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coverage: Make fn_sig_span optional, and note its quirks

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This commit is contained in:
Zalathar 2024-01-22 17:04:13 +11:00
parent fde1702db8
commit a246b6be1d
3 changed files with 17 additions and 11 deletions
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17
compiler/rustc_mir_transform/src/coverage/mod.rs
View File

@ -394,7 +394,9 @@ fn is_eligible_for_coverage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
struct ExtractedHirInfo {
function_source_hash: u64,
is_async_fn: bool,
fn_sig_span: Span,
/// The span of the function's signature, extended to the start of `body_span`.
/// Must have the same context and filename as the body span.
fn_sig_span_extended: Option<Span>,
body_span: Span,
}
@ -407,7 +409,8 @@ fn extract_hir_info<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> ExtractedHir
hir::map::associated_body(hir_node).expect("HIR node is a function with body");
let hir_body = tcx.hir().body(fn_body_id);
let is_async_fn = hir_node.fn_sig().is_some_and(|fn_sig| fn_sig.header.is_async());
let maybe_fn_sig = hir_node.fn_sig();
let is_async_fn = maybe_fn_sig.is_some_and(|fn_sig| fn_sig.header.is_async());
let mut body_span = hir_body.value.span;
@ -423,8 +426,8 @@ fn extract_hir_info<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> ExtractedHir
// The actual signature span is only used if it has the same context and
// filename as the body, and precedes the body.
let maybe_fn_sig_span = hir_node.fn_sig().map(|fn_sig| fn_sig.span);
let fn_sig_span = maybe_fn_sig_span
let fn_sig_span_extended = maybe_fn_sig
.map(|fn_sig| fn_sig.span)
.filter(|&fn_sig_span| {
let source_map = tcx.sess.source_map();
let file_idx = |span: Span| source_map.lookup_source_file_idx(span.lo());
@ -434,13 +437,11 @@ fn extract_hir_info<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> ExtractedHir
&& file_idx(fn_sig_span) == file_idx(body_span)
})
// If so, extend it to the start of the body span.
.map(|fn_sig_span| fn_sig_span.with_hi(body_span.lo()))
// Otherwise, create a dummy signature span at the start of the body.
.unwrap_or_else(|| body_span.shrink_to_lo());
.map(|fn_sig_span| fn_sig_span.with_hi(body_span.lo()));
let function_source_hash = hash_mir_source(tcx, hir_body);
ExtractedHirInfo { function_source_hash, is_async_fn, fn_sig_span, body_span }
ExtractedHirInfo { function_source_hash, is_async_fn, fn_sig_span_extended, body_span }
}
fn hash_mir_source<'tcx>(tcx: TyCtxt<'tcx>, hir_body: &'tcx rustc_hir::Body<'tcx>) -> u64 {

5
compiler/rustc_mir_transform/src/coverage/spans.rs
View File

@ -51,8 +51,9 @@ pub(super) fn generate_coverage_spans(
// with the user code wrapped in a closure. Any spans in the desugared
// outer function will be unhelpful, so just keep the signature span
// and ignore all of the spans in the MIR body.
let span = hir_info.fn_sig_span;
mappings.push(BcbMapping { kind: BcbMappingKind::Code(START_BCB), span });
if let Some(span) = hir_info.fn_sig_span_extended {
mappings.push(BcbMapping { kind: BcbMappingKind::Code(START_BCB), span });
}
} else {
let sorted_spans = from_mir::mir_to_initial_sorted_coverage_spans(
mir_body,

6
compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
View File

@ -23,7 +23,7 @@ pub(super) fn mir_to_initial_sorted_coverage_spans(
hir_info: &ExtractedHirInfo,
basic_coverage_blocks: &CoverageGraph,
) -> Vec<CoverageSpan> {
let &ExtractedHirInfo { fn_sig_span, body_span, .. } = hir_info;
let &ExtractedHirInfo { body_span, .. } = hir_info;
let mut initial_spans = vec![];
@ -33,6 +33,10 @@ pub(super) fn mir_to_initial_sorted_coverage_spans(
// Only add the signature span if we found at least one span in the body.
if !initial_spans.is_empty() {
// If there is no usable signature span, add a fake one (before refinement)
// to avoid an ugly gap between the body start and the first real span.
// FIXME: Find a more principled way to solve this problem.
let fn_sig_span = hir_info.fn_sig_span_extended.unwrap_or_else(|| body_span.shrink_to_lo());
initial_spans.push(SpanFromMir::for_fn_sig(fn_sig_span));
}