bjoernager/rust
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Simplify path compression logic

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This commit is contained in:
Amanda Stjerna 2024-05-17 15:11:59 +02:00
parent d2a01760bc
commit 905db03b28
3 changed files with 14 additions and 20 deletions
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19
compiler/rustc_data_structures/src/graph/scc/mod.rs
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@ -393,38 +393,23 @@ where
// `InCycleWith` upwards.
// This loop performs the downward link encoding mentioned above. Details below!
let node_state = {
let mut annotation = (self.to_annotation)(node);
loop {
debug!("find_state(r = {node:?} in state {:?})", self.node_states[node]);
match self.node_states[node] {
NodeState::NotVisited => break NodeState::NotVisited,
NodeState::BeingVisited { depth, annotation: previous_annotation } => {
break NodeState::BeingVisited {
depth,
annotation: previous_annotation.merge_scc(annotation),
};
}
s @ (NodeState::NotVisited | NodeState::BeingVisited{..} | NodeState::InCycle { .. }) => break s,
NodeState::InCycleWith { parent } => {
// We test this, to be extremely sure that we never
// ever break our termination condition for the
// reverse iteration loop.
assert!(node != parent, "Node can not be in cycle with itself");
annotation = annotation.merge_scc((self.to_annotation)(node));
// Store the previous node as an inverted list link
self.node_states[node] = NodeState::InCycleWith { parent: previous_node };
// Update to parent node.
previous_node = node;
node = parent;
}
NodeState::InCycle { scc_index, annotation: previous_annotation } => {
break NodeState::InCycle {
scc_index,
annotation: previous_annotation.merge_scc(annotation),
};
}
}
}
};