d9a50a6531
On amd64, Ctz must include special handling of zeros. But the prove pass has enough information to detect whether the input is non-zero, allowing a more efficient lowering. Introduce new CtzNonZero ops to capture and use this information. Benchmark code: func BenchmarkVisitBits(b *testing.B) { b.Run("8", func(b *testing.B) { for i := 0; i < b.N; i++ { x := uint8(0xff) for x != 0 { sink = bits.TrailingZeros8(x) x &= x - 1 } } }) // and similarly so for 16, 32, 64 } name old time/op new time/op delta VisitBits/8-8 7.27ns ± 4% 5.58ns ± 4% -23.35% (p=0.000 n=28+26) VisitBits/16-8 14.7ns ± 7% 10.5ns ± 4% -28.43% (p=0.000 n=30+28) VisitBits/32-8 27.6ns ± 8% 19.3ns ± 3% -30.14% (p=0.000 n=30+26) VisitBits/64-8 44.0ns ±11% 38.0ns ± 5% -13.48% (p=0.000 n=30+30) Fixes #25077 Change-Id: Ie6e5bd86baf39ee8a4ca7cadcf56d934e047f957 Reviewed-on: https://go-review.googlesource.com/109358 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org> |
||
---|---|---|
.github | ||
api | ||
doc | ||
lib/time | ||
misc | ||
src | ||
test | ||
.gitattributes | ||
.gitignore | ||
AUTHORS | ||
CONTRIBUTING.md | ||
CONTRIBUTORS | ||
favicon.ico | ||
LICENSE | ||
PATENTS | ||
README.md | ||
robots.txt |
The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
Gopher image by Renee French, licensed under Creative Commons 3.0 Attributions license.
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.
Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.
Download and Install
Binary Distributions
Official binary distributions are available at https://golang.org/dl/.
After downloading a binary release, visit https://golang.org/doc/install or load doc/install.html in your web browser for installation instructions.
Install From Source
If a binary distribution is not available for your combination of operating system and architecture, visit https://golang.org/doc/install/source or load doc/install-source.html in your web browser for source installation instructions.
Contributing
Go is the work of thousands of contributors. We appreciate your help!
To contribute, please read the contribution guidelines: https://golang.org/doc/contribute.html
Note that the Go project uses the issue tracker for bug reports and proposals only. See https://golang.org/wiki/Questions for a list of places to ask questions about the Go language.