bjoernager/rust
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coverage: Store covfun_section_name in the codegen context

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Adding an extra `OnceCell` to `CrateCoverageContext` is much nicer than trying
to thread this string through multiple layers of function calls that already
have access to the context.
This commit is contained in:
Zalathar 2024-10-24 22:05:42 +11:00
parent 0a96176533
commit 0356908cf5
2 changed files with 24 additions and 27 deletions
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7
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
View file

@ -1,4 +1,4 @@
use std::ffi::{CStr, CString};
use std::ffi::CString;
use itertools::Itertools as _;
use rustc_abi::Align;
@ -81,7 +81,6 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
generate_covmap_record(cx, covmap_version, filenames_size, filenames_val);
let mut unused_function_names = Vec::new();
let covfun_section_name = coverageinfo::covfun_section_name(cx);
// Encode coverage mappings and generate function records
for (instance, function_coverage) in function_coverage_entries {
@ -112,7 +111,6 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
generate_covfun_record(
cx,
&covfun_section_name,
mangled_function_name,
source_hash,
filenames_ref,
@ -360,7 +358,6 @@ fn generate_covmap_record<'ll>(
/// as a global variable in the `__llvm_covfun` section.
fn generate_covfun_record(
cx: &CodegenCx<'_, '_>,
covfun_section_name: &CStr,
mangled_function_name: &str,
source_hash: u64,
filenames_ref: u64,
@ -401,7 +398,7 @@ fn generate_covfun_record(
llvm::set_global_constant(llglobal, true);
llvm::set_linkage(llglobal, llvm::Linkage::LinkOnceODRLinkage);
llvm::set_visibility(llglobal, llvm::Visibility::Hidden);
llvm::set_section(llglobal, covfun_section_name);
llvm::set_section(llglobal, cx.covfun_section_name());
// LLVM's coverage mapping format specifies 8-byte alignment for items in this section.
llvm::set_alignment(llglobal, Align::EIGHT);
if cx.target_spec().supports_comdat() {

44
compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
View file

@ -1,5 +1,5 @@
use std::cell::RefCell;
use std::ffi::CString;
use std::cell::{OnceCell, RefCell};
use std::ffi::{CStr, CString};
use libc::c_uint;
use rustc_codegen_ssa::traits::{
@ -29,6 +29,8 @@ pub(crate) struct CrateCoverageContext<'ll, 'tcx> {
RefCell<FxIndexMap<Instance<'tcx>, FunctionCoverageCollector<'tcx>>>,
pub(crate) pgo_func_name_var_map: RefCell<FxHashMap<Instance<'tcx>, &'ll llvm::Value>>,
pub(crate) mcdc_condition_bitmap_map: RefCell<FxHashMap<Instance<'tcx>, Vec<&'ll llvm::Value>>>,
covfun_section_name: OnceCell<CString>,
}
impl<'ll, 'tcx> CrateCoverageContext<'ll, 'tcx> {
@ -37,6 +39,7 @@ impl<'ll, 'tcx> CrateCoverageContext<'ll, 'tcx> {
function_coverage_map: Default::default(),
pgo_func_name_var_map: Default::default(),
mcdc_condition_bitmap_map: Default::default(),
covfun_section_name: Default::default(),
}
}
@ -63,13 +66,28 @@ impl<'ll, 'tcx> CrateCoverageContext<'ll, 'tcx> {
}
}
// These methods used to be part of trait `CoverageInfoMethods`, which no longer
// exists after most coverage code was moved out of SSA.
impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
pub(crate) fn coverageinfo_finalize(&self) {
mapgen::finalize(self)
}
/// Returns the section name to use when embedding per-function coverage information
/// in the object file, according to the target's object file format. LLVM's coverage
/// tools use information 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)
fn covfun_section_name(&self) -> &CStr {
self.coverage_cx().covfun_section_name.get_or_init(|| {
CString::new(llvm::build_byte_buffer(|s| unsafe {
llvm::LLVMRustCoverageWriteFuncSectionNameToString(self.llmod, s);
}))
.expect("covfun section name should not contain NUL")
})
}
/// For LLVM codegen, returns a function-specific `Value` for a global
/// string, to hold the function name passed to LLVM intrinsic
/// `instrprof.increment()`. The `Value` is only created once per instance.
@ -278,21 +296,3 @@ pub(crate) fn hash_bytes(bytes: &[u8]) -> u64 {
pub(crate) fn mapping_version() -> u32 {
unsafe { llvm::LLVMRustCoverageMappingVersion() }
}
/// 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<'_, '_>) -> CString {
CString::new(llvm::build_byte_buffer(|s| unsafe {
llvm::LLVMRustCoverageWriteFuncSectionNameToString(cx.llmod, s);
}))
.expect("covfun section name should not contain NUL")
}