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| author | Robert Griesemer <gri@golang.org> | 2017-02-17 14:20:11 -0800 |
|---|---|---|
| committer | Robert Griesemer <gri@golang.org> | 2017-02-17 23:40:10 +0000 |
| commit | a12edb8db6f3fa93a1ccd96a0f84b647d08429ef (patch) | |
| tree | e65c5919b8b39fef70db23da29addc3ef1a0c58e /src/math/bits/bits_impl.go | |
| parent | 21c71d77887733c02a7ae31b65b1b12041485ee5 (diff) | |
| download | go-a12edb8db6f3fa93a1ccd96a0f84b647d08429ef.tar.xz | |
math/bits: faster OnesCount, added respective benchmarks
Also: Changed Reverse/ReverseBytes implementations to use
the same (smaller) masks as OnesCount.
BenchmarkOnesCount-8 37.0 6.26 -83.08%
BenchmarkOnesCount8-8 7.24 1.99 -72.51%
BenchmarkOnesCount16-8 11.3 2.47 -78.14%
BenchmarkOnesCount32-8 18.4 3.02 -83.59%
BenchmarkOnesCount64-8 40.0 3.78 -90.55%
BenchmarkReverse-8 6.69 6.22 -7.03%
BenchmarkReverse8-8 1.64 1.64 +0.00%
BenchmarkReverse16-8 2.26 2.18 -3.54%
BenchmarkReverse32-8 2.88 2.87 -0.35%
BenchmarkReverse64-8 5.64 4.34 -23.05%
BenchmarkReverseBytes-8 2.48 2.17 -12.50%
BenchmarkReverseBytes16-8 0.63 0.95 +50.79%
BenchmarkReverseBytes32-8 1.13 1.24 +9.73%
BenchmarkReverseBytes64-8 2.50 2.16 -13.60%
OnesCount-8 37.0ns ± 0% 6.3ns ± 0% ~ (p=1.000 n=1+1)
OnesCount8-8 7.24ns ± 0% 1.99ns ± 0% ~ (p=1.000 n=1+1)
OnesCount16-8 11.3ns ± 0% 2.5ns ± 0% ~ (p=1.000 n=1+1)
OnesCount32-8 18.4ns ± 0% 3.0ns ± 0% ~ (p=1.000 n=1+1)
OnesCount64-8 40.0ns ± 0% 3.8ns ± 0% ~ (p=1.000 n=1+1)
Reverse-8 6.69ns ± 0% 6.22ns ± 0% ~ (p=1.000 n=1+1)
Reverse8-8 1.64ns ± 0% 1.64ns ± 0% ~ (all samples are equal)
Reverse16-8 2.26ns ± 0% 2.18ns ± 0% ~ (p=1.000 n=1+1)
Reverse32-8 2.88ns ± 0% 2.87ns ± 0% ~ (p=1.000 n=1+1)
Reverse64-8 5.64ns ± 0% 4.34ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes-8 2.48ns ± 0% 2.17ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes16-8 0.63ns ± 0% 0.95ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes32-8 1.13ns ± 0% 1.24ns ± 0% ~ (p=1.000 n=1+1)
ReverseBytes64-8 2.50ns ± 0% 2.16ns ± 0% ~ (p=1.000 n=1+1)
Change-Id: I591b0ffc83fc3a42828256b6e5030f32c64f9497
Reviewed-on: https://go-review.googlesource.com/37218
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Diffstat (limited to 'src/math/bits/bits_impl.go')
| -rw-r--r-- | src/math/bits/bits_impl.go | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/src/math/bits/bits_impl.go b/src/math/bits/bits_impl.go index 3a425e3b83..c7834106c8 100644 --- a/src/math/bits/bits_impl.go +++ b/src/math/bits/bits_impl.go @@ -74,14 +74,6 @@ func ntz64(x uint64) int { return int(deBruijn64tab[(x&-x)*deBruijn64>>(64-6)]) } -func pop(x uint64) (n int) { - for x != 0 { - n++ - x &= x - 1 - } - return -} - func pos(k int) uint { if k < 0 { panic("negative rotation count") |