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Simplify span caches #145505

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Merged
merged 2 commits into from
Aug 19, 2025
Merged

Simplify span caches #145505

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6c15339
Simplify decode_span.
cjgillot Aug 16, 2025
a843730
Simplify span_data_to_lines_and_cols.
cjgillot Aug 16, 2025
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51 changes: 23 additions & 28 deletions compiler/rustc_middle/src/query/on_disk_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -645,34 +645,29 @@ impl<'a, 'tcx> SpanDecoder for CacheDecoder<'a, 'tcx> {
let parent = Option::<LocalDefId>::decode(self);
let tag: u8 = Decodable::decode(self);

if tag == TAG_PARTIAL_SPAN {
return Span::new(BytePos(0), BytePos(0), ctxt, parent);
} else if tag == TAG_RELATIVE_SPAN {
let dlo = u32::decode(self);
let dto = u32::decode(self);

let enclosing = self.tcx.source_span_untracked(parent.unwrap()).data_untracked();
let span = Span::new(
enclosing.lo + BytePos::from_u32(dlo),
enclosing.lo + BytePos::from_u32(dto),
ctxt,
parent,
);

return span;
} else {
debug_assert_eq!(tag, TAG_FULL_SPAN);
}

let file_lo_index = SourceFileIndex::decode(self);
let line_lo = usize::decode(self);
let col_lo = RelativeBytePos::decode(self);
let len = BytePos::decode(self);

let file_lo = self.file_index_to_file(file_lo_index);
let lo = file_lo.lines()[line_lo - 1] + col_lo;
let lo = file_lo.absolute_position(lo);
let hi = lo + len;
let (lo, hi) = match tag {
TAG_PARTIAL_SPAN => (BytePos(0), BytePos(0)),
TAG_RELATIVE_SPAN => {
let dlo = u32::decode(self);
let dto = u32::decode(self);

let enclosing = self.tcx.source_span_untracked(parent.unwrap()).data_untracked();
(enclosing.lo + BytePos::from_u32(dlo), enclosing.lo + BytePos::from_u32(dto))
}
TAG_FULL_SPAN => {
let file_lo_index = SourceFileIndex::decode(self);
let line_lo = usize::decode(self);
let col_lo = RelativeBytePos::decode(self);
let len = BytePos::decode(self);

let file_lo = self.file_index_to_file(file_lo_index);
let lo = file_lo.lines()[line_lo - 1] + col_lo;
let lo = file_lo.absolute_position(lo);
let hi = lo + len;
(lo, hi)
}
_ => unreachable!(),
};

Span::new(lo, hi, ctxt, parent)
}
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30 changes: 14 additions & 16 deletions compiler/rustc_span/src/caching_source_map_view.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -123,27 +123,25 @@ impl<'sm> CachingSourceMapView<'sm> {

if lo_cache_idx != -1 && hi_cache_idx != -1 {
// Cache hit for span lo and hi. Check if they belong to the same file.
let result = {
let lo = &self.line_cache[lo_cache_idx as usize];
let hi = &self.line_cache[hi_cache_idx as usize];
let lo_file_index = self.line_cache[lo_cache_idx as usize].file_index;
let hi_file_index = self.line_cache[hi_cache_idx as usize].file_index;

if lo.file_index != hi.file_index {
return None;
}

(
lo.file.stable_id,
lo.line_number,
span_data.lo - lo.line.start,
hi.line_number,
span_data.hi - hi.line.start,
)
};
if lo_file_index != hi_file_index {
return None;
}

self.line_cache[lo_cache_idx as usize].touch(self.time_stamp);
self.line_cache[hi_cache_idx as usize].touch(self.time_stamp);

return Some(result);
let lo = &self.line_cache[lo_cache_idx as usize];
let hi = &self.line_cache[hi_cache_idx as usize];
return Some((
lo.file.stable_id,
lo.line_number,
span_data.lo - lo.line.start,
hi.line_number,
span_data.hi - hi.line.start,
));
}

// No cache hit or cache hit for only one of span lo and hi.
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