sync/atomic: add support for GOARCH=mips{,le}

Change-Id: I10f36710dd95b9bd31b3b82a3c32edcadb90ffa9
Reviewed-on: https://go-review.googlesource.com/31510
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/runtime/internal/atomic/atomic_test.go

@@ -7,6 +7,7 @@ package atomic_test
 import (
 	"runtime"
 	"runtime/internal/atomic"
+	"runtime/internal/sys"
 	"testing"
 	"unsafe"
 )
@@ -51,13 +52,13 @@ func TestXadduintptr(t *testing.T) {
 // Tests that xadduintptr correctly updates 64-bit values. The place where
 // we actually do so is mstats.go, functions mSysStat{Inc,Dec}.
 func TestXadduintptrOnUint64(t *testing.T) {
-	/*	if runtime.BigEndian != 0 {
+	if sys.BigEndian != 0 {
 		// On big endian architectures, we never use xadduintptr to update
 		// 64-bit values and hence we skip the test.  (Note that functions
 		// mSysStat{Inc,Dec} in mstats.go have explicit checks for
 		// big-endianness.)
-		return
-	}*/
+		t.Skip("skip xadduintptr on big endian architecture")
+	}
 	const inc = 100
 	val := uint64(0)
 	atomic.Xadduintptr((*uintptr)(unsafe.Pointer(&val)), inc)

src/sync/atomic/asm_mipsx.s

@@ -0,0 +1,85 @@
+// Copyright 2016 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 mips mipsle
+
+#include "textflag.h"
+
+TEXT ·SwapInt32(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Xchg(SB)
+
+TEXT ·SwapUint32(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Xchg(SB)
+
+TEXT ·SwapInt64(SB),NOSPLIT,$0-24
+	JMP	runtime∕internal∕atomic·Xchg64(SB)
+
+TEXT ·SwapUint64(SB),NOSPLIT,$0-24
+	JMP	runtime∕internal∕atomic·Xchg64(SB)
+
+TEXT ·SwapUintptr(SB),NOSPLIT,$0-20
+	JMP	runtime∕internal∕atomic·Xchg(SB)
+
+TEXT ·CompareAndSwapInt32(SB),NOSPLIT,$0-13
+	JMP	runtime∕internal∕atomic·Cas(SB)
+
+TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0-13
+	JMP	runtime∕internal∕atomic·Cas(SB)
+
+TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0-13
+	JMP	runtime∕internal∕atomic·Cas(SB)
+
+TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0-21
+	JMP	runtime∕internal∕atomic·Cas64(SB)
+
+TEXT ·CompareAndSwapUint64(SB),NOSPLIT,$0-21
+	JMP	runtime∕internal∕atomic·Cas64(SB)
+
+TEXT ·AddInt32(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Xadd(SB)
+
+TEXT ·AddUint32(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Xadd(SB)
+
+TEXT ·AddUintptr(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Xadd(SB)
+
+TEXT ·AddInt64(SB),NOSPLIT,$0-20
+	JMP	runtime∕internal∕atomic·Xadd64(SB)
+
+TEXT ·AddUint64(SB),NOSPLIT,$0-20
+	JMP	runtime∕internal∕atomic·Xadd64(SB)
+
+TEXT ·LoadInt32(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Load(SB)
+
+TEXT ·LoadUint32(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Load(SB)
+
+TEXT ·LoadInt64(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Load64(SB)
+
+TEXT ·LoadUint64(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Load64(SB)
+
+TEXT ·LoadUintptr(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Load(SB)
+
+TEXT ·LoadPointer(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Load(SB)
+
+TEXT ·StoreInt32(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Store(SB)
+
+TEXT ·StoreUint32(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Store(SB)
+
+TEXT ·StoreInt64(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Store64(SB)
+
+TEXT ·StoreUint64(SB),NOSPLIT,$0-12
+	JMP	runtime∕internal∕atomic·Store64(SB)
+
+TEXT ·StoreUintptr(SB),NOSPLIT,$0-8
+	JMP	runtime∕internal∕atomic·Store(SB)

src/sync/atomic/atomic_test.go

@@ -1389,12 +1389,15 @@ func TestUnaligned64(t *testing.T) {
 	// Unaligned 64-bit atomics on 32-bit systems are
 	// a continual source of pain. Test that on 32-bit systems they crash
 	// instead of failing silently.
+
+	switch runtime.GOARCH {
+	default:
 		if unsafe.Sizeof(int(0)) != 4 {
 			t.Skip("test only runs on 32-bit systems")
 		}
-	if runtime.GOARCH == "amd64p32" {
-		// amd64p32 can handle unaligned atomics.
-		t.Skip("test not needed on amd64p32")
+	case "amd64p32", "mips", "mipsle":
+		// amd64p32 and mips can handle unaligned atomics.
+		t.Skipf("test not needed on %v", runtime.GOARCH)
 	}
 
 	x := make([]uint32, 4)