From 8289dadfbc5af6af9b7995e3d41b7cbda3a1139c Mon Sep 17 00:00:00 2001 From: Zalathar Date: Tue, 13 Feb 2024 23:00:49 +1100 Subject: [PATCH] coverage: Correctly report and check LLVM's coverage mapping version --- .../src/coverageinfo/mapgen.rs | 29 +++++++++++++------ .../llvm-wrapper/CoverageMappingWrapper.cpp | 5 +++- 2 files changed, 24 insertions(+), 10 deletions(-) diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs index 278db21b0a1..3f3969bbca3 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs @@ -17,11 +17,11 @@ use rustc_span::Symbol; /// Generates and exports the Coverage Map. /// -/// Rust Coverage Map generation supports LLVM Coverage Mapping Format version -/// 6 (zero-based encoded as 5), as defined at -/// [LLVM Code Coverage Mapping Format](https://github.com/rust-lang/llvm-project/blob/rustc/13.0-2021-09-30/llvm/docs/CoverageMappingFormat.rst#llvm-code-coverage-mapping-format). +/// Rust Coverage Map generation supports LLVM Coverage Mapping Format versions +/// 6 and 7 (encoded as 5 and 6 respectively), as described at +/// [LLVM Code Coverage Mapping Format](https://github.com/rust-lang/llvm-project/blob/rustc/18.0-2024-02-13/llvm/docs/CoverageMappingFormat.rst). /// These versions are supported by the LLVM coverage tools (`llvm-profdata` and `llvm-cov`) -/// bundled with Rust's fork of LLVM. +/// distributed in the `llvm-tools-preview` rustup component. /// /// Consequently, Rust's bundled version of Clang also generates Coverage Maps compliant with /// the same version. Clang's implementation of Coverage Map generation was referenced when @@ -31,10 +31,21 @@ use rustc_span::Symbol; pub fn finalize(cx: &CodegenCx<'_, '_>) { let tcx = cx.tcx; - // Ensure the installed version of LLVM supports Coverage Map Version 6 - // (encoded as a zero-based value: 5), which was introduced with LLVM 13. - let version = coverageinfo::mapping_version(); - assert_eq!(version, 5, "The `CoverageMappingVersion` exposed by `llvm-wrapper` is out of sync"); + // Ensure that LLVM is using a version of the coverage mapping format that + // agrees with our Rust-side code. Expected versions (encoded as n-1) are: + // - `CovMapVersion::Version6` (5) used by LLVM 13-17 + // - `CovMapVersion::Version7` (6) used by LLVM 18 + let covmap_version = { + let llvm_covmap_version = coverageinfo::mapping_version(); + let expected_versions = 5..=6; + assert!( + expected_versions.contains(&llvm_covmap_version), + "Coverage mapping version exposed by `llvm-wrapper` is out of sync; \ + expected {expected_versions:?} but was {llvm_covmap_version}" + ); + // This is the version number that we will embed in the covmap section: + llvm_covmap_version + }; debug!("Generating coverage map for CodegenUnit: `{}`", cx.codegen_unit.name()); @@ -74,7 +85,7 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) { // Generate the coverage map header, which contains the filenames used by // this CGU's coverage mappings, and store it in a well-known global. - let cov_data_val = generate_coverage_map(cx, version, filenames_size, filenames_val); + let cov_data_val = generate_coverage_map(cx, covmap_version, filenames_size, filenames_val); coverageinfo::save_cov_data_to_mod(cx, cov_data_val); let mut unused_function_names = Vec::new(); diff --git a/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp index 60789b07e54..8e0b1b38366 100644 --- a/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp @@ -205,5 +205,8 @@ extern "C" void LLVMRustCoverageWriteMappingVarNameToString(RustStringRef Str) { } extern "C" uint32_t LLVMRustCoverageMappingVersion() { - return coverage::CovMapVersion::Version6; + // This should always be `CurrentVersion`, because that's the version LLVM + // will use when encoding the data we give it. If for some reason we ever + // want to override the version number we _emit_, do it on the Rust side. + return coverage::CovMapVersion::CurrentVersion; }