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Avoid re-processing nodes in `find_cycles_from_node`.

This commit is contained in:
Nicholas Nethercote 2019-12-09 14:51:59 +11:00
parent 76916d7a4b
commit cb212938d4
1 changed files with 8 additions and 4 deletions
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12
src/librustc_data_structures/obligation_forest/mod.rs
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@ -584,7 +584,7 @@ impl<O: ForestObligation> ObligationForest<O> {
// function call.
if let NodeState::Success(waiting) = node.state.get() {
if !self.is_still_waiting(waiting) {
self.find_cycles_from_node(&mut stack, processor, index);
self.find_cycles_from_node(&mut stack, processor, index, index);
}
}
}
@ -592,7 +592,8 @@ impl<O: ForestObligation> ObligationForest<O> {
debug_assert!(stack.is_empty());
}
fn find_cycles_from_node<P>(&self, stack: &mut Vec<usize>, processor: &mut P, index: usize)
fn find_cycles_from_node<P>(&self, stack: &mut Vec<usize>, processor: &mut P, min_index: usize,
index: usize)
where P: ObligationProcessor<Obligation=O>
{
let node = &self.nodes[index];
@ -601,8 +602,11 @@ impl<O: ForestObligation> ObligationForest<O> {
match stack.iter().rposition(|&n| n == index) {
None => {
stack.push(index);
for &index in node.dependents.iter() {
self.find_cycles_from_node(stack, processor, index);
for &dep_index in node.dependents.iter() {
// The index check avoids re-considering a node.
if dep_index >= min_index {
self.find_cycles_from_node(stack, processor, min_index, dep_index);
}
}
stack.pop();
}