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Auto merge of #119438 - Zalathar:prepare-mappings, r=cjgillot

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coverage: Prepare mappings separately from injecting statements

These two tasks historically needed to be interleaved, but after various recent changes (including #116046 and #116917) they can now be fully separated.

---

`@rustbot` label +A-code-coverage
This commit is contained in:
bors 2023-12-30 13:39:44 +00:00
commit e45a937a11
4 changed files with 74 additions and 53 deletions
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30
compiler/rustc_mir_transform/src/coverage/counters.rs
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@ -61,27 +61,27 @@ pub(super) struct CoverageCounters {
}
impl CoverageCounters {
pub(super) fn new(basic_coverage_blocks: &CoverageGraph) -> Self {
/// Makes [`BcbCounter`] `Counter`s and `Expressions` for the `BasicCoverageBlock`s directly or
/// indirectly associated with coverage spans, and accumulates additional `Expression`s
/// representing intermediate values.
pub(super) fn make_bcb_counters(
basic_coverage_blocks: &CoverageGraph,
bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool,
) -> Self {
let num_bcbs = basic_coverage_blocks.num_nodes();
Self {
let mut this = Self {
next_counter_id: CounterId::START,
bcb_counters: IndexVec::from_elem_n(None, num_bcbs),
bcb_edge_counters: FxIndexMap::default(),
bcb_has_incoming_edge_counters: BitSet::new_empty(num_bcbs),
expressions: IndexVec::new(),
}
}
};
/// Makes [`BcbCounter`] `Counter`s and `Expressions` for the `BasicCoverageBlock`s directly or
/// indirectly associated with coverage spans, and accumulates additional `Expression`s
/// representing intermediate values.
pub fn make_bcb_counters(
&mut self,
basic_coverage_blocks: &CoverageGraph,
bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool,
) {
MakeBcbCounters::new(self, basic_coverage_blocks).make_bcb_counters(bcb_has_coverage_spans)
MakeBcbCounters::new(&mut this, basic_coverage_blocks)
.make_bcb_counters(bcb_has_coverage_spans);
this
}
fn make_counter(&mut self) -> BcbCounter {
@ -189,8 +189,8 @@ impl CoverageCounters {
.map(|(&(from_bcb, to_bcb), counter_kind)| (from_bcb, to_bcb, counter_kind))
}
pub(super) fn take_expressions(&mut self) -> IndexVec<ExpressionId, Expression> {
std::mem::take(&mut self.expressions)
pub(super) fn into_expressions(self) -> IndexVec<ExpressionId, Expression> {
self.expressions
}
}

