Sema: Remove ConstraintGraph::TypeVariables

Author: slavapestov

include/swift/Sema/ConstraintGraph.h

@@ -322,14 +322,6 @@ class ConstraintGraph {
                     llvm::function_ref<bool(Constraint *)> acceptConstraint =
                         [](Constraint *constraint) { return true; });
 
-  /// Retrieve the type variables that correspond to nodes in the graph.
-  ///
-  /// The subscript operator can be used to retrieve the nodes that
-  /// correspond to these type variables.
-  ArrayRef<TypeVariableType *> getTypeVariables() const {
-    return TypeVariables;
-  }
-
   /// Describes a single component, as produced by the connected components
   /// algorithm.
   struct Component {
@@ -473,9 +465,6 @@ class ConstraintGraph {
   /// The constraint system.
   ConstraintSystem &CS;
 
-  /// The type variables in this graph, in stable order.
-  std::vector<TypeVariableType *> TypeVariables;
-
   /// Constraints that are "orphaned" because they contain no type variables.
   SmallVector<Constraint *, 4> OrphanedConstraints;
 

include/swift/Sema/ConstraintSystem.h

@@ -339,10 +339,6 @@ class TypeVariableType::Implementation {
   /// The corresponding node in the constraint graph.
   constraints::ConstraintGraphNode *GraphNode = nullptr;
 
-  ///  Index into the list of type variables, as used by the
-  ///  constraint graph.
-  unsigned GraphIndex;
-
   friend class constraints::SolverTrail;
 
 public:
@@ -406,17 +402,6 @@ class TypeVariableType::Implementation {
   void setGraphNode(constraints::ConstraintGraphNode *newNode) { 
     GraphNode = newNode; 
   }
-
-  /// Retrieve the index into the constraint graph's list of type variables.
-  unsigned getGraphIndex() const { 
-    assert(GraphNode && "Graph node isn't set");
-    return GraphIndex;
-  }
-
-  /// Set the index into the constraint graph's list of type variables.
-  void setGraphIndex(unsigned newIndex) {
-    GraphIndex = newIndex;
-  }
 
   /// Check whether this type variable either has a representative that
   /// is not itself or has a fixed type binding.

lib/Sema/ConstraintGraph.cpp

@@ -38,11 +38,13 @@ using namespace constraints;
 ConstraintGraph::ConstraintGraph(ConstraintSystem &cs) : CS(cs) { }
 
 ConstraintGraph::~ConstraintGraph() {
-  for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
-    auto &impl = TypeVariables[i]->getImpl();
-    delete impl.getGraphNode();
-    impl.setGraphNode(nullptr);
+#ifndef NDEBUG
+  for (unsigned i = 0, n = CS.TypeVariables.size(); i != n; ++i) {
+    auto &impl = CS.TypeVariables[i]->getImpl();
+    ASSERT(impl.getGraphNode() == nullptr);
   }
+#endif
+
   for (auto *node : FreeList) {
     delete node;
   }
@@ -70,30 +72,16 @@ void ConstraintGraph::addTypeVariable(TypeVariableType *typeVar) {
     FreeList.pop_back();
     nodePtr->initTypeVariable(typeVar);
   }
-  unsigned index = TypeVariables.size();
   impl.setGraphNode(nodePtr);
-  impl.setGraphIndex(index);
-
-  // Record this type variable.
-  TypeVariables.push_back(typeVar);
 
   if (CS.solverState)
     CS.recordChange(SolverTrail::Change::AddedTypeVariable(typeVar));
 }
 
 ConstraintGraphNode &
 ConstraintGraph::operator[](TypeVariableType *typeVar) {
-  // Check whether we've already created a node for this type variable.
-  auto &impl = typeVar->getImpl();
-  auto *nodePtr = impl.getGraphNode();
-  if (!nodePtr) {
-    llvm::errs() << "Type variable $T" << impl.getID() << " not in constraint graph\n";
-    abort();
-  }
+  auto *nodePtr = typeVar->getImpl().getGraphNode();
   ASSERT(nodePtr->TypeVar == typeVar && "Use-after-free");
-  DEBUG_ASSERT(impl.getGraphIndex() < TypeVariables.size() && "Out-of-bounds index");
-  DEBUG_ASSERT(TypeVariables[impl.getGraphIndex()] == typeVar &&
-               "Type variable mismatch");
   return *nodePtr;
 }
 
@@ -357,17 +345,10 @@ void ConstraintGraphNode::introduceToInference(Type fixedType) {
 void ConstraintGraph::removeNode(TypeVariableType *typeVar) {
   // Remove this node.
   auto &impl = typeVar->getImpl();
-  unsigned index = impl.getGraphIndex();
   auto *node = impl.getGraphNode();
   node->reset();
   FreeList.push_back(node);
   impl.setGraphNode(nullptr);
-
-  // Remove this type variable from the list.
-  unsigned lastIndex = TypeVariables.size()-1;
-  if (index < lastIndex)
-    TypeVariables[index] = TypeVariables[lastIndex];
-  TypeVariables.pop_back();
 }
 
 void ConstraintGraph::addConstraint(Constraint *constraint) {
@@ -1633,7 +1614,7 @@ void ConstraintGraph::verify() {
   // Verify that the type variables are either representatives or represented
   // within their representative's equivalence class.
   // FIXME: Also check to make sure the equivalence classes aren't too large?
-  for (auto typeVar : TypeVariables) {
+  for (auto typeVar : CS.TypeVariables) {
     auto typeVarRep = CS.getRepresentative(typeVar);
     auto &repNode = (*this)[typeVarRep];
     if (typeVar != typeVarRep) {
@@ -1654,24 +1635,15 @@ void ConstraintGraph::verify() {
     }
   }
 
-  // Verify that our type variable map/vector are in sync.
-  for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
-    auto typeVar = TypeVariables[i];
-    auto &impl = typeVar->getImpl();
-    requireSameValue(impl.getGraphIndex(), i, "wrong graph node index");
-    require(impl.getGraphNode(), "null graph node");
-  }
-
   // Verify consistency of all of the nodes in the graph.
-  for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
-    auto typeVar = TypeVariables[i];
+  for (auto typeVar : CS.TypeVariables) {
     auto &impl = typeVar->getImpl();
     impl.getGraphNode()->verify(*this);
   }
 
   // Collect all of the constraints known to the constraint graph.
   llvm::SmallPtrSet<Constraint *, 4> knownConstraints;
-  for (auto typeVar : getTypeVariables()) {
+  for (auto typeVar : CS.TypeVariables) {
     for (auto constraint : (*this)[typeVar].getConstraints())
       knownConstraints.insert(constraint);
   }

lib/Sema/ConstraintSystem.cpp

@@ -130,7 +130,13 @@ ConstraintSystem::ConstraintSystem(DeclContext *dc,
     Options |= ConstraintSystemFlags::UseClangFunctionTypes;
 }
 
-ConstraintSystem::~ConstraintSystem() {}
+ConstraintSystem::~ConstraintSystem() {
+  for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
+    auto &impl = TypeVariables[i]->getImpl();
+    delete impl.getGraphNode();
+    impl.setGraphNode(nullptr);
+  }
+}
 
 void ConstraintSystem::startExpressionTimer(ExpressionTimer::AnchorType anchor) {
   ASSERT(!Timer);