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The API of the connected-components algorithm asks clients to provide the set of type variables of interest. However, the connected components algorithm itself was operating across the entire set of type variables, then narrowing the result down to the type variables of interest. Instead, only perform connected components on those type variables of interest, so that we are only doing work proportional to the subgraph we're working in.
1054 lines
36 KiB
C++
1054 lines
36 KiB
C++
//===--- ConstraintGraph.cpp - Constraint Graph ---------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the \c ConstraintGraph class, which describes the
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// relationships among the type variables within a constraint system.
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//
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//===----------------------------------------------------------------------===//
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#include "ConstraintGraph.h"
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#include "ConstraintGraphScope.h"
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#include "ConstraintSystem.h"
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#include "swift/Basic/Statistic.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/SaveAndRestore.h"
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#include <algorithm>
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#include <memory>
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#include <numeric>
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using namespace swift;
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using namespace constraints;
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#define DEBUG_TYPE "ConstraintGraph"
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#pragma mark Graph construction/destruction
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ConstraintGraph::ConstraintGraph(ConstraintSystem &cs) : CS(cs) { }
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ConstraintGraph::~ConstraintGraph() {
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assert(Changes.empty() && "Scope stack corrupted");
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for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
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auto &impl = TypeVariables[i]->getImpl();
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delete impl.getGraphNode();
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impl.setGraphNode(nullptr);
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}
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}
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#pragma mark Graph accessors
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std::pair<ConstraintGraphNode &, unsigned>
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ConstraintGraph::lookupNode(TypeVariableType *typeVar) {
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// Check whether we've already created a node for this type variable.
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auto &impl = typeVar->getImpl();
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if (auto nodePtr = impl.getGraphNode()) {
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assert(impl.getGraphIndex() < TypeVariables.size() && "Out-of-bounds index");
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assert(TypeVariables[impl.getGraphIndex()] == typeVar &&
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"Type variable mismatch");
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return { *nodePtr, impl.getGraphIndex() };
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}
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// Allocate the new node.
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auto nodePtr = new ConstraintGraphNode(typeVar);
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unsigned index = TypeVariables.size();
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impl.setGraphNode(nodePtr);
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impl.setGraphIndex(index);
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// Record this type variable.
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TypeVariables.push_back(typeVar);
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// Record the change, if there are active scopes.
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if (ActiveScope)
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Changes.push_back(Change::addedTypeVariable(typeVar));
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// If this type variable is not the representative of its equivalence class,
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// add it to its representative's set of equivalences.
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auto typeVarRep = CS.getRepresentative(typeVar);
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if (typeVar != typeVarRep)
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mergeNodes(typeVar, typeVarRep);
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else if (auto fixed = CS.getFixedType(typeVarRep)) {
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// Bind the type variable.
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bindTypeVariable(typeVar, fixed);
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}
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return { *nodePtr, index };
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}
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ArrayRef<TypeVariableType *> ConstraintGraphNode::getEquivalenceClass() const{
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assert(TypeVar == TypeVar->getImpl().getRepresentative(nullptr) &&
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"Can't request equivalence class from non-representative type var");
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return getEquivalenceClassUnsafe();
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}
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ArrayRef<TypeVariableType *>
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ConstraintGraphNode::getEquivalenceClassUnsafe() const{
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if (EquivalenceClass.empty())
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EquivalenceClass.push_back(TypeVar);
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return EquivalenceClass;
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}
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#pragma mark Node mutation
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void ConstraintGraphNode::addConstraint(Constraint *constraint) {
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assert(ConstraintIndex.count(constraint) == 0 && "Constraint re-insertion");
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ConstraintIndex[constraint] = Constraints.size();
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Constraints.push_back(constraint);
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}
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void ConstraintGraphNode::removeConstraint(Constraint *constraint) {
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auto pos = ConstraintIndex.find(constraint);
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assert(pos != ConstraintIndex.end());
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// Remove this constraint from the constraint mapping.
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auto index = pos->second;
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ConstraintIndex.erase(pos);
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assert(Constraints[index] == constraint && "Mismatched constraint");
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// If this is the last constraint, just pop it off the list and we're done.
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unsigned lastIndex = Constraints.size()-1;
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if (index == lastIndex) {
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Constraints.pop_back();
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return;
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}
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// This constraint is somewhere in the middle; swap it with the last
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// constraint, so we can remove the constraint from the vector in O(1)
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// time rather than O(n) time.
