bytes, strings: speed up TrimSpace
This change lifts bounds checks out of loops in the TrimSpace functions,
among other micro-optimizations. Here are some benchmark results
(no change to allocations):
goos: darwin
goarch: amd64
pkg: bytes
cpu: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
│ old │ new │
│ sec/op │ sec/op vs base │
TrimSpace/NoTrim-8 4.406n ± 0% 3.829n ± 1% -13.11% (p=0.000 n=20)
TrimSpace/ASCII-8 7.688n ± 1% 5.872n ± 1% -23.61% (p=0.000 n=20)
TrimSpace/SomeNonASCII-8 82.25n ± 1% 81.00n ± 1% -1.51% (p=0.001 n=20)
TrimSpace/JustNonASCII-8 131.6n ± 8% 132.2n ± 1% ~ (p=0.899 n=20)
geomean 24.61n 22.15n -9.99%
pkg: strings
│ old │ new │
│ sec/op │ sec/op vs base │
TrimSpace/NoTrim-8 4.178n ± 0% 3.857n ± 2% -7.68% (p=0.001 n=20)
TrimSpace/ASCII-8 7.708n ± 0% 5.585n ± 1% -27.55% (p=0.000 n=20)
TrimSpace/SomeNonASCII-8 98.70n ± 1% 88.54n ± 1% -10.30% (p=0.000 n=20)
TrimSpace/JustNonASCII-8 132.8n ± 2% 123.2n ± 0% -7.16% (p=0.000 n=20)
geomean 25.49n 22.02n -13.61%
Change-Id: I523f03a909c82a51940b44c7b2634985b7447982
GitHub-Last-Rev:
35163f04c63ce2ef5e9e831c4371750504edb892
GitHub-Pull-Request: golang/go#75127
Reviewed-on: https://go-review.googlesource.com/c/go/+/698735
Reviewed-by: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: Keith Randall <khr@google.com>