commit | e4a1cf8a5698d7351af0e33d61e4f7078f3ab1ce | [log] [tgz] |
---|---|---|
author | Lynn Boger <laboger@linux.vnet.ibm.com> | Thu Mar 26 16:01:40 2020 -0400 |
committer | Lynn Boger <laboger@linux.vnet.ibm.com> | Fri Mar 27 16:05:42 2020 +0000 |
tree | 4cb51369993067d67eac1850ba373efce872bb96 | |
parent | 3840aced142aeeca6ddf54cb90c07b54e4cf814b [diff] |
cmd/compile: add rules to eliminate unnecessary signed shifts This change to the rules removes some unnecessary signed shifts that appear in the math/rand functions. Existing rules did not cover some of the signed cases. A little improvement seen in math/rand due to removing 1 of 2 instructions generated for Int31n, which is inlined quite a bit. Intn1000 46.9ns ± 0% 45.5ns ± 0% -2.99% (p=1.000 n=1+1) Int63n1000 33.5ns ± 0% 32.8ns ± 0% -2.09% (p=1.000 n=1+1) Int31n1000 32.7ns ± 0% 32.6ns ± 0% -0.31% (p=1.000 n=1+1) Float32 32.7ns ± 0% 30.3ns ± 0% -7.34% (p=1.000 n=1+1) Float64 21.7ns ± 0% 20.9ns ± 0% -3.69% (p=1.000 n=1+1) Perm3 205ns ± 0% 202ns ± 0% -1.46% (p=1.000 n=1+1) Perm30 1.71µs ± 0% 1.68µs ± 0% -1.35% (p=1.000 n=1+1) Perm30ViaShuffle 1.65µs ± 0% 1.65µs ± 0% -0.30% (p=1.000 n=1+1) ShuffleOverhead 2.83µs ± 0% 2.83µs ± 0% -0.07% (p=1.000 n=1+1) Read3 18.7ns ± 0% 16.1ns ± 0% -13.90% (p=1.000 n=1+1) Read64 126ns ± 0% 124ns ± 0% -1.59% (p=1.000 n=1+1) Read1000 1.75µs ± 0% 1.63µs ± 0% -7.08% (p=1.000 n=1+1) Change-Id: I11502dfca7d65aafc76749a8d713e9e50c24a858 Reviewed-on: https://go-review.googlesource.com/c/go/+/225917 Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com> Reviewed-by: Cherry Zhang <cherryyz@google.com>
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