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coverage: Revert "unused local file IDs" due to empty function names

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This reverts commit 3b22c21dd8, reversing
changes made to 5f292eea6d.
This commit is contained in:
Zalathar
2025-05-27 23:25:57 +10:00
parent d76fe15402
commit 3f526eeec4
16 changed files with 62 additions and 154 deletions
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26
compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs
View File

@@ -155,20 +155,6 @@ pub(crate) struct Regions {
impl Regions {
/// Returns true if none of this structure's tables contain any regions.
pub(crate) fn has_no_regions(&self) -> bool {
// Every region has a span, so if there are no spans then there are no regions.
self.all_cov_spans().next().is_none()
}
pub(crate) fn all_cov_spans(&self) -> impl Iterator<Item = &CoverageSpan> {
macro_rules! iter_cov_spans {
( $( $regions:expr ),* $(,)? ) => {
std::iter::empty()
$(
.chain( $regions.iter().map(|region| &region.cov_span) )
)*
}
}
let Self {
code_regions,
expansion_regions,
@@ -177,13 +163,11 @@ impl Regions {
mcdc_decision_regions,
} = self;
iter_cov_spans!(
code_regions,
expansion_regions,
branch_regions,
mcdc_branch_regions,
mcdc_decision_regions,
)
code_regions.is_empty()
&& expansion_regions.is_empty()
&& branch_regions.is_empty()
&& mcdc_branch_regions.is_empty()
&& mcdc_decision_regions.is_empty()
}
}

44
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
View File

@@ -11,7 +11,6 @@ use rustc_abi::Align;
use rustc_codegen_ssa::traits::{
BaseTypeCodegenMethods as _, ConstCodegenMethods, StaticCodegenMethods,
};
use rustc_index::IndexVec;
use rustc_middle::mir::coverage::{
BasicCoverageBlock, CovTerm, CoverageIdsInfo, Expression, FunctionCoverageInfo, Mapping,
MappingKind, Op,
@@ -105,16 +104,6 @@ fn fill_region_tables<'tcx>(
ids_info: &'tcx CoverageIdsInfo,
covfun: &mut CovfunRecord<'tcx>,
) {
// If this function is unused, replace all counters with zero.
let counter_for_bcb = |bcb: BasicCoverageBlock| -> ffi::Counter {
let term = if covfun.is_used {
ids_info.term_for_bcb[bcb].expect("every BCB in a mapping was given a term")
} else {
CovTerm::Zero
};
ffi::Counter::from_term(term)
};
// Currently a function's mappings must all be in the same file, so use the
// first mapping's span to determine the file.
let source_map = tcx.sess.source_map();
@@ -126,12 +115,6 @@ fn fill_region_tables<'tcx>(
let local_file_id = covfun.virtual_file_mapping.push_file(&source_file);
// If this testing flag is set, add an extra unused entry to the local
// file table, to help test the code for detecting unused file IDs.
if tcx.sess.coverage_inject_unused_local_file() {
covfun.virtual_file_mapping.push_file(&source_file);
}
// In rare cases, _all_ of a function's spans are discarded, and coverage
// codegen needs to handle that gracefully to avoid #133606.
// It's hard for tests to trigger this organically, so instead we set
@@ -152,6 +135,16 @@ fn fill_region_tables<'tcx>(
// For each counter/region pair in this function+file, convert it to a
// form suitable for FFI.
for &Mapping { ref kind, span } in &fn_cov_info.mappings {
// If this function is unused, replace all counters with zero.
let counter_for_bcb = |bcb: BasicCoverageBlock| -> ffi::Counter {
let term = if covfun.is_used {
ids_info.term_for_bcb[bcb].expect("every BCB in a mapping was given a term")
} else {
CovTerm::Zero
};
ffi::Counter::from_term(term)
};
let Some(coords) = make_coords(span) else { continue };
let cov_span = coords.make_coverage_span(local_file_id);
@@ -184,19 +177,6 @@ fn fill_region_tables<'tcx>(
}
}
/// LLVM requires all local file IDs to have at least one mapping region.
/// If that's not the case, skip this function, to avoid an assertion failure
/// (or worse) in LLVM.
fn check_local_file_table(covfun: &CovfunRecord<'_>) -> bool {
let mut local_file_id_seen =
IndexVec::<u32, _>::from_elem_n(false, covfun.virtual_file_mapping.local_file_table.len());
for cov_span in covfun.regions.all_cov_spans() {
local_file_id_seen[cov_span.file_id] = true;
}
local_file_id_seen.into_iter().all(|seen| seen)
}
/// 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.
@@ -205,10 +185,6 @@ pub(crate) fn generate_covfun_record<'tcx>(
global_file_table: &GlobalFileTable,
covfun: &CovfunRecord<'tcx>,
) {
if !check_local_file_table(covfun) {
return;
}
let &CovfunRecord {
mangled_function_name,
source_hash,

28
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
View File

@@ -39,10 +39,7 @@ impl Coords {
/// or other expansions), and if it does happen then skipping a span or function is
/// better than an ICE or `llvm-cov` failure that the user might have no way to avoid.
pub(crate) fn make_coords(source_map: &SourceMap, file: &SourceFile, span: Span) -> Option<Coords> {
if span.is_empty() {
debug_assert!(false, "can't make coords from empty span: {span:?}");
return None;
}
let span = ensure_non_empty_span(source_map, span)?;
let lo = span.lo();
let hi = span.hi();
@@ -73,6 +70,29 @@ pub(crate) fn make_coords(source_map: &SourceMap, file: &SourceFile, span: Span)
})
}
fn ensure_non_empty_span(source_map: &SourceMap, span: Span) -> Option<Span> {
if !span.is_empty() {
return Some(span);
}
// The span is empty, so try to enlarge it to cover an adjacent '{' or '}'.
source_map
.span_to_source(span, |src, start, end| try {
// Adjusting span endpoints by `BytePos(1)` is normally a bug,
// but in this case we have specifically checked that the character
// we're skipping over is one of two specific ASCII characters, so
// adjusting by exactly 1 byte is correct.
if src.as_bytes().get(end).copied() == Some(b'{') {
Some(span.with_hi(span.hi() + BytePos(1)))
} else if start > 0 && src.as_bytes()[start - 1] == b'}' {
Some(span.with_lo(span.lo() - BytePos(1)))
} else {
None
}
})
.ok()?
}
/// If `llvm-cov` sees a source region that is improperly ordered (end < start),
/// it will immediately exit with a fatal error. To prevent that from happening,
/// discard regions that are improperly ordered, or might be interpreted in a