go/types: add gccgo sizes information

This will need to be updated from time to time as new targets are
added to gccgo. But that is better than always returning nil.

Change-Id: I04b8c4d0f8efa38e2a148eb2e38b16b09f0351c3
Reviewed-on: https://go-review.googlesource.com/c/158844
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/go/types/gccgosizes.go

+// Copyright 2019 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.
+
+// This is a copy of the file generated during the gccgo build process.
+// Last update 2019-01-22.
+
+package types
+
+var gccgoArchSizes = map[string]*StdSizes{
+	"386":         {4, 4},
+	"alpha":       {8, 8},
+	"amd64":       {8, 8},
+	"amd64p32":    {4, 8},
+	"arm":         {4, 8},
+	"armbe":       {4, 8},
+	"arm64":       {8, 8},
+	"arm64be":     {8, 8},
+	"ia64":        {8, 8},
+	"m68k":        {4, 2},
+	"mips":        {4, 8},
+	"mipsle":      {4, 8},
+	"mips64":      {8, 8},
+	"mips64le":    {8, 8},
+	"mips64p32":   {4, 8},
+	"mips64p32le": {4, 8},
+	"nios2":       {4, 8},
+	"ppc":         {4, 8},
+	"ppc64":       {8, 8},
+	"ppc64le":     {8, 8},
+	"riscv":       {4, 8},
+	"riscv64":     {8, 8},
+	"s390":        {4, 8},
+	"s390x":       {8, 8},
+	"sh":          {4, 8},
+	"shbe":        {4, 8},
+	"sparc":       {4, 8},
+	"sparc64":     {8, 8},
+	"wasm":        {8, 8},
+}

src/go/types/sizes.go

@@ -182,10 +182,16 @@ var gcArchSizes = map[string]*StdSizes{
 // "386", "arm", "arm64", "amd64", "amd64p32", "mips", "mipsle",
 // "mips64", "mips64le", "ppc64", "ppc64le", "riscv64", "s390x", "sparc64", "wasm".
 func SizesFor(compiler, arch string) Sizes {
-	if compiler != "gc" {
+	var m map[string]*StdSizes
+	switch compiler {
+	case "gc":
+		m = gcArchSizes
+	case "gccgo":
+		m = gccgoArchSizes
+	default:
 		return nil
 	}
-	s, ok := gcArchSizes[arch]
+	s, ok := m[arch]
 	if !ok {
 		return nil
 	}