = inf2one(b)
+			e = inf * (a*c + b*d)
+			f = inf * (b*c - a*d)
+
+		case (isInf(c) || isInf(d)) && isFinite(a) && isFinite(b):
+			c = inf2one(c)
+			d = inf2one(d)
+			e = 0 * (a*c + b*d)
+			f = 0 * (b*c - a*d)
+		}
+	}
+
+	return complex(e, f)
+}

src/runtime/float.go

@@ -0,0 +1,53 @@
+// Copyright 2017 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 runtime
+
+import "unsafe"
+
+var inf = float64frombits(0x7FF0000000000000)
+
+// isNaN reports whether f is an IEEE 754 ``not-a-number'' value.
+func isNaN(f float64) (is bool) {
+	// IEEE 754 says that only NaNs satisfy f != f.
+	return f != f
+}
+
+// isFinite reports whether f is neither NaN nor an infinity.
+func isFinite(f float64) bool {
+	return !isNaN(f - f)
+}
+
+// isInf reports whether f is an infinity.
+func isInf(f float64) bool {
+	return !isNaN(f) && !isFinite(f)
+}
+
+// Abs returns the absolute value of x.
+//
+// Special cases are:
+//	Abs(±Inf) = +Inf
+//	Abs(NaN) = NaN
+func abs(x float64) float64 {
+	const sign = 1 << 63
+	return float64frombits(float64bits(x) &^ sign)
+}
+
+// copysign returns a value with the magnitude
+// of x and the sign of y.
+func copysign(x, y float64) float64 {
+	const sign = 1 << 63
+	return float64frombits(float64bits(x)&^sign | float64bits(y)&sign)
+}
+
+// Float64bits returns the IEEE 754 binary representation of f.
+func float64bits(f float64) uint64 {
+	return *(*uint64)(unsafe.Pointer(&f))
+}
+
+// Float64frombits returns the floating point number corresponding
+// the IEEE 754 binary representation b.
+func float64frombits(b uint64) float64 {
+	return *(*float64)(unsafe.Pointer(&b))
+}

src/runtime/print.go

@@ -4,6 +4,10 @@ import (
 	"unsafe"
 )
 
+type stringer interface {
+	String() string
+}
+
 //go:nobounds
 func printstring(s string) {
 	for i := 0; i < len(s); i++ {
@@ -199,8 +203,44 @@ func printnl() {
 
 func printitf(msg interface{}) {
 	switch msg := msg.(type) {
+	case bool:
+		print(msg)
+	case int:
+		print(msg)
+	case int8:
+		print(msg)
+	case int16:
+		print(msg)
+	case int32:
+		print(msg)
+	case int64:
+		print(msg)
+	case uint:
+		print(msg)
+	case uint8:
+		print(msg)
+	case uint16:
+		print(msg)
+	case uint32:
+		print(msg)
+	case uint64:
+		print(msg)
+	case uintptr:
+		print(msg)
+	case float32:
+		print(msg)
+	case float64:
+		print(msg)
+	case complex64:
+		print(msg)
+	case complex128:
+		print(msg)
 	case string:
 		print(msg)
+	case error:
+		print(msg.Error())
+	case stringer:
+		print(msg.String())
 	default:
 		// cast to underlying type
 		itf := *(*_interface)(unsafe.Pointer(&msg))

src/runtime/scheduler.go

@@ -49,13 +49,17 @@ func (t *coroutine) promise() *taskState {
 
 func makeGoroutine(*uint8) *uint8
 
+// Compiler stub to get the current goroutine. Calls to this function are
+// removed in the goroutine lowering pass.
+func getCoroutine() *coroutine
+
 // State/promise of a task. Internally represented as:
 //
 //     {i8* next, i1 commaOk, i32/i64 data}
 type taskState struct {
-	next    *coroutine
+	next *coroutine
-	commaOk bool // 'comma-ok' flag for channel receive operation
+	ptr  unsafe.Pointer
-	data    uint
+	data uint
 }
 
