diff options
| -rw-r--r-- | compiler/rustc_borrowck/src/region_infer/mod.rs | 12 | ||||
| -rw-r--r-- | compiler/rustc_borrowck/src/region_infer/opaque_types.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs | 13 |
3 files changed, 11 insertions, 18 deletions
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs index b4ff3d66f3d..aa584713593 100644 --- a/compiler/rustc_borrowck/src/region_infer/mod.rs +++ b/compiler/rustc_borrowck/src/region_infer/mod.rs @@ -1,3 +1,4 @@ +use std::cell::OnceCell; use std::collections::VecDeque; use std::rc::Rc; @@ -197,8 +198,8 @@ pub struct RegionInferenceContext<'tcx> { /// Reverse of the SCC constraint graph -- i.e., an edge `A -> B` exists if /// `B: A`. This is used to compute the universal regions that are required - /// to outlive a given SCC. Computed lazily. - rev_scc_graph: Option<ReverseSccGraph>, + /// to outlive a given SCC. + rev_scc_graph: OnceCell<ReverseSccGraph>, /// The "R0 member of [R1..Rn]" constraints, indexed by SCC. member_constraints: Rc<MemberConstraintSet<'tcx, ConstraintSccIndex>>, @@ -502,7 +503,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { constraint_graph, constraint_sccs, scc_annotations, - rev_scc_graph: None, + rev_scc_graph: OnceCell::new(), member_constraints, member_constraints_applied: Vec::new(), universe_causes, @@ -809,9 +810,6 @@ impl<'tcx> RegionInferenceContext<'tcx> { member_constraint_index: NllMemberConstraintIndex, choice_regions: &[ty::RegionVid], ) { - // Lazily compute the reverse graph, we'll need it later. - self.compute_reverse_scc_graph(); - // Create a mutable vector of the options. We'll try to winnow // them down. let mut choice_regions: Vec<ty::RegionVid> = choice_regions.to_vec(); @@ -849,7 +847,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { // R0`). Therefore, we need only keep an option `O` if `UB: O` // for all UB. let universal_region_relations = &self.universal_region_relations; - for ub in self.rev_scc_graph.as_ref().unwrap().upper_bounds(scc) { + for ub in self.reverse_scc_graph().upper_bounds(scc) { debug!(?ub); choice_regions.retain(|&o_r| universal_region_relations.outlives(ub, o_r)); } diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs index 25cbd579ea1..f0d72085c40 100644 --- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs +++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs @@ -215,9 +215,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { // FIXME: We could probably compute the LUB if there is one. let scc = self.constraint_sccs.scc(vid); let upper_bounds: Vec<_> = self - .rev_scc_graph - .as_ref() - .unwrap() + .reverse_scc_graph() .upper_bounds(scc) .filter_map(|vid| self.definitions[vid].external_name) .filter(|r| !r.is_static()) diff --git a/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs b/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs index 8e04791461b..604265f8940 100644 --- a/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs +++ b/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs @@ -59,13 +59,10 @@ impl ReverseSccGraph { } impl RegionInferenceContext<'_> { - /// Compute the reverse SCC-based constraint graph (lazily). - pub(super) fn compute_reverse_scc_graph(&mut self) { - if self.rev_scc_graph.is_some() { - return; - } - - self.rev_scc_graph = - Some(ReverseSccGraph::compute(&self.constraint_sccs, self.universal_regions())); + /// Return the reverse graph of the region SCCs, initialising it if needed. + pub(super) fn reverse_scc_graph(&self) -> &ReverseSccGraph { + self.rev_scc_graph.get_or_init(|| { + ReverseSccGraph::compute(&self.constraint_sccs, self.universal_regions()) + }) } } |