Skip to content

Optimize core::str::Chars::count #90414

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Feb 6, 2022
+379 −29
Merged

Optimize core::str::Chars::count #90414

Changes from 1 commit
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
628b217
Optimize `core::str::Chars::count`
thomcc Oct 30, 2021
ed01324
Fix zh::SMALL string in core::str benchmarks
thomcc Oct 30, 2021
002aaf2
Ensure non-power-of-two sizes are tested in the Chars::count test
thomcc Oct 30, 2021
ebbccaf
Respond to review feedback, and improve implementation somewhat
thomcc Feb 1, 2022
41f8214
Fix comment grammar for `do_count_chars`
thomcc Feb 5, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Fix comment grammar for do_count_chars
@thomcc
thomcc committed Feb 5, 2022

Unverified

This user has not yet uploaded their public signing key.
GPG key ID: 606D1A738C09287A
Learn about vigilant mode
commit 41f821461f0235912501a58feb0d86c58167a015
2 changes: 1 addition & 1 deletion library/core/src/str/count.rs
View file
Original file line number Diff line number Diff line change
@@ -40,7 +40,7 @@ fn do_count_chars(s: &str) -> usize {
//
// - Less than or equal to 255, otherwise we'll overflow bytes in `counts`.
// - A multiple of `UNROLL_INNER`, otherwise our `break` inside the
// `body.chunks(CHUNK_SIZE)` loop.
// `body.chunks(CHUNK_SIZE)` loop is incorrect.
//
// For performance, `CHUNK_SIZE` should be:
// - Relatively cheap to `/` against (so some simple sum of powers of two).