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Rollup merge of #114008 - Zalathar:covfun-section-name, r=cjgillot

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coverage: Obtain the `__llvm_covfun` section name outside a per-function loop

This section name is always constant for a given target, but obtaining it from LLVM requires a few intermediate allocations. There's no need to do so repeatedly from inside a per-function loop.
This commit is contained in:
Matthias Krüger 2023-07-25 19:21:36 +02:00 committed by GitHub
commit 24e34e2014
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 31 additions and 8 deletions
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11
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
View File

@ -100,9 +100,11 @@ pub fn finalize(cx: &CodegenCx<'_, '_>) {
// Generate the LLVM IR representation of the coverage map and store it in a well-known global
let cov_data_val = mapgen.generate_coverage_map(cx, version, filenames_size, filenames_val);
let covfun_section_name = coverageinfo::covfun_section_name(cx);
for (mangled_function_name, source_hash, is_used, coverage_mapping_buffer) in function_data {
save_function_record(
cx,
&covfun_section_name,
mangled_function_name,
source_hash,
filenames_ref,
@ -228,6 +230,7 @@ fn generate_coverage_map<'ll>(
/// specific, well-known section and name.
fn save_function_record(
cx: &CodegenCx<'_, '_>,
covfun_section_name: &str,
mangled_function_name: &str,
source_hash: u64,
filenames_ref: u64,
@ -254,7 +257,13 @@ fn save_function_record(
/*packed=*/ true,
);
coverageinfo::save_func_record_to_mod(cx, func_name_hash, func_record_val, is_used);
coverageinfo::save_func_record_to_mod(
cx,
covfun_section_name,
func_name_hash,
func_record_val,
is_used,
);
}
/// When finalizing the coverage map, `FunctionCoverage` only has the `CodeRegion`s and counters for

28
compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
View File

@ -408,6 +408,7 @@ pub(crate) fn save_cov_data_to_mod<'ll, 'tcx>(
pub(crate) fn save_func_record_to_mod<'ll, 'tcx>(
cx: &CodegenCx<'ll, 'tcx>,
covfun_section_name: &str,
func_name_hash: u64,
func_record_val: &'ll llvm::Value,
is_used: bool,
@ -423,20 +424,33 @@ pub(crate) fn save_func_record_to_mod<'ll, 'tcx>(
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);
debug!("function record section name: {:?}", covfun_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_section(llglobal, covfun_section_name);
llvm::set_alignment(llglobal, VAR_ALIGN_BYTES);
llvm::set_comdat(cx.llmod, llglobal, &func_record_var_name);
cx.add_used_global(llglobal);
}
/// Returns the section name string to pass through to the linker when embedding
/// per-function coverage information in the object file, according to the target
/// platform's object file format.
///
/// LLVM's coverage tools read coverage mapping details from this section when
/// producing coverage reports.
///
/// Typical values are:
/// - `__llvm_covfun` on Linux
/// - `__LLVM_COV,__llvm_covfun` on macOS (includes `__LLVM_COV,` segment prefix)
/// - `.lcovfun$M` on Windows (includes `$M` sorting suffix)
pub(crate) fn covfun_section_name(cx: &CodegenCx<'_, '_>) -> String {
llvm::build_string(|s| unsafe {
llvm::LLVMRustCoverageWriteFuncSectionNameToString(cx.llmod, s);
})
.expect("Rust Coverage function record section name failed UTF-8 conversion")
}