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auto lastConstraint = Constraints[lastIndex];
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Constraints[index] = lastConstraint;
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ConstraintIndex[lastConstraint] = index;
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Constraints.pop_back();
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}
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void ConstraintGraphNode::addToEquivalenceClass(
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ArrayRef<TypeVariableType *> typeVars) {
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assert(TypeVar == TypeVar->getImpl().getRepresentative(nullptr) &&
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"Can't extend equivalence class of non-representative type var");
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if (EquivalenceClass.empty())
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EquivalenceClass.push_back(TypeVar);
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EquivalenceClass.append(typeVars.begin(), typeVars.end());
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}
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void ConstraintGraphNode::addFixedBinding(TypeVariableType *typeVar) {
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FixedBindings.push_back(typeVar);
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}
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void ConstraintGraphNode::removeFixedBinding(TypeVariableType *typeVar) {
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FixedBindings.pop_back();
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}
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#pragma mark Graph scope management
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ConstraintGraphScope::ConstraintGraphScope(ConstraintGraph &CG)
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: CG(CG), ParentScope(CG.ActiveScope), NumChanges(CG.Changes.size())
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{
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CG.ActiveScope = this;
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}
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ConstraintGraphScope::~ConstraintGraphScope() {
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// Pop changes off the stack until we hit the change could we had prior to
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// introducing this scope.
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assert(CG.Changes.size() >= NumChanges && "Scope stack corrupted");
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while (CG.Changes.size() > NumChanges) {
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CG.Changes.back().undo(CG);
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CG.Changes.pop_back();
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}
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// The active scope is now the parent scope.
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CG.ActiveScope = ParentScope;
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}
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ConstraintGraph::Change
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ConstraintGraph::Change::addedTypeVariable(TypeVariableType *typeVar) {
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Change result;
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result.Kind = ChangeKind::AddedTypeVariable;
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result.TypeVar = typeVar;
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return result;
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}
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ConstraintGraph::Change
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ConstraintGraph::Change::addedConstraint(Constraint *constraint) {
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Change result;
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result.Kind = ChangeKind::AddedConstraint;
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result.TheConstraint = constraint;
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return result;
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}
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ConstraintGraph::Change
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ConstraintGraph::Change::removedConstraint(Constraint *constraint) {
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Change result;
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result.Kind = ChangeKind::RemovedConstraint;
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result.TheConstraint = constraint;
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return result;
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}
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ConstraintGraph::Change
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ConstraintGraph::Change::extendedEquivalenceClass(TypeVariableType *typeVar,
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unsigned prevSize) {
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Change result;
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result.Kind = ChangeKind::ExtendedEquivalenceClass;
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result.EquivClass.TypeVar = typeVar;
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result.EquivClass.PrevSize = prevSize;
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return result;
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}
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ConstraintGraph::Change
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ConstraintGraph::Change::boundTypeVariable(TypeVariableType *typeVar,
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Type fixed) {
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Change result;
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result.Kind = ChangeKind::BoundTypeVariable;
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result.Binding.TypeVar = typeVar;
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result.Binding.FixedType = fixed.getPointer();
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return result;
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}
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void ConstraintGraph::Change::undo(ConstraintGraph &cg) {
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/// Temporarily change the active scope to null, so we don't record
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/// any changes made while performing the undo operation.
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llvm::SaveAndRestore<ConstraintGraphScope *> prevActiveScope(cg.ActiveScope,
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nullptr);
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switch (Kind) {
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case ChangeKind::AddedTypeVariable:
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cg.removeNode(TypeVar);
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break;
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case ChangeKind::AddedConstraint:
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cg.removeConstraint(TheConstraint);
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break;
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case ChangeKind::RemovedConstraint:
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cg.addConstraint(TheConstraint);
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break;
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case ChangeKind::ExtendedEquivalenceClass: {
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auto &node = cg[EquivClass.TypeVar];
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node.EquivalenceClass.erase(
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node.EquivalenceClass.begin() + EquivClass.PrevSize,
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node.EquivalenceClass.end());
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break;
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}
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case ChangeKind::BoundTypeVariable:
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cg.unbindTypeVariable(Binding.TypeVar, Binding.FixedType);
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break;
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}
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}
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#pragma mark Graph mutation
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void ConstraintGraph::removeNode(TypeVariableType *typeVar) {
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// Remove this node.
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auto &impl = typeVar->getImpl();
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unsigned index = impl.getGraphIndex();
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delete impl.getGraphNode();
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impl.setGraphNode(nullptr);
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// Remove this type variable from the list.
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unsigned lastIndex = TypeVariables.size()-1;
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if (index < lastIndex)
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TypeVariables[index] = TypeVariables[lastIndex];
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TypeVariables.pop_back();
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}
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void ConstraintGraph::addConstraint(Constraint *constraint) {
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// For the nodes corresponding to each type variable...
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auto referencedTypeVars = constraint->getTypeVariables();
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for (auto typeVar : referencedTypeVars) {
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// Find the node for this type variable.
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auto &node = (*this)[typeVar];
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// Note the constraint within the node for that type variable.
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node.addConstraint(constraint);
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}
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// If the constraint doesn't reference any type variables, it's orphaned;
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// track it as such.
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if (referencedTypeVars.empty()) {
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OrphanedConstraints.push_back(constraint);
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}
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// Record the change, if there are active scopes.
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if (ActiveScope)
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Changes.push_back(Change::addedConstraint(constraint));
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}
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void ConstraintGraph::removeConstraint(Constraint *constraint) {
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// For the nodes corresponding to each type variable...
