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cmd/compile: add an optimization rule for math/bits.ReverseBytes16 on arm

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This CL adds two rules to turn patterns like ((x<<8) | (x>>8)) (the type of
x is uint16, "|" can also be "+" or "^") to a REV16 instruction on arm v6+.
This optimization rule can be used for math/bits.ReverseBytes16.

Benchmarks on arm v6:
name               old time/op  new time/op  delta
ReverseBytes-32    2.86ns ± 0%  2.86ns ± 0%   ~     (all equal)
ReverseBytes16-32  2.86ns ± 0%  2.86ns ± 0%   ~     (all equal)
ReverseBytes32-32  1.29ns ± 0%  1.29ns ± 0%   ~     (all equal)
ReverseBytes64-32  1.43ns ± 0%  1.43ns ± 0%   ~     (all equal)

Change-Id: I819e633c9a9d308f8e476fb0c82d73fb73dd019f
Reviewed-on: https://go-review.googlesource.com/c/go/+/159019
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
erifan01 2019-02-11 09:40:02 +00:00 • committed by Cherry Zhang
parent a2ace8ec18
commit fee84cc905
9 changed files with 445 additions and 210 deletions
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1
src/cmd/compile/internal/arm/ssa.go
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@ -659,6 +659,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
case ssa.OpARMMVN,
ssa.OpARMCLZ,
ssa.OpARMREV,
ssa.OpARMREV16,
ssa.OpARMRBIT,
ssa.OpARMSQRTD,
ssa.OpARMNEGF,