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Reorder the state handling in process_cycles().

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This gives a slight speed-up.
This commit is contained in:
Nicholas Nethercote 2019-09-19 16:51:41 +10:00
parent 9b9d2aff8d
commit aaff05bd1c
1 changed files with 9 additions and 6 deletions
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15
src/librustc_data_structures/obligation_forest/mod.rs
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@ -484,13 +484,16 @@ impl<O: ForestObligation> ObligationForest<O> {
debug!("process_cycles()");
for (index, node) in self.nodes.iter().enumerate() {
// For rustc-benchmarks/inflate-0.1.0 this state test is extremely
// hot and the state is almost always `Pending` or `Waiting`. It's
// a win to handle the no-op cases immediately to avoid the cost of
// the function call.
// For some benchmarks this state test is extremely
// hot. It's a win to handle the no-op cases immediately to avoid
// the cost of the function call.
match node.state.get() {
NodeState::Waiting | NodeState::Pending | NodeState::Done | NodeState::Error => {},
_ => self.find_cycles_from_node(&mut stack, processor, index),
// Match arms are in order of frequency. Pending, Success and
// Waiting dominate; the others are rare.
NodeState::Pending => {},
NodeState::Success => self.find_cycles_from_node(&mut stack, processor, index),
NodeState::Waiting | NodeState::Done | NodeState::Error => {},
NodeState::OnDfsStack => self.find_cycles_from_node(&mut stack, processor, index),
}
}