cmd: enable -buildmode=pie on aix/ppc64

Change-Id: I939518462c931ba9feb125b2f299ef0706b124ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/168879
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/test.go

@@ -963,7 +963,8 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		return false
 	case "pie":
 		switch pair {
-		case "linux-386", "linux-amd64", "linux-arm", "linux-arm64", "linux-ppc64le", "linux-s390x",
+		case "aix/ppc64",
+			"linux-386", "linux-amd64", "linux-arm", "linux-arm64", "linux-ppc64le", "linux-s390x",
 			"android-amd64", "android-arm", "android-arm64", "android-386":
 			return true
 		case "darwin-amd64":

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

@@ -164,6 +164,7 @@ func buildModeInit() {
 				codegenArg = "-shared"
 			case "darwin/amd64":
 				codegenArg = "-shared"
+			case "aix/ppc64":
 			default:
 				base.Fatalf("-buildmode=pie not supported on %s\n", platform)
 			}

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

@@ -38,7 +38,7 @@ func (mode *BuildMode) Set(s string) error {
 		*mode = BuildModeExe
 	case "pie":
 		switch objabi.GOOS {
-		case "android", "linux":
+		case "aix", "android", "linux":
 		case "darwin", "freebsd":
 			switch objabi.GOARCH {
 			case "amd64":

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

@@ -179,7 +179,7 @@ func (ctxt *Link) CanUsePlugins() bool {
 func (ctxt *Link) UseRelro() bool {
 	switch ctxt.BuildMode {
 	case BuildModeCArchive, BuildModeCShared, BuildModeShared, BuildModePIE, BuildModePlugin:
-		return ctxt.IsELF
+		return ctxt.IsELF || ctxt.HeadType == objabi.Haix
 	default:
 		return ctxt.linkShared || (ctxt.HeadType == objabi.Haix && ctxt.LinkMode == LinkExternal)
 	}
@@ -1173,7 +1173,7 @@ func (ctxt *Link) hostlink() {
 		}
 	case BuildModePIE:
 		// ELF.
-		if ctxt.HeadType != objabi.Hdarwin {
+		if ctxt.HeadType != objabi.Hdarwin && ctxt.HeadType != objabi.Haix {
 			if ctxt.UseRelro() {
 				argv = append(argv, "-Wl,-z,relro")
 			}