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Use otherwise_block for or-pattern shortcutting

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Nadrieril 2024-03-04 01:41:37 +01:00
parent 5fe2ca65cf
commit 764f086f2c
1 changed files with 8 additions and 3 deletions
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11
compiler/rustc_mir_build/src/build/matches/mod.rs
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@ -1585,18 +1585,23 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// We could add them to the or-candidates before the call to `test_or_pattern` but this // We could add them to the or-candidates before the call to `test_or_pattern` but this
// would make it impossible to detect simplifiable or-patterns. That would guarantee // would make it impossible to detect simplifiable or-patterns. That would guarantee
// exponentially large CFGs for cases like `(1 | 2, 3 | 4, ...)`. // exponentially large CFGs for cases like `(1 | 2, 3 | 4, ...)`.
let mut last_otherwise = None;
first_candidate.visit_leaves(|leaf_candidate| {
last_otherwise = leaf_candidate.otherwise_block;
});
first_candidate.visit_leaves(|leaf_candidate| { first_candidate.visit_leaves(|leaf_candidate| {
assert!(leaf_candidate.match_pairs.is_empty()); assert!(leaf_candidate.match_pairs.is_empty());
leaf_candidate.match_pairs.extend(remaining_match_pairs.iter().cloned()); leaf_candidate.match_pairs.extend(remaining_match_pairs.iter().cloned());
let or_start = leaf_candidate.pre_binding_block.unwrap(); let or_start = leaf_candidate.pre_binding_block.unwrap();
// In a case like `(P | Q, R | S)`, if `P` succeeds and `R | S` fails, we know `(Q, // In a case like `(P | Q, R | S)`, if `P` succeeds and `R | S` fails, we know `(Q,
// R | S)` will fail too. If there is no guard, we skip testing of `Q` by branching // R | S)` will fail too. If there is no guard, we skip testing of `Q` by branching
// directly to `remainder_start`. If there is a guard, `or_otherwise` can be reached // directly to `last_otherwise`. If there is a guard,
// by guard failure as well, so we can't skip `Q`. // `leaf_candidate.otherwise_block` can be reached by guard failure as well, so we
// can't skip `Q`.
let or_otherwise = if leaf_candidate.has_guard { let or_otherwise = if leaf_candidate.has_guard {
leaf_candidate.otherwise_block.unwrap() leaf_candidate.otherwise_block.unwrap()
} else { } else {
remainder_start last_otherwise.unwrap()
}; };
self.test_candidates_with_or( self.test_candidates_with_or(
span, span,