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go/test/linkx.go
Matthew Dempsky c33d45a898 cmd/compile: don't statically copy string-typed variables
During package initialization, the compiler tries to optimize:

    var A = "foo"
    var B = A

into

    var A = "foo"
    var B = "foo"

so that we can statically initialize both A and B and skip emitting
dynamic initialization code to assign "B = A".

However, this isn't safe in the presence of cmd/link's -X flag, which
might overwrite an initialized string-typed variable at link time. In
particular, if cmd/link changes A's static initialization, it won't
know it also needs to change B's static initialization.

To address this, this CL disables this optimization for string-typed
variables.

Fixes #34675.

Change-Id: I1c18f3b855f6d7114aeb39f96aaaf1b452b88236
Reviewed-on: https://go-review.googlesource.com/c/go/+/198657
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-10-03 18:08:32 +00:00

33 lines
609 B
Go

// skip
// Copyright 2012 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.
// Test the -X facility of the gc linker (6l etc.).
// This test is run by linkx_run.go.
package main
import "fmt"
var tbd string
var overwrite string = "dibs"
var tbdcopy = tbd
var overwritecopy = overwrite
var arraycopy = [2]string{tbd, overwrite}
var b bool
var x int
func main() {
fmt.Println(tbd)
fmt.Println(tbdcopy)
fmt.Println(arraycopy[0])
fmt.Println(overwrite)
fmt.Println(overwritecopy)
fmt.Println(arraycopy[1])
}