 // Queues used by the scheduler.
@@ -107,6 +111,24 @@ func activateTask(task *coroutine) {
 	runqueuePushBack(task)
 }
 
+// getTaskPromisePtr is a helper function to set the current .ptr field of a
+// coroutine promise.
+func setTaskPromisePtr(task *coroutine, value unsafe.Pointer) {
+	task.promise().ptr = value
+}
+
+// getTaskPromisePtr is a helper function to get the current .ptr field from a
+// coroutine promise.
+func getTaskPromisePtr(task *coroutine) unsafe.Pointer {
+	return task.promise().ptr
+}
+
+// getTaskPromiseData is a helper function to get the current .data field of a
+// coroutine promise.
+func getTaskPromiseData(task *coroutine) uint {
+	return task.promise().data
+}
+
 // Add this task to the end of the run queue. May also destroy the task if it's
 // done.
 func runqueuePushBack(t *coroutine) {

target.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/exec"
 	"os/user"
 	"path/filepath"
 	"runtime"
@@ -211,7 +212,7 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		GOOS:      goos,
 		GOARCH:    goarch,
 		BuildTags: []string{goos, goarch},
-		Compiler:  commands["clang"],
+		Compiler:  "clang",
 		Linker:    "cc",
 		GDB:       "gdb",
 		GDBCmds:   []string{"run"},
@@ -310,3 +311,60 @@ func getHomeDir() string {
 	}
 	return u.HomeDir
 }
+
+// getGoroot returns an appropriate GOROOT from various sources. If it can't be
+// found, it returns an empty string.
+func getGoroot() string {
+	goroot := os.Getenv("GOROOT")
+	if goroot != "" {
+		// An explicitly set GOROOT always has preference.
+		return goroot
+	}
+
+	// Check for the location of the 'go' binary and base GOROOT on that.
+	binpath, err := exec.LookPath("go")
+	if err == nil {
+		binpath, err = filepath.EvalSymlinks(binpath)
+		if err == nil {
+			goroot := filepath.Dir(filepath.Dir(binpath))
+			if isGoroot(goroot) {
+				return goroot
+			}
+		}
+	}
+
+	// Check what GOROOT was at compile time.
+	if isGoroot(runtime.GOROOT()) {
+		return runtime.GOROOT()
+	}
+
+	// Check for some standard locations, as a last resort.
+	var candidates []string
+	switch runtime.GOOS {
+	case "linux":
+		candidates = []string{
+			"/usr/local/go", // manually installed
+			"/usr/lib/go",   // from the distribution
+		}
+	case "darwin":
+		candidates = []string{
+			"/usr/local/go",             // manually installed
+			"/usr/local/opt/go/libexec", // from Homebrew
+		}
+	}
+
+	for _, candidate := range candidates {
+		if isGoroot(candidate) {
+			return candidate
+		}
+	}
+
+	// Can't find GOROOT...
+	return ""
+}
+
+// isGoroot checks whether the given path looks like a GOROOT.
+func isGoroot(goroot string) bool {
+	_, err := os.Stat(filepath.Join(goroot, "src", "runtime", "internal", "sys", "zversion.go"))
+	return err == nil
+}

targets/cortex-m.json

@@ -2,14 +2,17 @@
 	"build-tags": ["cortexm", "linux", "arm"],
 	"goos": "linux",
 	"goarch": "arm",
-	"compiler": "clang-8",
+	"compiler": "clang",
 	"gc": "marksweep",
 	"linker": "ld.lld",
 	"rtlib": "compiler-rt",
 	"cflags": [
 		"-Oz",
 		"-mthumb",
+		"-Werror",
 		"-fshort-enums",
+		"-nostdlibinc",
+		"-Wno-macro-redefined",
 		"-fno-exceptions", "-fno-unwind-tables",
 		"-ffunction-sections", "-fdata-sections"
 	],

