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erifan01 42f99b203d cmd/compile: optimize cmp to cmn under conditions < and >= on arm64 
Under the right conditions we can optimize cmp comparisons to cmn
comparisons, such as:
func foo(a, b int) int {
  var c int
  if a + b < 0 {
  	c = 1
  }
  return c
}

Previously it's compiled as:
  ADD     R1, R0, R1
  CMP     $0, R1
  CSET    LT, R0
With this CL it's compiled as:
  CMN     R1, R0
  CSET    MI, R0
Here we need to pay attention to the overflow situation of a+b, the MI
flag means N==1, which doesn't honor the overflow flag V, its value
depends only on the sign of the result. So it has the same semantic of
the Go code, so it's correct.

Similarly, this CL also optimizes the case of >= comparison
using the PL conditional flag.

Change-Id: I47179faba5b30cca84ea69bafa2ad5241bf6dfba
Reviewed-on: https://go-review.googlesource.com/c/go/+/476116
Run-TryBot: Eric Fang <eric.fang@arm.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
 		2023-03-24 01:19:09 +00:00
.github .github: suggest using private browsing in pkgsite template 2023-01-03 18:52:47 +00:00
api log/slog: initial commit 2023-03-21 20:55:33 +00:00
doc runtime: for deep stacks, print both the top 50 and bottom 50 frames 2023-03-21 19:14:14 +00:00
lib/time time/tzdata: generate zip constant during cmd/dist 2023-01-17 22:30:53 +00:00
misc cmd/compile: re-compile instantiated generic methods in linkshared mode 2023-03-22 04:04:11 +00:00
src cmd/compile: optimize cmp to cmn under conditions < and >= on arm64 2023-03-24 01:19:09 +00:00
test cmd/compile: optimize cmp to cmn under conditions < and >= on arm64 2023-03-24 01:19:09 +00:00
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README.md README: update from CC-BY-3.0 to CC-BY-4.0 2022-11-02 20:14:56 +00:00
SECURITY.md SECURITY.md: replace golang.org with go.dev 2022-04-26 19:59:47 +00:00
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go.env cmd/go: introduce GOROOT/go.env and move proxy/sumdb config there 2023-01-17 23:10:39 +00:00

README.md

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

Gopher image Gopher image by Renee French, licensed under Creative Commons 4.0 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://go.dev/dl/.

After downloading a binary release, visit https://go.dev/doc/install for installation instructions.

Install From Source

If a binary distribution is not available for your combination of operating system and architecture, visit https://go.dev/doc/install/source for source installation instructions.

Contributing

Go is the work of thousands of contributors. We appreciate your help!

To contribute, please read the contribution guidelines at https://go.dev/doc/contribute.

Note that the Go project uses the issue tracker for bug reports and proposals only. See https://go.dev/wiki/Questions for a list of places to ask questions about the Go language.