cmd/compile: mark some AMD64 atomic ops as clobberFlags

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>

diff --git a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
index d8659a51b03d718d05853b6931b07d506f74d98c..53aa1dffe7099ea9878848e71543f6cd011742f4 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
@@ -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{

diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 7e332025b3f63df142dd3198c93d1f3ecd800346..229009fa5fce9bc6ae58a1c35933a2bf6f4dbf09 100644 (file)
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -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{
@@ -6910,10 +6912,11 @@ var opcodeTable = [...]opInfo{
                reg:    regInfo{},
        },
        {
-               name:    "CMPXCHGLlock",
-               auxType: auxSymOff,
-               argLen:  4,
-               asm:     x86.ACMPXCHGL,
+               name:         "CMPXCHGLlock",
+               auxType:      auxSymOff,
+               argLen:       4,
+               clobberFlags: true,
+               asm:          x86.ACMPXCHGL,
                reg: regInfo{
                        inputs: []inputInfo{
                                {1, 1},     // AX
@@ -6928,10 +6931,11 @@ var opcodeTable = [...]opInfo{
                },
        },
        {
-               name:    "CMPXCHGQlock",
-               auxType: auxSymOff,
-               argLen:  4,
-               asm:     x86.ACMPXCHGQ,
+               name:         "CMPXCHGQlock",
+               auxType:      auxSymOff,
+               argLen:       4,
+               clobberFlags: true,
+               asm:          x86.ACMPXCHGQ,
                reg: regInfo{
                        inputs: []inputInfo{
                                {1, 1},     // AX
@@ -6946,10 +6950,11 @@ var opcodeTable = [...]opInfo{
                },
        },
        {
-               name:    "ANDBlock",
-               auxType: auxSymOff,
-               argLen:  3,
-               asm:     x86.AANDB,
+               name:         "ANDBlock",
+               auxType:      auxSymOff,
+               argLen:       3,
+               clobberFlags: true,
+               asm:          x86.AANDB,
                reg: regInfo{
                        inputs: []inputInfo{
                                {1, 65535},      // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
@@ -6958,10 +6963,11 @@ var opcodeTable = [...]opInfo{
                },
        },
        {
-               name:    "ORBlock",
-               auxType: auxSymOff,
-               argLen:  3,
-               asm:     x86.AORB,
+               name:         "ORBlock",
+               auxType:      auxSymOff,
+               argLen:       3,
+               clobberFlags: true,
+               asm:          x86.AORB,
                reg: regInfo{
                        inputs: []inputInfo{
                                {1, 65535},      // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15

diff --git a/test/fixedbugs/issue16985.go b/test/fixedbugs/issue16985.go
new file mode 100644 (file)
index 0000000..0cb0dae
--- /dev/null
+++ b/test/fixedbugs/issue16985.go
@@ -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++
+       }
+}