cmd/go: buildmode=c-shared support for linux/arm64

Change-Id: Ic826dc25b5203b2e9fc253d6fe997e4b41de3789
Reviewed-on: https://go-review.googlesource.com/16453Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

misc/cgo/testcshared/src/libgo2/dup2.go

+// Copyright 2015 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.
+
+// +build darwin dragonfly freebsd linux,!arm64 netbsd openbsd
+
+package main
+
+import "syscall"
+
+func dup2(oldfd, newfd int) error {
+	return syscall.Dup2(oldfd, newfd)
+}

misc/cgo/testcshared/src/libgo2/dup3.go

+// Copyright 2015 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.
+
+// +build linux,arm64
+
+package main
+
+import "syscall"
+
+func dup2(oldfd, newfd int) error {
+	return syscall.Dup3(oldfd, newfd, 0)
+}

misc/cgo/testcshared/src/libgo2/libgo2.go

@@ -31,7 +31,7 @@ func init() {
 		os.Exit(2)
 	}
 
-	if e := syscall.Dup2(p[0], fd); e != nil {
+	if e := dup2(p[0], fd); e != nil {
 		fmt.Fprintf(os.Stderr, "dup2: %v\n", e)
 		os.Exit(2)
 	}

misc/cgo/testcshared/test.bash

@@ -114,7 +114,7 @@ if [ "$output" != "PASS" ]; then
 fi
 
 # test2: tests libgo2 which does not export any functions.
-GOPATH=$(pwd) go build -buildmode=c-shared $suffix -o libgo2.$libext src/libgo2/libgo2.go
+GOPATH=$(pwd) go build -buildmode=c-shared $suffix -o libgo2.$libext libgo2
 binpush libgo2.$libext
 linkflags="-Wl,--no-as-needed"
 if [ "$goos" == "darwin" ]; then

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

@@ -220,7 +220,8 @@ func Main() {
 	obj.Flagcount("y", "debug declarations in canned imports (with -d)", &Debug['y'])
 	var flag_shared int
 	var flag_dynlink bool
-	if Thearch.Thechar == '5' || Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+	switch Thearch.Thechar {
+	case '5', '6', '7', '9':
 		obj.Flagcount("shared", "generate code that can be linked into a shared library", &flag_shared)
 	}
 	if Thearch.Thechar == '6' {

src/cmd/dist/test.go

@@ -581,7 +581,7 @@ func (t *tester) supportedBuildmode(mode string) bool {
 	case "c-shared":
 		// TODO(hyangah): add linux-386.
 		switch pair {
-		case "linux-amd64", "darwin-amd64", "android-arm", "linux-arm":
+		case "linux-amd64", "darwin-amd64", "android-arm", "linux-arm", "linux-arm64":
 			return true
 		}
 		return false

src/cmd/go/build.go

@@ -350,7 +350,7 @@ func buildModeInit() {
 			codegenArg = "-fPIC"
 		} else {
 			switch platform {
-			case "linux/amd64", "linux/arm",
+			case "linux/amd64", "linux/arm", "linux/arm64",
 				"android/amd64", "android/arm":
 				codegenArg = "-shared"
 			case "darwin/amd64":

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

@@ -104,6 +104,10 @@ func archinit() {
 		break
 	}
 
+	if ld.Buildmode == ld.BuildmodeCShared {
+		ld.Linkmode = ld.LinkExternal
+	}
+
 	switch ld.HEADTYPE {
 	default:
 		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)

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

@@ -316,7 +316,7 @@ func (mode *BuildMode) Set(s string) error {
 		}
 		*mode = BuildmodeCArchive
 	case "c-shared":
-		if goarch != "amd64" && goarch != "arm" {
+		if goarch != "amd64" && goarch != "arm" && goarch != "arm64" {
 			return badmode()
 		}
 		*mode = BuildmodeCShared