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coverage: Only generate a CGU's covmap record if it has covfun records

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This commit is contained in:
Zalathar 2024-12-11 15:12:23 +11:00
parent 9e6b7c17c8
commit 512f3fdebe
1 changed files with 14 additions and 4 deletions
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18
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
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@ -80,10 +80,6 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
let filenames_val = cx.const_bytes(&filenames_buffer);
let filenames_ref = llvm_cov::hash_bytes(&filenames_buffer);
// Generate the coverage map header, which contains the filenames used by
// this CGU's coverage mappings, and store it in a well-known global.
generate_covmap_record(cx, covmap_version, filenames_size, filenames_val);
let mut unused_function_names = Vec::new();
let covfun_records = function_coverage_map
@ -93,6 +89,15 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
})
.collect::<Vec<_>>();
// If there are no covfun records for this CGU, don't generate a covmap record.
// Emitting a covmap record without any covfun records causes `llvm-cov` to
// fail when generating coverage reports, and if there are no covfun records
// then the covmap record isn't useful anyway.
// This should prevent a repeat of <https://github.com/rust-lang/rust/issues/133606>.
if covfun_records.is_empty() {
return;
}
for covfun in &covfun_records {
unused_function_names.extend(covfun.mangled_function_name_if_unused());
@ -117,6 +122,11 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
llvm::set_linkage(array, llvm::Linkage::InternalLinkage);
llvm::set_initializer(array, initializer);
}
// Generate the coverage map header, which contains the filenames used by
// this CGU's coverage mappings, and store it in a well-known global.
// (This is skipped if we returned early due to having no covfun records.)
generate_covmap_record(cx, covmap_version, filenames_size, filenames_val);
}
/// Maps "global" (per-CGU) file ID numbers to their underlying filenames.