Skip to content

[EXPERIMENT] Avoid tracking span to compute end_point. #144930

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

Draft
wants to merge 2 commits into
base: master
Choose a base branch
from
+10 −10
Draft

[EXPERIMENT] Avoid tracking span to compute end_point. #144930

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
acc04fd
Fix doc-comment.
cjgillot Aug 4, 2025
08260ee
Avoid tracking span to compute end_point.
cjgillot Aug 4, 2025
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
15 changes: 8 additions & 7 deletions compiler/rustc_span/src/source_map.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -911,12 +911,14 @@ impl SourceMap {

/// Returns a new span representing just the last character of this span.
pub fn end_point(&self, sp: Span) -> Span {
let pos = sp.hi().0;
// We restrict the current span, so we cannot look around. Using the untracked data is ok.
let sp = sp.data_untracked();
let pos = sp.hi.0;

let width = self.find_width_of_character_at_span(sp, false);
let corrected_end_position = pos.checked_sub(width).unwrap_or(pos);

let end_point = BytePos(cmp::max(corrected_end_position, sp.lo().0));
let end_point = BytePos(cmp::max(corrected_end_position, sp.lo.0));
sp.with_lo(end_point)
}

Expand All @@ -930,8 +932,9 @@ impl SourceMap {
if sp.is_dummy() {
return sp;
}
let start_of_next_point = sp.hi().0;

let sp = sp.data();
let start_of_next_point = sp.hi.0;
let width = self.find_width_of_character_at_span(sp, true);
// If the width is 1, then the next span should only contain the next char besides current ending.
// However, in the case of a multibyte character, where the width != 1, the next span should
Expand All @@ -940,7 +943,7 @@ impl SourceMap {
start_of_next_point.checked_add(width).unwrap_or(start_of_next_point);

let end_of_next_point = BytePos(cmp::max(start_of_next_point + 1, end_of_next_point));
Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt(), None)
Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt, None)
}

/// Check whether span is followed by some specified expected string in limit scope
Expand All @@ -963,9 +966,7 @@ impl SourceMap {
/// Finds the width of the character, either before or after the end of provided span,
/// depending on the `forwards` parameter.
#[instrument(skip(self, sp))]
fn find_width_of_character_at_span(&self, sp: Span, forwards: bool) -> u32 {
let sp = sp.data();

fn find_width_of_character_at_span(&self, sp: SpanData, forwards: bool) -> u32 {
if sp.lo == sp.hi && !forwards {
debug!("early return empty span");
return 1;
Expand Down
5 changes: 2 additions & 3 deletions compiler/rustc_span/src/span_encoding.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -74,9 +74,8 @@ use crate::{BytePos, SPAN_TRACK, SpanData};
/// because `parent` isn't currently used by default.
///
/// In order to reliably use parented spans in incremental compilation,
/// the dependency to the parent definition's span. This is performed
/// using the callback `SPAN_TRACK` to access the query engine.
///
/// accesses to `lo` and `hi` must introduce a dependency to the parent definition's span.
/// This is performed using the callback `SPAN_TRACK` to access the query engine.
#[derive(Clone, Copy, Eq, PartialEq, Hash)]
#[rustc_pass_by_value]
pub struct Span {
Expand Down
Loading