tree e588a18c508cf92b44232709ffc04baa84492749
parent 21964bba6549f73cc16f1ddbc95bcbbb5b679985
author Rob Pike <r@golang.org> 1550733828 +1100
committer Rob Pike <r@golang.org> 1550783016 +0000

exp: use new operations from math/bits for faster generation

Code by josharian.

benchmark                        old ns/op     new ns/op     delta
BenchmarkPCGMultiply-4           3.48          2.31          -33.62%
BenchmarkSource-4                7.46          3.54          -52.55%
BenchmarkInt63Threadsafe-4       21.6          19.4          -10.19%
BenchmarkInt63Unthreadsafe-4     7.69          3.60          -53.19%
BenchmarkIntn1000-4              17.3          13.2          -23.70%
BenchmarkInt63n1000-4            17.7          13.2          -25.42%
BenchmarkInt31n1000-4            17.4          13.2          -24.14%
BenchmarkFloat32-4               13.5          8.57          -36.52%
BenchmarkFloat64-4               11.1          6.43          -42.07%
BenchmarkPerm3-4                 64.6          49.2          -23.84%
BenchmarkPerm30-4                614           430           -29.97%
BenchmarkPerm30ViaShuffle-4      556           450           -19.06%
BenchmarkShuffleOverhead-4       969           788           -18.68%
BenchmarkRead3-4                 11.7          10.1          -13.68%
BenchmarkRead64-4                127           83.0          -34.65%
BenchmarkRead1000-4              1820          1191          -34.56%

Also move the rotate out from under the 1.9 build tag, as 1.9 is old.
The new code goes under a 1.12 build tag.

Update golang/go#21835.

Change-Id: I66d5cac6578b8df2cdfc3b90ed097c5525adb6bc
Reviewed-on: https://go-review.googlesource.com/c/163258
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>