5353cde080
When stack growth is not needed, as it usually is not,
execute only a single conditional branch
rather than three conditional instructions.
This adds 4 bytes to every function,
but might speed up execution in the common case.
Sample disassembly for
func f() {
_ = [128]byte{}
}
Before:
TEXT main.f(SB) x.go
x.go:3 0x2000 e59a1008 MOVW 0x8(R10), R1
x.go:3 0x2004 e59fb028 MOVW 0x28(R15), R11
x.go:3 0x2008 e08d200b ADD R11, R13, R2
x.go:3 0x200c e1520001 CMP R1, R2
x.go:3 0x2010 91a0300e MOVW.LS R14, R3
x.go:3 0x2014 9b0118a9 BL.LS runtime.morestack_noctxt(SB)
x.go:3 0x2018 9afffff8 B.LS main.f(SB)
x.go:3 0x201c e52de084 MOVW.W R14, -0x84(R13)
x.go:4 0x2020 e28d1004 ADD $4, R13, R1
x.go:4 0x2024 e3a00000 MOVW $0, R0
x.go:4 0x2028 eb012255 BL 0x4a984
x.go:5 0x202c e49df084 RET #132
x.go:5 0x2030 eafffffe B 0x2030
x.go:5 0x2034 ffffff7c ?
After:
TEXT main.f(SB) x.go
x.go:3 0x2000 e59a1008 MOVW 0x8(R10), R1
x.go:3 0x2004 e59fb02c MOVW 0x2c(R15), R11
x.go:3 0x2008 e08d200b ADD R11, R13, R2
x.go:3 0x200c e1520001 CMP R1, R2
x.go:3 0x2010 9a000004 B.LS 0x2028
x.go:3 0x2014 e52de084 MOVW.W R14, -0x84(R13)
x.go:4 0x2018 e28d1004 ADD $4, R13, R1
x.go:4 0x201c e3a00000 MOVW $0, R0
x.go:4 0x2020 eb0124dc BL 0x4b398
x.go:5 0x2024 e49df084 RET #132
x.go:5 0x2028 e1a0300e MOVW R14, R3
x.go:5 0x202c eb011b0d BL runtime.morestack_noctxt(SB)
x.go:5 0x2030 eafffff2 B main.f(SB)
x.go:5 0x2034 eafffffe B 0x2034
x.go:5 0x2038 ffffff7c ?
Updates #10587.
package sort benchmarks on an iPhone 6:
name old time/op new time/op delta
SortString1K 569µs ± 0% 565µs ± 1% -0.75% (p=0.000 n=23+24)
StableString1K 872µs ± 1% 870µs ± 1% -0.16% (p=0.009 n=23+24)
SortInt1K 317µs ± 2% 316µs ± 2% ~ (p=0.410 n=26+26)
StableInt1K 343µs ± 1% 339µs ± 1% -1.07% (p=0.000 n=22+23)
SortInt64K 30.0ms ± 1% 30.0ms ± 1% ~ (p=0.091 n=25+24)
StableInt64K 30.2ms ± 0% 30.0ms ± 0% -0.69% (p=0.000 n=22+22)
Sort1e2 147µs ± 1% 146µs ± 0% -0.48% (p=0.000 n=25+24)
Stable1e2 290µs ± 1% 286µs ± 1% -1.30% (p=0.000 n=23+24)
Sort1e4 29.5ms ± 2% 29.7ms ± 1% +0.71% (p=0.000 n=23+23)
Stable1e4 88.7ms ± 4% 88.6ms ± 8% -0.07% (p=0.022 n=26+26)
Sort1e6 4.81s ± 7% 4.83s ± 7% ~ (p=0.192 n=26+26)
Stable1e6 18.3s ± 1% 18.1s ± 1% -0.76% (p=0.000 n=25+23)
SearchWrappers 318ns ± 1% 344ns ± 1% +8.14% (p=0.000 n=23+26)
package sort benchmarks on a first generation rpi:
name old time/op new time/op delta
SearchWrappers 4.13µs ± 0% 3.95µs ± 0% -4.42% (p=0.000 n=15+13)
SortString1K 5.81ms ± 1% 5.82ms ± 2% ~ (p=0.400 n=14+15)
StableString1K 9.69ms ± 1% 9.73ms ± 0% ~ (p=0.121 n=15+11)
SortInt1K 3.30ms ± 2% 3.66ms ±19% +10.82% (p=0.000 n=15+14)
StableInt1K 5.97ms ±15% 4.17ms ± 8% -30.05% (p=0.000 n=15+15)
SortInt64K 319ms ± 1% 295ms ± 1% -7.65% (p=0.000 n=15+15)
StableInt64K 343ms ± 0% 332ms ± 0% -3.26% (p=0.000 n=12+13)
Sort1e2 3.36ms ± 2% 3.22ms ± 4% -4.10% (p=0.000 n=15+15)
Stable1e2 6.74ms ± 1% 6.43ms ± 2% -4.67% (p=0.000 n=15+15)
Sort1e4 247ms ± 1% 247ms ± 1% ~ (p=0.331 n=15+14)
Stable1e4 864ms ± 0% 820ms ± 0% -5.15% (p=0.000 n=14+15)
Sort1e6 41.2s ± 0% 41.2s ± 0% +0.15% (p=0.000 n=13+14)
Stable1e6 192s ± 0% 182s ± 0% -5.07% (p=0.000 n=14+14)
Change-Id: I8a9db77e1d4ea1956575895893bc9d04bd81204b
Reviewed-on: https://go-review.googlesource.com/10497
Reviewed-by: Russ Cox <rsc@golang.org>
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|---|---|---|
| api | ||
| doc | ||
| lib/time | ||
| misc | ||
| src | ||
| test | ||
| .gitattributes | ||
| .gitignore | ||
| AUTHORS | ||
| CONTRIBUTING.md | ||
| CONTRIBUTORS | ||
| LICENSE | ||
| PATENTS | ||
| README.md | ||
| favicon.ico | ||
| robots.txt | ||
README.md
The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
For documentation about how to install and use Go, visit https://golang.org/ or load doc/install-source.html in your web browser.
Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.
Please report issues here: https://golang.org/issue/new
Go is the work of hundreds of contributors. We appreciate your help!
To contribute, please read the contribution guidelines: https://golang.org/doc/contribute.html
Please note that we do not use pull requests.
Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.
--
Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set the environment variable $GOROOT to the full path of the go directory (the one containing this file). You can omit the variable if you unpack it into /usr/local/go, or if you rebuild from sources by running all.bash (see doc/install-source.html). You should also add the Go binary directory $GOROOT/bin to your shell's path.
For example, if you extracted the tar file into $HOME/go, you might put the following in your .profile:
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
See https://golang.org/doc/install or doc/install.html for more details.