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auto referencedTypeVars = constraint->getTypeVariables();
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for (auto typeVar : referencedTypeVars) {
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// Find the node for this type variable.
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auto &node = (*this)[typeVar];
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// Remove the constraint.
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node.removeConstraint(constraint);
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}
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// If this is an orphaned constraint, remove it from the list.
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if (referencedTypeVars.empty()) {
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auto known = std::find(OrphanedConstraints.begin(),
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OrphanedConstraints.end(),
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constraint);
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assert(known != OrphanedConstraints.end() && "missing orphaned constraint");
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*known = OrphanedConstraints.back();
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OrphanedConstraints.pop_back();
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}
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// Record the change, if there are active scopes.
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if (ActiveScope)
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Changes.push_back(Change::removedConstraint(constraint));
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}
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void ConstraintGraph::mergeNodes(TypeVariableType *typeVar1,
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TypeVariableType *typeVar2) {
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assert(CS.getRepresentative(typeVar1) == CS.getRepresentative(typeVar2) &&
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"type representatives don't match");
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// Retrieve the node for the representative that we're merging into.
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auto typeVarRep = CS.getRepresentative(typeVar1);
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auto &repNode = (*this)[typeVarRep];
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// Retrieve the node for the non-representative.
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assert((typeVar1 == typeVarRep || typeVar2 == typeVarRep) &&
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"neither type variable is the new representative?");
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auto typeVarNonRep = typeVar1 == typeVarRep? typeVar2 : typeVar1;
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// Record the change, if there are active scopes.
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if (ActiveScope)
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Changes.push_back(Change::extendedEquivalenceClass(
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typeVarRep,
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repNode.getEquivalenceClass().size()));
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// Merge equivalence class from the non-representative type variable.
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auto &nonRepNode = (*this)[typeVarNonRep];
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repNode.addToEquivalenceClass(nonRepNode.getEquivalenceClassUnsafe());
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}
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void ConstraintGraph::bindTypeVariable(TypeVariableType *typeVar, Type fixed) {
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// If there are no type variables in the fixed type, there's nothing to do.
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if (!fixed->hasTypeVariable())
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return;
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SmallVector<TypeVariableType *, 4> typeVars;
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llvm::SmallPtrSet<TypeVariableType *, 4> knownTypeVars;
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fixed->getTypeVariables(typeVars);
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auto &node = (*this)[typeVar];
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for (auto otherTypeVar : typeVars) {
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if (knownTypeVars.insert(otherTypeVar).second) {
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if (typeVar == otherTypeVar) continue;
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(*this)[otherTypeVar].addFixedBinding(typeVar);
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node.addFixedBinding(otherTypeVar);
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}
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}
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// Record the change, if there are active scopes.
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// Note: If we ever use this to undo the actual variable binding,
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// we'll need to store the change along the early-exit path as well.
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if (ActiveScope)
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Changes.push_back(Change::boundTypeVariable(typeVar, fixed));
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}
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void ConstraintGraph::unbindTypeVariable(TypeVariableType *typeVar, Type fixed){
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// If there are no type variables in the fixed type, there's nothing to do.
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if (!fixed->hasTypeVariable())
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return;
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SmallVector<TypeVariableType *, 4> typeVars;
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llvm::SmallPtrSet<TypeVariableType *, 4> knownTypeVars;
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fixed->getTypeVariables(typeVars);
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auto &node = (*this)[typeVar];
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for (auto otherTypeVar : typeVars) {
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if (knownTypeVars.insert(otherTypeVar).second) {
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(*this)[otherTypeVar].removeFixedBinding(typeVar);
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node.removeFixedBinding(otherTypeVar);
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}
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}
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}
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llvm::TinyPtrVector<Constraint *> ConstraintGraph::gatherConstraints(
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TypeVariableType *typeVar, GatheringKind kind,
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llvm::function_ref<bool(Constraint *)> acceptConstraint) {
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llvm::TinyPtrVector<Constraint *> constraints;
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/// Add constraints for the given adjacent type variable.
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llvm::SmallPtrSet<TypeVariableType *, 4> typeVars;
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llvm::SmallPtrSet<Constraint *, 4> visitedConstraints;
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auto addAdjacentConstraints = [&](TypeVariableType *adjTypeVar) {
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auto adjTypeVarsToVisit =
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(*this)[CS.getRepresentative(adjTypeVar)].getEquivalenceClass();
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for (auto adjTypeVarEquiv : adjTypeVarsToVisit) {
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if (!typeVars.insert(adjTypeVarEquiv).second)
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continue;
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for (auto constraint : (*this)[adjTypeVarEquiv].getConstraints()) {
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if (!visitedConstraints.insert(constraint).second)
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continue;
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if (acceptConstraint(constraint))
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constraints.push_back(constraint);
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}
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}
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};
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auto &reprNode = (*this)[CS.getRepresentative(typeVar)];
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auto equivClass = reprNode.getEquivalenceClass();
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for (auto typeVar : equivClass) {
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auto &node = (*this)[typeVar];
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for (auto constraint : node.getConstraints()) {
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if (visitedConstraints.insert(constraint).second &&
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acceptConstraint(constraint))
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constraints.push_back(constraint);
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// If we want all mentions, visit type variables within each of our
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// constraints.
