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| author | The8472 <git@infinite-source.de> | 2021-09-10 21:37:42 +0200 |
|---|---|---|
| committer | The8472 <git@infinite-source.de> | 2021-09-11 00:25:41 +0200 |
| commit | b6278664af23004be3fbf9ecd64505e9abdf3644 (patch) | |
| tree | 15aab672681faa15f75ec87d9dcc2a12cdcaab3f | |
| parent | 4c44f061d80390a07081c7cefa5da3ddae7807c3 (diff) | |
| download | rust-b6278664af23004be3fbf9ecd64505e9abdf3644.tar.gz rust-b6278664af23004be3fbf9ecd64505e9abdf3644.zip | |
optimize utf8_is_cont_byte() to speed up str.chars().count()
it shows consistent improvements across several x86_64 feature levels ``` old, -O2, x86-64 test str::str_char_count_emoji ... bench: 1,924 ns/iter (+/- 26) test str::str_char_count_lorem ... bench: 879 ns/iter (+/- 12) test str::str_char_count_lorem_short ... bench: 5 ns/iter (+/- 0) new, -O2, x86-64 test str::str_char_count_emoji ... bench: 1,878 ns/iter (+/- 21) test str::str_char_count_lorem ... bench: 851 ns/iter (+/- 11) test str::str_char_count_lorem_short ... bench: 4 ns/iter (+/- 0) old, -O2, x86-64-v2 test str::str_char_count_emoji ... bench: 1,477 ns/iter (+/- 46) test str::str_char_count_lorem ... bench: 675 ns/iter (+/- 15) test str::str_char_count_lorem_short ... bench: 5 ns/iter (+/- 0) new, -O2, x86-64-v2 test str::str_char_count_emoji ... bench: 1,323 ns/iter (+/- 39) test str::str_char_count_lorem ... bench: 593 ns/iter (+/- 18) test str::str_char_count_lorem_short ... bench: 4 ns/iter (+/- 0) old, -O2, x86-64-v3 test str::str_char_count_emoji ... bench: 748 ns/iter (+/- 7) test str::str_char_count_lorem ... bench: 348 ns/iter (+/- 2) test str::str_char_count_lorem_short ... bench: 5 ns/iter (+/- 0) new, -O2, x86-64-v3 test str::str_char_count_emoji ... bench: 650 ns/iter (+/- 4) test str::str_char_count_lorem ... bench: 301 ns/iter (+/- 1) test str::str_char_count_lorem_short ... bench: 5 ns/iter (+/- 0) ```
| -rw-r--r-- | library/core/src/str/validations.rs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/library/core/src/str/validations.rs b/library/core/src/str/validations.rs index 373a8212425..fc8f47dced4 100644 --- a/library/core/src/str/validations.rs +++ b/library/core/src/str/validations.rs @@ -22,7 +22,7 @@ fn utf8_acc_cont_byte(ch: u32, byte: u8) -> u32 { /// bits `10`). #[inline] pub(super) fn utf8_is_cont_byte(byte: u8) -> bool { - (byte & !CONT_MASK) == TAG_CONT_U8 + (byte as i8) < -64 } #[inline] |