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cmd/compile: optimize ARM's math.bits.RotateLeft32

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This CL optimizes math.bits.RotateLeft32 to inline
"MOVW Rx@>Ry, Rd" on ARM.

The benchmark results of math/bits show some improvements.
name               old time/op  new time/op  delta
RotateLeft-4       9.42ns ± 0%  6.91ns ± 0%  -26.66%  (p=0.000 n=40+33)
RotateLeft8-4      8.79ns ± 0%  8.79ns ± 0%   -0.04%  (p=0.000 n=40+31)
RotateLeft16-4     8.79ns ± 0%  8.79ns ± 0%   -0.04%  (p=0.000 n=40+32)
RotateLeft32-4     8.16ns ± 0%  7.54ns ± 0%   -7.68%  (p=0.000 n=40+40)
RotateLeft64-4     15.7ns ± 0%  15.7ns ± 0%     ~     (all equal)

updates #31265

Change-Id: I77bc1c2c702d5323fc7cad5264a8e2d5666bf712
Reviewed-on: https://go-review.googlesource.com/c/go/+/188697
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Ben Shi 2019-08-02 02:20:38 +00:00 • committed by Brad Fitzpatrick
parent c683ab8128
commit 3cfd003a8a
7 changed files with 36 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

2
test/codegen/mathbits.go
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@ -208,6 +208,7 @@ func RotateLeft64(n uint64) uint64 {
func RotateLeft32(n uint32) uint32 {
// amd64:"ROLL" 386:"ROLL"
// arm:`MOVW\tR[0-9]+@>[$]23`
// arm64:"RORW"
// ppc64:"ROTLW"
// ppc64le:"ROTLW"
@ -244,6 +245,7 @@ func RotateLeftVariable64(n uint64, m int) uint64 {
}
func RotateLeftVariable32(n uint32, m int) uint32 {
// arm:`MOVW\tR[0-9]+@>R[0-9]+`
// amd64:"ROLL"
// arm64:"RORW"
// ppc64:"ROTLW"