diff options
3 files changed, 28 insertions, 29 deletions
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs index f4f452d474f..fcfd05ccbac 100644 --- a/compiler/rustc_mir_build/src/build/matches/mod.rs +++ b/compiler/rustc_mir_build/src/build/matches/mod.rs @@ -1006,6 +1006,10 @@ struct Candidate<'pat, 'tcx> { /// If the candidate matches, bindings and ascriptions must be established. extra_data: PatternExtraData<'tcx>, + /// If we filled `self.subcandidate`, we store here the span of the or-pattern they came from. + // Invariant: it is `None` iff `subcandidates.is_empty()`. + or_span: Option<Span>, + /// The block before the `bindings` have been established. pre_binding_block: Option<BasicBlock>, /// The pre-binding block of the next candidate. @@ -1028,6 +1032,7 @@ impl<'tcx, 'pat> Candidate<'pat, 'tcx> { extra_data: flat_pat.extra_data, has_guard, subcandidates: Vec::new(), + or_span: None, otherwise_block: None, pre_binding_block: None, next_candidate_pre_binding_block: None, @@ -1277,7 +1282,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { // // only generates a single switch. candidate.subcandidates = self.create_or_subcandidates(pats, candidate.has_guard); - candidate.match_pairs.pop(); + let first_match_pair = candidate.match_pairs.pop().unwrap(); + candidate.or_span = Some(first_match_pair.pattern.span); split_or_candidate = true; } } @@ -1287,8 +1293,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { // 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 { + for candidate in candidates.iter_mut() { candidate.visit_leaves(|leaf_candidate| new_candidates.push(leaf_candidate)); } self.match_simplified_candidates( @@ -1298,6 +1303,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { otherwise_block, &mut *new_candidates, ); + + for candidate in candidates { + self.merge_trivial_subcandidates(candidate); + } } else { self.match_simplified_candidates( span, @@ -1531,16 +1540,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { &mut or_candidate_refs, ); candidate.subcandidates = or_candidates; - self.merge_trivial_subcandidates(candidate, self.source_info(or_span)); + candidate.or_span = Some(or_span); + self.merge_trivial_subcandidates(candidate); } /// Try to merge all of the subcandidates of the given candidate into one. /// This avoids exponentially large CFGs in cases like `(1 | 2, 3 | 4, ...)`. - fn merge_trivial_subcandidates( - &mut self, - candidate: &mut Candidate<'_, 'tcx>, - source_info: SourceInfo, - ) { + fn merge_trivial_subcandidates(&mut self, candidate: &mut Candidate<'_, 'tcx>) { if candidate.subcandidates.is_empty() || candidate.has_guard { // FIXME(or_patterns; matthewjasper) Don't give up if we have a guard. return; @@ -1550,7 +1556,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { // Not `Iterator::all` because we don't want to short-circuit. for subcandidate in &mut candidate.subcandidates { - self.merge_trivial_subcandidates(subcandidate, source_info); + self.merge_trivial_subcandidates(subcandidate); // FIXME(or_patterns; matthewjasper) Try to be more aggressive here. can_merge &= @@ -1559,6 +1565,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { if can_merge { let any_matches = self.cfg.start_new_block(); + let or_span = candidate.or_span.take().unwrap(); + let source_info = self.source_info(or_span); for subcandidate in mem::take(&mut candidate.subcandidates) { let or_block = subcandidate.pre_binding_block.unwrap(); self.cfg.goto(or_block, source_info, any_matches); diff --git a/compiler/rustc_mir_build/src/build/matches/simplify.rs b/compiler/rustc_mir_build/src/build/matches/simplify.rs index 97b94a0b362..bf1906f370b 100644 --- a/compiler/rustc_mir_build/src/build/matches/simplify.rs +++ b/compiler/rustc_mir_build/src/build/matches/simplify.rs @@ -82,7 +82,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { &*candidate.match_pairs { candidate.subcandidates = self.create_or_subcandidates(pats, has_guard); - candidate.match_pairs.pop(); + let first_match_pair = candidate.match_pairs.pop().unwrap(); + candidate.or_span = Some(first_match_pair.pattern.span); } candidate }) diff --git a/tests/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff b/tests/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff index f1d18b0f7ff..f11c993340f 100644 --- a/tests/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff +++ b/tests/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff @@ -26,18 +26,20 @@ _3 = _1; _2 = move _3 as [u32; 4] (Transmute); StorageDead(_3); - switchInt(_2[0 of 4]) -> [0: bb1, otherwise: bb6]; + switchInt(_2[0 of 4]) -> [0: bb1, otherwise: bb4]; } bb1: { - switchInt(_2[1 of 4]) -> [0: bb2, otherwise: bb6]; + switchInt(_2[1 of 4]) -> [0: bb2, otherwise: bb4]; } bb2: { - switchInt(_2[2 of 4]) -> [0: bb4, 4294901760: bb5, otherwise: bb6]; + switchInt(_2[2 of 4]) -> [0: bb3, 4294901760: bb3, otherwise: bb4]; } bb3: { + StorageLive(_4); + _4 = _2[3 of 4]; StorageLive(_5); StorageLive(_6); _6 = _4; @@ -46,27 +48,15 @@ _0 = Option::<[u8; 4]>::Some(move _5); StorageDead(_5); StorageDead(_4); - goto -> bb7; + goto -> bb5; } bb4: { - StorageLive(_4); - _4 = _2[3 of 4]; - goto -> bb3; - } - - bb5: { - StorageLive(_4); - _4 = _2[3 of 4]; - goto -> bb3; - } - - bb6: { _0 = Option::<[u8; 4]>::None; - goto -> bb7; + goto -> bb5; } - bb7: { + bb5: { StorageDead(_2); return; } |