cmd/go, cmd/link: enable -buildmode=shared on linux/ppc64le

Change-Id: Ifba76413b8aa78a221385bf505b92a3a5fbc3d24
Reviewed-on: https://go-review.googlesource.com/16713Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/build.go

@@ -391,7 +391,7 @@ func buildModeInit() {
 			codegenArg = "-fPIC"
 		} else {
 			switch platform {
-			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64":
+			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le":
 			default:
 				fatalf("-buildmode=shared not supported on %s\n", platform)
 			}
@@ -412,7 +412,7 @@ func buildModeInit() {
 			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le":
 				buildAsmflags = append(buildAsmflags, "-D=GOBUILDMODE_shared=1")
 			default:
-				fatalf("-buildmode=shared not supported on %s\n", platform)
+				fatalf("-linkshared not supported on %s\n", platform)
 			}
 			codegenArg = "-dynlink"
 			// TODO(mwhudson): remove -w when that gets fixed in linker.

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

@@ -322,7 +322,7 @@ func (mode *BuildMode) Set(s string) error {
 		}
 		*mode = BuildmodeCShared
 	case "shared":
-		if goos != "linux" || (goarch != "386" && goarch != "amd64" && goarch != "arm" && goarch != "arm64") {
+		if goos != "linux" || (goarch != "386" && goarch != "amd64" && goarch != "arm" && goarch != "arm64" && goarch != "ppc64le") {
 			return badmode()
 		}
 		*mode = BuildmodeShared

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

@@ -162,7 +162,7 @@ func putelfsym(x *LSym, s string, t int, addr int64, size int64, ver int, go_ *L
 	if x.Type&obj.SHIDDEN != 0 {
 		other = STV_HIDDEN
 	}
-	if Buildmode == BuildmodePIE && Thearch.Thechar == '9' && type_ == STT_FUNC && x.Name != "runtime.duffzero" && x.Name != "runtime.duffcopy" {
+	if (Buildmode == BuildmodePIE || DynlinkingGo()) && Thearch.Thechar == '9' && type_ == STT_FUNC && x.Name != "runtime.duffzero" && x.Name != "runtime.duffcopy" {
 		// On ppc64 the top three bits of the st_other field indicate how
 		// many instructions separate the global and local entry points. In
 		// our case it is two instructions, indicated by the value 3.

src/cmd/link/internal/ppc64/obj.go

@@ -99,7 +99,11 @@ func archinit() {
 	}
 
 	switch ld.Buildmode {
-	case ld.BuildmodePIE:
+	case ld.BuildmodePIE, ld.BuildmodeShared:
+		ld.Linkmode = ld.LinkExternal
+	}
+
+	if ld.Linkshared {
 		ld.Linkmode = ld.LinkExternal
 	}