|author||Michael Munday <email@example.com>||Thu Jun 04 10:55:01 2020 -0700|
|committer||Michael Munday <firstname.lastname@example.org>||Tue Aug 18 15:39:44 2020 +0000|
cmd/compile: clean up and optimize s390x multiplication rules Some of the existing optimizations aren't triggered because they are handled by the generic rules so this CL removes them. Also some constraints were copied without much thought from the amd64 rules and they don't make sense on s390x, so we remove those constraints. Finally, add a 'multiply by the sum of two powers of two' optimization. This makes sense on s390x as shifts are low latency and can also sometimes be optimized further (especially if we add support for RISBG instructions). name old time/op new time/op delta IntMulByConst/3-8 1.70ns ±11% 1.10ns ± 5% -35.26% (p=0.000 n=10+10) IntMulByConst/5-8 1.64ns ± 7% 1.10ns ± 4% -32.94% (p=0.000 n=10+9) IntMulByConst/12-8 1.65ns ± 6% 1.20ns ± 4% -27.16% (p=0.000 n=10+9) IntMulByConst/120-8 1.66ns ± 4% 1.22ns ±13% -26.43% (p=0.000 n=10+10) IntMulByConst/-120-8 1.65ns ± 7% 1.19ns ± 4% -28.06% (p=0.000 n=9+10) IntMulByConst/65537-8 0.86ns ± 9% 1.12ns ±12% +30.41% (p=0.000 n=10+10) IntMulByConst/65538-8 1.65ns ± 5% 1.23ns ± 5% -25.11% (p=0.000 n=10+10) Change-Id: Ib196e6bff1e97febfd266134d0a2b2a62897989f Reviewed-on: https://go-review.googlesource.com/c/go/+/248937 Run-TryBot: Michael Munday <email@example.com> TryBot-Result: Gobot Gobot <firstname.lastname@example.org> Reviewed-by: Keith Randall <email@example.com>
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