all: add support for GOARM

builder/builder_test.go

@@ -52,7 +52,9 @@ func TestClangAttributes(t *testing.T) {
 	for _, options := range []*compileopts.Options{
 		{GOOS: "linux", GOARCH: "386"},
 		{GOOS: "linux", GOARCH: "amd64"},
-		{GOOS: "linux", GOARCH: "arm"},
+		{GOOS: "linux", GOARCH: "arm", GOARM: "5"},
+		{GOOS: "linux", GOARCH: "arm", GOARM: "6"},
+		{GOOS: "linux", GOARCH: "arm", GOARM: "7"},
 		{GOOS: "linux", GOARCH: "arm64"},
 		{GOOS: "darwin", GOARCH: "amd64"},
 		{GOOS: "darwin", GOARCH: "arm64"},

compileopts/config.go

@@ -60,6 +60,12 @@ func (c *Config) GOARCH() string {
 	return c.Target.GOARCH
 }
 
+// GOARM will return the GOARM environment variable given to the compiler when
+// building a program.
+func (c *Config) GOARM() string {
+	return c.Options.GOARM
+}
+
 // BuildTags returns the complete list of build tags used during this build.
 func (c *Config) BuildTags() []string {
 	tags := append(c.Target.BuildTags, []string{"tinygo", "math_big_pure_go", "gc." + c.GC(), "scheduler." + c.Scheduler(), "serial." + c.Serial()}...)

compileopts/options.go

@@ -21,6 +21,7 @@ var (
 type Options struct {
 	GOOS            string // environment variable
 	GOARCH          string // environment variable
+	GOARM           string // environment variable (only used with GOARCH=arm)
 	Target          string
 	Opt             string
 	GC              string

compileopts/target.go

@@ -5,6 +5,7 @@ package compileopts
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"os"
 	"os/exec"
@@ -165,13 +166,26 @@ func LoadTarget(options *Options) (*TargetSpec, error) {
 	if options.Target == "" {
 		// Configure based on GOOS/GOARCH environment variables (falling back to
 		// runtime.GOOS/runtime.GOARCH), and generate a LLVM target based on it.
-		llvmarch := map[string]string{
-			"386":   "i386",
-			"amd64": "x86_64",
-			"arm64": "aarch64",
-			"arm":   "armv7",
-		}[options.GOARCH]
-		if llvmarch == "" {
+		var llvmarch string
+		switch options.GOARCH {
+		case "386":
+			llvmarch = "i386"
+		case "amd64":
+			llvmarch = "x86_64"
+		case "arm64":
+			llvmarch = "aarch64"
+		case "arm":
+			switch options.GOARM {
+			case "5":
+				llvmarch = "armv5"
+			case "6":
+				llvmarch = "armv6"
+			case "7":
+				llvmarch = "armv7"
+			default:
+				return nil, fmt.Errorf("invalid GOARM=%s, must be 5, 6, or 7", options.GOARM)
+			}
+		default:
 			llvmarch = options.GOARCH
 		}
 		llvmos := options.GOOS
@@ -245,7 +259,14 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		spec.Features = "+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
 	case "arm":
 		spec.CPU = "generic"
-		spec.Features = "+armv7-a,+dsp,+fp64,+vfp2,+vfp2sp,+vfp3d16,+vfp3d16sp,-thumb-mode"
+		switch strings.Split(triple, "-")[0] {
+		case "armv5":
+			spec.Features = "+armv5t,+strict-align,-thumb-mode"
+		case "armv6":
+			spec.Features = "+armv6,+dsp,+fp64,+strict-align,+vfp2,+vfp2sp,-thumb-mode"
+		case "armv7":
+			spec.Features = "+armv7-a,+dsp,+fp64,+vfp2,+vfp2sp,+vfp3d16,+vfp3d16sp,-thumb-mode"
+		}
 	case "arm64":
 		spec.CPU = "generic"
 		spec.Features = "+neon"

goenv/goenv.go

@@ -25,6 +25,12 @@ var Keys = []string{
 	"TINYGOROOT",
 }
 
+func init() {
+	if Get("GOARCH") == "arm" {
+		Keys = append(Keys, "GOARM")
+	}
+}
+
 // TINYGOROOT is the path to the final location for checking tinygo files. If
 // unset (by a -X ldflag), then sourceDir() will fallback to the original build
 // directory.
@@ -44,6 +50,20 @@ func Get(name string) string {
 			return dir
 		}
 		return runtime.GOARCH
+	case "GOARM":
+		if goarm := os.Getenv("GOARM"); goarm != "" {
+			return goarm
+		}
+		if goos := Get("GOOS"); goos == "windows" || goos == "android" {
+			// Assume Windows and Android are running on modern CPU cores.
+			// This matches upstream Go.
+			return "7"
+		}
+		// Default to ARMv6 on other devices.
+		// The difference between ARMv5 and ARMv6 is big, much bigger than the
+		// difference between ARMv6 and ARMv7. ARMv6 binaries are much smaller,
+		// especially when floating point instructions are involved.
+		return "6"
 	case "GOROOT":
 		return getGoroot()
 	case "GOPATH":

