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cmd/compile: mark some AMD64 atomic ops as clobberFlags

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Fixes #16985.

Change-Id: I5954db28f7b70dd3ac7768e471d5df871a5b20f9
Reviewed-on: https://go-review.googlesource.com/28510
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Cherry Zhang 2016-09-04 23:51:22 -04:00
parent 6db13e071b
commit f1ef5a06d2
3 changed files with 65 additions and 22 deletions
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12
src/cmd/compile/internal/ssa/gen/AMD64Ops.go
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@ -526,8 +526,8 @@ func init() {
// *(arg1+auxint+aux) += arg0. arg2=mem.
// Returns a tuple of <old contents of *(arg1+auxint+aux), memory>.
// Note: arg0 and arg1 are backwards compared to MOVLstore (to facilitate resultInArg0)!
{name: "XADDLlock", argLength: 3, reg: gpstorexchg, asm: "XADDL", typ: "(UInt32,Mem)", aux: "SymOff", resultInArg0: true},
{name: "XADDQlock", argLength: 3, reg: gpstorexchg, asm: "XADDQ", typ: "(UInt64,Mem)", aux: "SymOff", resultInArg0: true},
{name: "XADDLlock", argLength: 3, reg: gpstorexchg, asm: "XADDL", typ: "(UInt32,Mem)", aux: "SymOff", resultInArg0: true, clobberFlags: true},
{name: "XADDQlock", argLength: 3, reg: gpstorexchg, asm: "XADDQ", typ: "(UInt64,Mem)", aux: "SymOff", resultInArg0: true, clobberFlags: true},
{name: "AddTupleFirst32", argLength: 2}, // arg0=tuple <x,y>. Returns <x+arg1,y>.
{name: "AddTupleFirst64", argLength: 2}, // arg0=tuple <x,y>. Returns <x+arg1,y>.
@ -550,12 +550,12 @@ func init() {
// JEQ ...
// but we can't do that because memory-using ops can't generate flags yet
// (flagalloc wants to move flag-generating instructions around).
{name: "CMPXCHGLlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGL", aux: "SymOff"},
{name: "CMPXCHGQlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGQ", aux: "SymOff"},
{name: "CMPXCHGLlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGL", aux: "SymOff", clobberFlags: true},
{name: "CMPXCHGQlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGQ", aux: "SymOff", clobberFlags: true},
// Atomic memory updates.
{name: "ANDBlock", argLength: 3, reg: gpstore, asm: "ANDB", aux: "SymOff"}, // *(arg0+auxint+aux) &= arg1
{name: "ORBlock", argLength: 3, reg: gpstore, asm: "ORB", aux: "SymOff"}, // *(arg0+auxint+aux) |= arg1
{name: "ANDBlock", argLength: 3, reg: gpstore, asm: "ANDB", aux: "SymOff", clobberFlags: true}, // *(arg0+auxint+aux) &= arg1
{name: "ORBlock", argLength: 3, reg: gpstore, asm: "ORB", aux: "SymOff", clobberFlags: true}, // *(arg0+auxint+aux) |= arg1
}
var AMD64blocks = []blockData{

6
src/cmd/compile/internal/ssa/opGen.go
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@ -6872,6 +6872,7 @@ var opcodeTable = [...]opInfo{
auxType: auxSymOff,
argLen: 3,
resultInArg0: true,
clobberFlags: true,
asm: x86.AXADDL,
reg: regInfo{
inputs: []inputInfo{
@ -6888,6 +6889,7 @@ var opcodeTable = [...]opInfo{
auxType: auxSymOff,
argLen: 3,
resultInArg0: true,
clobberFlags: true,
asm: x86.AXADDQ,
reg: regInfo{
inputs: []inputInfo{
@ -6913,6 +6915,7 @@ var opcodeTable = [...]opInfo{
name: "CMPXCHGLlock",
auxType: auxSymOff,
argLen: 4,
clobberFlags: true,
asm: x86.ACMPXCHGL,
reg: regInfo{
inputs: []inputInfo{
@ -6931,6 +6934,7 @@ var opcodeTable = [...]opInfo{
name: "CMPXCHGQlock",
auxType: auxSymOff,
argLen: 4,
clobberFlags: true,
asm: x86.ACMPXCHGQ,
reg: regInfo{
inputs: []inputInfo{
@ -6949,6 +6953,7 @@ var opcodeTable = [...]opInfo{
name: "ANDBlock",
auxType: auxSymOff,
argLen: 3,
clobberFlags: true,
asm: x86.AANDB,
reg: regInfo{
inputs: []inputInfo{
@ -6961,6 +6966,7 @@ var opcodeTable = [...]opInfo{
name: "ORBlock",
auxType: auxSymOff,
argLen: 3,
clobberFlags: true,
asm: x86.AORB,
reg: regInfo{
inputs: []inputInfo{

37
test/fixedbugs/issue16985.go Normal file
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@ -0,0 +1,37 @@
// run
// 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.
// issue 16985: intrinsified AMD64 atomic ops should clobber flags
package main
import "sync/atomic"
var count uint32
func main() {
buffer := []byte("T")
for i := 0; i < len(buffer); {
atomic.AddUint32(&count, 1)
_ = buffer[i]
i++
i++
}
for i := 0; i < len(buffer); {
atomic.CompareAndSwapUint32(&count, 0, 1)
_ = buffer[i]
i++
i++
}
for i := 0; i < len(buffer); {
atomic.SwapUint32(&count, 1)
_ = buffer[i]
i++
i++
}
}