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if (kind == GatheringKind::AllMentions) {
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for (auto adjTypeVar : constraint->getTypeVariables()) {
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addAdjacentConstraints(adjTypeVar);
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}
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}
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}
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// For any type variable mentioned in a fixed binding, add adjacent
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// constraints.
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for (auto adjTypeVar : node.getFixedBindings()) {
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addAdjacentConstraints(adjTypeVar);
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}
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}
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return constraints;
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}
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#pragma mark Algorithms
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/// Perform a depth-first search.
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///
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/// \param cg The constraint graph.
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/// \param node The current constraint graph node.
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/// \param nodeIndex The index of the current constraint graph node.
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/// \param visitFixedBindings Whether to visit the nodes by following
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/// fixed bindings.
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/// \param preVisitNode Called before traversing a node. Must return \c
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/// false when the node has already been visited.
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/// \param visitConstraint Called before considering a constraint. If it
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/// returns \c false, that constraint will be skipped.
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/// \param visitedConstraints Set of already-visited constraints, used
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/// internally to avoid duplicated work.
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static void depthFirstSearch(
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ConstraintGraph &cg,
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ConstraintGraphNode &node,
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unsigned nodeIndex,
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bool visitFixedBindings,
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llvm::function_ref<bool(unsigned)> preVisitNode,
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llvm::function_ref<bool(Constraint *)> visitConstraint,
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llvm::DenseSet<Constraint *> &visitedConstraints) {
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// Visit this node. If we've already seen it, bail out.
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if (!preVisitNode(nodeIndex))
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return;
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// Local function to visit adjacent type variables.
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auto visitAdjacencies = [&](ArrayRef<TypeVariableType *> adjTypeVars) {
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for (auto adj : adjTypeVars) {
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if (adj == node.getTypeVariable())
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continue;
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auto adjNodeAndIndex = cg.lookupNode(adj);
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// Recurse into this node.
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depthFirstSearch(cg, adjNodeAndIndex.first, adjNodeAndIndex.second,
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visitFixedBindings, preVisitNode, visitConstraint,
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visitedConstraints);
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}
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};
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// Walk all of the constraints associated with this node to find related
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// nodes.
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for (auto constraint : node.getConstraints()) {
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// If we've already seen this constraint, skip it.
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if (!visitedConstraints.insert(constraint).second)
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continue;
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if (visitConstraint(constraint))
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visitAdjacencies(constraint->getTypeVariables());
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}
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// Visit all of the other nodes in the equivalence class.
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auto nodeTypeVar = node.getTypeVariable();
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auto repTypeVar = cg.getConstraintSystem().getRepresentative(nodeTypeVar);
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if (nodeTypeVar == repTypeVar) {
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// We are the representative, so visit all of the other type variables
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// in this equivalence class.
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visitAdjacencies(node.getEquivalenceClass());
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} else {
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// We are not the representative; visit the representative.
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visitAdjacencies(repTypeVar);
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}
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if (visitFixedBindings) {
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// Walk any type variables related via fixed bindings.
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visitAdjacencies(node.getFixedBindings());
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}
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}
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/// Perform a depth-first search.
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///
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/// \param cg The constraint graph.
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/// \param node The current constraint graph node.
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/// \param nodeIndex The index of the current constraint graph node.
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/// \param visitFixedBindings Whether to visit the nodes by following
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/// fixed bindings.
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/// \param preVisitNode Called before traversing a node. Must return \c
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/// false when the node has already been visited.
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/// \param visitConstraint Called before considering a constraint. If it
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/// returns \c false, that constraint will be skipped.
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static void depthFirstSearch(
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ConstraintGraph &cg,
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ConstraintGraphNode &node,
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unsigned nodeIndex,
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bool visitFixedBindings,
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llvm::function_ref<bool(unsigned)> preVisitNode,
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llvm::function_ref<bool(Constraint *)> visitConstraint) {
|
|
llvm::DenseSet<Constraint *> visitedConstraints;
|
|
depthFirstSearch(cg, node, nodeIndex, visitFixedBindings, preVisitNode,
|
|
visitConstraint, visitedConstraints);
|
|
}
|
|
|
|
unsigned ConstraintGraph::computeConnectedComponents(
|
|
std::vector<TypeVariableType *> &typeVars,
|
|
std::vector<unsigned> &components) {
|
|
// Track those type variables that the caller cares about.
|
|
llvm::SmallPtrSet<TypeVariableType *, 4> typeVarSubset(typeVars.begin(),
|
|
typeVars.end());
|
|
|
|
// Initialize the components with component == # of type variables,
|
|
// a sentinel value indicating that we have yet to assign a component to
|
|
// that particular type variable.
|
|
unsigned numTypeVariables = TypeVariables.size();
|
|
components.assign(numTypeVariables, numTypeVariables);
|
|
|
|
// Perform a depth-first search from each type variable to identify
|
|
// what component it is in.
