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perf(semantic): grow unresolved_references by doubling #4387

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perf(semantic): grow unresolved_references by doubling #4387

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24b149d
perf(semantic): grow `unresolved_references` by doubling
overlookmotel Jul 21, 2024
593a1a6
Dummy comment to re-run benchmarks
overlookmotel Jul 21, 2024
4dd2c9a
Revert "Dummy comment to re-run benchmarks"
overlookmotel Jul 21, 2024
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16 changes: 12 additions & 4 deletions crates/oxc_semantic/src/builder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -110,7 +110,7 @@ impl<'a> SemanticBuilder<'a> {
// This is just an estimate of a good initial size, but certainly better than
// `Vec`'s default initial capacity of 4.
let mut unresolved_references = vec![];
unresolved_references.resize_with(16, Default::default);
unresolved_references.resize_with(16, UnresolvedReferences::default);

let trivias = Trivias::default();
Self {
Expand Down Expand Up @@ -481,11 +481,19 @@ impl<'a> Visit<'a> for SemanticBuilder<'a> {
self.scope.get_bindings_mut(self.current_scope_id).extend(bindings);
}

// Increment scope depth, and ensure stack is large enough that
// `self.unresolved_references[self.current_scope_depth]` is initialized
// Increment scope depth.
// If stack is not large enough, double its size.
// This ensures `self.unresolved_references[self.current_scope_depth]` is initialized.
// We could just push a single entry to stack, but doubling growth strategy makes this branch
// more consistently not taken, so can mark it `#[cold]`.
self.current_scope_depth += 1;
if self.unresolved_references.len() <= self.current_scope_depth {
self.unresolved_references.push(UnresolvedReferences::default());
#[cold]
fn grow(builder: &mut SemanticBuilder) {
let new_len = builder.unresolved_references.len() * 2;
builder.unresolved_references.resize_with(new_len, UnresolvedReferences::default);
}
grow(self);
}
}

Expand Down