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add ReverseSccGraph::compute

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This commit is contained in:
lcnr 2025-05-03 02:47:14 +00:00
parent 2d5ffc513f
commit ad3c35bea5
1 changed files with 27 additions and 18 deletions
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45
compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
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@ -7,6 +7,8 @@ use rustc_middle::ty::RegionVid;
use crate::RegionInferenceContext;
use crate::constraints::ConstraintSccIndex;
use crate::region_infer::ConstraintSccs;
use crate::universal_regions::UniversalRegions;
pub(crate) struct ReverseSccGraph {
graph: VecGraph<ConstraintSccIndex>,
@ -19,6 +21,29 @@ pub(crate) struct ReverseSccGraph {
}
impl ReverseSccGraph {
pub(super) fn compute(
constraint_sccs: &ConstraintSccs,
universal_regions: &UniversalRegions<'_>,
) -> Self {
let graph = constraint_sccs.reverse();
let mut paired_scc_regions = universal_regions
.universal_regions_iter()
.map(|region| (constraint_sccs.scc(region), region))
.collect::<Vec<_>>();
paired_scc_regions.sort();
let universal_regions = paired_scc_regions.iter().map(|&(_, region)| region).collect();
let mut scc_regions = FxIndexMap::default();
let mut start = 0;
for chunk in paired_scc_regions.chunk_by(|&(scc1, _), &(scc2, _)| scc1 == scc2) {
let (scc, _) = chunk[0];
scc_regions.insert(scc, start..start + chunk.len());
start += chunk.len();
}
ReverseSccGraph { graph, scc_regions, universal_regions }
}
/// Find all universal regions that are required to outlive the given SCC.
pub(super) fn upper_bounds(&self, scc0: ConstraintSccIndex) -> impl Iterator<Item = RegionVid> {
let mut duplicates = FxIndexSet::default();
@ -40,23 +65,7 @@ impl RegionInferenceContext<'_> {
return;
}
let graph = self.constraint_sccs.reverse();
let mut paired_scc_regions = self
.universal_regions()
.universal_regions_iter()
.map(|region| (self.constraint_sccs.scc(region), region))
.collect::<Vec<_>>();
paired_scc_regions.sort();
let universal_regions = paired_scc_regions.iter().map(|&(_, region)| region).collect();
let mut scc_regions = FxIndexMap::default();
let mut start = 0;
for chunk in paired_scc_regions.chunk_by(|&(scc1, _), &(scc2, _)| scc1 == scc2) {
let (scc, _) = chunk[0];
scc_regions.insert(scc, start..start + chunk.len());
start += chunk.len();
}
self.rev_scc_graph = Some(ReverseSccGraph { graph, scc_regions, universal_regions });
self.rev_scc_graph =
Some(ReverseSccGraph::compute(&self.constraint_sccs, self.universal_regions()));
}
}