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go/test/fixedbugs/issue15747.go
David Chase 9c066bab64 cmd/compile: mark temps with new AutoTemp flag, and use it.
This is an extension of
https://go-review.googlesource.com/c/31662/
to mark all the temporaries, not just the ssa-generated ones.

Before-and-after ls -l `go tool -n compile` shows a 3%
reduction in size (or rather, a prior 3% inflation for
failing to filter temps out properly.)

Replaced name-dependent "is it a temp?" tests with calls to
*Node.IsAutoTmp(), which depends on AutoTemp.  Also replace
calls to istemp(n) with n.IsAutoTmp(), to reduce duplication
and clean up function name space.  Generated temporaries
now come with a "." prefix to avoid (apparently harmless)
clashes with legal Go variable names.

Fixes #17644.
Fixes #17240.

Change-Id: If1417f29c79a7275d7303ddf859b51472890fd43
Reviewed-on: https://go-review.googlesource.com/32255
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2016-10-31 19:38:50 +00:00

43 lines
1.2 KiB
Go

// errorcheck -0 -live
// Copyright 2016 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.
// Issue 15747: liveness analysis was marking heap-escaped params live too much,
// and worse was using the wrong bitmap bits to do so.
package p
var global *[]byte
type Q struct{}
type T struct{ M string }
var b bool
func f1(q *Q, xx []byte) interface{} { // ERROR "live at call to newobject: xx$" "live at call to writebarrierptr: &xx$" "live at entry to f1: xx$"
// xx was copied from the stack to the heap on the previous line:
// xx was live for the first two prints but then it switched to &xx
// being live. We should not see plain xx again.
if b {
global = &xx // ERROR "live at call to writebarrierptr: &xx$"
}
xx, _, err := f2(xx, 5) // ERROR "live at call to f2: &xx$" "live at call to writebarrierptr: err.data err.type$"
if err != nil {
return err
}
return nil
}
//go:noinline
func f2(d []byte, n int) (odata, res []byte, e interface{}) { // ERROR "live at entry to f2: d$"
if n > len(d) {
return d, nil, &T{M: "hello"} // ERROR "live at call to newobject: d" "live at call to writebarrierptr: d"
}
res = d[:n]
odata = d[n:]
return
}