60b500dc6c
Make explicit a shrVU_g precondition. Replace i with i+1 throughout the loop. The resulting loop is functionally identical, but the compiler can do better BCE without the i-1 slice offset. Benchmarks results on amd64 with -tags=math_big_pure_go. name old time/op new time/op delta NonZeroShifts/1/shrVU-8 4.55ns ± 2% 4.45ns ± 3% -2.27% (p=0.000 n=28+30) NonZeroShifts/1/shlVU-8 4.07ns ± 1% 4.13ns ± 4% +1.55% (p=0.000 n=26+29) NonZeroShifts/2/shrVU-8 6.12ns ± 1% 5.55ns ± 1% -9.30% (p=0.000 n=28+28) NonZeroShifts/2/shlVU-8 5.65ns ± 3% 5.70ns ± 2% +0.92% (p=0.008 n=30+29) NonZeroShifts/3/shrVU-8 7.58ns ± 2% 6.79ns ± 2% -10.46% (p=0.000 n=28+28) NonZeroShifts/3/shlVU-8 6.62ns ± 2% 6.69ns ± 1% +1.07% (p=0.000 n=29+28) NonZeroShifts/4/shrVU-8 9.02ns ± 1% 7.79ns ± 2% -13.59% (p=0.000 n=27+30) NonZeroShifts/4/shlVU-8 7.74ns ± 1% 7.82ns ± 1% +0.92% (p=0.000 n=26+28) NonZeroShifts/5/shrVU-8 10.6ns ± 1% 8.9ns ± 3% -16.31% (p=0.000 n=25+29) NonZeroShifts/5/shlVU-8 8.59ns ± 1% 8.68ns ± 1% +1.13% (p=0.000 n=27+29) NonZeroShifts/10/shrVU-8 18.2ns ± 2% 14.4ns ± 1% -20.96% (p=0.000 n=27+28) NonZeroShifts/10/shlVU-8 14.1ns ± 1% 14.1ns ± 1% +0.46% (p=0.001 n=26+28) NonZeroShifts/100/shrVU-8 161ns ± 2% 118ns ± 1% -26.83% (p=0.000 n=29+30) NonZeroShifts/100/shlVU-8 119ns ± 2% 120ns ± 2% +0.92% (p=0.000 n=29+29) NonZeroShifts/1000/shrVU-8 1.54µs ± 1% 1.10µs ± 1% -28.63% (p=0.000 n=29+29) NonZeroShifts/1000/shlVU-8 1.10µs ± 1% 1.10µs ± 2% ~ (p=0.701 n=28+29) NonZeroShifts/10000/shrVU-8 15.3µs ± 2% 10.9µs ± 1% -28.68% (p=0.000 n=28+28) NonZeroShifts/10000/shlVU-8 10.9µs ± 2% 10.9µs ± 2% -0.57% (p=0.003 n=26+29) NonZeroShifts/100000/shrVU-8 154µs ± 1% 111µs ± 2% -28.04% (p=0.000 n=27+28) NonZeroShifts/100000/shlVU-8 113µs ± 2% 113µs ± 2% ~ (p=0.790 n=30+30) Change-Id: Ib6a621ee7c88b27f0f18121fb2cba3606c40c9b0 Reviewed-on: https://go-review.googlesource.com/c/go/+/297049 Trust: Josh Bleecher Snyder <josharian@gmail.com> Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org> |
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