|
|
llvm::DenseSet<Constraint *> visitedConstraints;
|
|
unsigned numComponents = 0;
|
|
for (auto typeVar : typeVars) {
|
|
// Look up the node for this type variable.
|
|
auto nodeAndIndex = lookupNode(typeVar);
|
|
|
|
// If we're already assigned a component for this node, skip it.
|
|
unsigned &curComponent = components[nodeAndIndex.second];
|
|
if (curComponent != numTypeVariables)
|
|
continue;
|
|
|
|
// Record this component.
|
|
unsigned component = numComponents++;
|
|
|
|
// Note that this node is part of this component, then visit it.
|
|
depthFirstSearch(
|
|
*this, nodeAndIndex.first, nodeAndIndex.second,
|
|
/*visitFixedBindings=*/true,
|
|
[&](unsigned nodeIndex) {
|
|
// If we have already seen this node, we're done.
|
|
unsigned &nodeComponent = components[nodeIndex];
|
|
if (nodeComponent == component)
|
|
return false;
|
|
|
|
assert(nodeComponent == components.size() &&
|
|
"Already in a component?");
|
|
nodeComponent = component;
|
|
return true;
|
|
},
|
|
[&](Constraint *constraint) {
|
|
return true;
|
|
});
|
|
}
|
|
|
|
// Figure out which components have unbound type variables; these
|
|
// are the only components and type variables we want to report.
|
|
SmallVector<bool, 4> componentHasUnboundTypeVar(numComponents, false);
|
|
for (unsigned i = 0; i != numTypeVariables; ++i) {
|
|
// If we didn't look at this type variable, there's nothing to do.
|
|
if (components[i] == numTypeVariables)
|
|
continue;
|
|
|
|
// If this type variable has a fixed type, skip it.
|
|
if (CS.getFixedType(TypeVariables[i]))
|
|
continue;
|
|
|
|
// If this type variable isn't in the subset of type variables we care
|
|
// about, skip it.
|
|
if (typeVarSubset.count(TypeVariables[i]) == 0)
|
|
continue;
|
|
|
|
componentHasUnboundTypeVar[components[i]] = true;
|
|
}
|
|
|
|
// Renumber the old components to the new components.
|
|
SmallVector<unsigned, 4> componentRenumbering(numComponents, 0);
|
|
numComponents = 0;
|
|
for (unsigned i = 0, n = componentHasUnboundTypeVar.size(); i != n; ++i) {
|
|
// If we didn't look at this type variable, there's nothing to do.
|
|
if (components[i] == numTypeVariables)
|
|
continue;
|
|
|
|
// Skip components that have no unbound type variables.
|
|
if (!componentHasUnboundTypeVar[i])
|
|
continue;
|
|
|
|
componentRenumbering[i] = numComponents++;
|
|
}
|
|
|
|
// Copy over the type variables in the live components and remap
|
|
// component numbers.
|
|
typeVars.clear();
|
|
unsigned outIndex = 0;
|
|
for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
|
|
// If we didn't look at this type variable, there's nothing to do.
|
|
if (components[i] == numTypeVariables)
|
|
continue;
|
|
|
|
// Skip type variables in dead components.
|
|
if (!componentHasUnboundTypeVar[components[i]])
|
|
continue;
|
|
|
|
typeVars.push_back(TypeVariables[i]);
|
|
components[outIndex] = componentRenumbering[components[i]];
|
|
++outIndex;
|
|
}
|
|
components.erase(components.begin() + outIndex, components.end());
|
|
|
|
return numComponents + getOrphanedConstraints().size();
|
|
}
|
|
|
|
|
|
/// For a given constraint kind, decide if we should attempt to eliminate its
|
|
/// edge in the graph.
|
|
static bool shouldContractEdge(ConstraintKind kind) {
|
|
switch (kind) {
|
|
case ConstraintKind::Bind:
|
|
case ConstraintKind::BindParam:
|
|
case ConstraintKind::BindToPointerType:
|
|
case ConstraintKind::Equal:
|
|
return true;
|
|
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
bool ConstraintGraph::contractEdges() {
|
|
SmallVector<Constraint *, 16> constraints;
|
|
CS.findConstraints(constraints, [&](const Constraint &constraint) {
|
|
// Track how many constraints did contraction algorithm iterated over.
|
|
incrementConstraintsPerContractionCounter();
|
|
return shouldContractEdge(constraint.getKind());
|
|
});
|
|
|
|
bool didContractEdges = false;
|
|
for (auto *constraint : constraints) {
|
|
auto kind = constraint->getKind();
|
|
|
|
// Contract binding edges between type variables.
