diff options
| -rw-r--r-- | compiler/rustc_borrowck/src/region_infer/mod.rs | 87 |
1 files changed, 51 insertions, 36 deletions
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs index abe9efe8364..bb209a95711 100644 --- a/compiler/rustc_borrowck/src/region_infer/mod.rs +++ b/compiler/rustc_borrowck/src/region_infer/mod.rs @@ -311,9 +311,11 @@ enum RegionRelationCheckResult { } #[derive(Clone, PartialEq, Eq, Debug)] -enum Trace<'tcx> { +enum Trace<'a, 'tcx> { StartRegion, - FromOutlivesConstraint(OutlivesConstraint<'tcx>), + FromGraph(&'a OutlivesConstraint<'tcx>), + FromStatic(RegionVid), + FromMember(RegionVid, RegionVid, Span), NotVisited, } @@ -1764,6 +1766,8 @@ impl<'tcx> RegionInferenceContext<'tcx> { let mut context = IndexVec::from_elem(Trace::NotVisited, &self.definitions); context[from_region] = Trace::StartRegion; + let fr_static = self.universal_regions().fr_static; + // Use a deque so that we do a breadth-first search. We will // stop at the first match, which ought to be the shortest // path (fewest constraints). @@ -1783,13 +1787,39 @@ impl<'tcx> RegionInferenceContext<'tcx> { if target_test(r) { let mut result = vec![]; let mut p = r; + // This loop is cold and runs at the end, which is why we delay + // `OutlivesConstraint` construction until now. loop { - match context[p].clone() { - Trace::NotVisited => { - bug!("found unvisited region {:?} on path to {:?}", p, r) + match context[p] { + Trace::FromGraph(c) => { + p = c.sup; + result.push(*c); } - Trace::FromOutlivesConstraint(c) => { + Trace::FromStatic(sub) => { + let c = OutlivesConstraint { + sup: fr_static, + sub, + locations: Locations::All(DUMMY_SP), + span: DUMMY_SP, + category: ConstraintCategory::Internal, + variance_info: ty::VarianceDiagInfo::default(), + from_closure: false, + }; + p = c.sup; + result.push(c); + } + + Trace::FromMember(sup, sub, span) => { + let c = OutlivesConstraint { + sup, + sub, + locations: Locations::All(span), + span, + category: ConstraintCategory::OpaqueType, + variance_info: ty::VarianceDiagInfo::default(), + from_closure: false, + }; p = c.sup; result.push(c); } @@ -1798,6 +1828,10 @@ impl<'tcx> RegionInferenceContext<'tcx> { result.reverse(); return Some((result, r)); } + + Trace::NotVisited => { + bug!("found unvisited region {:?} on path to {:?}", p, r) + } } } } @@ -1808,33 +1842,21 @@ impl<'tcx> RegionInferenceContext<'tcx> { // A constraint like `'r: 'x` can come from our constraint // graph. - let fr_static = self.universal_regions().fr_static; // Always inline this closure because it can be hot. - let mut handle_constraint = #[inline(always)] - |constraint: &OutlivesConstraint<'tcx>| { - debug_assert_eq!(constraint.sup, r); - let sub_region = constraint.sub; - if let Trace::NotVisited = context[sub_region] { - context[sub_region] = Trace::FromOutlivesConstraint(*constraint); - deque.push_back(sub_region); + let mut handle_trace = #[inline(always)] + |sub, trace| { + if let Trace::NotVisited = context[sub] { + context[sub] = trace; + deque.push_back(sub); } }; // If this is the `'static` region and the graph's direction is normal, then set up the // Edges iterator to return all regions (#53178). if r == fr_static && self.constraint_graph.is_normal() { - for next_static_idx in self.constraint_graph.outgoing_edges_from_static() { - let constraint = OutlivesConstraint { - sup: fr_static, - sub: next_static_idx, - locations: Locations::All(DUMMY_SP), - span: DUMMY_SP, - category: ConstraintCategory::Internal, - variance_info: ty::VarianceDiagInfo::default(), - from_closure: false, - }; - handle_constraint(&constraint); + for sub in self.constraint_graph.outgoing_edges_from_static() { + handle_trace(sub, Trace::FromStatic(sub)); } } else { let edges = self.constraint_graph.outgoing_edges_from_graph(r, &self.constraints); @@ -1844,7 +1866,8 @@ impl<'tcx> RegionInferenceContext<'tcx> { debug!("Ignoring illegal universe constraint: {constraint:?}"); continue; } - handle_constraint(constraint); + debug_assert_eq!(constraint.sup, r); + handle_trace(constraint.sub, Trace::FromGraph(constraint)); } } @@ -1852,17 +1875,9 @@ impl<'tcx> RegionInferenceContext<'tcx> { // were not part of the graph initially, so watch out for those. // (But they are extremely rare; this loop is very cold.) for constraint in self.applied_member_constraints(self.constraint_sccs.scc(r)) { + let sub = constraint.min_choice; let p_c = &self.member_constraints[constraint.member_constraint_index]; - let constraint = OutlivesConstraint { - sup: r, - sub: constraint.min_choice, - locations: Locations::All(p_c.definition_span), - span: p_c.definition_span, - category: ConstraintCategory::OpaqueType, - variance_info: ty::VarianceDiagInfo::default(), - from_closure: false, - }; - handle_constraint(&constraint); + handle_trace(sub, Trace::FromMember(r, sub, p_c.definition_span)); } } |