use rustc_data_structures::fx::FxHashMap;
use rustc_index::bit_set::HybridBitSet;
use rustc_middle::mir;
#[derive(Default)]
pub(super) struct TransitiveRelation {
relations: FxHashMap<mir::Local, Vec<mir::Local>>,
}
impl TransitiveRelation {
pub fn add(&mut self, a: mir::Local, b: mir::Local) {
self.relations.entry(a).or_default().push(b);
}
pub fn reachable_from(&self, a: mir::Local, domain_size: usize) -> HybridBitSet<mir::Local> {
let mut seen = HybridBitSet::new_empty(domain_size);
let mut stack = vec![a];
while let Some(u) = stack.pop() {
if let Some(edges) = self.relations.get(&u) {
for &v in edges {
if seen.insert(v) {
stack.push(v);
}
}
}
}
seen
}
}