|
|
assert(shouldContractEdge(kind));
|
|
|
|
auto t1 = constraint->getFirstType()->getDesugaredType();
|
|
auto t2 = constraint->getSecondType()->getDesugaredType();
|
|
|
|
auto tyvar1 = t1->getAs<TypeVariableType>();
|
|
auto tyvar2 = t2->getAs<TypeVariableType>();
|
|
|
|
if (!(tyvar1 && tyvar2))
|
|
continue;
|
|
|
|
auto isParamBindingConstraint = kind == ConstraintKind::BindParam;
|
|
|
|
// If the argument is allowed to bind to `inout`, in general,
|
|
// it's invalid to contract the edge between argument and parameter,
|
|
// but if we can prove that there are no possible bindings
|
|
// which result in attempt to bind `inout` type to argument
|
|
// type variable, we should go ahead and allow (temporary)
|
|
// contraction, because that greatly helps with performance.
|
|
// Such action is valid because argument type variable can
|
|
// only get its bindings from related overload, which gives
|
|
// us enough information to decided on l-valueness.
|
|
if (isParamBindingConstraint && tyvar1->getImpl().canBindToInOut()) {
|
|
bool isNotContractable = true;
|
|
if (auto bindings = CS.getPotentialBindings(tyvar1)) {
|
|
for (auto &binding : bindings.Bindings) {
|
|
auto type = binding.BindingType;
|
|
isNotContractable = type.findIf([&](Type nestedType) -> bool {
|
|
if (auto tv = nestedType->getAs<TypeVariableType>()) {
|
|
if (tv->getImpl().canBindToInOut())
|
|
return true;
|
|
}
|
|
|
|
return nestedType->is<InOutType>();
|
|
});
|
|
|
|
// If there is at least one non-contractable binding, let's
|
|
// not risk contracting this edge.
|
|
if (isNotContractable)
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (isNotContractable)
|
|
continue;
|
|
}
|
|
|
|
auto rep1 = CS.getRepresentative(tyvar1);
|
|
auto rep2 = CS.getRepresentative(tyvar2);
|
|
|
|
if (((rep1->getImpl().canBindToLValue() ==
|
|
rep2->getImpl().canBindToLValue()) ||
|
|
// Allow l-value contractions when binding parameter types.
|
|
isParamBindingConstraint)) {
|
|
if (CS.TC.getLangOpts().DebugConstraintSolver) {
|
|
auto &log = CS.getASTContext().TypeCheckerDebug->getStream();
|
|
if (CS.solverState)
|
|
log.indent(CS.solverState->depth * 2);
|
|
|
|
log << "Contracting constraint ";
|
|
constraint->print(log, &CS.getASTContext().SourceMgr);
|
|
log << "\n";
|
|
}
|
|
|
|
// Merge the edges and remove the constraint.
|
|
removeEdge(constraint);
|
|
if (rep1 != rep2)
|
|
CS.mergeEquivalenceClasses(rep1, rep2, /*updateWorkList*/ false);
|
|
didContractEdges = true;
|
|
}
|
|
}
|
|
return didContractEdges;
|
|
}
|
|
|
|
void ConstraintGraph::removeEdge(Constraint *constraint) {
|
|
bool isExistingConstraint = false;
|
|
|
|
for (auto &active : CS.ActiveConstraints) {
|
|
if (&active == constraint) {
|
|
CS.ActiveConstraints.erase(constraint);
|
|
isExistingConstraint = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
for (auto &inactive : CS.InactiveConstraints) {
|
|
if (&inactive == constraint) {
|
|
CS.InactiveConstraints.erase(constraint);
|
|
isExistingConstraint = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (CS.solverState) {
|
|
if (isExistingConstraint)
|
|
CS.solverState->retireConstraint(constraint);
|
|
else
|
|
CS.solverState->removeGeneratedConstraint(constraint);
|
|
}
|
|
|
|
removeConstraint(constraint);
|
|
}
|
|
|
|
void ConstraintGraph::optimize() {
|
|
// Merge equivalence classes until a fixed point is reached.
|
|
while (contractEdges()) {}
|
|
}
|
|
|
|
void ConstraintGraph::incrementConstraintsPerContractionCounter() {
|
|
SWIFT_FUNC_STAT;
|
|
auto &context = CS.getASTContext();
|
|
if (context.Stats)
|
|
context.Stats->getFrontendCounters()
|
|
.NumConstraintsConsideredForEdgeContraction++;
|
|
}
|
|
|
|
#pragma mark Debugging output
|
|
|
|
void ConstraintGraphNode::print(llvm::raw_ostream &out, unsigned indent) {
|
|
out.indent(indent);
|
|
TypeVar->print(out);
|
|
out << ":\n";
|
|
|
|
// Print constraints.
|
|
if (!Constraints.empty()) {
|
|
out.indent(indent + 2);
|
|
out << "Constraints:\n";
|
|
SmallVector<Constraint *, 4> sortedConstraints(Constraints.begin(),
|
|
Constraints.end());
|
|
std::sort(sortedConstraints.begin(), sortedConstraints.end());
|
|
for (auto constraint : sortedConstraints) {
|
|
out.indent(indent + 4);
|
|
constraint->print(out, &TypeVar->getASTContext().SourceMgr);
|
|
out << "\n";
|
|
}
|
|
}
|
|
|
|
// Print fixed bindings.