targets/nrf51.json

@@ -6,7 +6,7 @@
 		"--target=armv6m-none-eabi",
 		"-Qunused-arguments",
 		"-DNRF51",
-		"-Ilib/CMSIS/CMSIS/Include"
+		"-I{root}/lib/CMSIS/CMSIS/Include"
 	],
 	"ldflags": [
 		"-T", "targets/nrf51.ld"

targets/nrf52.json

@@ -7,7 +7,7 @@
 		"-mfloat-abi=soft",
 		"-Qunused-arguments",
 		"-DNRF52832_XXAA",
-		"-Ilib/CMSIS/CMSIS/Include"
+		"-I{root}/lib/CMSIS/CMSIS/Include"
 	],
 	"ldflags": [
 		"-T", "targets/nrf52.ld"

targets/nrf52840.json

@@ -7,7 +7,7 @@
 		"-mfloat-abi=soft",
 		"-Qunused-arguments",
 		"-DNRF52840_XXAA",
-		"-Ilib/CMSIS/CMSIS/Include"
+		"-I{root}/lib/CMSIS/CMSIS/Include"
 	],
 	"ldflags": [
 		"-T", "targets/nrf52840.ld"

targets/wasm.json

@@ -3,10 +3,12 @@
 	"build-tags":    ["js", "wasm"],
 	"goos":          "js",
 	"goarch":        "wasm",
-	"compiler":      "clang-8",
+	"compiler":      "clang",
 	"linker":        "wasm-ld",
 	"cflags": [
 		"--target=wasm32",
+		"-nostdlibinc",
+		"-Wno-macro-redefined",
 		"-Oz"
 	],
 	"ldflags": [

testdata/cgo/main.c

@@ -1,13 +1,17 @@
 #include "main.h"
 
 int global = 3;
-_Bool globalBool = 1;
+bool globalBool = 1;
-_Bool globalBool2 = 10; // test narrowing
+bool globalBool2 = 10; // test narrowing
 float globalFloat = 3.1;
 double globalDouble = 3.2;
 _Complex float globalComplexFloat = 4.1+3.3i;
 _Complex double globalComplexDouble = 4.2+3.4i;
 _Complex double globalComplexLongDouble = 4.3+3.5i;
+char globalChar = 100;
+void *globalVoidPtrSet = &global;
+void *globalVoidPtrNull;
+int64_t globalInt64 = -(2LL << 40);
 collection_t globalStruct = {256, -123456, 3.14, 88};
 int globalStructSize = sizeof(globalStruct);
 short globalArray[3] = {5, 6, 7};

testdata/cgo/main.go

@@ -9,10 +9,6 @@ import "C"
 
 import "unsafe"
 
-func (s C.myint) Int() int {
-	return int(s)
-}
-
 func main() {
 	println("fortytwo:", C.fortytwo())
 	println("add:", C.add(C.int(3), 5))
@@ -33,6 +29,10 @@ func main() {
 	cb = C.binop_t(C.mul)
 	println("callback 2:", C.doCallback(20, 30, cb))
 
+	// equivalent types
+	var goInt8 int8 = 5
+	var _ C.int8_t = goInt8
+
 	// more globals
 	println("bool:", C.globalBool, C.globalBool2 == true)
 	println("float:", C.globalFloat)
@@ -40,6 +40,10 @@ func main() {
 	println("complex float:", C.globalComplexFloat)
 	println("complex double:", C.globalComplexDouble)
 	println("complex long double:", C.globalComplexLongDouble)
+	println("char match:", C.globalChar == 100)
+	var voidPtr unsafe.Pointer = C.globalVoidPtrNull
+	println("void* match:", voidPtr == nil, C.globalVoidPtrNull == nil, (*C.int)(C.globalVoidPtrSet) == &C.global)
+	println("int64_t match:", C.globalInt64 == C.int64_t(-(2<<40)))
 
