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cmd/compile: don't pull constant offsets out of pointer arithmetic

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This could lead to manufacturing a pointer that points outside
its original allocation.

Bug was introduced in CL 629858.

Fixes #71932

Change-Id: Ia86ab0b65ce5f80a8e0f4f4c81babd07c5904f8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/652078
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Keith Randall 2025-02-24 13:07:29 -08:00
parent 4c75671871
commit 8b8bff7bb2
3 changed files with 120 additions and 52 deletions
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10
src/cmd/compile/internal/ssa/_gen/ARM64.rules
View File

@ -1149,10 +1149,12 @@
(SUB a l:(MNEGW x y)) && v.Type.Size() <= 4 && l.Uses==1 && clobber(l) => (MADDW a x y)
// madd/msub can't take constant arguments, so do a bit of reordering if a non-constant is available.
(ADD a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (ADDconst [c] (ADD <v.Type> a m))
(ADD a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (SUBconst [c] (ADD <v.Type> a m))
(SUB a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (SUBconst [c] (SUB <v.Type> a m))
(SUB a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (ADDconst [c] (SUB <v.Type> a m))
// Note: don't reorder arithmetic concerning pointers, as we must ensure that
// no intermediate computations are invalid pointers.
(ADD <t> a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (ADDconst [c] (ADD <v.Type> a m))
(ADD <t> a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (SUBconst [c] (ADD <v.Type> a m))
(SUB <t> a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (SUBconst [c] (SUB <v.Type> a m))
(SUB <t> a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (ADDconst [c] (SUB <v.Type> a m))
// optimize ADCSflags, SBCSflags and friends
(ADCSflags x y (Select1 <types.TypeFlags> (ADDSconstflags [-1] (ADCzerocarry <typ.UInt64> c)))) => (ADCSflags x y c)

112
src/cmd/compile/internal/ssa/rewriteARM64.go
View File

@ -1335,10 +1335,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1347,7 +1348,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1359,10 +1360,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1371,7 +1373,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1383,10 +1385,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1395,7 +1398,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1407,10 +1410,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1419,7 +1423,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1431,10 +1435,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1443,7 +1448,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -1455,10 +1460,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1467,7 +1473,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -1479,10 +1485,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1491,7 +1498,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -1503,10 +1510,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1515,7 +1523,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -16647,10 +16655,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg3(a, x, y)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16658,7 +16667,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16668,10 +16677,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16679,7 +16689,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16689,10 +16699,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16700,7 +16711,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16710,10 +16721,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16721,7 +16733,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16731,10 +16743,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16742,7 +16755,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)
@ -16752,10 +16765,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16763,7 +16777,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)
@ -16773,10 +16787,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16784,7 +16799,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)
@ -16794,10 +16809,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16805,7 +16821,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)

50
test/fixedbugs/issue71932.go Normal file
View File

@ -0,0 +1,50 @@
// run
// Copyright 2025 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 "runtime"
const C = 16
type T [C * C]byte
func main() {
var ts []*T
for i := 0; i < 100; i++ {
t := new(T)
// Save every even object.
if i%2 == 0 {
ts = append(ts, t)
}
}
// Make sure the odd objects are collected.
runtime.GC()
for _, t := range ts {
f(t, C, C)
}
}
//go:noinline
func f(t *T, i, j uint) {
if i == 0 || i > C || j == 0 || j > C {
return // gets rid of bounds check below (via prove pass)
}
p := &t[i*j-1]
*p = 0
runtime.GC()
*p = 0
// This goes badly if compiled to
// q := &t[i*j]
// *(q-1) = 0
// runtime.GC()
// *(q-1) = 0
// as at the GC call, q is an invalid pointer
// (it points past the end of t's allocation).
}