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cmd/compile: avoid memmove -> SSA move rewrite when size is negative

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We should panic in this situation. Rewriting to a SSA op just leads
to a compiler panic.

Fixes #36259

Change-Id: I6e0bccbed7dd0fdac7ebae76b98a211947947386
Reviewed-on: https://go-review.googlesource.com/c/go/+/212405
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Keith Randall 2019-12-23 18:16:22 -08:00
parent e092fc352a
commit bc98e35b53
3 changed files with 33 additions and 4 deletions
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1
src/cmd/compile/internal/ssa/gen/generic.rules
View file

@ -1938,6 +1938,7 @@
// Inline small or disjoint runtime.memmove calls with constant length.
(StaticCall {sym} s1:(Store _ (Const(64|32) [sz]) s2:(Store _ src s3:(Store {t} _ dst mem))))
&& sz >= 0
&& isSameSym(sym,"runtime.memmove")
&& t.(*types.Type).IsPtr() // avoids TUINTPTR, see issue 30061
&& s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1

8
src/cmd/compile/internal/ssa/rewritegeneric.go
View file

@ -19680,7 +19680,7 @@ func rewriteValuegeneric_OpStaticCall(v *Value) bool {
b := v.Block
config := b.Func.Config
// match: (StaticCall {sym} s1:(Store _ (Const64 [sz]) s2:(Store _ src s3:(Store {t} _ dst mem))))
// cond: isSameSym(sym,"runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst,src,sz,config) && clobber(s1) && clobber(s2) && clobber(s3)
// cond: sz >= 0 && isSameSym(sym,"runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst,src,sz,config) && clobber(s1) && clobber(s2) && clobber(s3)
// result: (Move {t.(*types.Type).Elem()} [sz] dst src mem)
for {
sym := v.Aux
@ -19707,7 +19707,7 @@ func rewriteValuegeneric_OpStaticCall(v *Value) bool {
t := s3.Aux
mem := s3.Args[2]
dst := s3.Args[1]
if !(isSameSym(sym, "runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(s1) && clobber(s2) && clobber(s3)) {
if !(sz >= 0 && isSameSym(sym, "runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(s1) && clobber(s2) && clobber(s3)) {
break
}
v.reset(OpMove)
@ -19719,7 +19719,7 @@ func rewriteValuegeneric_OpStaticCall(v *Value) bool {
return true
}
// match: (StaticCall {sym} s1:(Store _ (Const32 [sz]) s2:(Store _ src s3:(Store {t} _ dst mem))))
// cond: isSameSym(sym,"runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst,src,sz,config) && clobber(s1) && clobber(s2) && clobber(s3)
// cond: sz >= 0 && isSameSym(sym,"runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst,src,sz,config) && clobber(s1) && clobber(s2) && clobber(s3)
// result: (Move {t.(*types.Type).Elem()} [sz] dst src mem)
for {
sym := v.Aux
@ -19746,7 +19746,7 @@ func rewriteValuegeneric_OpStaticCall(v *Value) bool {
t := s3.Aux
mem := s3.Args[2]
dst := s3.Args[1]
if !(isSameSym(sym, "runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(s1) && clobber(s2) && clobber(s3)) {
if !(sz >= 0 && isSameSym(sym, "runtime.memmove") && t.(*types.Type).IsPtr() && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(s1) && clobber(s2) && clobber(s3)) {
break
}
v.reset(OpMove)

28
test/fixedbugs/issue36259.go Normal file
View file

@ -0,0 +1,28 @@
// compile
// Copyright 2019 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
func rotate(s []int, m int) {
l := len(s)
m = m % l
buf := make([]int, m)
copy(buf, s)
copy(s, s[m:])
copy(s[l-m:], buf)
}
func main() {
a0 := [...]int{1,2,3,4,5}
println(a0[0])
rotate(a0[:], 1)
println(a0[0])
rotate(a0[:], -3)
println(a0[0])
}