|
|
if (!FixedBindings.empty()) {
|
|
out.indent(indent + 2);
|
|
out << "Fixed bindings: ";
|
|
SmallVector<TypeVariableType *, 4> sortedFixedBindings(
|
|
FixedBindings.begin(), FixedBindings.end());
|
|
std::sort(sortedFixedBindings.begin(), sortedFixedBindings.end(),
|
|
[&](TypeVariableType *typeVar1, TypeVariableType *typeVar2) {
|
|
return typeVar1->getID() < typeVar2->getID();
|
|
});
|
|
|
|
interleave(sortedFixedBindings,
|
|
[&](TypeVariableType *typeVar) {
|
|
out << "$T" << typeVar->getID();
|
|
},
|
|
[&]() {
|
|
out << ", ";
|
|
});
|
|
out << "\n";
|
|
}
|
|
|
|
// Print equivalence class.
|
|
if (TypeVar->getImpl().getRepresentative(nullptr) == TypeVar &&
|
|
EquivalenceClass.size() > 1) {
|
|
out.indent(indent + 2);
|
|
out << "Equivalence class:";
|
|
for (unsigned i = 1, n = EquivalenceClass.size(); i != n; ++i) {
|
|
out << ' ';
|
|
EquivalenceClass[i]->print(out);
|
|
}
|
|
out << "\n";
|
|
}
|
|
}
|
|
|
|
void ConstraintGraphNode::dump() {
|
|
llvm::SaveAndRestore<bool>
|
|
debug(TypeVar->getASTContext().LangOpts.DebugConstraintSolver, true);
|
|
print(llvm::dbgs(), 0);
|
|
}
|
|
|
|
void ConstraintGraph::print(llvm::raw_ostream &out) {
|
|
for (auto typeVar : TypeVariables) {
|
|
(*this)[typeVar].print(out, 2);
|
|
out << "\n";
|
|
}
|
|
}
|
|
|
|
void ConstraintGraph::dump() {
|
|
llvm::SaveAndRestore<bool>
|
|
debug(CS.getASTContext().LangOpts.DebugConstraintSolver, true);
|
|
print(llvm::dbgs());
|
|
}
|
|
|
|
void ConstraintGraph::printConnectedComponents(llvm::raw_ostream &out) {
|
|
std::vector<TypeVariableType *> typeVars;
|
|
typeVars.insert(typeVars.end(), TypeVariables.begin(), TypeVariables.end());
|
|
std::vector<unsigned> components;
|
|
unsigned numComponents = computeConnectedComponents(typeVars, components);
|
|
for (unsigned component = 0; component != numComponents; ++component) {
|
|
out.indent(2);
|
|
out << component << ":";
|
|
for (unsigned i = 0, n = typeVars.size(); i != n; ++i) {
|
|
if (components[i] == component) {
|
|
out << ' ';
|
|
typeVars[i]->print(out);
|
|
}
|
|
}
|
|
out << '\n';
|
|
}
|
|
}
|
|
|
|
void ConstraintGraph::dumpConnectedComponents() {
|
|
printConnectedComponents(llvm::dbgs());
|
|
}
|
|
|
|
#pragma mark Verification of graph invariants
|
|
|
|
/// Require that the given condition evaluate true.
|
|
///
|
|
/// If the condition is not true, complain about the problem and abort.
|
|
///
|
|
/// \param condition The actual Boolean condition.
|
|
///
|
|
/// \param complaint A string that describes the problem.
|
|
///
|
|
/// \param cg The constraint graph that failed verification.
|
|
///
|
|
/// \param node If non-null, the graph node that failed verification.
|
|
///
|
|
/// \param extraContext If provided, a function that will be called to
|
|
/// provide extra, contextual information about the failure.
|
|
static void _require(bool condition, const Twine &complaint,
|
|
ConstraintGraph &cg,
|
|
ConstraintGraphNode *node,
|
|
const std::function<void()> &extraContext = nullptr) {
|
|
if (condition)
|
|
return;
|
|
|
|
// Complain
|
|
llvm::dbgs() << "Constraint graph verification failed: " << complaint << '\n';
|
|
if (extraContext)
|
|
extraContext();
|
|
|
|
// Print the graph.
|
|
// FIXME: Highlight the offending node/constraint/etc.
|
|
cg.print(llvm::dbgs());
|
|
|
|
abort();
|
|
}
|
|
|
|
/// Print a type variable value.
|
|
static void printValue(llvm::raw_ostream &os, TypeVariableType *typeVar) {
|
|
typeVar->print(os);
|
|
}
|
|
|
|
/// Print a constraint value.
|
|
static void printValue(llvm::raw_ostream &os, Constraint *constraint) {
|
|
constraint->print(os, nullptr);
|
|
}
|
|
|
|
/// Print an unsigned value.
