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cmd/compile: improve atomic add intrinsics with ARMv8.1 new instruction

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ARMv8.1 has added new instruction (LDADDAL) for atomic memory operations. This
CL improves existing atomic add intrinsics with the new instruction. Since the
new instruction is only guaranteed to be present after ARMv8.1, we guard its
usage with a conditional on CPU feature.

Performance result on ARMv8.1 machine:
name        old time/op  new time/op  delta
Xadd-224    1.05µs ± 6%  0.02µs ± 4%  -98.06%  (p=0.000 n=10+8)
Xadd64-224  1.05µs ± 3%  0.02µs ±13%  -98.10%  (p=0.000 n=9+10)
[Geo mean]  1.05µs       0.02µs       -98.08%

Performance result on ARMv8.0 machine:
name        old time/op  new time/op  delta
Xadd-46      538ns ± 1%   541ns ± 1%  +0.62%  (p=0.000 n=9+9)
Xadd64-46    505ns ± 1%   508ns ± 0%  +0.48%  (p=0.003 n=9+8)
[Geo mean]   521ns        524ns       +0.55%

Change-Id: If4b5d8d0e2d6f84fe1492a4f5de0789910ad0ee9
Reviewed-on: https://go-review.googlesource.com/81877
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Wei Xiao 2017-11-03 02:05:28 +00:00 • committed by Cherry Zhang
parent 1988b3ed0e
commit 0a7ac93c27
16 changed files with 211 additions and 6 deletions
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1
src/cmd/compile/internal/gc/go.go
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@ -303,6 +303,7 @@ var (
racewriterange,
supportPopcnt,
supportSSE41,
arm64SupportAtomics,
typedmemclr,
typedmemmove,
Udiv,