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| author | Josh Bleecher Snyder <josharian@gmail.com> | 2015-03-17 16:10:31 -0700 |
|---|---|---|
| committer | Josh Bleecher Snyder <josharian@gmail.com> | 2015-03-18 21:38:40 +0000 |
| commit | 4bc9badd759f863f784e5f8d105a25c615324359 (patch) | |
| tree | 1e5d07daa4255aa4e93783ecefa690e332886e62 /src/runtime/stack.h | |
| parent | 6ffed3020c0fb749868b71d5b13fef65ff248902 (diff) | |
| download | go-4bc9badd759f863f784e5f8d105a25c615324359.tar.xz | |
cmd/internal/gc: speed up large string switches
Switch statements do a binary search on long runs of constants.
Doing a less-than comparison on a string is much more expensive
than on (say) an int. Use two part comparison for strings:
First compare length, then the strings themselves.
Benchmarks from issue 10000:
benchmark old ns/op new ns/op delta
BenchmarkIf0 3.36 3.35 -0.30%
BenchmarkIf1 4.45 4.47 +0.45%
BenchmarkIf2 5.22 5.26 +0.77%
BenchmarkIf3 5.56 5.58 +0.36%
BenchmarkIf4 10.5 10.6 +0.95%
BenchmarkIfNewStr0 5.26 5.30 +0.76%
BenchmarkIfNewStr1 7.19 7.15 -0.56%
BenchmarkIfNewStr2 7.23 7.16 -0.97%
BenchmarkIfNewStr3 7.47 7.43 -0.54%
BenchmarkIfNewStr4 12.4 12.2 -1.61%
BenchmarkSwitch0 9.56 4.24 -55.65%
BenchmarkSwitch1 8.64 5.58 -35.42%
BenchmarkSwitch2 9.38 10.1 +7.68%
BenchmarkSwitch3 8.66 5.00 -42.26%
BenchmarkSwitch4 7.99 8.18 +2.38%
BenchmarkSwitchNewStr0 11.3 6.12 -45.84%
BenchmarkSwitchNewStr1 11.1 8.33 -24.95%
BenchmarkSwitchNewStr2 11.0 11.1 +0.91%
BenchmarkSwitchNewStr3 10.3 6.93 -32.72%
BenchmarkSwitchNewStr4 11.0 11.2 +1.82%
Fixes #10000
Change-Id: Ia2fffc32e9843425374c274064f709ec7ee46d80
Reviewed-on: https://go-review.googlesource.com/7698
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src/runtime/stack.h')
0 files changed, 0 insertions, 0 deletions