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cmd/asm: process forward jump to PCALIGN

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The forward jump target are not processed when the target is PCALIGN, so
process it before emit nops for PCALIGN.

Fixes #74648

Change-Id: I690fbfacf79e26d7a37628a2551729b2381616c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/696915
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
ZhouGuangyuan 2025-08-18 19:27:46 +08:00 • committed by Cherry Mui
parent 13c082601d
commit 1ad30844d9
4 changed files with 45 additions and 13 deletions
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25
src/cmd/internal/obj/x86/asm6.go
View file

@ -2120,19 +2120,6 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
c0 := c
c = pjc.padJump(ctxt, s, p, c)
if p.As == obj.APCALIGN || p.As == obj.APCALIGNMAX {
v := obj.AlignmentPadding(c, p, ctxt, s)
if v > 0 {
s.Grow(int64(c) + int64(v))
fillnop(s.P[c:], int(v))
}
p.Pc = int64(c)
c += int32(v)
pPrev = p
continue
}
if maxLoopPad > 0 && p.Back&branchLoopHead != 0 && c&(loopAlign-1) != 0 {
// pad with NOPs
v := -c & (loopAlign - 1)
@ -2165,6 +2152,18 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
}
}
if p.As == obj.APCALIGN || p.As == obj.APCALIGNMAX {
v := obj.AlignmentPadding(c, p, ctxt, s)
if v > 0 {
s.Grow(int64(c) + int64(v))
fillnop(s.P[c:], int(v))
}
p.Pc = int64(c)
c += int32(v)
pPrev = p
continue
}
p.Rel = nil
p.Pc = int64(c)

11
test/fixedbugs/issue74648.dir/a.s Normal file
View file

@ -0,0 +1,11 @@
// 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.
TEXT ·F(SB), $0
JMP prealigned
INT $3 // should never be reached
prealigned:
PCALIGN $0x10
aligned:
RET

13
test/fixedbugs/issue74648.dir/x.go Normal file
View file

@ -0,0 +1,13 @@
// 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.
// Issue 74648: wrong jump target when using PCALIGN.
package main
func F()
func main() {
F()
}

9
test/fixedbugs/issue74648.go Normal file
View file

@ -0,0 +1,9 @@
// runindir
//go:build amd64
// 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 ignored