atomicbitops package cleanups

- Redocument memory ordering from "no ordering" to "acquire-release". (No
  functional change: both LOCK WHATEVER on x86, and LDAXR/STLXR loops on ARM64,
  already have this property.)

- Remove IncUnlessZeroInt32 and DecUnlessOneInt32, which were only faster than
  the equivalent loops using sync/atomic before the Go compiler inlined
  non-unsafe.Pointer atomics many releases ago.

PiperOrigin-RevId: 295811743

1 files changed, 77 insertions, 0 deletions

diff --git a/pkg/atomicbitops/atomicbitops_amd64.s b/pkg/atomicbitops/atomicbitops_amd64.s
new file mode 100644
index 000000000..54c887ee5
--- /dev/null
+++ b/pkg/atomicbitops/atomicbitops_amd64.s
@@ -0,0 +1,77 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build amd64
+
+#include "textflag.h"
+
+TEXT ·AndUint32(SB),$0-12
+  MOVQ  addr+0(FP), BP
+  MOVL  val+8(FP), AX
+  LOCK
+  ANDL   AX, 0(BP)
+  RET
+
+TEXT ·OrUint32(SB),$0-12
+  MOVQ  addr+0(FP), BP
+  MOVL  val+8(FP), AX
+  LOCK
+  ORL   AX, 0(BP)
+  RET
+
+TEXT ·XorUint32(SB),$0-12
+  MOVQ  addr+0(FP), BP
+  MOVL  val+8(FP), AX
+  LOCK
+  XORL   AX, 0(BP)
+  RET
+
+TEXT ·CompareAndSwapUint32(SB),$0-20
+  MOVQ  addr+0(FP), DI
+  MOVL  old+8(FP), AX
+  MOVL  new+12(FP), DX
+  LOCK
+  CMPXCHGL DX, 0(DI)
+  MOVL  AX, ret+16(FP)
+  RET
+
+TEXT ·AndUint64(SB),$0-16
+  MOVQ  addr+0(FP), BP
+  MOVQ  val+8(FP), AX
+  LOCK
+  ANDQ   AX, 0(BP)
+  RET
+
+TEXT ·OrUint64(SB),$0-16
+  MOVQ  addr+0(FP), BP
+  MOVQ  val+8(FP), AX
+  LOCK
+  ORQ   AX, 0(BP)
+  RET
+
+TEXT ·XorUint64(SB),$0-16
+  MOVQ  addr+0(FP), BP
+  MOVQ  val+8(FP), AX
+  LOCK
+  XORQ   AX, 0(BP)
+  RET
+
+TEXT ·CompareAndSwapUint64(SB),$0-32
+  MOVQ  addr+0(FP), DI
+  MOVQ  old+8(FP), AX
+  MOVQ  new+16(FP), DX
+  LOCK
+  CMPXCHGQ DX, 0(DI)
+  MOVQ  AX, ret+24(FP)
+  RET