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cmd/compile: fix conditional select rule

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ARM64 maintains booleans in the low byte of registers. Upper parts
of that register are junk.
This rule is using all 32 bits of a boolean-containing register, which
is wrong. Change the rule to only look at the low bit.

Fixes #57184

Change-Id: Ibbef86b2be859df3d06d993db00e1231c481c428
Reviewed-on: https://go-review.googlesource.com/c/go/+/456556
Auto-Submit: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
This commit is contained in:
Keith Randall 2022-12-09 10:55:28 -08:00 committed by Gopher Robot
parent e76c87b191
commit e8f78cb60c
3 changed files with 45 additions and 5 deletions
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4
src/cmd/compile/internal/ssa/_gen/ARM64.rules
View File

@ -342,9 +342,9 @@
(FCMPD x (FMOVDconst [0])) => (FCMPD0 x)
(FCMPD (FMOVDconst [0]) x) => (InvertFlags (FCMPD0 x))
// CSEL needs a flag-generating argument. Synthesize a CMPW if necessary.
// CSEL needs a flag-generating argument. Synthesize a TSTW if necessary.
(CondSelect x y boolval) && flagArg(boolval) != nil => (CSEL [boolval.Op] x y flagArg(boolval))
(CondSelect x y boolval) && flagArg(boolval) == nil => (CSEL [OpARM64NotEqual] x y (CMPWconst [0] boolval))
(CondSelect x y boolval) && flagArg(boolval) == nil => (CSEL [OpARM64NotEqual] x y (TSTWconst [1] boolval))
(OffPtr [off] ptr:(SP)) && is32Bit(off) => (MOVDaddr [int32(off)] ptr)
(OffPtr [off] ptr) => (ADDconst [off] ptr)

6
src/cmd/compile/internal/ssa/rewriteARM64.go
View File

@ -23561,7 +23561,7 @@ func rewriteValueARM64_OpCondSelect(v *Value) bool {
}
// match: (CondSelect x y boolval)
// cond: flagArg(boolval) == nil
// result: (CSEL [OpARM64NotEqual] x y (CMPWconst [0] boolval))
// result: (CSEL [OpARM64NotEqual] x y (TSTWconst [1] boolval))
for {
x := v_0
y := v_1
@ -23571,8 +23571,8 @@ func rewriteValueARM64_OpCondSelect(v *Value) bool {
}
v.reset(OpARM64CSEL)
v.AuxInt = opToAuxInt(OpARM64NotEqual)
v0 := b.NewValue0(v.Pos, OpARM64CMPWconst, types.TypeFlags)
v0.AuxInt = int32ToAuxInt(0)
v0 := b.NewValue0(v.Pos, OpARM64TSTWconst, types.TypeFlags)
v0.AuxInt = int32ToAuxInt(1)
v0.AddArg(boolval)
v.AddArg3(x, y, v0)
return true

40
test/fixedbugs/issue57184.go Normal file
View File

@ -0,0 +1,40 @@
// run
// Copyright 2022 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
import (
"log"
"reflect"
"sort"
)
func main() {
const length = 257
x := make([]int64, length)
for i := 0; i < length; i++ {
x[i] = int64(i) * 27644437 % int64(length)
}
isLessStatic := func(i, j int) bool {
return x[i] < x[j]
}
isLessReflect := reflect.MakeFunc(reflect.TypeOf(isLessStatic), func(args []reflect.Value) []reflect.Value {
i := args[0].Int()
j := args[1].Int()
b := x[i] < x[j]
return []reflect.Value{reflect.ValueOf(b)}
}).Interface().(func(i, j int) bool)
sort.SliceStable(x, isLessReflect)
for i := 0; i < length-1; i++ {
if x[i] >= x[i+1] {
log.Fatalf("not sorted! (length=%v, idx=%v)\n%v\n", length, i, x)
}
}
}