cmd/compile: only support -race and -msan where they work

Consolidate decision about whether -race and -msan options are
supported in cmd/internal/sys. Use consolidated functions in
cmd/compile and cmd/go. Use a copy of them in cmd/dist; cmd/dist can't
import cmd/internal/sys because Go 1.4 doesn't have it.

Fixes #24315

Change-Id: I9cecaed4895eb1a2a49379b4848db40de66d32a9
Reviewed-on: https://go-review.googlesource.com/121816
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/main.go

@@ -216,14 +216,18 @@ func Main(archInit func(*Arch)) {
 	flag.StringVar(&linkobj, "linkobj", "", "write linker-specific object to `file`")
 	objabi.Flagcount("live", "debug liveness analysis", &debuglive)
 	objabi.Flagcount("m", "print optimization decisions", &Debug['m'])
-	flag.BoolVar(&flag_msan, "msan", false, "build code compatible with C/C++ memory sanitizer")
+	if sys.MSanSupported(objabi.GOOS, objabi.GOARCH) {
+		flag.BoolVar(&flag_msan, "msan", false, "build code compatible with C/C++ memory sanitizer")
+	}
 	flag.BoolVar(&dolinkobj, "dolinkobj", true, "generate linker-specific objects; if false, some invalid code may compile")
 	flag.BoolVar(&nolocalimports, "nolocalimports", false, "reject local (relative) imports")
 	flag.StringVar(&outfile, "o", "", "write output to `file`")
 	flag.StringVar(&myimportpath, "p", "", "set expected package import `path`")
 	flag.BoolVar(&writearchive, "pack", false, "write to file.a instead of file.o")
 	objabi.Flagcount("r", "debug generated wrappers", &Debug['r'])
-	flag.BoolVar(&flag_race, "race", false, "enable race detector")
+	if sys.RaceDetectorSupported(objabi.GOOS, objabi.GOARCH) {
+		flag.BoolVar(&flag_race, "race", false, "enable race detector")
+	}
 	objabi.Flagcount("s", "warn about composite literals that can be simplified", &Debug['s'])
 	flag.StringVar(&pathPrefix, "trimpath", "", "remove `prefix` from recorded source file paths")
 	flag.BoolVar(&safemode, "u", false, "reject unsafe code")

src/cmd/dist/test.go

@@ -705,7 +705,7 @@ func (t *tester) registerTests() {
 		if gohostos == "linux" && goarch == "amd64" {
 			t.registerTest("testasan", "../misc/cgo/testasan", "go", "run", "main.go")
 		}
-		if goos == "linux" && (goarch == "amd64" || goarch == "arm64") {
+		if mSanSupported(goos, goarch) {
 			t.registerHostTest("testsanitizers/msan", "../misc/cgo/testsanitizers", "misc/cgo/testsanitizers", ".")
 		}
 		if t.hasBash() && goos != "android" && !t.iOS() && gohostos != "windows" {
@@ -1329,13 +1329,21 @@ func (t *tester) hasSwig() bool {
 }
 
 func (t *tester) raceDetectorSupported() bool {
-	switch gohostos {
-	case "linux", "darwin", "freebsd", "windows":
-		// The race detector doesn't work on Alpine Linux:
-		// golang.org/issue/14481
-		return t.cgoEnabled && (goarch == "amd64" || goarch == "ppc64le") && gohostos == goos && !isAlpineLinux()
+	if gohostos != goos {
+		return false
 	}
-	return false
+	if !t.cgoEnabled {
+		return false
+	}
+	if !raceDetectorSupported(goos, goarch) {
+		return false
+	}
+	// The race detector doesn't work on Alpine Linux:
+	// golang.org/issue/14481
+	if isAlpineLinux() {
+		return false
+	}
+	return true
 }
 
 func isAlpineLinux() bool {
@@ -1450,3 +1458,26 @@ func (t *tester) packageHasBenchmarks(pkg string) bool {
 	}
 	return false
 }
+
+// raceDetectorSupported is a copy of the function
+// cmd/internal/sys.RaceDetectorSupported, which can't be used here
+// because cmd/dist has to be buildable by Go 1.4.
+func raceDetectorSupported(goos, goarch string) bool {
+	switch goos {
+	case "linux", "darwin", "freebsd", "netbsd", "windows":
+		return goarch == "amd64" || goarch == "ppc64le"
+	default:
+		return false
+	}
+}
+
+// mSanSupported is a copy of the function cmd/internal/sys.MSanSupported,
+// which can't be used here because cmd/dist has to be buildable by Go 1.4.
+func mSanSupported(goos, goarch string) bool {
+	switch goos {
+	case "linux":
+		return goarch == "amd64" || goarch == "arm64"
+	default:
+		return false
+	}
+}

src/cmd/go/go_test.go

@@ -6,6 +6,7 @@ package main_test
 
 import (
 	"bytes"
+	"cmd/internal/sys"
 	"debug/elf"
 	"debug/macho"
 	"flag"
@@ -209,15 +210,13 @@ func TestMain(m *testing.M) {
 		}
 		testGOCACHE = strings.TrimSpace(string(out))
 