 	// complex types
 	println("struct:", C.int(unsafe.Sizeof(C.globalStruct)) == C.globalStructSize, C.globalStruct.s, C.globalStruct.l, C.globalStruct.f)
@@ -53,10 +57,14 @@ func main() {
 	C.unionSetData(5, 8, 1)
 	println("union global data:", C.globalUnion.data[0], C.globalUnion.data[1], C.globalUnion.data[2])
 	println("union field:", printUnion(C.globalUnion).f)
+	var _ C.union_joined = C.globalUnion
+
+	// elaborated type
+	p := C.struct_point{x: 3, y: 5}
+	println("struct:", p.x, p.y)
 
 	// recursive types, test using a linked list
-	lastElement := &C.list_t{n: 7, next: nil}
+	list := &C.list_t{n: 3, next: &C.struct_list_t{n: 6, next: &C.list_t{n: 7, next: nil}}}
-	list := &C.list_t{n: 3, next: &C.struct_list_t{n: 6, next: (*C.struct_list_t)(lastElement)}}
 	for list != nil {
 		println("n in chain:", list.n)
 		list = (*C.list_t)(list.next)
@@ -66,7 +74,7 @@ func main() {
 func printUnion(union C.joined_t) C.joined_t {
 	println("union local data: ", union.data[0], union.data[1], union.data[2])
 	union.s = -33
-	println("union s method:", union.s.Int(), union.data[0] == 5)
+	println("union s:", union.data[0] == -33)
 	union.f = 6.28
 	println("union f:", union.f)
 	return union

testdata/cgo/main.h

@@ -1,10 +1,18 @@
+#include <stdbool.h>
+#include <stdint.h>
+
 typedef short myint;
+typedef short unusedTypedef;
 int add(int a, int b);
+int unusedFunction(void);
 typedef int (*binop_t) (int, int);
 int doCallback(int a, int b, binop_t cb);
 typedef int * intPointer;
 void store(int value, int *ptr);
 
+// this signature should not be included by CGo
+void unusedFunction2(int x, __builtin_va_list args);
+
 typedef struct collection {
 	short         s;
 	long          l;
@@ -12,6 +20,11 @@ typedef struct collection {
 	unsigned char c;
 } collection_t;
 
+struct point {
+	int x;
+	int y;
+};
+
 // linked list
 typedef struct list_t {
 	int           n;
@@ -27,15 +40,20 @@ void unionSetShort(short s);
 void unionSetFloat(float f);
 void unionSetData(short f0, short f1, short f2);
 
-// test globals
+// test globals and datatypes
 extern int global;
-extern _Bool globalBool;
+extern int unusedGlobal;
-extern _Bool globalBool2;
+extern bool globalBool;
+extern bool globalBool2;
 extern float globalFloat;
 extern double globalDouble;
 extern _Complex float globalComplexFloat;
 extern _Complex double globalComplexDouble;
 extern _Complex double globalComplexLongDouble;
+extern char globalChar;
+extern void *globalVoidPtrSet;
+extern void *globalVoidPtrNull;
+extern int64_t globalInt64;
 extern collection_t globalStruct;
 extern int globalStructSize;
 extern short globalArray[3];

testdata/cgo/out.txt

@@ -14,6 +14,9 @@ double: +3.200000e+000
 complex float: (+4.100000e+000+3.300000e+000i)
 complex double: (+4.200000e+000+3.400000e+000i)
 complex long double: (+4.300000e+000+3.500000e+000i)
+char match: true
+void* match: true true true
+int64_t match: true
 struct: true 256 -123456 +3.140000e+000
 array: 5 6 7
 union: true
@@ -21,9 +24,10 @@ union s: 22
 union f: +3.140000e+000
 union global data: 5 8 1
 union local data:  5 8 1
-union s method: -33 false
+union s: true
 union f: +6.280000e+000
 union field: +6.280000e+000
+struct: 3 5
 n in chain: 3
 n in chain: 6
 n in chain: 7

testdata/channel.go

@@ -20,6 +20,11 @@ func main() {
 	n, ok = <-ch
 	println("recv from closed channel:", n, ok)
 
