bjoernager/rust
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coverage: Discard spans that fill the entire function body

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When we try to extract coverage-relevant spans from MIR, sometimes we see MIR
statements/terminators whose spans cover the entire function body. Those spans
tend to be unhelpful for coverage purposes, because they often represent
compiler-inserted code, e.g. the implicit return value of `()`.
This commit is contained in:
Zalathar 2024-02-15 18:12:27 +11:00
parent 75af3c58f9
commit cd9021e8cb
10 changed files with 29 additions and 33 deletions
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13
compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
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@ -132,18 +132,23 @@ fn bcb_to_initial_coverage_spans<'a, 'tcx>(
bcb_data.basic_blocks.iter().flat_map(move |&bb| {
let data = &mir_body[bb];
let unexpand = move |expn_span| {
unexpand_into_body_span_with_visible_macro(expn_span, body_span)
// Discard any spans that fill the entire body, because they tend
// to represent compiler-inserted code, e.g. implicitly returning `()`.
.filter(|(span, _)| !span.source_equal(body_span))
};
let statement_spans = data.statements.iter().filter_map(move |statement| {
let expn_span = filtered_statement_span(statement)?;
let (span, visible_macro) =
unexpand_into_body_span_with_visible_macro(expn_span, body_span)?;
let (span, visible_macro) = unexpand(expn_span)?;
Some(SpanFromMir::new(span, visible_macro, bcb, is_closure_like(statement)))
});
let terminator_span = Some(data.terminator()).into_iter().filter_map(move |terminator| {
let expn_span = filtered_terminator_span(terminator)?;
let (span, visible_macro) =
unexpand_into_body_span_with_visible_macro(expn_span, body_span)?;
let (span, visible_macro) = unexpand(expn_span)?;
Some(SpanFromMir::new(span, visible_macro, bcb, false))
});