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go/test/live2.go
Michael Munday 744ebfde04 cmd/compile: eliminate stores to unread auto variables
This is a crude compiler pass to eliminate stores to auto variables
that are only ever written to.

Eliminates an unnecessary store to x from the following code:

func f() int {
	var x := 1
	return *(&x)
}

Fixes #19765.

Change-Id: If2c63a8ae67b8c590b6e0cc98a9610939a3eeffa
Reviewed-on: https://go-review.googlesource.com/38746
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-08-24 16:53:56 +00:00

43 lines
1.1 KiB
Go

// errorcheck -0 -live -wb=0
// Copyright 2014 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.
// liveness tests with inlining ENABLED
// see also live.go.
package main
// issue 8142: lost 'addrtaken' bit on inlined variables.
// no inlining in this test, so just checking that non-inlined works.
func printnl()
//go:noescape
func useT40(*T40)
type T40 struct {
m map[int]int
}
func newT40() *T40 {
ret := T40{}
ret.m = make(map[int]int) // ERROR "live at call to makemap: &ret$"
return &ret
}
func bad40() {
t := newT40() // ERROR "live at call to makemap: .autotmp_[0-9]+ ret$"
printnl() // ERROR "live at call to printnl: .autotmp_[0-9]+ ret$"
useT40(t) // ERROR "live at call to useT40: .autotmp_[0-9]+ ret$"
}
func good40() {
ret := T40{}
ret.m = make(map[int]int) // ERROR "live at call to makemap: .autotmp_[0-9]+ ret$"
t := &ret
printnl() // ERROR "live at call to printnl: .autotmp_[0-9]+ ret$"
useT40(t) // ERROR "live at call to useT40: .autotmp_[0-9]+ ret$"
}