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ce88e341b9
When appending, if the backing store doesn't escape and a
constant-sized backing store is big enough, use a constant-sized
stack-allocated backing store instead of allocating it from the heap.
cmd/go is <0.1% bigger.
As an example of how this helps, if you edit strings/strings.go:FieldsFunc
to replace
spans := make([]span, 0, 32)
with
var spans []span
then this CL removes the first 2 allocations that are part of the growth sequence:
│ base │ exp │
│ allocs/op │ allocs/op vs base │
FieldsFunc/ASCII/16-24 3.000 ± ∞ ¹ 2.000 ± ∞ ¹ -33.33% (p=0.008 n=5)
FieldsFunc/ASCII/256-24 7.000 ± ∞ ¹ 5.000 ± ∞ ¹ -28.57% (p=0.008 n=5)
FieldsFunc/ASCII/4096-24 11.000 ± ∞ ¹ 9.000 ± ∞ ¹ -18.18% (p=0.008 n=5)
FieldsFunc/ASCII/65536-24 18.00 ± ∞ ¹ 16.00 ± ∞ ¹ -11.11% (p=0.008 n=5)
FieldsFunc/ASCII/1048576-24 30.00 ± ∞ ¹ 28.00 ± ∞ ¹ -6.67% (p=0.008 n=5)
FieldsFunc/Mixed/16-24 2.000 ± ∞ ¹ 2.000 ± ∞ ¹ ~ (p=1.000 n=5)
FieldsFunc/Mixed/256-24 7.000 ± ∞ ¹ 5.000 ± ∞ ¹ -28.57% (p=0.008 n=5)
FieldsFunc/Mixed/4096-24 11.000 ± ∞ ¹ 9.000 ± ∞ ¹ -18.18% (p=0.008 n=5)
FieldsFunc/Mixed/65536-24 18.00 ± ∞ ¹ 16.00 ± ∞ ¹ -11.11% (p=0.008 n=5)
FieldsFunc/Mixed/1048576-24 30.00 ± ∞ ¹ 28.00 ± ∞ ¹ -6.67% (p=0.008 n=5)
(Of course, people have spotted and fixed a bunch of allocation sites
like this, but now we're ~automatically doing it everywhere going forward.)
No significant increases in frame sizes in cmd/go.
Change-Id: I301c4d9676667eacdae0058960321041d173751a
Reviewed-on: https://go-review.googlesource.com/c/go/+/664299
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org>
36 lines
1.8 KiB
Go
36 lines
1.8 KiB
Go
// errorcheckwithauto -0 -m -d=inlfuncswithclosures=1
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//go:build (386 || amd64 || arm64 || ppc64le || s390x) && !gcflags_noopt
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// Copyright 2021 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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// Similar to inline.go, but only for architectures that can merge loads.
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package foo
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import (
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"encoding/binary"
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)
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// Ensure that simple encoding/binary functions are cheap enough
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// that functions using them can also be inlined (issue 42958).
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func endian(b []byte) uint64 { // ERROR "can inline endian" "b does not escape"
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return binary.LittleEndian.Uint64(b) + binary.BigEndian.Uint64(b) // ERROR "inlining call to binary.littleEndian.Uint64" "inlining call to binary.bigEndian.Uint64"
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}
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func appendLittleEndian(b []byte) []byte { // ERROR "can inline appendLittleEndian" "leaking param: b to result ~r0 level=0"
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b = binary.LittleEndian.AppendUint64(b, 64) // ERROR "inlining call to binary.littleEndian.AppendUint64" "append escapes to heap"
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b = binary.LittleEndian.AppendUint32(b, 32) // ERROR "inlining call to binary.littleEndian.AppendUint32" "append escapes to heap"
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b = binary.LittleEndian.AppendUint16(b, 16) // ERROR "inlining call to binary.littleEndian.AppendUint16" "append escapes to heap"
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return b
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}
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func appendBigEndian(b []byte) []byte { // ERROR "can inline appendBigEndian" "leaking param: b to result ~r0 level=0"
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b = binary.BigEndian.AppendUint64(b, 64) // ERROR "inlining call to binary.bigEndian.AppendUint64" "append escapes to heap"
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b = binary.BigEndian.AppendUint32(b, 32) // ERROR "inlining call to binary.bigEndian.AppendUint32" "append escapes to heap"
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b = binary.BigEndian.AppendUint16(b, 16) // ERROR "inlining call to binary.bigEndian.AppendUint16" "append escapes to heap"
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return b
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}
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