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