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Jonathan Swinney ecc3f5112e cmd/compile: improve atomic swap intrinsics on arm64 ARMv8.1 has added new instructions for atomic memory operations. This change builds on the previous change which added support for atomic add, `0a7ac93c27`, to include similar support for atomic-compare-and-swap, atomic-swap, atomic-or, and atomic-and intrinsics. Since the new instructions are not guaranteed to be present, we guard their usages with a branch on a CPU feature. Peformance on an ARMv8.1 machine: name old time/op new time/op delta CompareAndSwap-16 37.9ns ±16% 24.1ns ± 4% -36.44% (p=0.000 n=10+9) CompareAndSwap64-16 38.6ns ±15% 24.1ns ± 3% -37.47% (p=0.000 n=10+10) name old time/op new time/op delta Swap-16 46.9ns ±32% 12.5ns ± 6% -73.40% (p=0.000 n=10+10) Swap64-16 53.4ns ± 1% 12.5ns ± 6% -76.56% (p=0.000 n=10+10) name old time/op new time/op delta Or8-16 8.81ns ± 0% 5.61ns ± 0% -36.32% (p=0.000 n=10+10) Or-16 7.21ns ± 0% 5.61ns ± 0% -22.19% (p=0.000 n=10+10) Or8Parallel-16 59.8ns ± 3% 12.5ns ± 2% -79.10% (p=0.000 n=10+10) OrParallel-16 51.7ns ± 3% 12.5ns ± 2% -75.84% (p=0.000 n=10+10) name old time/op new time/op delta And8-16 8.81ns ± 0% 5.61ns ± 0% -36.32% (p=0.000 n=10+10) And-16 7.21ns ± 0% 5.61ns ± 0% -22.19% (p=0.000 n=10+10) And8Parallel-16 59.1ns ± 6% 12.8ns ± 3% -78.33% (p=0.000 n=10+10) AndParallel-16 51.4ns ± 7% 12.8ns ± 3% -75.03% (p=0.000 n=10+10) Performance on an ARMv8.0 machine (no atomics instructions): name old time/op new time/op delta CompareAndSwap-16 61.3ns ± 0% 62.4ns ± 0% +1.70% (p=0.000 n=8+9) CompareAndSwap64-16 62.0ns ± 3% 61.3ns ± 2% ~ (p=0.093 n=10+10) name old time/op new time/op delta Swap-16 127ns ± 2% 131ns ± 2% +2.91% (p=0.001 n=10+10) Swap64-16 128ns ± 1% 131ns ± 2% +2.43% (p=0.001 n=10+10) name old time/op new time/op delta Or8-16 14.9ns ± 0% 15.3ns ± 0% +2.68% (p=0.000 n=10+10) Or-16 11.8ns ± 0% 12.3ns ± 0% +4.24% (p=0.000 n=10+10) Or8Parallel-16 137ns ± 1% 144ns ± 1% +4.97% (p=0.000 n=10+10) OrParallel-16 128ns ± 1% 136ns ± 1% +6.34% (p=0.000 n=10+10) name old time/op new time/op delta And8-16 14.9ns ± 0% 15.3ns ± 0% +2.68% (p=0.000 n=10+10) And-16 11.8ns ± 0% 12.3ns ± 0% +4.24% (p=0.000 n=10+10) And8Parallel-16 134ns ± 2% 141ns ± 1% +5.29% (p=0.000 n=10+10) AndParallel-16 125ns ± 2% 134ns ± 1% +7.10% (p=0.000 n=10+10) Fixes #39304 Change-Id: Idaca68701d4751650be6b4bedca3d57f51571712 Reviewed-on: https://go-review.googlesource.com/c/go/+/234217 Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com> Trust: fannie zhang <Fannie.Zhang@arm.com>		2020-11-05 23:21:33 +00:00
.github	.github: add link to questions in ISSUE_TEMPLATE	2020-01-06 17:05:31 +00:00
api	api: update next.txt	2020-10-29 20:51:49 +00:00
doc	cmd/go/internal/modget: resolve paths at the requested versions	2020-11-05 17:52:17 +00:00
lib/time	lib/time, time/tzdata: update tz data to 2020d	2020-10-24 21:42:44 +00:00
misc	cmd/dist,cmd/go,runtime: add support for cgo on linux/riscv64	2020-11-03 12:59:51 +00:00
src	cmd/compile: improve atomic swap intrinsics on arm64	2020-11-05 23:21:33 +00:00
test	cmd/compile: remove racefuncenterfp when it is not needed	2020-11-02 03:03:16 +00:00
.gitattributes	all: treat all files as binary, but check in .bat with CRLF	2020-06-08 15:31:43 +00:00
.gitignore
AUTHORS	A+C: add Kush Patel (corporate CLA for Hootsuite Inc)	2020-07-08 00:10:44 +00:00
CONTRIBUTING.md	all: restore changes from faulty merge/revert	2018-02-12 20:13:59 +00:00
CONTRIBUTORS	CONTRIBUTORS: update for the Go 1.15 release	2020-08-10 21:51:48 +00:00
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README.md	README: linkify some paths	2018-06-06 18:07:01 +00:00
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SECURITY.md	SECURITY.md: update go versions	2019-09-26 15:34:57 +00:00

README.md

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