cmd/link: pass arch-specific flags to external linker when testing supported flag

When testing if a flag (e.g. "-no-pie") is supported by the
external linker, pass arch-specific flags (like "-marm").

In particular, on the ARM builder, if CGO_LDFLAGS=-march=armv6
is set, the C toolchain fails to build if -marm is not passed.

	# cc -march=armv6 1.c
	1.c: In function 'main':
	1.c:3:1: sorry, unimplemented: Thumb-1 hard-float VFP ABI
	 int main() {
	 ^~~

This makes the Go linker think "-no-pie" is not supported when it
actually is.

Passing -marm makes it work.

Fixes #43202.

Change-Id: I4e8b71f08818993cbbcb2494b310c68d812d6b50
Reviewed-on: https://go-review.googlesource.com/c/go/+/278592
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Zhang 2020-12-15 18:31:21 -05:00
parent f4e7a6b905
commit a318d56c1e

View file

@ -1458,7 +1458,7 @@ func (ctxt *Link) hostlink() {
}
const compressDWARF = "-Wl,--compress-debug-sections=zlib-gnu"
if ctxt.compressDWARF && linkerFlagSupported(argv[0], altLinker, compressDWARF) {
if ctxt.compressDWARF && linkerFlagSupported(ctxt.Arch, argv[0], altLinker, compressDWARF) {
argv = append(argv, compressDWARF)
}
@ -1548,7 +1548,7 @@ func (ctxt *Link) hostlink() {
if ctxt.BuildMode == BuildModeExe && !ctxt.linkShared && !(ctxt.IsDarwin() && ctxt.IsARM64()) {
// GCC uses -no-pie, clang uses -nopie.
for _, nopie := range []string{"-no-pie", "-nopie"} {
if linkerFlagSupported(argv[0], altLinker, nopie) {
if linkerFlagSupported(ctxt.Arch, argv[0], altLinker, nopie) {
argv = append(argv, nopie)
break
}
@ -1657,7 +1657,7 @@ func (ctxt *Link) hostlink() {
var createTrivialCOnce sync.Once
func linkerFlagSupported(linker, altLinker, flag string) bool {
func linkerFlagSupported(arch *sys.Arch, linker, altLinker, flag string) bool {
createTrivialCOnce.Do(func() {
src := filepath.Join(*flagTmpdir, "trivial.c")
if err := ioutil.WriteFile(src, []byte("int main() { return 0; }"), 0666); err != nil {
@ -1691,7 +1691,7 @@ func linkerFlagSupported(linker, altLinker, flag string) bool {
"-target",
}
var flags []string
flags := hostlinkArchArgs(arch)
keep := false
skip := false
extldflags := strings.Fields(*flagExtldflags)