cmd/link, cmd/go: enable DWARF on darwin/arm and darwin/arm64

Fixes #24883.

Change-Id: Iff992ec3f2f31f4d82923d7cc806df4ee58e70b0
Reviewed-on: https://go-review.googlesource.com/108295
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Elias Naur <elias.naur@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/internal/work/gc.go

@@ -89,7 +89,7 @@ func (gcToolchain) gc(b *Builder, a *Action, archive string, importcfg []byte, a
 		gcargs = append(gcargs, "-buildid", a.buildID)
 	}
 	platform := cfg.Goos + "/" + cfg.Goarch
-	if p.Internal.OmitDebug || platform == "nacl/amd64p32" || platform == "darwin/arm" || platform == "darwin/arm64" || cfg.Goos == "plan9" {
+	if p.Internal.OmitDebug || platform == "nacl/amd64p32" || cfg.Goos == "plan9" {
 		gcargs = append(gcargs, "-dwarf=false")
 	}
 	if strings.HasPrefix(runtimeVersion, "go1") && !strings.Contains(os.Args[0], "go_bootstrap") {

src/cmd/link/dwarf_test.go

@@ -19,7 +19,7 @@ import (
 	"testing"
 )
 
-func TestDWARF(t *testing.T) {
+func testDWARF(t *testing.T, env ...string) {
 	testenv.MustHaveCGO(t)
 	testenv.MustHaveGoBuild(t)
 
@@ -48,7 +48,11 @@ func TestDWARF(t *testing.T) {
 		t.Run(prog, func(t *testing.T) {
 			exe := filepath.Join(tmpDir, prog+".exe")
 			dir := "../../runtime/testdata/" + prog
-			out, err := exec.Command(testenv.GoToolPath(t), "build", "-o", exe, dir).CombinedOutput()
+			cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", exe, dir)
+			if env != nil {
+				cmd.Env = append(os.Environ(), env...)
+			}
+			out, err := cmd.CombinedOutput()
 			if err != nil {
 				t.Fatalf("go build -o %v %v: %v\n%s", exe, dir, err, out)
 			}
@@ -122,3 +126,25 @@ func TestDWARF(t *testing.T) {
 		})
 	}
 }
+
+func TestDWARF(t *testing.T) {
+	testDWARF(t)
+}
+
+func TestDWARFiOS(t *testing.T) {
+	// Normally we run TestDWARF on native platform. But on iOS we don't have
+	// go build, so we do this test with a cross build.
+	// Only run this on darwin/amd64, where we can cross build for iOS.
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	if runtime.GOARCH != "amd64" || runtime.GOOS != "darwin" {
+		t.Skip("skipping on non-darwin/amd64 platform")
+	}
+	if err := exec.Command("xcrun", "--help").Run(); err != nil {
+		t.Skipf("error running xcrun, required for iOS cross build: %v", err)
+	}
+	cc := "CC=" + runtime.GOROOT() + "/misc/ios/clangwrap.sh"
+	testDWARF(t, cc, "CGO_ENABLED=1", "GOOS=darwin", "GOARCH=arm", "GOARM=7")
+	testDWARF(t, cc, "CGO_ENABLED=1", "GOOS=darwin", "GOARCH=arm64")
+}

src/cmd/link/internal/arm/obj.go

@@ -120,7 +120,6 @@ func archinit(ctxt *ld.Link) {
 		}
 
 	case objabi.Hdarwin: /* apple MACH */
-		*ld.FlagW = true // disable DWARF generation
 		ld.HEADR = ld.INITIAL_MACHO_HEADR
 		if *ld.FlagTextAddr == -1 {
 			*ld.FlagTextAddr = 4096 + int64(ld.HEADR)

src/cmd/link/internal/arm64/obj.go

@@ -101,7 +101,6 @@ func archinit(ctxt *ld.Link) {
 		}
 
 	case objabi.Hdarwin: /* apple MACH */
-		*ld.FlagW = true // disable DWARF generation
 		ld.HEADR = ld.INITIAL_MACHO_HEADR
 		if *ld.FlagTextAddr == -1 {
 			*ld.FlagTextAddr = 4096 + int64(ld.HEADR)

src/cmd/link/internal/ld/lib.go

@@ -1333,8 +1333,6 @@ func (ctxt *Link) hostlink() {
 	}
 
 	if !*FlagS && !*FlagW && !debug_s && ctxt.HeadType == objabi.Hdarwin {
-		// Skip combining dwarf on arm.
-		if !ctxt.Arch.InFamily(sys.ARM, sys.ARM64) {
 		dsym := filepath.Join(*flagTmpdir, "go.dwarf")
 		if out, err := exec.Command("dsymutil", "-f", *flagOutfile, "-o", dsym).CombinedOutput(); err != nil {
 			Exitf("%s: running dsymutil failed: %v\n%s", os.Args[0], err, out)
@@ -1354,7 +1352,6 @@ func (ctxt *Link) hostlink() {
 		}
 	}
 }
-}
 
 // hostlinkArchArgs returns arguments to pass to the external linker
 // based on the architecture.