bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

coverage: Extract function metadata handling to a covfun submodule

Browse source
This commit is contained in:
Zalathar 2024-12-11 14:28:55 +11:00
parent 33c245b9e9
commit 7c4ac71ad1
2 changed files with 206 additions and 166 deletions
Download patch file Download diff file Expand all files Collapse all files

174
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
View file

@ -1,4 +1,3 @@
use std::ffi::CString;
use std::iter;
use itertools::Itertools as _;
@ -9,21 +8,21 @@ use rustc_codegen_ssa::traits::{
use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_index::IndexVec;
use rustc_middle::mir::coverage::MappingKind;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{bug, mir};
use rustc_session::RemapFileNameExt;
use rustc_session::config::RemapPathScopeComponents;
use rustc_span::def_id::DefIdSet;
use rustc_span::{Span, Symbol};
use rustc_target::spec::HasTargetSpec;
use tracing::debug;
use crate::common::CodegenCx;
use crate::coverageinfo::llvm_cov;
use crate::coverageinfo::map_data::FunctionCoverage;
use crate::coverageinfo::{ffi, llvm_cov};
use crate::llvm;
mod covfun;
/// Generates and exports the coverage map, which is embedded in special
/// linker sections in the final binary.
///
@ -88,38 +87,13 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
// Encode coverage mappings and generate function records
for (instance, function_coverage) in function_coverage_map {
debug!("Generate function coverage for {}, {:?}", cx.codegen_unit.name(), instance);
let mangled_function_name = tcx.symbol_name(instance).name;
let source_hash = function_coverage.source_hash();
let is_used = function_coverage.is_used();
let coverage_mapping_buffer =
encode_mappings_for_function(tcx, &global_file_table, &function_coverage);
if coverage_mapping_buffer.is_empty() {
if function_coverage.is_used() {
bug!(
"A used function should have had coverage mapping data but did not: {}",
mangled_function_name
);
} else {
debug!("unused function had no coverage mapping data: {}", mangled_function_name);
continue;
}
}
if !is_used {
unused_function_names.push(mangled_function_name);
}
generate_covfun_record(
covfun::prepare_and_generate_covfun_record(
cx,
mangled_function_name,
source_hash,
&global_file_table,
filenames_ref,
coverage_mapping_buffer,
is_used,
&mut unused_function_names,
instance,
&function_coverage,
);
}
@ -236,83 +210,6 @@ fn span_file_name(tcx: TyCtxt<'_>, span: Span) -> Symbol {
Symbol::intern(&name)
}
/// Using the expressions and counter regions collected for a single function,
/// generate the variable-sized payload of its corresponding `__llvm_covfun`
/// entry. The payload is returned as a vector of bytes.
///
/// Newly-encountered filenames will be added to the global file table.
fn encode_mappings_for_function(
tcx: TyCtxt<'_>,
global_file_table: &GlobalFileTable,
function_coverage: &FunctionCoverage<'_>,
) -> Vec<u8> {
let counter_regions = function_coverage.counter_regions();
if counter_regions.is_empty() {
return Vec::new();
}
let expressions = function_coverage.counter_expressions().collect::<Vec<_>>();
let mut virtual_file_mapping = VirtualFileMapping::default();
let mut code_regions = vec![];
let mut branch_regions = vec![];
let mut mcdc_branch_regions = vec![];
let mut mcdc_decision_regions = vec![];
// Currently a function's mappings must all be in the same file as its body span.
let file_name = span_file_name(tcx, function_coverage.function_coverage_info.body_span);
// Look up the global file ID for that filename.
let global_file_id = global_file_table.global_file_id_for_file_name(file_name);
// Associate that global file ID with a local file ID for this function.
let local_file_id = virtual_file_mapping.local_id_for_global(global_file_id);
debug!(" file id: {local_file_id:?} => {global_file_id:?} = '{file_name:?}'");
// For each counter/region pair in this function+file, convert it to a
// form suitable for FFI.
for (mapping_kind, region) in counter_regions {
debug!("Adding counter {mapping_kind:?} to map for {region:?}");
let span = ffi::CoverageSpan::from_source_region(local_file_id, region);
match mapping_kind {
MappingKind::Code(term) => {
code_regions.push(ffi::CodeRegion { span, counter: ffi::Counter::from_term(term) });
}
MappingKind::Branch { true_term, false_term } => {
branch_regions.push(ffi::BranchRegion {
span,
true_counter: ffi::Counter::from_term(true_term),
false_counter: ffi::Counter::from_term(false_term),
});
}
MappingKind::MCDCBranch { true_term, false_term, mcdc_params } => {
mcdc_branch_regions.push(ffi::MCDCBranchRegion {
span,
true_counter: ffi::Counter::from_term(true_term),
false_counter: ffi::Counter::from_term(false_term),
mcdc_branch_params: ffi::mcdc::BranchParameters::from(mcdc_params),
});
}
MappingKind::MCDCDecision(mcdc_decision_params) => {
mcdc_decision_regions.push(ffi::MCDCDecisionRegion {
span,
mcdc_decision_params: ffi::mcdc::DecisionParameters::from(mcdc_decision_params),
});
}
}
}
// Encode the function's coverage mappings into a buffer.
llvm_cov::write_function_mappings_to_buffer(
&virtual_file_mapping.into_vec(),
&expressions,
&code_regions,
&branch_regions,
&mcdc_branch_regions,
&mcdc_decision_regions,
)
}
/// 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.
@ -350,61 +247,6 @@ fn generate_covmap_record<'ll>(
cx.add_used_global(llglobal);
}
/// Generates the contents of the covfun record for this function, which
/// contains the function's coverage mapping data. The record is then stored
/// as a global variable in the `__llvm_covfun` section.
fn generate_covfun_record(
cx: &CodegenCx<'_, '_>,
mangled_function_name: &str,
source_hash: u64,
filenames_ref: u64,
coverage_mapping_buffer: Vec<u8>,
is_used: bool,
) {
// Concatenate the encoded coverage mappings
let coverage_mapping_size = coverage_mapping_buffer.len();
let coverage_mapping_val = cx.const_bytes(&coverage_mapping_buffer);
let func_name_hash = llvm_cov::hash_bytes(mangled_function_name.as_bytes());
let func_name_hash_val = cx.const_u64(func_name_hash);
let coverage_mapping_size_val = cx.const_u32(coverage_mapping_size as u32);
let source_hash_val = cx.const_u64(source_hash);
let filenames_ref_val = cx.const_u64(filenames_ref);
let func_record_val = cx.const_struct(
&[
func_name_hash_val,
coverage_mapping_size_val,
source_hash_val,
filenames_ref_val,
coverage_mapping_val,
],
/*packed=*/ true,
);
// Choose a variable name to hold this function's covfun data.
// Functions that are used have a suffix ("u") to distinguish them from
// unused copies of the same function (from different CGUs), so that if a
// linker sees both it won't discard the used copy's data.
let func_record_var_name =
CString::new(format!("__covrec_{:X}{}", func_name_hash, if is_used { "u" } else { "" }))
.unwrap();
debug!("function record var name: {:?}", func_record_var_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, cx.covfun_section_name());
// 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);
if cx.target_spec().supports_comdat() {
llvm::set_comdat(cx.llmod, llglobal, &func_record_var_name);
}
cx.add_used_global(llglobal);
}
/// Each CGU will normally only emit coverage metadata for the functions that it actually generates.
/// But since we don't want unused functions to disappear from coverage reports, we also scan for
/// functions that were instrumented but are not participating in codegen.