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13baf4b2cd
This is a simple tweak to allow a bit more mid-stack inlining.
In cases like this:
func f() {
g()
}
We'd really like to inline f into its callers. It can't hurt.
We implement this optimization by making calls a bit cheaper, enough
to afford a single call in the function body, but not 2.
The remaining budget allows for some argument modification, or perhaps
a wrapping conditional:
func f(x int) {
g(x, 0)
}
func f(x int) {
if x > 0 {
g()
}
}
Update #19348
Change-Id: Ifb1ea0dd1db216c3fd5c453c31c3355561fe406f
Reviewed-on: https://go-review.googlesource.com/c/147361
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David Chase <drchase@google.com>
58 lines
2.0 KiB
Go
58 lines
2.0 KiB
Go
// +build !gcflags_noopt
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// errorcheck -0 -m
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package foo
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import "bytes"
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// In order to get desired results, we need a combination of
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// both escape analysis and inlining.
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func bufferNotEscape() string {
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// b itself does not escape, only its buf field will be
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// copied during String() call, but object "handle" itself
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// can be stack-allocated.
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var b bytes.Buffer
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b.WriteString("123") // ERROR "b does not escape"
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b.Write([]byte{'4'}) // ERROR "b does not escape" "\[\]byte literal does not escape"
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return b.String() // ERROR "b does not escape" "inlining call" "string\(bytes\.b\.buf\[bytes.b.off:\]\) escapes to heap"
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}
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func bufferNoEscape2(xs []string) int { // ERROR "xs does not escape"
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b := bytes.NewBuffer(make([]byte, 0, 64)) // ERROR "inlining call" "make\(\[\]byte, 0, 64\) does not escape" "&bytes.Buffer literal does not escape"
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for _, x := range xs {
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b.WriteString(x)
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}
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return b.Len() // ERROR "inlining call"
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}
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func bufferNoEscape3(xs []string) string { // ERROR "xs does not escape"
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b := bytes.NewBuffer(make([]byte, 0, 64)) // ERROR "inlining call" "make\(\[\]byte, 0, 64\) does not escape" "&bytes.Buffer literal does not escape"
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for _, x := range xs {
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b.WriteString(x)
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b.WriteByte(',')
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}
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return b.String() // ERROR "inlining call" "string\(bytes.b.buf\[bytes\.b\.off:\]\) escapes to heap"
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}
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func bufferNoEscape4() []byte {
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var b bytes.Buffer
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b.Grow(64) // ERROR "b does not escape"
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useBuffer(&b) // ERROR "&b does not escape"
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return b.Bytes() // ERROR "inlining call" "b does not escape"
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}
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func bufferNoEscape5() { // ERROR "can inline bufferNoEscape5"
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b := bytes.NewBuffer(make([]byte, 0, 128)) // ERROR "inlining call" "make\(\[\]byte, 0, 128\) does not escape" "&bytes.Buffer literal does not escape"
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useBuffer(b)
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}
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//go:noinline
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func useBuffer(b *bytes.Buffer) { // ERROR "b does not escape"
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b.WriteString("1234")
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}
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