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authorbors <bors@rust-lang.org>2021-10-04 12:49:57 +0000
committerbors <bors@rust-lang.org>2021-10-04 12:49:57 +0000
commit175b8db73bfd078b4bcd3c28c8d6f51d5895ebf3 (patch)
treebe5ea44b10f6f928aa881c468aa6a602a2c192ab /compiler/rustc_codegen_llvm/src/builder.rs
parenta4797664ba9c7d71e586122853858eeb6c153bb9 (diff)
parent5e1428e18be47b48c5c94d6e067d24f44074cd32 (diff)
downloadrust-175b8db73bfd078b4bcd3c28c8d6f51d5895ebf3.tar.gz
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Auto merge of #88834 - the8472:char-count, r=joshtriplett
optimize str::from_utf8() validation when slice contains multibyte chars and str.chars().count() in all cases

The change shows small but consistent improvements across several x86 target feature levels. I also tried to optimize counting with `slice.as_chunks` but that yielded more inconsistent results, bigger improvements for some optimization levels, lesser ones in others.

```
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)
```

and for the multibyte-char string validation:

```
old, -O2, x86-64
test str::str_validate_emoji                                    ... bench:       4,606 ns/iter (+/- 64)

new, -O2, x86-64
test str::str_validate_emoji                                    ... bench:       3,837 ns/iter (+/- 60)
```
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/builder.rs')
0 files changed, 0 insertions, 0 deletions