From c57f28bbf75572e10c6165c33a2aef922315fdb4 Mon Sep 17 00:00:00 2001 From: Zalathar Date: Tue, 12 Dec 2023 13:49:19 +1100 Subject: [PATCH] coverage: Avoid creating `func_coverage` for marker statements Coverage marker statements should have no effect on codegen, but in some cases they could have the side-effect of creating a `func_coverage` entry for their enclosing function. That can lead to an ICE for functions that don't actually have any coverage spans. --- .../rustc_codegen_llvm/src/coverageinfo/mod.rs | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs index 8386f067baf..0befbb5a39b 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs @@ -85,6 +85,14 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> { let bx = self; + match coverage.kind { + // Marker statements have no effect during codegen, + // so return early and don't create `func_coverage`. + CoverageKind::SpanMarker => return, + // Match exhaustively to ensure that newly-added kinds are classified correctly. + CoverageKind::CounterIncrement { .. } | CoverageKind::ExpressionUsed { .. } => {} + } + let Some(function_coverage_info) = bx.tcx.instance_mir(instance.def).function_coverage_info.as_deref() else { @@ -100,9 +108,9 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> { let Coverage { kind } = coverage; match *kind { - // Span markers are only meaningful during MIR instrumentation, - // and have no effect during codegen. - CoverageKind::SpanMarker => {} + CoverageKind::SpanMarker => unreachable!( + "unexpected marker statement {kind:?} should have caused an early return" + ), CoverageKind::CounterIncrement { id } => { func_coverage.mark_counter_id_seen(id); // We need to explicitly drop the `RefMut` before calling into `instrprof_increment`,