Skip to content

Make char::is_ascii_whitespace branchless on 32 and 64-bit targets #77021

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

Closed
wants to merge 3 commits into from
Closed

Make char::is_ascii_whitespace branchless on 32 and 64-bit targets #77021

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
82ff02b
Make char::is_ascii_whitespace branchless on 64-bit
lnicola Sep 21, 2020
960c039
Update mailmap
lnicola Sep 21, 2020
f1e7495
Use a 32-bit implementation
lnicola Sep 22, 2020
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
3 changes: 2 additions & 1 deletion .mailmap
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,8 @@ Kyle J Strand <[email protected]> <[email protected]>
Kyle J Strand <[email protected]> <[email protected]>
Kyle J Strand <[email protected]> <[email protected]>
Kyle J Strand <[email protected]> <[email protected]>
Laurențiu Nicola <[email protected]>
Laurențiu Nicola <[email protected]> Laurentiu Nicola <[email protected]>
Laurențiu Nicola <[email protected]> <[email protected]>
Lee Jeffery <[email protected]> Lee Jeffery <[email protected]>
Lee Wondong <[email protected]>
Lennart Kudling <[email protected]>
Expand Down
15 changes: 12 additions & 3 deletions library/core/src/char/methods.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1544,9 +1544,18 @@ impl char {
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_whitespace(&self) -> bool {
match *self {
'\t' | '\n' | '\x0C' | '\r' | ' ' => true,
_ => false,
#[cfg(target_pointer_width = "64")]
{
// Inspired from https://pdimov.github.io/blog/2020/07/19/llvm-and-memchr/
const MASK: u64 = 1 << b'\t' | 1 << b'\n' | 1 << b'\x0C' | 1 << b'\r' | 1 << b' ';
*self <= ' ' && 1u64 << (*self as u8) & MASK != 0
}
#[cfg(not(target_pointer_width = "64"))]
{
match *self {
'\t' | '\n' | '\x0C' | '\r' | ' ' => true,
_ => false,
}
}
}

Expand Down