main.go

@@ -1192,6 +1192,7 @@ func main() {
 	options := &compileopts.Options{
 		GOOS:            goenv.Get("GOOS"),
 		GOARCH:          goenv.Get("GOARCH"),
+		GOARM:           goenv.Get("GOARM"),
 		Target:          *target,
 		Opt:             *opt,
 		GC:              *gc,
@@ -1401,6 +1402,7 @@ func main() {
 		fmt.Printf("LLVM triple:       %s\n", config.Triple())
 		fmt.Printf("GOOS:              %s\n", config.GOOS())
 		fmt.Printf("GOARCH:            %s\n", config.GOARCH())
+		fmt.Printf("GOARM:             %s\n", config.GOARM())
 		fmt.Printf("build tags:        %s\n", strings.Join(config.BuildTags(), " "))
 		fmt.Printf("garbage collector: %s\n", config.GC())
 		fmt.Printf("scheduler:         %s\n", config.Scheduler())

main_test.go

@@ -95,13 +95,13 @@ func TestCompiler(t *testing.T) {
 
 	if runtime.GOOS == "linux" {
 		t.Run("X86Linux", func(t *testing.T) {
-			runPlatTests(optionsFromOSARCH("linux", "386"), tests, t)
+			runPlatTests(optionsFromOSARCH("linux/386"), tests, t)
 		})
 		t.Run("ARMLinux", func(t *testing.T) {
-			runPlatTests(optionsFromOSARCH("linux", "arm"), tests, t)
+			runPlatTests(optionsFromOSARCH("linux/arm/6"), tests, t)
 		})
 		t.Run("ARM64Linux", func(t *testing.T) {
-			runPlatTests(optionsFromOSARCH("linux", "arm64"), tests, t)
+			runPlatTests(optionsFromOSARCH("linux/arm64"), tests, t)
 		})
 		t.Run("WebAssembly", func(t *testing.T) {
 			runPlatTests(optionsFromTarget("wasm"), tests, t)
@@ -125,6 +125,7 @@ func TestCompiler(t *testing.T) {
 			runTestWithConfig("stdlib.go", t, compileopts.Options{
 				GOOS:   goenv.Get("GOOS"),
 				GOARCH: goenv.Get("GOARCH"),
+				GOARM:  goenv.Get("GOARM"),
 				Opt:    "1",
 			}, nil, nil)
 		})
@@ -136,6 +137,7 @@ func TestCompiler(t *testing.T) {
 			runTestWithConfig("print.go", t, compileopts.Options{
 				GOOS:   goenv.Get("GOOS"),
 				GOARCH: goenv.Get("GOARCH"),
+				GOARM:  goenv.Get("GOARM"),
 				Opt:    "0",
 			}, nil, nil)
 		})
@@ -145,6 +147,7 @@ func TestCompiler(t *testing.T) {
 			runTestWithConfig("ldflags.go", t, compileopts.Options{
 				GOOS:   goenv.Get("GOOS"),
 				GOARCH: goenv.Get("GOARCH"),
+				GOARM:  goenv.Get("GOARM"),
 				GlobalValues: map[string]map[string]string{
 					"main": {
 						"someGlobal": "foobar",
@@ -200,15 +203,24 @@ func optionsFromTarget(target string) compileopts.Options {
 		// GOOS/GOARCH are only used if target == ""
 		GOOS:   goenv.Get("GOOS"),
 		GOARCH: goenv.Get("GOARCH"),
+		GOARM:  goenv.Get("GOARM"),
 		Target: target,
 	}
 }
 
-func optionsFromOSARCH(goos, goarch string) compileopts.Options {
-	return compileopts.Options{
-		GOOS:   goos,
-		GOARCH: goarch,
+// optionsFromOSARCH returns a set of options based on the "osarch" string. This
+// string is in the form of "os/arch/subarch", with the subarch only sometimes
+// being necessary. Examples are "darwin/amd64" or "linux/arm/7".
+func optionsFromOSARCH(osarch string) compileopts.Options {
+	parts := strings.Split(osarch, "/")
+	options := compileopts.Options{
+		GOOS:   parts[0],
+		GOARCH: parts[1],
+	}
+	if options.GOARCH == "arm" {
+		options.GOARM = parts[2]
 	}
+	return options
 }
 
 func runTest(name string, options compileopts.Options, t *testing.T, cmdArgs, environmentVars []string) {