diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs | 201 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs | 54 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 8 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/llvm/mod.rs | 12 |
4 files changed, 161 insertions, 114 deletions
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs index 41827a91ba4..a6372a77a70 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs @@ -4,7 +4,7 @@ use crate::llvm; use llvm::coverageinfo::CounterMappingRegion; use rustc_codegen_ssa::coverageinfo::map::{Counter, CounterExpression}; -use rustc_codegen_ssa::traits::{BaseTypeMethods, ConstMethods}; +use rustc_codegen_ssa::traits::ConstMethods; use rustc_data_structures::fx::FxIndexSet; use rustc_llvm::RustString; use rustc_middle::mir::coverage::CodeRegion; @@ -38,46 +38,50 @@ pub fn finalize<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) { let mut mapgen = CoverageMapGenerator::new(); // Encode coverage mappings and generate function records - let mut function_records = Vec::<&'ll llvm::Value>::new(); - let coverage_mappings_buffer = llvm::build_byte_buffer(|coverage_mappings_buffer| { - for (instance, function_coverage) in function_coverage_map.into_iter() { - debug!("Generate coverage map for: {:?}", instance); - - let mangled_function_name = cx.tcx.symbol_name(instance).to_string(); - let function_source_hash = function_coverage.source_hash(); - let (expressions, counter_regions) = - function_coverage.get_expressions_and_counter_regions(); - - let old_len = coverage_mappings_buffer.len(); - mapgen.write_coverage_mappings(expressions, counter_regions, coverage_mappings_buffer); - let mapping_data_size = coverage_mappings_buffer.len() - old_len; - debug_assert!( - mapping_data_size > 0, - "Every `FunctionCoverage` should have at least one counter" - ); - - let function_record = mapgen.make_function_record( - cx, - mangled_function_name, - function_source_hash, - mapping_data_size, - ); - function_records.push(function_record); - } - }); + let mut function_data = Vec::new(); + for (instance, function_coverage) in function_coverage_map.into_iter() { + debug!("Generate coverage map for: {:?}", instance); + + let mangled_function_name = cx.tcx.symbol_name(instance).to_string(); + let function_source_hash = function_coverage.source_hash(); + let (expressions, counter_regions) = + function_coverage.get_expressions_and_counter_regions(); + + let coverage_mapping_buffer = llvm::build_byte_buffer(|coverage_mapping_buffer| { + mapgen.write_coverage_mapping(expressions, counter_regions, coverage_mapping_buffer); + }); + debug_assert!( + coverage_mapping_buffer.len() > 0, + "Every `FunctionCoverage` should have at least one counter" + ); + + function_data.push((mangled_function_name, function_source_hash, coverage_mapping_buffer)); + } // Encode all filenames referenced by counters/expressions in this module let filenames_buffer = llvm::build_byte_buffer(|filenames_buffer| { coverageinfo::write_filenames_section_to_buffer(&mapgen.filenames, filenames_buffer); }); + let filenames_size = filenames_buffer.len(); + let filenames_val = cx.const_bytes(&filenames_buffer[..]); + let filenames_ref = coverageinfo::hash_bytes(filenames_buffer); + // Generate the LLVM IR representation of the coverage map and store it in a well-known global - mapgen.save_generated_coverage_map( - cx, - function_records, - filenames_buffer, - coverage_mappings_buffer, - ); + let cov_data_val = mapgen.generate_coverage_map(cx, filenames_size, filenames_val); + + for (mangled_function_name, function_source_hash, coverage_mapping_buffer) in function_data { + save_function_record( + cx, + mangled_function_name, + function_source_hash, + filenames_ref, + coverage_mapping_buffer, + ); + } + + // Save the coverage data value to LLVM IR + coverageinfo::save_cov_data_to_mod(cx, cov_data_val); } struct CoverageMapGenerator { @@ -92,12 +96,12 @@ impl CoverageMapGenerator { /// Using the `expressions` and `counter_regions` collected for the current function, generate /// the `mapping_regions` and `virtual_file_mapping`, and capture