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go/src/runtime/noasm.go
Dave Cheney ee349b5d77 runtime: add arm64 runtime.cmpstring and bytes.Compare
Add arm64 assembly implementation of runtime.cmpstring and bytes.Compare.

benchmark                                old ns/op     new ns/op     delta
BenchmarkCompareBytesEqual               98.0          27.5          -71.94%
BenchmarkCompareBytesToNil               9.38          10.0          +6.61%
BenchmarkCompareBytesEmpty               13.3          10.0          -24.81%
BenchmarkCompareBytesIdentical           98.0          27.5          -71.94%
BenchmarkCompareBytesSameLength          43.3          16.3          -62.36%
BenchmarkCompareBytesDifferentLength     43.4          16.3          -62.44%
BenchmarkCompareBytesBigUnaligned        6979680       1360979       -80.50%
BenchmarkCompareBytesBig                 6915995       1381979       -80.02%
BenchmarkCompareBytesBigIdentical        6781440       1327304       -80.43%

benchmark                             old MB/s     new MB/s     speedup
BenchmarkCompareBytesBigUnaligned     150.23       770.46       5.13x
BenchmarkCompareBytesBig              151.62       758.76       5.00x
BenchmarkCompareBytesBigIdentical     154.63       790.01       5.11x

* note, the machine we are benchmarking on has some issues. What is clear is
compared to a few days ago the old MB/s value has increased from ~115 to 150.
I'm less certain about the new MB/s number, which used to be close to 1Gb/s.

Change-Id: I4f31b2c7a06296e13912aacc958525632cb0450d
Reviewed-on: https://go-review.googlesource.com/8541
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-04-09 14:49:31 +00:00

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950 B
Go

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Routines that are implemented in assembly in asm_{amd64,386,arm,arm64}.s
// +build ppc64 ppc64le
package runtime
import _ "unsafe" // for go:linkname
func cmpstring(s1, s2 string) int {
l := len(s1)
if len(s2) < l {
l = len(s2)
}
for i := 0; i < l; i++ {
c1, c2 := s1[i], s2[i]
if c1 < c2 {
return -1
}
if c1 > c2 {
return +1
}
}
if len(s1) < len(s2) {
return -1
}
if len(s1) > len(s2) {
return +1
}
return 0
}
//go:linkname bytes_Compare bytes.Compare
func bytes_Compare(s1, s2 []byte) int {
l := len(s1)
if len(s2) < l {
l = len(s2)
}
for i := 0; i < l; i++ {
c1, c2 := s1[i], s2[i]
if c1 < c2 {
return -1
}
if c1 > c2 {
return +1
}
}
if len(s1) < len(s2) {
return -1
}
if len(s1) > len(s2) {
return +1
}
return 0
}