rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

coverage: Enlarge empty spans during MIR instrumentation, not codegen

Browse Source 
This allows us to assume that coverage spans will only be discarded during
codegen in very unusual situations.
This commit is contained in:
Zalathar
2025-05-04 14:09:52 +10:00
parent 9748d87dc7
commit f877aa7d14
8 changed files with 57 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
View File

@@ -39,7 +39,10 @@ impl Coords {
/// or other expansions), and if it does happen then skipping a span or function is
/// better than an ICE or `llvm-cov` failure that the user might have no way to avoid.
pub(crate) fn make_coords(source_map: &SourceMap, file: &SourceFile, span: Span) -> Option<Coords> {
let span = ensure_non_empty_span(source_map, span)?;
if span.is_empty() {
debug_assert!(false, "can't make coords from empty span: {span:?}");
return None;
}
let lo = span.lo();
let hi = span.hi();
@@ -70,29 +73,6 @@ pub(crate) fn make_coords(source_map: &SourceMap, file: &SourceFile, span: Span)
})
}
fn ensure_non_empty_span(source_map: &SourceMap, span: Span) -> Option<Span> {
if !span.is_empty() {
return Some(span);
}
// The span is empty, so try to enlarge it to cover an adjacent '{' or '}'.
source_map
.span_to_source(span, |src, start, end| try {
// Adjusting span endpoints by `BytePos(1)` is normally a bug,
// but in this case we have specifically checked that the character
// we're skipping over is one of two specific ASCII characters, so
// adjusting by exactly 1 byte is correct.
if src.as_bytes().get(end).copied() == Some(b'{') {
Some(span.with_hi(span.hi() + BytePos(1)))
} else if start > 0 && src.as_bytes()[start - 1] == b'}' {
Some(span.with_lo(span.lo() - BytePos(1)))
} else {
None
}
})
.ok()?
}
/// If `llvm-cov` sees a source region that is improperly ordered (end < start),
/// it will immediately exit with a fatal error. To prevent that from happening,
/// discard regions that are improperly ordered, or might be interpreted in a