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cmd/compile: when comparing 0-size types, make sure expr side-effects survive

Fixes #23837

Change-Id: I53f524d87946a0065f28a4ddbe47b40f2b43c459
Reviewed-on: https://go-review.googlesource.com/c/145757
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Keith Randall 2018-10-29 17:02:42 -07:00 committed by Keith Randall
parent 5168fcf63f
commit f14067f3c1
2 changed files with 78 additions and 0 deletions

View File

@ -3297,6 +3297,14 @@ func walkcompare(n *Node, init *Nodes) *Node {
}
if expr == nil {
expr = nodbool(n.Op == OEQ)
// We still need to use cmpl and cmpr, in case they contain
// an expression which might panic. See issue 23837.
t := temp(cmpl.Type)
a1 := nod(OAS, t, cmpl)
a1 = typecheck(a1, Etop)
a2 := nod(OAS, t, cmpr)
a2 = typecheck(a2, Etop)
init.Append(a1, a2)
}
n = finishcompare(n, expr, init)
return n

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@ -0,0 +1,70 @@
// run
// Copyright 2018 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
//go:noinline
func f(p, q *struct{}) bool {
return *p == *q
}
type T struct {
x struct{}
y int
}
//go:noinline
func g(p, q *T) bool {
return p.x == q.x
}
//go:noinline
func h(p, q func() struct{}) bool {
return p() == q()
}
func fi(p, q *struct{}) bool {
return *p == *q
}
func gi(p, q *T) bool {
return p.x == q.x
}
func hi(p, q func() struct{}) bool {
return p() == q()
}
func main() {
shouldPanic(func() { f(nil, nil) })
shouldPanic(func() { g(nil, nil) })
shouldPanic(func() { h(nil, nil) })
shouldPanic(func() { fi(nil, nil) })
shouldPanic(func() { gi(nil, nil) })
shouldPanic(func() { hi(nil, nil) })
n := 0
inc := func() struct{} {
n++
return struct{}{}
}
h(inc, inc)
if n != 2 {
panic("inc not called")
}
hi(inc, inc)
if n != 4 {
panic("inc not called")
}
}
func shouldPanic(x func()) {
defer func() {
if recover() == nil {
panic("did not panic")
}
}()
x()
}