|
|
static void printValue(llvm::raw_ostream &os, unsigned value) {
|
|
os << value;
|
|
}
|
|
|
|
void ConstraintGraphNode::verify(ConstraintGraph &cg) {
|
|
#define require(condition, complaint) _require(condition, complaint, cg, this)
|
|
#define requireWithContext(condition, complaint, context) \
|
|
_require(condition, complaint, cg, this, context)
|
|
#define requireSameValue(value1, value2, complaint) \
|
|
_require(value1 == value2, complaint, cg, this, [&] { \
|
|
llvm::dbgs() << " "; \
|
|
printValue(llvm::dbgs(), value1); \
|
|
llvm::dbgs() << " != "; \
|
|
printValue(llvm::dbgs(), value2); \
|
|
llvm::dbgs() << '\n'; \
|
|
})
|
|
|
|
// Verify that the constraint map/vector haven't gotten out of sync.
|
|
requireSameValue(Constraints.size(), ConstraintIndex.size(),
|
|
"constraint vector and map have different sizes");
|
|
for (auto info : ConstraintIndex) {
|
|
require(info.second < Constraints.size(), "constraint index out-of-range");
|
|
requireSameValue(info.first, Constraints[info.second],
|
|
"constraint map provides wrong index into vector");
|
|
}
|
|
#undef requireSameValue
|
|
#undef requireWithContext
|
|
#undef require
|
|
}
|
|
|
|
void ConstraintGraph::verify() {
|
|
#define require(condition, complaint) \
|
|
_require(condition, complaint, *this, nullptr)
|
|
#define requireWithContext(condition, complaint, context) \
|
|
_require(condition, complaint, *this, nullptr, context)
|
|
#define requireSameValue(value1, value2, complaint) \
|
|
_require(value1 == value2, complaint, *this, nullptr, [&] { \
|
|
llvm::dbgs() << " "; \
|
|
printValue(llvm::dbgs(), value1); \
|
|
llvm::dbgs() << " != "; \
|
|
printValue(llvm::dbgs(), value2); \
|
|
llvm::dbgs() << '\n'; \
|
|
})
|
|
|
|
// 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) {
|
|
auto typeVarRep = CS.getRepresentative(typeVar);
|
|
auto &repNode = (*this)[typeVarRep];
|
|
if (typeVar != typeVarRep) {
|
|
// This type variable should be in the equivalence class of its
|
|
// representative.
|
|
require(std::find(repNode.getEquivalenceClass().begin(),
|
|
repNode.getEquivalenceClass().end(),
|
|
typeVar) != repNode.getEquivalenceClass().end(),
|
|
"type variable not present in its representative's equiv class");
|
|
} else {
|
|
// Each of the type variables in the same equivalence class as this type
|
|
// should have this type variable as their representative.
|
|
for (auto equiv : repNode.getEquivalenceClass()) {
|
|
requireSameValue(
|
|
typeVar, equiv->getImpl().getRepresentative(nullptr),
|
|
"representative and an equivalent type variable's representative");
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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];
|
|
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 constraint : (*this)[typeVar].getConstraints())
|
|
knownConstraints.insert(constraint);
|
|
}
|
|
|
|
// Verify that all of the constraints in the constraint system
|
|
// are accounted for.
|
|
for (auto &constraint : CS.getConstraints()) {
|
|
// Check whether the constraint graph knows about this constraint.
|
|
auto referencedTypeVars = constraint.getTypeVariables();
|
|
requireWithContext((knownConstraints.count(&constraint) ||
|
|
referencedTypeVars.empty()),
|
|
"constraint graph doesn't know about constraint",
|
|
[&] {
|
|
llvm::dbgs() << "constraint = ";
|
|
printValue(llvm::dbgs(), &constraint);
|
|
llvm::dbgs() << "\n";
|
|
});
|
|
|
|
// Make sure each of the type variables referenced knows about this
|
|
// constraint.
|
|
for (auto typeVar : referencedTypeVars) {
|
|
auto nodePtr = typeVar->getImpl().getGraphNode();
|
|
requireWithContext(nodePtr,
|
|
"type variable in constraint not known",
|
|
[&] {
|
|
llvm::dbgs() << "type variable = ";
|
|
printValue(llvm::dbgs(), typeVar);
|
|
llvm::dbgs() << ", constraint = ";
|
|
printValue(llvm::dbgs(), &constraint);
|
|
llvm::dbgs() << "\n";
|
|
});
|
|
|
|
auto &node = *nodePtr;
|
|
auto constraintPos = node.ConstraintIndex.find(&constraint);
|
|
requireWithContext(constraintPos != node.ConstraintIndex.end(),
|
|
"type variable doesn't know about constraint",
|
|
[&] {
|
|
llvm::dbgs() << "type variable = ";
|
|
printValue(llvm::dbgs(), typeVar);
|
|
llvm::dbgs() << ", constraint = ";
|
|
printValue(llvm::dbgs(), &constraint);
|
|
llvm::dbgs() << "\n";
|
|
});
|
|
}
|
|
}
|
|
|
|
#undef requireSameValue
|
|
#undef requireWithContext
|
|
#undef require
|
|
}
|
|
|
|
|