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coverage: Tidy up creation of covmap records

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This commit is contained in:
Zalathar 2024-12-12 18:33:33 +11:00
parent 903d2976fd
commit de53fe245d
1 changed files with 26 additions and 32 deletions
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58
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
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@ -75,9 +75,6 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
// Encode all filenames referenced by coverage mappings in this CGU.
let filenames_buffer = global_file_table.make_filenames_buffer(tcx);
let filenames_size = filenames_buffer.len();
let filenames_val = cx.const_bytes(&filenames_buffer);
let filenames_ref = llvm_cov::hash_bytes(&filenames_buffer);
let mut unused_function_names = Vec::new();
@ -126,7 +123,7 @@ pub(crate) 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.
// (This is skipped if we returned early due to having no covfun records.)
generate_covmap_record(cx, covmap_version, filenames_size, filenames_val);
generate_covmap_record(cx, covmap_version, &filenames_buffer);
}
/// Maps "global" (per-CGU) file ID numbers to their underlying filenames.
@ -225,38 +222,35 @@ fn span_file_name(tcx: TyCtxt<'_>, span: Span) -> Symbol {
/// Generates the contents of the covmap record for this CGU, which mostly
/// consists of a header and a list of filenames. The record is then stored
/// as a global variable in the `__llvm_covmap` section.
fn generate_covmap_record<'ll>(
cx: &CodegenCx<'ll, '_>,
version: u32,
filenames_size: usize,
filenames_val: &'ll llvm::Value,
) {
debug!("cov map: filenames_size = {}, 0-based version = {}", filenames_size, version);
// 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 zero_was_coverage_size_val = cx.const_u32(0);
let version_val = cx.const_u32(version);
let cov_data_header_val = cx.const_struct(
&[zero_was_n_records_val, filenames_size_val, zero_was_coverage_size_val, version_val],
/*packed=*/ false,
fn generate_covmap_record<'ll>(cx: &CodegenCx<'ll, '_>, version: u32, filenames_buffer: &[u8]) {
// A covmap record consists of four target-endian u32 values, followed by
// the encoded filenames table. Two of the header fields are unused in
// modern versions of the LLVM coverage mapping format, and are always 0.
// <https://llvm.org/docs/CoverageMappingFormat.html#llvm-ir-representation>
// See also `src/llvm-project/clang/lib/CodeGen/CoverageMappingGen.cpp`.
let covmap_header = cx.const_struct(
&[
cx.const_u32(0), // (unused)
cx.const_u32(filenames_buffer.len() as u32),
cx.const_u32(0), // (unused)
cx.const_u32(version),
],
/* packed */ false,
);
let covmap_record = cx
.const_struct(&[covmap_header, cx.const_bytes(filenames_buffer)], /* packed */ false);
// Create the complete LLVM coverage data value to add to the LLVM IR
let covmap_data =
cx.const_struct(&[cov_data_header_val, filenames_val], /*packed=*/ false);
let llglobal = llvm::add_global(cx.llmod, cx.val_ty(covmap_data), &llvm_cov::covmap_var_name());
llvm::set_initializer(llglobal, covmap_data);
llvm::set_global_constant(llglobal, true);
llvm::set_linkage(llglobal, llvm::Linkage::PrivateLinkage);
llvm::set_section(llglobal, &llvm_cov::covmap_section_name(cx.llmod));
let covmap_global =
llvm::add_global(cx.llmod, cx.val_ty(covmap_record), &llvm_cov::covmap_var_name());
llvm::set_initializer(covmap_global, covmap_record);
llvm::set_global_constant(covmap_global, true);
llvm::set_linkage(covmap_global, llvm::Linkage::PrivateLinkage);
llvm::set_section(covmap_global, &llvm_cov::covmap_section_name(cx.llmod));
// LLVM's coverage mapping format specifies 8-byte alignment for items in this section.
// <https://llvm.org/docs/CoverageMappingFormat.html>
llvm::set_alignment(llglobal, Align::EIGHT);
cx.add_used_global(llglobal);
llvm::set_alignment(covmap_global, Align::EIGHT);
cx.add_used_global(covmap_global);
}
/// Each CGU will normally only emit coverage metadata for the functions that it actually generates.