1
0
mirror of https://github.com/golang/go synced 2024-11-05 12:06:15 -07:00
go/test/fixedbugs/issue8606b.go
Keith Randall 42fd1306ce cmd/compile: clean up equality generation
We're using sort.SliceStable, so no need to keep track of indexes as well.

Use a more robust test for whether a node is a call.

Add a test that we're actually reordering comparisons. This test fails
without the alg.go changes in this CL because eqstring uses OCALLFUNC
instead of OCALL for its data comparisons.

Update #8606

Change-Id: Ieeec33434c72e3aa328deb11cc415cfda05632e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/237921
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-08-27 23:25:58 +00:00

64 lines
1.6 KiB
Go

// run
// Copyright 2020 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.
// This is an optimization check. We want to make sure that we compare
// string lengths, and other scalar fields, before checking string
// contents. There's no way to verify this in the language, and
// codegen tests in test/codegen can't really detect ordering
// optimizations like this. Instead, we generate invalid strings with
// bad backing store pointers but nonzero length, so we can check that
// the backing store never gets compared.
//
// We use two different bad strings so that pointer comparisons of
// backing store pointers fail.
package main
import (
"fmt"
"reflect"
"unsafe"
)
func bad1() string {
s := "foo"
(*reflect.StringHeader)(unsafe.Pointer(&s)).Data = 1 // write bad value to data ptr
return s
}
func bad2() string {
s := "foo"
(*reflect.StringHeader)(unsafe.Pointer(&s)).Data = 2 // write bad value to data ptr
return s
}
type SI struct {
s string
i int
}
type SS struct {
s string
t string
}
func main() {
for _, test := range []struct {
a, b interface{}
}{
{SI{s: bad1(), i: 1}, SI{s: bad2(), i: 2}},
{SS{s: bad1(), t: "a"}, SS{s: bad2(), t: "aa"}},
{SS{s: "a", t: bad1()}, SS{s: "b", t: bad2()}},
// This one would panic because the length of both strings match, and we check
// the body of the bad strings before the body of the good strings.
//{SS{s: bad1(), t: "a"}, SS{s: bad2(), t: "b"}},
} {
if test.a == test.b {
panic(fmt.Sprintf("values %#v and %#v should not be equal", test.a, test.b))
}
}
}