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Tweak simple or-pattern expansion

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This commit is contained in:
Nadrieril 2024-03-20 15:53:25 +01:00
parent 6b84d7566e
commit e74b30e3a9
1 changed files with 21 additions and 16 deletions
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37
compiler/rustc_mir_build/src/build/matches/mod.rs
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@ -1364,9 +1364,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
otherwise_block: BasicBlock,
candidates: &mut [&mut Candidate<'pat, 'tcx>],
) {
let mut split_or_candidate = false;
for candidate in &mut *candidates {
if let [MatchPair { test_case: TestCase::Or { .. }, .. }] = &*candidate.match_pairs {
let expand_or_pats = candidates.iter().any(|candidate| {
matches!(&*candidate.match_pairs, [MatchPair { test_case: TestCase::Or { .. }, .. }])
});
ensure_sufficient_stack(|| {
if expand_or_pats {
// Split a candidate in which the only match-pair is an or-pattern into multiple
// candidates. This is so that
//
@ -1376,30 +1379,32 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// }
//
// only generates a single switch.
let match_pair = candidate.match_pairs.pop().unwrap();
self.create_or_subcandidates(candidate, match_pair);
split_or_candidate = true;
}
}
ensure_sufficient_stack(|| {
if split_or_candidate {
// At least one of the candidates has been split into subcandidates.
// We need to change the candidate list to include those.
let mut new_candidates = Vec::new();
for candidate in candidates.iter_mut() {
candidate.visit_leaves(|leaf_candidate| new_candidates.push(leaf_candidate));
if let [MatchPair { test_case: TestCase::Or { .. }, .. }] =
&*candidate.match_pairs
{
let match_pair = candidate.match_pairs.pop().unwrap();
self.create_or_subcandidates(candidate, match_pair);
for subcandidate in candidate.subcandidates.iter_mut() {
new_candidates.push(subcandidate);
}
} else {
new_candidates.push(candidate);
}
}
self.match_candidates(
span,
scrutinee_span,
start_block,
otherwise_block,
&mut *new_candidates,
new_candidates.as_mut_slice(),
);
for candidate in candidates {
self.merge_trivial_subcandidates(candidate);
if !candidate.subcandidates.is_empty() {
self.merge_trivial_subcandidates(candidate);
}
}
} else {
self.match_simplified_candidates(