diff options
4 files changed, 59 insertions, 36 deletions
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs index ab3a0ef7f15..32f18419753 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs @@ -273,7 +273,9 @@ fn save_function_record( /// `codegened_and_inlined_items`). /// /// These unused functions are then codegen'd in one of the CGUs which is marked as the -/// "code coverage dead code cgu" during the partitioning process. +/// "code coverage dead code cgu" during the partitioning process. This prevents us from generating +/// code regions for the same function more than once which can lead to linker errors regarding +/// duplicate symbols. fn add_unused_functions<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) { assert!(cx.codegen_unit.is_code_coverage_dead_code_cgu()); @@ -281,12 +283,24 @@ fn add_unused_functions<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) { let ignore_unused_generics = tcx.sess.instrument_coverage_except_unused_generics(); - let all_def_ids: DefIdSet = tcx + let eligible_def_ids: DefIdSet = tcx .mir_keys(()) .iter() .filter_map(|local_def_id| { let def_id = local_def_id.to_def_id(); - if ignore_unused_generics && tcx.generics_of(def_id).requires_monomorphization(tcx) { + let kind = tcx.def_kind(def_id); + // `mir_keys` will give us `DefId`s for all kinds of things, not + // just "functions", like consts, statics, etc. Filter those out. + // If `ignore_unused_generics` was specified, filter out any + // generic functions from consideration as well. + if !matches!( + kind, + DefKind::Fn | DefKind::AssocFn | DefKind::Closure | DefKind::Generator + ) { + return None; + } else if ignore_unused_generics + && tcx.generics_of(def_id).requires_monomorphization(tcx) + { return None; } Some(local_def_id.to_def_id()) @@ -295,24 +309,17 @@ fn add_unused_functions<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) { let codegenned_def_ids = tcx.codegened_and_inlined_items(()); - for &non_codegenned_def_id in all_def_ids.difference(codegenned_def_ids) { - // `all_def_ids` contains things besides just "functions" such as constants, - // statics, etc. We need to filter those out. - let kind = tcx.def_kind(non_codegenned_def_id); - if matches!(kind, DefKind::Fn | DefKind::AssocFn | DefKind::Closure | DefKind::Generator) { - let codegen_fn_attrs = tcx.codegen_fn_attrs(non_codegenned_def_id); - - // If a function is marked `#[no_coverage]`, then skip generating a - // dead code stub for it. - if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_COVERAGE) { - debug!("skipping unused fn marked #[no_coverage]: {:?}", non_codegenned_def_id); - continue; - } + for &non_codegenned_def_id in eligible_def_ids.difference(codegenned_def_ids) { + let codegen_fn_attrs = tcx.codegen_fn_attrs(non_codegenned_def_id); - debug!("generating unused fn: {:?}", non_codegenned_def_id); - cx.define_unused_fn(non_codegenned_def_id); - } else { - debug!("skipping unused {:?}: {:?}", kind, non_codegenned_def_id); + // If a function is marked `#[no_coverage]`, then skip generating a + // dead code stub for it. + if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_COVERAGE) { + debug!("skipping unused fn marked #[no_coverage]: {:?}", non_codegenned_def_id); + continue; } + + debug!("generating unused fn: {:?}", non_codegenned_def_id); + cx.define_unused_fn(non_codegenned_def_id); } } diff --git a/compiler/rustc_monomorphize/src/partitioning/mod.rs b/compiler/rustc_monomorphize/src/partitioning/mod.rs index 463c2135364..67597a0d7b4 100644 --- a/compiler/rustc_monomorphize/src/partitioning/mod.rs +++ b/compiler/rustc_monomorphize/src/partitioning/mod.rs @@ -205,17 +205,33 @@ pub fn partition<'tcx>( tcx.sess.instrument_coverage() && !tcx.sess.instrument_coverage_except_unused_functions(); if instrument_dead_code { + assert!