diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs | 150 |
1 files changed, 65 insertions, 85 deletions
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs index 4f2af732527..ca334286200 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs @@ -1,6 +1,6 @@ use std::iter; -use itertools::Itertools as _; +use itertools::Itertools; use rustc_abi::Align; use rustc_codegen_ssa::traits::{ BaseTypeCodegenMethods, ConstCodegenMethods, StaticCodegenMethods, @@ -8,8 +8,8 @@ use rustc_codegen_ssa::traits::{ use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet}; use rustc_hir::def_id::{DefId, LocalDefId}; use rustc_index::IndexVec; +use rustc_middle::mir; use rustc_middle::ty::{self, TyCtxt}; -use rustc_middle::{bug, mir}; use rustc_session::RemapFileNameExt; use rustc_session::config::RemapPathScopeComponents; use rustc_span::def_id::DefIdSet; @@ -18,7 +18,6 @@ use tracing::debug; use crate::common::CodegenCx; use crate::coverageinfo::llvm_cov; -use crate::coverageinfo::map_data::FunctionCoverage; use crate::coverageinfo::mapgen::covfun::prepare_covfun_record; use crate::llvm; @@ -49,46 +48,40 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) { debug!("Generating coverage map for CodegenUnit: `{}`", cx.codegen_unit.name()); - // In order to show that unused functions have coverage counts of zero (0), LLVM requires the - // functions exist. Generate synthetic functions with a (required) single counter, and add the - // MIR `Coverage` code regions to the `function_coverage_map`, before calling - // `ctx.take_function_coverage_map()`. - if cx.codegen_unit.is_code_coverage_dead_code_cgu() { - add_unused_functions(cx); - } - // FIXME(#132395): Can this be none even when coverage is enabled? - let function_coverage_map = match cx.coverage_cx { - Some(ref cx) => cx.take_function_coverage_map(), + let instances_used = match cx.coverage_cx { + Some(ref cx) => cx.instances_used.borrow(), None => return, }; - if function_coverage_map.is_empty() { - // This CGU has no functions with coverage instrumentation. - return; - } - let all_file_names = function_coverage_map - .iter() - .map(|(_, fn_cov)| fn_cov.function_coverage_info.body_span) - .map(|span| span_file_name(tcx, span)); - let global_file_table = GlobalFileTable::new(all_file_names); + // The order of entries in this global file table needs to be deterministic, + // and ideally should also be independent of the details of stable-hashing, + // because coverage tests snapshots (`.cov-map`) can observe the order and + // would need to be re-blessed if it changes. As long as those requirements + // are satisfied, the order can be arbitrary. + let mut global_file_table = GlobalFileTable::new(); - // Encode all filenames referenced by coverage mappings in this CGU. - let filenames_buffer = global_file_table.make_filenames_buffer(tcx); - // The `llvm-cov` tool uses this hash to associate each covfun record with - // its corresponding filenames table, since the final binary will typically - // contain multiple covmap records from different compilation units. - let filenames_hash = llvm_cov::hash_bytes(&filenames_buffer); - - let mut unused_function_names = Vec::new(); - - let covfun_records = function_coverage_map - .into_iter() - .filter_map(|(instance, function_coverage)| { - prepare_covfun_record(tcx, &global_file_table, instance, &function_coverage) - }) + let mut covfun_records = instances_used + .iter() + .copied() + // Sort by symbol name, so that the global file table is built in an + // order that doesn't depend on the stable-hash-based order in which + // instances were visited during codegen. + .sorted_by_cached_key(|&instance| tcx.symbol_name(instance).name) + .filter_map(|instance| prepare_covfun_record(tcx, &mut global_file_table, instance, true)) .collect::<Vec<_>>(); + // In a single designated CGU, also prepare covfun records for functions + // in this crate that were instrumented for coverage, but are unused. + if cx.codegen_unit.is_code_coverage_dead_code_cgu() { + let mut unused_instances = gather_unused_function_instances(cx); + // Sort the unused instances by symbol name, for the same reason as the used ones. + unused_instances.sort_by_cached_key(|&instance| tcx.symbol_name(instance).name); + covfun_records.extend(unused_instances.into_iter().filter_map(|instance| { + prepare_covfun_record(tcx, &mut global_file_table, instance, false) + })); + } + // 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 @@ -98,6 +91,15 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) { return; } + // Encode all filenames referenced by coverage mappings in this CGU. + let filenames_buffer = global_file_table.make_filenames_buffer(tcx); + // The `llvm-cov` tool uses this hash to associate each covfun record with + // its corresponding filenames table, since the final binary will typically + // contain multiple covmap records from different compilation units. + let filenames_hash = llvm_cov::hash_bytes(&filenames_buffer); + + let mut unused_function_names = vec![]; + for covfun in &covfun_records { unused_function_names.extend(covfun.mangled_function_name_if_unused()); @@ -137,22 +139,13 @@ struct GlobalFileTable { } impl GlobalFileTable { - fn new(all_file_names: impl IntoIterator<Item = Symbol>) -> Self { - // Collect all of the filenames into a set. Filenames usually come in - // contiguous runs, so we can dedup adjacent ones to save work. - let mut raw_file_table = all_file_names.into_iter().dedup().collect::<FxIndexSet<Symbol>>(); - - // Sort the file table by its actual string values, not the arbitrary - // ordering of its symbols. - raw_file_table.sort_unstable_by(|a, b| a.as_str().cmp(b.as_str())); - - Self { raw_file_table } + fn new() -> Self { + Self { raw_file_table: FxIndexSet::default() } } - fn global_file_id_for_file_name(&self, file_name: Symbol) -> GlobalFileId { - let raw_id = self.raw_file_table.get_index_of(&file_name).unwrap_or_else(|| { - bug!("file name not found in prepared global file table: {file_name}"); - }); + fn global_file_id_for_file_name(&mut self, file_name: Symbol) -> GlobalFileId { + // Ensure the given file has a table entry, and get its index. + let (raw_id, _) = self.raw_file_table.insert_full(file_name); // The raw file table doesn't include an entry for the working dir // (which has ID 0), so add 1 to get the correct ID. GlobalFileId::from_usize(raw_id + 1) @@ -264,39 +257,35 @@ fn generate_covmap_record<'ll>(cx: &CodegenCx<'ll, '_>, version: u32, filenames_ /// coverage map (in a single designated CGU) so that we still emit coverage mappings for them. /// We also end up adding their symbol names to a special global array that LLVM will include in /// its embedded coverage data. -fn add_unused_functions(cx: &CodegenCx<'_, '_>) { +fn gather_unused_function_instances<'tcx>(cx: &CodegenCx<'_, 'tcx>) -> Vec<ty::Instance<'tcx>> { assert!(cx.codegen_unit.is_code_coverage_dead_code_cgu()); let tcx = cx.tcx; let usage = prepare_usage_sets(tcx); let is_unused_fn = |def_id: LocalDefId| -> bool { - let def_id = def_id.to_def_id(); - - // To be eligible for "unused function" mappings, a definition must: - // - Be function-like + // Usage sets expect `DefId`, so convert from `LocalDefId`. + let d: DefId = LocalDefId::to_def_id(def_id); + // To be potentially eligible for "unused function" mappings, a definition must: + // - Be eligible for coverage instrumentation // - Not participate directly in codegen (or have lost all its coverage statements) // - Not have any coverage statements inlined into codegenned functions - tcx.def_kind(def_id).is_fn_like() - && (!usage.all_mono_items.contains(&def_id) - || usage.missing_own_coverage.contains(&def_id)) - && !usage.used_via_inlining.contains(&def_id) + tcx.is_eligible_for_coverage(def_id) + && (!usage.all_mono_items.contains(&d) || usage.missing_own_coverage.contains(&d)) + && !usage.used_via_inlining.contains(&d) }; - // Scan for unused functions that were instrumented for coverage. - for def_id in tcx.mir_keys(()).iter().copied().filter(|&def_id| is_unused_fn(def_id)) { - // Get the coverage info from MIR, skipping functions that were never instrumented. - let body = tcx.optimized_mir(def_id); - let Some(function_coverage_info) = body.function_coverage_info.as_deref() else { continue }; + // FIXME(#79651): Consider trying to filter out dummy instantiations of + // unused generic functions from library crates, because they can produce + // "unused instantiation" in coverage reports even when they are actually + // used by some downstream crate in the same binary. - // FIXME(79651): Consider trying to filter out dummy instantiations of - // unused generic functions from library crates, because they can produce - // "unused instantiation" in coverage reports even when they are actually - // used by some downstream crate in the same binary. - - debug!("generating unused fn: {def_id:?}"); - add_unused_function_coverage(cx, def_id, function_coverage_info); - } + tcx.mir_keys(()) + .iter() + .copied() + .filter(|&def_id| is_unused_fn(def_id)) + .map(|def_id| make_dummy_instance(tcx, def_id)) + .collect::<Vec<_>>() } struct UsageSets<'tcx> { @@ -361,16 +350,11 @@ fn prepare_usage_sets<'tcx>(tcx: TyCtxt<'tcx>) -> UsageSets<'tcx> { UsageSets { all_mono_items, used_via_inlining, missing_own_coverage } } -fn add_unused_function_coverage<'tcx>( - cx: &CodegenCx<'_, 'tcx>, - def_id: LocalDefId, - function_coverage_info: &'tcx mir::coverage::FunctionCoverageInfo, -) { - let tcx = cx.tcx; - let def_id = def_id.to_def_id(); +fn make_dummy_instance<'tcx>(tcx: TyCtxt<'tcx>, local_def_id: LocalDefId) -> ty::Instance<'tcx> { + let def_id = local_def_id.to_def_id(); // Make a dummy instance that fills in all generics with placeholders. - let instance = ty::Instance::new( + ty::Instance::new( def_id, ty::GenericArgs::for_item(tcx, def_id, |param, _| { if let ty::GenericParamDefKind::Lifetime = param.kind { @@ -379,9 +363,5 @@ fn add_unused_function_coverage<'tcx>( tcx.mk_param_from_def(param) } }), - ); - - // An unused function's mappings will all be rewritten to map to zero. - let function_coverage = FunctionCoverage::new_unused(function_coverage_info); - cx.coverage_cx().function_coverage_map.borrow_mut().insert(instance, function_coverage); + ) } |