1 use crate::common::CodegenCx;
2 use crate::coverageinfo;
5 use llvm::coverageinfo::CounterMappingRegion;
6 use rustc_codegen_ssa::coverageinfo::map::{Counter, CounterExpression};
7 use rustc_codegen_ssa::traits::{BaseTypeMethods, ConstMethods};
8 use rustc_data_structures::fx::FxIndexSet;
9 use rustc_llvm::RustString;
10 use rustc_middle::mir::coverage::CodeRegion;
12 use std::ffi::CString;
16 /// Generates and exports the Coverage Map.
18 /// This Coverage Map complies with Coverage Mapping Format version 3 (zero-based encoded as 2),
19 /// as defined at [LLVM Code Coverage Mapping Format](https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#llvm-code-coverage-mapping-format)
20 /// and published in Rust's current (July 2020) fork of LLVM. This version is supported by the
21 /// LLVM coverage tools (`llvm-profdata` and `llvm-cov`) bundled with Rust's fork of LLVM.
23 /// Consequently, Rust's bundled version of Clang also generates Coverage Maps compliant with
24 /// version 3. Clang's implementation of Coverage Map generation was referenced when implementing
25 /// this Rust version, and though the format documentation is very explicit and detailed, some
26 /// undocumented details in Clang's implementation (that may or may not be important) were also
27 /// replicated for Rust's Coverage Map.
28 pub fn finalize<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) {
29 let function_coverage_map = match cx.coverage_context() {
30 Some(ctx) => ctx.take_function_coverage_map(),
33 if function_coverage_map.is_empty() {
34 // This module has no functions with coverage instrumentation
38 let mut mapgen = CoverageMapGenerator::new();
40 // Encode coverage mappings and generate function records
41 let mut function_records = Vec::<&'ll llvm::Value>::new();
42 let coverage_mappings_buffer = llvm::build_byte_buffer(|coverage_mappings_buffer| {
43 for (instance, function_coverage) in function_coverage_map.into_iter() {
44 debug!("Generate coverage map for: {:?}", instance);
46 let mangled_function_name = cx.tcx.symbol_name(instance).to_string();
47 let function_source_hash = function_coverage.source_hash();
48 let (expressions, counter_regions) =
49 function_coverage.get_expressions_and_counter_regions();
51 let old_len = coverage_mappings_buffer.len();
52 mapgen.write_coverage_mappings(expressions, counter_regions, coverage_mappings_buffer);
53 let mapping_data_size = coverage_mappings_buffer.len() - old_len;
55 mapping_data_size > 0,
56 "Every `FunctionCoverage` should have at least one counter"
59 let function_record = mapgen.make_function_record(
61 mangled_function_name,
65 function_records.push(function_record);
69 // Encode all filenames referenced by counters/expressions in this module
70 let filenames_buffer = llvm::build_byte_buffer(|filenames_buffer| {
71 coverageinfo::write_filenames_section_to_buffer(&mapgen.filenames, filenames_buffer);
74 // Generate the LLVM IR representation of the coverage map and store it in a well-known global
75 mapgen.save_generated_coverage_map(
79 coverage_mappings_buffer,
83 struct CoverageMapGenerator {
84 filenames: FxIndexSet<CString>,
87 impl CoverageMapGenerator {
89 Self { filenames: FxIndexSet::default() }
92 /// Using the `expressions` and `counter_regions` collected for the current function, generate
93 /// the `mapping_regions` and `virtual_file_mapping`, and capture any new filenames. Then use
94 /// LLVM APIs to encode the `virtual_file_mapping`, `expressions`, and `mapping_regions` into
95 /// the given `coverage_mappings` byte buffer, compliant with the LLVM Coverage Mapping format.
96 fn write_coverage_mappings(
98 expressions: Vec<CounterExpression>,
99 counter_regions: impl Iterator<Item = (Counter, &'a CodeRegion)>,
100 coverage_mappings_buffer: &RustString,
102 let mut counter_regions = counter_regions.collect::<Vec<_>>();
103 if counter_regions.is_empty() {
107 let mut virtual_file_mapping = Vec::new();
108 let mut mapping_regions = Vec::new();
109 let mut current_file_name = None;
110 let mut current_file_id = 0;
112 // Convert the list of (Counter, CodeRegion) pairs to an array of `CounterMappingRegion`, sorted
113 // by filename and position. Capture any new files to compute the `CounterMappingRegion`s
114 // `file_id` (indexing files referenced by the current function), and construct the
115 // function-specific `virtual_file_mapping` from `file_id` to its index in the module's
116 // `filenames` array.
