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runtime: teach peephole optimizer that duffcopy clobbers X0

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Duffcopy now uses X0, as of 5cf281a.  Teach the peephole
optimizer that duffcopy clobbers X0 so that it does not
rename registers use X0 across the duffcopy instruction.

Fixes #13171

Change-Id: I389cbf1982cb6eb2f51e6152ac96736a8589f085
Reviewed-on: https://go-review.googlesource.com/16715
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
This commit is contained in:
Keith Randall 2015-11-06 00:06:52 -08:00
parent 59bac0be90
commit ffb20631fc
4 changed files with 40 additions and 1 deletions
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4
src/cmd/compile/internal/amd64/peep.go
View file

@ -823,6 +823,10 @@ func copyu(p *obj.Prog, v *obj.Addr, s *obj.Addr) int {
return 2
}
if (p.Info.Reguse|p.Info.Regset)&FtoB(int(v.Reg)) != 0 {
return 2
}
if p.Info.Flags&gc.LeftAddr != 0 {
if copyas(&p.From, v) {
return 2

2
src/cmd/compile/internal/amd64/prog.go
View file

@ -140,7 +140,7 @@ var progtable = [x86.ALAST]obj.ProgInfo{
x86.AMOVSL: {Flags: gc.OK, Reguse: DI | SI, Regset: DI | SI},
x86.AMOVSQ: {Flags: gc.OK, Reguse: DI | SI, Regset: DI | SI},
x86.AMOVSW: {Flags: gc.OK, Reguse: DI | SI, Regset: DI | SI},
obj.ADUFFCOPY: {Flags: gc.OK, Reguse: DI | SI, Regset: DI | SI | CX},
obj.ADUFFCOPY: {Flags: gc.OK, Reguse: DI | SI, Regset: DI | SI | X0},
x86.AMOVSD: {Flags: gc.SizeD | gc.LeftRead | gc.RightWrite | gc.Move},
x86.AMOVSS: {Flags: gc.SizeF | gc.LeftRead | gc.RightWrite | gc.Move},

1
src/cmd/compile/internal/amd64/reg.go
View file

@ -107,6 +107,7 @@ const (
DI = 1 << (x86.REG_DI - x86.REG_AX)
SI = 1 << (x86.REG_SI - x86.REG_AX)
R15 = 1 << (x86.REG_R15 - x86.REG_AX)
X0 = 1 << 16
)
func RtoB(r int) uint64 {

34
test/fixedbugs/issue13171.go Normal file
View file

@ -0,0 +1,34 @@
// run
// Copyright 2015 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.
package main
// Make sure the compiler knows that DUFFCOPY clobbers X0
import "fmt"
//go:noinline
func f(x float64) float64 {
// y is allocated to X0
y := x + 5
// marshals z before y. Marshalling z
// calls DUFFCOPY.
return g(z, y)
}
//go:noinline
func g(b [64]byte, y float64) float64 {
return y
}
var z [64]byte
func main() {
got := f(5)
if got != 10 {
panic(fmt.Sprintf("want 10, got %f", got))
}
}