-		// As of Sept 2017, MSan is only supported on linux/amd64.
-		// https://github.com/google/sanitizers/wiki/MemorySanitizer#getting-memorysanitizer
-		canMSan = canCgo && runtime.GOOS == "linux" && runtime.GOARCH == "amd64"
-
-		switch runtime.GOOS {
-		case "linux", "darwin", "freebsd", "windows":
-			// The race detector doesn't work on Alpine Linux:
-			// golang.org/issue/14481
-			canRace = canCgo && runtime.GOARCH == "amd64" && !isAlpineLinux() && runtime.Compiler != "gccgo"
+		canMSan = canCgo && sys.MSanSupported(runtime.GOOS, runtime.GOARCH)
+		canRace = canCgo && sys.RaceDetectorSupported(runtime.GOOS, runtime.GOARCH)
+		// The race detector doesn't work on Alpine Linux:
+		// golang.org/issue/14481
+		// gccgo does not support the race detector.
+		if isAlpineLinux() || runtime.Compiler == "gccgo" {
+			canRace = false
 		}
 	}
 	// Don't let these environment variables confuse the test.

src/cmd/go/internal/work/init.go

@@ -10,6 +10,7 @@ import (
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
+	"cmd/internal/sys"
 	"flag"
 	"fmt"
 	"os"
@@ -42,18 +43,14 @@ func instrumentInit() {
 		fmt.Fprintf(os.Stderr, "go %s: may not use -race and -msan simultaneously\n", flag.Args()[0])
 		os.Exit(2)
 	}
-	if cfg.BuildMSan && (cfg.Goos != "linux" || cfg.Goarch != "amd64" && cfg.Goarch != "arm64") {
+	if cfg.BuildMSan && !sys.MSanSupported(cfg.Goos, cfg.Goarch) {
 		fmt.Fprintf(os.Stderr, "-msan is not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
 		os.Exit(2)
 	}
 	if cfg.BuildRace {
-		platform := cfg.Goos + "/" + cfg.Goarch
-		switch platform {
-		default:
+		if !sys.RaceDetectorSupported(cfg.Goos, cfg.Goarch) {
 			fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, linux/ppc64le, freebsd/amd64, netbsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
 			os.Exit(2)
-		case "linux/amd64", "linux/ppc64le", "freebsd/amd64", "netbsd/amd64", "darwin/amd64", "windows/amd64":
-			// race supported on these platforms
 		}
 	}
 	mode := "race"

src/cmd/internal/sys/supported.go

@@ -0,0 +1,29 @@
+// Copyright 2018 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 sys
+
+// RaceDetectorSupported reports whether goos/goarch supports the race
+// detector. There is a copy of this function in cmd/dist/test.go.
+func RaceDetectorSupported(goos, goarch string) bool {
+	switch goos {
+	case "linux":
+		return goarch == "amd64" || goarch == "ppc64le"
+	case "darwin", "freebsd", "netbsd", "windows":
+		return goarch == "amd64"
+	default:
+		return false
+	}
+}
+
+// MSanSupported reports whether goos/goarch supports the memory
+// sanitizer option. There is a copy of this function in cmd/dist/test.go.
+func MSanSupported(goos, goarch string) bool {
+	switch goos {
+	case "linux":
+		return goarch == "amd64" || goarch == "arm64"
+	default:
+		return false
+	}
+}

test/fixedbugs/issue13265.go

@@ -1,4 +1,5 @@
 // errorcheck -0 -race
+// +build linux,amd64 linux,ppc64le darwin,amd64 freebsd,amd64 netbsd,amd64 windows,amd64
 
 // Copyright 2017 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/fixedbugs/issue15091.go

@@ -1,4 +1,5 @@
 // errorcheck -0 -race
+// +build linux,amd64 linux,ppc64le darwin,amd64 freebsd,amd64 netbsd,amd64 windows,amd64
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/fixedbugs/issue16008.go

@@ -1,4 +1,5 @@
 // errorcheck -0 -race
+// +build linux,amd64 linux,ppc64le darwin,amd64 freebsd,amd64 netbsd,amd64 windows,amd64
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/fixedbugs/issue17449.go

@@ -1,4 +1,5 @@
 // errorcheck -0 -race
+// +build linux,amd64 linux,ppc64le darwin,amd64 freebsd,amd64 netbsd,amd64 windows,amd64
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

test/fixedbugs/issue24651a.go

@@ -1,4 +1,5 @@
 //errorcheck -0 -race -m -m
+// +build linux,amd64 linux,ppc64le darwin,amd64 freebsd,amd64 netbsd,amd64 windows,amd64
 
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style