117 counter_regions.sort_unstable_by_key(|(_counter, region)| *region);
118 for (counter, region) in counter_regions {
119 let CodeRegion { file_name, start_line, start_col, end_line, end_col } = *region;
120 let same_file = current_file_name.as_ref().map_or(false, |p| *p == file_name);
122 if current_file_name.is_some() {
123 current_file_id += 1;
125 current_file_name = Some(file_name);
126 let c_filename = CString::new(file_name.to_string())
127 .expect("null error converting filename to C string");
128 debug!(" file_id: {} = '{:?}'", current_file_id, c_filename);
129 let (filenames_index, _) = self.filenames.insert_full(c_filename);
130 virtual_file_mapping.push(filenames_index as u32);
132 debug!("Adding counter {:?} to map for {:?}", counter, region,);
133 mapping_regions.push(CounterMappingRegion::code_region(
143 // Encode and append the current function's coverage mapping data
144 coverageinfo::write_mapping_to_buffer(
145 virtual_file_mapping,
148 coverage_mappings_buffer,
152 /// Generate and return the function record `Value`
153 fn make_function_record(
155 cx: &CodegenCx<'ll, 'tcx>,
156 mangled_function_name: String,
157 function_source_hash: u64,
158 mapping_data_size: usize,
159 ) -> &'ll llvm::Value {
160 let name_ref = coverageinfo::compute_hash(&mangled_function_name);
161 let name_ref_val = cx.const_u64(name_ref);
162 let mapping_data_size_val = cx.const_u32(mapping_data_size as u32);
163 let func_hash_val = cx.const_u64(function_source_hash);
165 &[name_ref_val, mapping_data_size_val, func_hash_val],
170 /// Combine the filenames and coverage mappings buffers, construct coverage map header and the
171 /// array of function records, and combine everything into the complete coverage map. Save the
172 /// coverage map data into the LLVM IR as a static global using a specific, well-known section
174 fn save_generated_coverage_map(
176 cx: &CodegenCx<'ll, 'tcx>,
177 function_records: Vec<&'ll llvm::Value>,
178 filenames_buffer: Vec<u8>,
179 mut coverage_mappings_buffer: Vec<u8>,
181 // Concatenate the encoded filenames and encoded coverage mappings, and add additional zero
182 // bytes as-needed to ensure 8-byte alignment.
183 let mut coverage_size = coverage_mappings_buffer.len();
184 let filenames_size = filenames_buffer.len();
185 let remaining_bytes =
186 (filenames_size + coverage_size) % coverageinfo::COVMAP_VAR_ALIGN_BYTES;
187 if remaining_bytes > 0 {
188 let pad = coverageinfo::COVMAP_VAR_ALIGN_BYTES - remaining_bytes;
189 coverage_mappings_buffer.append(&mut [0].repeat(pad));
190 coverage_size += pad;
192 let filenames_and_coverage_mappings = [filenames_buffer, coverage_mappings_buffer].concat();
193 let filenames_and_coverage_mappings_val =
194 cx.const_bytes(&filenames_and_coverage_mappings[..]);
197 "cov map: n_records = {}, filenames_size = {}, coverage_size = {}, 0-based version = {}",
198 function_records.len(),
201 coverageinfo::mapping_version()
204 // Create the coverage data header
205 let n_records_val = cx.const_u32(function_records.len() as u32);
206 let filenames_size_val = cx.const_u32(filenames_size as u32);
207 let coverage_size_val = cx.const_u32(coverage_size as u32);
208 let version_val = cx.const_u32(coverageinfo::mapping_version());
209 let cov_data_header_val = cx.const_struct(
210 &[n_records_val, filenames_size_val, coverage_size_val, version_val],
214 // Create the function records array
215 let name_ref_from_u64 = cx.type_i64();
216 let mapping_data_size_from_u32 = cx.type_i32();
217 let func_hash_from_u64 = cx.type_i64();
218 let function_record_ty = cx.type_struct(
219 &[name_ref_from_u64, mapping_data_size_from_u32, func_hash_from_u64],
222 let function_records_val = cx.const_array(function_record_ty, &function_records[..]);
224 // Create the complete LLVM coverage data value to add to the LLVM IR
225 let cov_data_val = cx.const_struct(
226 &[cov_data_header_val, function_records_val, filenames_and_coverage_mappings_val],
230 // Save the coverage data value to LLVM IR
231 coverageinfo::save_map_to_mod(cx, cov_data_val);