unicode: improve SimpleFold performance for ascii
This change significantly speeds up case-insensitive regexp matching.
benchmark old ns/op new ns/op delta
BenchmarkMatchEasy0i_32-8 2690 1473 -45.24%
BenchmarkMatchEasy0i_1K-8 80404 42269 -47.43%
BenchmarkMatchEasy0i_32K-8
3272187 2076118 -36.55%
BenchmarkMatchEasy0i_1M-8
104805990 66503805 -36.55%
BenchmarkMatchEasy0i_32M-8
3360192200 2126121600 -36.73%
benchmark old MB/s new MB/s speedup
BenchmarkMatchEasy0i_32-8 11.90 21.72 1.83x
BenchmarkMatchEasy0i_1K-8 12.74 24.23 1.90x
BenchmarkMatchEasy0i_32K-8 10.01 15.78 1.58x
BenchmarkMatchEasy0i_1M-8 10.00 15.77 1.58x
BenchmarkMatchEasy0i_32M-8 9.99 15.78 1.58x
Issue #13288
Change-Id: I94af7bb29e75d60b4f6ee760124867ab271b9642
Reviewed-on: https://go-review.googlesource.com/16943
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>