+	// Test bigger values
+	ch2 := make(chan complex128)
+	go sendComplex(ch2)
+	println("complex128:", <-ch2)
+
 	// Test multi-sender.
 	ch = make(chan int)
 	go fastsender(ch)
@@ -62,6 +67,10 @@ func sender(ch chan int) {
 	close(ch)
 }
 
+func sendComplex(ch chan complex128) {
+	ch <- 7+10.5i
+}
+
 func fastsender(ch chan int) {
 	ch <- 10
 	ch <- 11

testdata/channel.txt

@@ -9,6 +9,7 @@ received num: 6
 received num: 7
 received num: 8
 recv from closed channel: 0 false
+complex128: (+7.000000e+000+1.050000e+001i)
 got n: 10
 got n: 11
 got n: 10

testdata/coroutines.go

@@ -15,12 +15,19 @@ func main() {
 	wait()
 	println("end waiting")
 
+	value := delayedValue()
+	println("value produced after some time:", value)
+
 	// Run a non-blocking call in a goroutine. This should be turned into a
 	// regular call, so should be equivalent to calling nowait() without 'go'
 	// prefix.
 	go nowait()
 	time.Sleep(time.Millisecond)
 	println("done with non-blocking goroutine")
+
+	var printer Printer
+	printer = &myPrinter{}
+	printer.Print()
 }
 
 func sub() {
@@ -35,6 +42,23 @@ func wait() {
 	println("  wait end")
 }
 
+func delayedValue() int {
+	time.Sleep(time.Millisecond)
+	return 42
+}
+
 func nowait() {
 	println("non-blocking goroutine")
 }
+
+type Printer interface {
+	Print()
+}
+
+type myPrinter struct{
+}
+
+func (i *myPrinter) Print() {
+	time.Sleep(time.Millisecond)
+	println("async interface method call")
+}

testdata/coroutines.txt

@@ -7,5 +7,7 @@ wait:
   wait start
   wait end
 end waiting
+value produced after some time: 42
 non-blocking goroutine
 done with non-blocking goroutine
+async interface method call

testdata/float.go

@@ -56,4 +56,16 @@ func main() {
 	// cast complex
 	println(complex64(c128))
 	println(complex128(c64))
+
+	// binops on complex numbers
+	c64 = 5+2i
+	println("complex64 add: ", c64 + -3+8i)
+	println("complex64 sub: ", c64 - -3+8i)
+	println("complex64 mul: ", c64 * -3+8i)
+	println("complex64 div: ", c64 / -3+8i)
+	c128 = -5+2i
+	println("complex128 add:", c128 + 2+6i)
+	println("complex128 sub:", c128 - 2+6i)
+	println("complex128 mul:", c128 * 2+6i)
+	println("complex128 div:", c128 / 2+6i)
 }

testdata/float.txt

@@ -23,3 +23,11 @@
 (+2.000000e+000-2.000000e+000i)
 (+6.666667e-001-2.000000e+000i)
 (+6.666667e-001+1.200000e+000i)
+complex64 add:  (+2.000000e+000+1.000000e+001i)
+complex64 sub:  (+8.000000e+000+1.000000e+001i)
+complex64 mul:  (-1.500000e+001+2.000000e+000i)
+complex64 div:  (-1.666667e+000+7.333333e+000i)
+complex128 add: (-3.000000e+000+8.000000e+000i)
+complex128 sub: (-7.000000e+000+8.000000e+000i)
+complex128 mul: (-1.000000e+001+1.000000e+001i)
+complex128 div: (-2.500000e+000+7.000000e+000i)