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[Constraint graph] Use adjacency info for constraint gathering.

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This reinstates the use of direct adjacency information when gathering
constraints, effectively reverting
54bdd7b840.
Fixes the regression that commit caused, which is tracked by
rdar://problem/54274245.
This commit is contained in:
Doug Gregor
2019-08-22 10:02:01 -07:00
parent cf1732cce2
commit 34a7515aee
2 changed files with 43 additions and 24 deletions
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62
lib/Sema/ConstraintGraph.cpp
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@@ -473,7 +473,6 @@ llvm::TinyPtrVector<Constraint *> ConstraintGraph::gatherConstraints(
TypeVariableType *typeVar, GatheringKind kind,
llvm::function_ref<bool(Constraint *)> acceptConstraintFn) {
llvm::TinyPtrVector<Constraint *> constraints;
// Whether we should consider this constraint at all.
auto rep = CS.getRepresentative(typeVar);
auto shouldConsiderConstraint = [&](Constraint *constraint) {
@@ -505,19 +504,29 @@ llvm::TinyPtrVector<Constraint *> ConstraintGraph::gatherConstraints(
// Add constraints for the given adjacent type variable.
llvm::SmallPtrSet<TypeVariableType *, 4> typeVars;
// Local function to add constraints
llvm::SmallPtrSet<Constraint *, 4> visitedConstraints;
auto addAdjacentConstraints = [&](TypeVariableType *adjTypeVar) {
auto adjTypeVarsToVisit =
(*this)[CS.getRepresentative(adjTypeVar)].getEquivalenceClass();
auto addConstraintsOfAdjacency = [&](TypeVariableType *adjTypeVar) {
ArrayRef<TypeVariableType *> adjTypeVarsToVisit;
switch (kind) {
case GatheringKind::EquivalenceClass:
adjTypeVarsToVisit = adjTypeVar;
break;
case GatheringKind::AllMentions:
adjTypeVarsToVisit
= (*this)[CS.getRepresentative(adjTypeVar)].getEquivalenceClass();
break;
}
for (auto adjTypeVarEquiv : adjTypeVarsToVisit) {
if (!typeVars.insert(adjTypeVarEquiv).second)
continue;
for (auto constraint : (*this)[adjTypeVarEquiv].getConstraints()) {
if (!visitedConstraints.insert(constraint).second)
continue;
if (acceptConstraint(constraint))
if (visitedConstraints.insert(constraint).second &&
acceptConstraint(constraint))
constraints.push_back(constraint);
}
}
@@ -526,29 +535,34 @@ llvm::TinyPtrVector<Constraint *> ConstraintGraph::gatherConstraints(
auto &reprNode = (*this)[CS.getRepresentative(typeVar)];
auto equivClass = reprNode.getEquivalenceClass();
for (auto typeVar : equivClass) {
auto &node = (*this)[typeVar];
for (auto constraint : node.getConstraints()) {
if (!typeVars.insert(typeVar).second)
continue;
for (auto constraint : (*this)[typeVar].getConstraints()) {
if (visitedConstraints.insert(constraint).second &&
acceptConstraint(constraint))
constraints.push_back(constraint);
// If we want all mentions, visit type variables within each of our
// constraints.
if (kind == GatheringKind::AllMentions) {
if (!shouldConsiderConstraint(constraint))
continue;
for (auto adjTypeVar : constraint->getTypeVariables()) {
addAdjacentConstraints(adjTypeVar);
}
}
}
// For any type variable mentioned in a fixed binding, add adjacent
// constraints.
auto &node = (*this)[typeVar];
for (auto adjTypeVar : node.getFixedBindings()) {
addAdjacentConstraints(adjTypeVar);
addConstraintsOfAdjacency(adjTypeVar);
}
switch (kind) {
case GatheringKind::EquivalenceClass:
break;
case GatheringKind::AllMentions:
// Retrieve the constraints from adjacent bindings.
for (auto adjTypeVar : node.getAdjacencies()) {
addConstraintsOfAdjacency(adjTypeVar);
}
break;
}
}
return constraints;