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>

2 files changed, 94 insertions, 6 deletions

diff --git a/src/sync/atomic/asm_mipsx.s b/src/sync/atomic/asm_mipsx.s
new file mode 100644
index 0000000000..cf3318ff85
--- /dev/null
+++ b/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)
diff --git a/src/sync/atomic/atomic_test.go b/src/sync/atomic/atomic_test.go
index 4f44f48f51..a230d63329 100644
--- a/src/sync/atomic/atomic_test.go
+++ b/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.
-	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")
+
+	switch runtime.GOARCH {
+	default:
+		if unsafe.Sizeof(int(0)) != 4 {
+			t.Skip("test only runs on 32-bit systems")
+		}
+	case "amd64p32", "mips", "mipsle":
+		// amd64p32 and mips can handle unaligned atomics.
+		t.Skipf("test not needed on %v", runtime.GOARCH)
 	}
 
 	x := make([]uint32, 4)