bjoernager/rust
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coverage: Don't split bang-macro spans, just truncate them

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This commit is contained in:
Zalathar 2025-03-25 22:02:22 +11:00
parent 62a533ce78
commit 26cea8a286
25 changed files with 142 additions and 159 deletions
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2
compiler/rustc_mir_transform/src/coverage/mappings.rs
View file

@ -96,7 +96,7 @@ pub(super) fn extract_all_mapping_info_from_mir<'tcx>(
}
} else {
// Extract coverage spans from MIR statements/terminators as normal.
extract_refined_covspans(mir_body, hir_info, graph, &mut code_mappings);
extract_refined_covspans(tcx, mir_body, hir_info, graph, &mut code_mappings);
}
branch_pairs.extend(extract_branch_pairs(mir_body, hir_info, graph));

43
compiler/rustc_mir_transform/src/coverage/spans.rs
View file

@ -3,6 +3,7 @@ use std::iter;
use rustc_data_structures::fx::FxHashSet;
use rustc_middle::mir;
use rustc_middle::ty::TyCtxt;
use rustc_span::{DesugaringKind, ExpnKind, MacroKind, Span};
use tracing::{debug, debug_span, instrument};
@ -12,8 +13,9 @@ use crate::coverage::{ExtractedHirInfo, mappings, unexpand};
mod from_mir;
pub(super) fn extract_refined_covspans(
mir_body: &mir::Body<'_>,
pub(super) fn extract_refined_covspans<'tcx>(
tcx: TyCtxt<'tcx>,
mir_body: &mir::Body<'tcx>,
hir_info: &ExtractedHirInfo,
graph: &CoverageGraph,
code_mappings: &mut impl Extend<mappings::CodeMapping>,
@ -51,7 +53,7 @@ pub(super) fn extract_refined_covspans(
// First, perform the passes that need macro information.
covspans.sort_by(|a, b| graph.cmp_in_dominator_order(a.bcb, b.bcb));
remove_unwanted_expansion_spans(&mut covspans);
split_visible_macro_spans(&mut covspans);
shrink_visible_macro_spans(tcx, &mut covspans);
// We no longer need the extra information in `SpanFromMir`, so convert to `Covspan`.
let mut covspans = covspans.into_iter().map(SpanFromMir::into_covspan).collect::<Vec<_>>();
@ -128,35 +130,16 @@ fn remove_unwanted_expansion_spans(covspans: &mut Vec<SpanFromMir>) {
}
/// When a span corresponds to a macro invocation that is visible from the
/// function body, split it into two parts. The first part covers just the
/// macro name plus `!`, and the second part covers the rest of the macro
/// invocation. This seems to give better results for code that uses macros.
fn split_visible_macro_spans(covspans: &mut Vec<SpanFromMir>) {
let mut extra_spans = vec![];
/// function body, truncate it to just the macro name plus `!`.
/// This seems to give better results for code that uses macros.
fn shrink_visible_macro_spans(tcx: TyCtxt<'_>, covspans: &mut Vec<SpanFromMir>) {
let source_map = tcx.sess.source_map();
covspans.retain(|covspan| {
let Some(ExpnKind::Macro(MacroKind::Bang, visible_macro)) = covspan.expn_kind else {
return true;
};
let split_len = visible_macro.as_str().len() as u32 + 1;
let (before, after) = covspan.span.split_at(split_len);
if !covspan.span.contains(before) || !covspan.span.contains(after) {
// Something is unexpectedly wrong with the split point.
// The debug assertion in `split_at` will have already caught this,
// but in release builds it's safer to do nothing and maybe get a
// bug report for unexpected coverage, rather than risk an ICE.
return true;
for covspan in covspans {
if matches!(covspan.expn_kind, Some(ExpnKind::Macro(MacroKind::Bang, _))) {
covspan.span = source_map.span_through_char(covspan.span, '!');
}
extra_spans.push(SpanFromMir::new(before, covspan.expn_kind.clone(), covspan.bcb));
extra_spans.push(SpanFromMir::new(after, covspan.expn_kind.clone(), covspan.bcb));
false // Discard the original covspan that we just split.
});
// The newly-split spans are added at the end, so any previous sorting
// is not preserved.
covspans.extend(extra_spans);
}
}
/// Uses the holes to divide the given covspans into buckets, such that: