Skip to content

rope: Micro optimize the creation of masks #41132

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 1 commit into from
Oct 27, 2025
Merged

rope: Micro optimize the creation of masks #41132

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
35 changes: 15 additions & 20 deletions crates/rope/src/chunk.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,16 @@ pub struct Chunk {
pub text: ArrayString<MAX_BASE>,
}

#[inline(always)]
const fn saturating_shl_mask(offset: u32) -> Bitmap {
(1 as Bitmap).unbounded_shl(offset).wrapping_sub(1)
}

#[inline(always)]
const fn saturating_shr_mask(offset: u32) -> Bitmap {
!Bitmap::MAX.unbounded_shr(offset)
}

impl Chunk {
pub const MASK_BITS: usize = Bitmap::BITS as usize;

Expand Down Expand Up @@ -290,34 +300,19 @@ impl<'a> ChunkSlice<'a> {
/// Get number of chars in first line
#[inline(always)]
pub fn first_line_chars(&self) -> u32 {
if self.newlines == 0 {
self.chars.count_ones()
} else {
let mask = ((1 as Bitmap) << self.newlines.trailing_zeros()) - 1;
(self.chars & mask).count_ones()
}
(self.chars & saturating_shl_mask(self.newlines.trailing_zeros())).count_ones()
}

/// Get number of chars in last line
#[inline(always)]
pub fn last_line_chars(&self) -> u32 {
if self.newlines == 0 {
self.chars.count_ones()
} else {
let mask = !(Bitmap::MAX >> self.newlines.leading_zeros());
(self.chars & mask).count_ones()
}
(self.chars & saturating_shr_mask(self.newlines.leading_zeros())).count_ones()
}

/// Get number of UTF-16 code units in last line
#[inline(always)]
pub fn last_line_len_utf16(&self) -> u32 {
if self.newlines == 0 {
self.chars_utf16.count_ones()
} else {
let mask = !(Bitmap::MAX >> self.newlines.leading_zeros());
(self.chars_utf16 & mask).count_ones()
}
(self.chars_utf16 & saturating_shr_mask(self.newlines.leading_zeros())).count_ones()
}

/// Get the longest row in the chunk and its length in characters.
Expand Down Expand Up @@ -491,8 +486,8 @@ impl<'a> ChunkSlice<'a> {

#[inline(always)]
pub fn offset_to_point_utf16(&self, offset: usize) -> PointUtf16 {
let mask = (1 as Bitmap).unbounded_shl(offset as u32).wrapping_sub(1);
let row = (self.newlines & mask).count_ones();
let mask = saturating_shl_mask(offset as u32);
let row = (self.newlines & saturating_shl_mask(offset as u32)).count_ones();
let newline_ix = Bitmap::BITS - (self.newlines & mask).leading_zeros();
let column = if newline_ix as usize == MAX_BASE {
0
Expand Down