( + post_inlining.codegen_units.len() > 0, + "There must be at least one CGU that code coverage data can be generated in." + ); + // Find the smallest CGU that has exported symbols and put the dead // function stubs in that CGU. We look for exported symbols to increase - // the likelyhood the linker won't throw away the dead functions. - let mut cgus_with_exported_symbols: Vec<_> = post_inlining - .codegen_units - .iter_mut() + // the likelihood the linker won't throw away the dead functions. + // FIXME(#92165): In order to truly resolve this, we need to make sure + // the object file (CGU) containing the dead function stubs is included + // in the final binary. This will probably require forcing these + // function symbols to be included via `-u` or `/include` linker args. + let mut cgus: Vec<_> = post_inlining.codegen_units.iter_mut().collect(); + cgus.sort_by_key(|cgu| cgu.size_estimate()); + + let dead_code_cgu = if let Some(cgu) = cgus + .into_iter() + .rev() .filter(|cgu| cgu.items().iter().any(|(_, (linkage, _))| *linkage == Linkage::External)) - .collect(); - cgus_with_exported_symbols.sort_by_key(|cgu| cgu.size_estimate()); - - let dead_code_cgu = cgus_with_exported_symbols.last_mut().unwrap(); + .next() + { + cgu + } else { + // If there are no CGUs that have externally linked items, + // then we just pick the first CGU as a fallback. + &mut post_inlining.codegen_units[0] + }; dead_code_cgu.make_code_coverage_dead_code_cgu(); } diff --git a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt index c2d5143a618..768dcb2f608 100644 --- a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt +++ b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt @@ -19,12 +19,12 @@ 18| 2| println!("used_only_from_bin_crate_generic_function with {:?}", arg); 19| 2|} ------------------ - | used_crate::used_only_from_bin_crate_generic_function::<&str>: + | used_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>: | 17| 1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) { | 18| 1| println!("used_only_from_bin_crate_generic_function with {:?}", arg); | 19| 1|} ------------------ - | used_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>: + | used_crate::used_only_from_bin_crate_generic_function::<&str>: | 17| 1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) { | 18| 1| println!("used_only_from_bin_crate_generic_function with {:?}", arg); | 19| 1|} @@ -36,12 +36,12 @@ 22| 2| println!("used_only_from_this_lib_crate_generic_function with {:?}", arg); 23| 2|} ------------------ - | used_crate::used_only_from_this_lib_crate_generic_function::<&str>: + | used_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>: | 21| 1|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) { | 22| 1| println!("used_only_from_this_lib_crate_generic_function with {:?}", arg); | 23| 1|} ------------------ - | used_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>: + | used_crate::used_only_from_this_lib_crate_generic_function::<&str>: | 21| 1|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) { | 22| 1| println!("used_only_from_this_lib_crate_generic_function with {:?}", arg); | 23| 1|} diff --git a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt index dab31cbf4ac..89636294035 100644 --- a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt +++ b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt @@ -42,12 +42,12 @@ 40| 2| println!("used_only_from_bin_crate_generic_function with {:?}", arg); 41| 2|} ------------------ - | used_inline_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>: + | used_inline_crate::used_only_from_bin_crate_generic_function::<&str>: | 39| 1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) { | 40| 1| println!("used_only_from_bin_crate_generic_function with {:?}", arg); | 41| 1|} ------------------ - | used_inline_crate::used_only_from_bin_crate_generic_function::<&str>: + | used_inline_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>: | 39| 1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) { | 40| 1| println!("used_only_from_bin_crate_generic_function with {:?}", arg); | 41| 1|} @@ -61,12 +61,12 @@ 46| 4| println!("used_only_from_this_lib_crate_generic_function with {:?}", arg); 47| 4|} ------------------ - | used_inline_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>: + | used_inline_crate::used_only_from_this_lib_crate_generic_function::<&str>: | 45| 2|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) { | 46| 2| println!("used_only_from_this_lib_crate_generic_function with {:?}", arg); | 47| 2|} ------------------ - | used_inline_crate::used_only_from_this_lib_crate_generic_function::<&str>: + | used_inline_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>: | 45| 2|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) { | 46| 2| println!("used_only_from_this_lib_crate_generic_function with {:?}", arg); | 47| 2|} |