any new filenames. Then use /// LLVM APIs to encode the `virtual_file_mapping`, `expressions`, and `mapping_regions` into - /// the given `coverage_mappings` byte buffer, compliant with the LLVM Coverage Mapping format. - fn write_coverage_mappings( + /// the given `coverage_mapping` byte buffer, compliant with the LLVM Coverage Mapping format. + fn write_coverage_mapping( &mut self, expressions: Vec<CounterExpression>, counter_regions: impl Iterator<Item = (Counter, &'a CodeRegion)>, - coverage_mappings_buffer: &RustString, + coverage_mapping_buffer: &RustString, ) { let mut counter_regions = counter_regions.collect::<Vec<_>>(); if counter_regions.is_empty() { @@ -145,89 +149,78 @@ impl CoverageMapGenerator { virtual_file_mapping, expressions, mapping_regions, - coverage_mappings_buffer, + coverage_mapping_buffer, ); } - /// Generate and return the function record `Value` - fn make_function_record( - &mut self, - cx: &CodegenCx<'ll, 'tcx>, - mangled_function_name: String, - function_source_hash: u64, - mapping_data_size: usize, - ) -> &'ll llvm::Value { - let name_ref = coverageinfo::compute_hash(&mangled_function_name); - let name_ref_val = cx.const_u64(name_ref); - let mapping_data_size_val = cx.const_u32(mapping_data_size as u32); - let func_hash_val = cx.const_u64(function_source_hash); - cx.const_struct( - &[name_ref_val, mapping_data_size_val, func_hash_val], - /*packed=*/ true, - ) - } - - /// Combine the filenames and coverage mappings buffers, construct coverage map header and the - /// array of function records, and combine everything into the complete coverage map. Save the - /// coverage map data into the LLVM IR as a static global using a specific, well-known section - /// and name. - fn save_generated_coverage_map( + /// Construct coverage map header and the array of function records, and combine them into the + /// coverage map. Save the coverage map data into the LLVM IR as a static global using a + /// specific, well-known section and name. + fn generate_coverage_map( self, cx: &CodegenCx<'ll, 'tcx>, - function_records: Vec<&'ll llvm::Value>, - filenames_buffer: Vec<u8>, - mut coverage_mappings_buffer: Vec<u8>, - ) { - // Concatenate the encoded filenames and encoded coverage mappings, and add additional zero - // bytes as-needed to ensure 8-byte alignment. - let mut coverage_size = coverage_mappings_buffer.len(); - let filenames_size = filenames_buffer.len(); - let remaining_bytes = - (filenames_size + coverage_size) % coverageinfo::COVMAP_VAR_ALIGN_BYTES; - if remaining_bytes > 0 { - let pad = coverageinfo::COVMAP_VAR_ALIGN_BYTES - remaining_bytes; - coverage_mappings_buffer.append(&mut [0].repeat(pad)); - coverage_size += pad; - } - let filenames_and_coverage_mappings = [filenames_buffer, coverage_mappings_buffer].concat(); - let filenames_and_coverage_mappings_val = - cx.const_bytes(&filenames_and_coverage_mappings[..]); - + filenames_size: usize, + filenames_val: &'ll llvm::Value, + ) -> &'ll llvm::Value { debug!( - "cov map: n_records = {}, filenames_size = {}, coverage_size = {}, 0-based version = {}", - function_records.len(), + "cov map: filenames_size = {}, 0-based version = {}", filenames_size, - coverage_size, coverageinfo::mapping_version() ); - // Create the coverage data header - let n_records_val = cx.const_u32(function_records.len() as u32); + // Create the coverage data header (Note, fields 0 and 2 are now always zero, + // as of `llvm::coverage::CovMapVersion::Version4`. + let zero_was_n_records_val = cx.const_u32(0); let filenames_size_val = cx.const_u32(filenames_size as u32); - let coverage_size_val = cx.const_u32(coverage_size as u32); + let zero_was_coverage_size_val = cx.const_u32(0 as u32); let version_val = cx.const_u32(coverageinfo::mapping_version()); let cov_data_header_val = cx.const_struct( - &[n_records_val, filenames_size_val, coverage_size_val, version_val], + &[zero_was_n_records_val, filenames_size_val, zero_was_coverage_size_val, version_val], /*packed=*/ false, ); - // Create the function records array - let name_ref_from_u64 = cx.type_i64(); - let mapping_data_size_from_u32 = cx.type_i32(); - let func_hash_from_u64 = cx.type_i64(); - let function_record_ty = cx.type_struct( - &[name_ref_from_u64, mapping_data_size_from_u32, func_hash_from_u64], - /*packed=*/ true, - ); - let function_records_val = cx.const_array(function_record_ty, &function_records[..]); - // Create the complete LLVM coverage data value to add to the LLVM IR - let cov_data_val = cx.const_struct( - &[cov_data_header_val, function_records_val, filenames_and_coverage_mappings_val], - /*packed=*/ false, - ); - - // Save the coverage data value to LLVM IR - coverageinfo::save_map_to_mod(cx, cov_data_val); + cx.const_struct(&[cov_data_header_val, filenames_val], /*packed=*/ false) } } + +/// Construct a function record and combine it with the function's coverage mapping data. +/// Save the function record into the LLVM IR as a static global using a +/// specific, well-known section and name. +fn save_function_record( + cx: &CodegenCx<'ll, 'tcx>, + mangled_function_name: String, + function_source_hash: u64, + filenames_ref: u64, + coverage_mapping_buffer: Vec<u8>, +) { + // Concatenate the encoded coverage mappings + let coverage_mapping_size = coverage_mapping_buffer.len(); + let coverage_mapping_val = cx.const_bytes(&coverage_mapping_buffer[..]); + + let func_name_hash = coverageinfo::hash_str(&mangled_function_name); + let func_name_hash_val = cx.const_u64(func_name_hash); + let coverage_mapping_size_val = cx.const_u32(coverage_mapping_size as u32); + let func_hash_val = cx.const_u64(function_source_hash); + let filenames_ref_val = cx.const_u64(filenames_ref); + let func_record_val = cx.const_struct( + &[ + func_name_hash_val, + coverage_mapping_size_val, + func_hash_val, + filenames_ref_val, + coverage_mapping_val, + ], + /*packed=*/ true, + ); + + // At the present time, the coverage map for Rust assumes every instrumented function `is_used`. + // Note that Clang marks functions as "unused" in `CodeGenPGO::emitEmptyCounterMapping`. (See: + // https://github.com/rust-lang/llvm-project/blob/de02a75e398415bad4df27b4547c25b896c8bf3b/clang%2Flib%2FCodeGen%2FCodeGenPGO.cpp#L877-L878 + // for example.) + // + // It's not yet clear if or how this may be applied to Rust in the future, but the `is_used` + // argument is available and handled similarly. + let is_used = true; + coverageinfo::save_func_record_to_mod(cx, func_name_hash, func_record_val, is_used); +} diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs index e21e03822eb..e777f363eb0 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs @@ -23,7 +23,7 @@ use tracing::debug; pub mod mapgen; -const COVMAP_VAR_ALIGN_BYTES: usize = 8; +const VAR_ALIGN_BYTES: usize = 8; /// A context object for maintaining all state needed by the coverageinfo module. pub struct CrateCoverageContext<'tcx> { @@ -177,17 +177,20 @@ pub(crate) fn write_mapping_to_buffer( ); } } +pub(crate) fn hash_str(strval: &str) -> u64 { + let strval = CString::new(strval).expect("null error converting hashable str to C string"); + unsafe { llvm::LLVMRustCoverageHashCString(strval.as_ptr()) } +} -pub(crate) fn compute_hash(name: &str) -> u64 { - let name = CString::new(name).expect("null error converting hashable name to C string"); - unsafe { llvm::LLVMRustCoverageComputeHash(name.as_ptr()) } +pub(crate) fn hash_bytes(bytes: Vec<u8>) -> u64 { + unsafe { llvm::LLVMRustCoverageHashByteArray(bytes.as_ptr().cast(), bytes.len()) } } pub(crate) fn mapping_version() -> u32 { unsafe { llvm::LLVMRustCoverageMappingVersion() } } -pub(crate) fn save_map_to_mod<'ll, 'tcx>( +pub(crate) fn save_cov_data_to_mod<'ll, 'tcx>( cx: &CodegenCx<'ll, 'tcx>, cov_data_val: &'ll llvm::Value, ) { @@ -198,7 +201,7 @@ pub(crate) fn save_map_to_mod<'ll, 'tcx>( debug!("covmap var name: {:?}", covmap_var_name); let covmap_section_name = llvm::build_string(|s| unsafe { - llvm::LLVMRustCoverageWriteSectionNameToString(cx.llmod, s); + llvm::LLVMRustCoverageWriteMapSectionNameToString(cx.llmod, s); }) .expect("Rust Coverage section name failed UTF-8 conversion"); debug!("covmap section name: {:?