82
compiler/rustc_mir_transform/src/coverage/mod.rs
View File

@ -8,7 +8,7 @@ mod spans;
mod tests;
use self::counters::{BcbCounter, CoverageCounters};
use self::graph::CoverageGraph;
use self::graph::{BasicCoverageBlock, CoverageGraph};
use self::spans::CoverageSpans;
use crate::MirPass;
@ -70,7 +70,6 @@ struct Instrumentor<'a, 'tcx> {
mir_body: &'a mut mir::Body<'tcx>,
hir_info: ExtractedHirInfo,
basic_coverage_blocks: CoverageGraph,
coverage_counters: CoverageCounters,
}
impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
@ -80,9 +79,8 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
debug!(?hir_info, "instrumenting {:?}", mir_body.source.def_id());
let basic_coverage_blocks = CoverageGraph::from_mir(mir_body);
let coverage_counters = CoverageCounters::new(&basic_coverage_blocks);
Self { tcx, mir_body, hir_info, basic_coverage_blocks, coverage_counters }
Self { tcx, mir_body, hir_info, basic_coverage_blocks }
}
fn inject_counters(&'a mut self) {
@ -103,25 +101,31 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
// and all `Expression` dependencies (operands) are also generated, for any other
// `BasicCoverageBlock`s not already associated with a coverage span.
let bcb_has_coverage_spans = |bcb| coverage_spans.bcb_has_coverage_spans(bcb);
self.coverage_counters
.make_bcb_counters(&self.basic_coverage_blocks, bcb_has_coverage_spans);
let coverage_counters = CoverageCounters::make_bcb_counters(
&self.basic_coverage_blocks,
bcb_has_coverage_spans,
);
let mappings = self.create_mappings_and_inject_coverage_statements(&coverage_spans);
let mappings = self.create_mappings(&coverage_spans, &coverage_counters);
self.inject_coverage_statements(bcb_has_coverage_spans, &coverage_counters);
self.mir_body.function_coverage_info = Some(Box::new(FunctionCoverageInfo {
function_source_hash: self.hir_info.function_source_hash,
num_counters: self.coverage_counters.num_counters(),
expressions: self.coverage_counters.take_expressions(),
num_counters: coverage_counters.num_counters(),
expressions: coverage_counters.into_expressions(),
mappings,
}));
}
/// For each [`BcbCounter`] associated with a BCB node or BCB edge, create
/// any corresponding mappings (for BCB nodes only), and inject any necessary
/// coverage statements into MIR.
fn create_mappings_and_inject_coverage_statements(
&mut self,
/// For each coverage span extracted from MIR, create a corresponding
/// mapping.
///
/// Precondition: All BCBs corresponding to those spans have been given
/// coverage counters.
fn create_mappings(
&self,
coverage_spans: &CoverageSpans,
coverage_counters: &CoverageCounters,
) -> Vec<Mapping> {
let source_map = self.tcx.sess.source_map();
let body_span = self.hir_info.body_span;
@ -131,30 +135,42 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
let file_name =
Symbol::intern(&source_file.name.for_codegen(self.tcx.sess).to_string_lossy());
let mut mappings = Vec::new();
// Process the counters and spans associated with BCB nodes.
for (bcb, counter_kind) in self.coverage_counters.bcb_node_counters() {
let spans = coverage_spans.spans_for_bcb(bcb);
let has_mappings = !spans.is_empty();
// If this BCB has any coverage spans, add corresponding mappings to
// the mappings table.
if has_mappings {
let term = counter_kind.as_term();
mappings.extend(spans.iter().map(|&span| {
let code_region = make_code_region(source_map, file_name, span, body_span);
Mapping { code_region, term }
}));
}
coverage_spans
.bcbs_with_coverage_spans()
// For each BCB with spans, get a coverage term for its counter.
.map(|(bcb, spans)| {
let term = coverage_counters
.bcb_counter(bcb)
.expect("all BCBs with spans were given counters")
.as_term();
(term, spans)
})
// Flatten the spans into individual term/span pairs.
.flat_map(|(term, spans)| spans.iter().map(move |&span| (term, span)))
// Convert each span to a code region, and create the final mapping.
.map(|(term, span)| {
let code_region = make_code_region(source_map, file_name, span, body_span);
Mapping { term, code_region }
})
.collect::<Vec<_>>()
}
/// For each BCB node or BCB edge that has an associated coverage counter,
/// inject any necessary coverage statements into MIR.
fn inject_coverage_statements(
&mut self,
bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool,
coverage_counters: &CoverageCounters,
) {
// Process the counters associated with BCB nodes.
for (bcb, counter_kind) in coverage_counters.bcb_node_counters() {
let do_inject = match counter_kind {
// Counter-increment statements always need to be injected.
BcbCounter::Counter { .. } => true,
// The only purpose of expression-used statements is to detect
// when a mapping is unreachable, so we only inject them for
// expressions with one or more mappings.
BcbCounter::Expression { .. } => has_mappings,
BcbCounter::Expression { .. } => bcb_has_coverage_spans(bcb),
};
if do_inject {
inject_statement(
@ -166,7 +182,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
}
// Process the counters associated with BCB edges.
for (from_bcb, to_bcb, counter_kind) in self.coverage_counters.bcb_edge_counters() {
for (from_bcb, to_bcb, counter_kind) in coverage_counters.bcb_edge_counters() {
let do_inject = match counter_kind {
// Counter-increment statements always need to be injected.
BcbCounter::Counter { .. } => true,
@ -192,8 +208,6 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
// Inject a counter into the newly-created BB.
inject_statement(self.mir_body, self.make_mir_coverage_kind(counter_kind), new_bb);
}
mappings
}
fn make_mir_coverage_kind(&self, counter_kind: &BcbCounter) -> CoverageKind {

9
compiler/rustc_mir_transform/src/coverage/spans.rs
View File

@ -48,8 +48,13 @@ impl CoverageSpans {
!self.bcb_to_spans[bcb].is_empty()
}
pub(super) fn spans_for_bcb(&self, bcb: BasicCoverageBlock) -> &[Span] {
&self.bcb_to_spans[bcb]
pub(super) fn bcbs_with_coverage_spans(
&self,
) -> impl Iterator<Item = (BasicCoverageBlock, &[Span])> {
self.bcb_to_spans.iter_enumerated().filter_map(|(bcb, spans)| {
// Only yield BCBs that have at least one coverage span.
(!spans.is_empty()).then_some((bcb, spans.as_slice()))
})
}
}

6
compiler/rustc_mir_transform/src/coverage/tests.rs
View File

@ -630,8 +630,10 @@ fn test_make_bcb_counters() {
// coverage spans for BCBs 1 and 2. Now we skip that step and just tell
// BCB counter construction that those BCBs have spans.
let bcb_has_coverage_spans = |bcb: BasicCoverageBlock| (1..=2).contains(&bcb.as_usize());
let mut coverage_counters = counters::CoverageCounters::new(&basic_coverage_blocks);
coverage_counters.make_bcb_counters(&basic_coverage_blocks, bcb_has_coverage_spans);
let coverage_counters = counters::CoverageCounters::make_bcb_counters(
&basic_coverage_blocks,
bcb_has_coverage_spans,
);
assert_eq!(coverage_counters.num_expressions(), 0);
assert_eq!(