}", covmap_section_name); @@ -206,8 +209,43 @@ pub(crate) fn save_map_to_mod<'ll, 'tcx>( let llglobal = llvm::add_global(cx.llmod, cx.val_ty(cov_data_val), &covmap_var_name); llvm::set_initializer(llglobal, cov_data_val); llvm::set_global_constant(llglobal, true); - llvm::set_linkage(llglobal, llvm::Linkage::InternalLinkage); + llvm::set_linkage(llglobal, llvm::Linkage::PrivateLinkage); llvm::set_section(llglobal, &covmap_section_name); - llvm::set_alignment(llglobal, COVMAP_VAR_ALIGN_BYTES); + llvm::set_alignment(llglobal, VAR_ALIGN_BYTES); + cx.add_used_global(llglobal); +} + +pub(crate) fn save_func_record_to_mod<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + func_name_hash: u64, + func_record_val: &'ll llvm::Value, + is_used: bool, +) { + // Assign a name to the function record. This is used to merge duplicates. + // + // In LLVM, a "translation unit" (effectively, a `Crate` in Rust) can describe functions that + // are included-but-not-used. If (or when) Rust generates functions that are + // included-but-not-used, note that a dummy description for a function included-but-not-used + // in a Crate can be replaced by full description provided by a different Crate. The two kinds + // of descriptions play distinct roles in LLVM IR; therefore, assign them different names (by + // appending "u" to the end of the function record var name, to prevent `linkonce_odr` merging. + let func_record_var_name = + format!("__covrec_{:X}{}", func_name_hash, if is_used { "u" } else { "" }); + debug!("function record var name: {:?}", func_record_var_name); + + let func_record_section_name = llvm::build_string(|s| unsafe { + llvm::LLVMRustCoverageWriteFuncSectionNameToString(cx.llmod, s); + }) + .expect("Rust Coverage function record section name failed UTF-8 conversion"); + debug!("function record section name: {:?}", func_record_section_name); + + let llglobal = llvm::add_global(cx.llmod, cx.val_ty(func_record_val), &func_record_var_name); + llvm::set_initializer(llglobal, func_record_val); + llvm::set_global_constant(llglobal, true); + llvm::set_linkage(llglobal, llvm::Linkage::LinkOnceODRLinkage); + llvm::set_visibility(llglobal, llvm::Visibility::Hidden); + llvm::set_section(llglobal, &func_record_section_name); + llvm::set_alignment(llglobal, VAR_ALIGN_BYTES); + llvm::set_comdat(cx.llmod, llglobal, &func_record_var_name); cx.add_used_global(llglobal); } diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs index 8b15c8b0eb6..69a37dba0f1 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs @@ -1791,10 +1791,14 @@ extern "C" { pub fn LLVMRustCoverageCreatePGOFuncNameVar(F: &'a Value, FuncName: *const c_char) -> &'a Value; - pub fn LLVMRustCoverageComputeHash(Name: *const c_char) -> u64; + pub fn LLVMRustCoverageHashCString(StrVal: *const c_char) -> u64; + pub fn LLVMRustCoverageHashByteArray(Bytes: *const c_char, NumBytes: size_t) -> u64; #[allow(improper_ctypes)] - pub fn LLVMRustCoverageWriteSectionNameToString(M: &Module, Str: &RustString); + pub fn LLVMRustCoverageWriteMapSectionNameToString(M: &Module, Str: &RustString); + + #[allow(improper_ctypes)] + pub fn LLVMRustCoverageWriteFuncSectionNameToString(M: &Module, Str: &RustString); #[allow(improper_ctypes)] pub fn LLVMRustCoverageWriteMappingVarNameToString(Str: &RustString); diff --git a/compiler/rustc_codegen_llvm/src/llvm/mod.rs b/compiler/rustc_codegen_llvm/src/llvm/mod.rs index 53a404ee019..fc40065a966 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/mod.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/mod.rs @@ -220,12 +220,24 @@ pub fn set_linkage(llglobal: &Value, linkage: Linkage) { } } +pub fn set_visibility(llglobal: &Value, visibility: Visibility) { + unsafe { + LLVMRustSetVisibility(llglobal, visibility); + } +} + pub fn set_alignment(llglobal: &Value, bytes: usize) { unsafe { ffi::LLVMSetAlignment(llglobal, bytes as c_uint); } } +pub fn set_comdat(llmod: &Module, llglobal: &Value, name: &str) { + unsafe { + LLVMRustSetComdat(llmod, llglobal, name.as_ptr().cast(), name.len()); + } +} + /// Safe wrapper around `LLVMGetParam`, because segfaults are no fun. pub fn get_param(llfn: &Value, index: c_uint) -> &Value { unsafe { |