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48dd1e837b
Most of the use-cases of `gatherConstraints` require filtering at least based on the constraint kind that caller is interested in, so instead of returning unrelated results and asking caller to filter separately, let's add that functionality directly to `gatherConstraints`.
1136 lines
38 KiB
C++
1136 lines
38 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/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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ConstraintGraphNode::Adjacency &
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ConstraintGraphNode::getAdjacency(TypeVariableType *typeVar) {
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assert(typeVar != TypeVar && "Cannot be adjacent to oneself");
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// Look for existing adjacency information.
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auto pos = AdjacencyInfo.find(typeVar);
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if (pos != AdjacencyInfo.end())
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return pos->second;
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// If we weren't already adjacent to this type variable, add it to the
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// list of adjacencies.
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pos = AdjacencyInfo.insert(
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{ typeVar, { static_cast<unsigned>(Adjacencies.size()), 0, 0 } })
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.first;
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Adjacencies.push_back(typeVar);
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return pos->second;
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}
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void ConstraintGraphNode::modifyAdjacency(
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TypeVariableType *typeVar,
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llvm::function_ref<void(Adjacency& adj)> modify) {
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// Find the adjacency information.
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auto pos = AdjacencyInfo.find(typeVar);
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assert(pos != AdjacencyInfo.end() && "Type variables not adjacent");
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assert(Adjacencies[pos->second.Index] == typeVar && "Mismatched adjacency");
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// Perform the modification .
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modify(pos->second);
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// If the adjacency is not empty, leave the information in there.
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if (!pos->second.empty())
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return;
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// Remove this adjacency from the mapping.
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unsigned index = pos->second.Index;
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AdjacencyInfo.erase(pos);
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// If this adjacency is last in the vector, just pop it off.
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unsigned lastIndex = Adjacencies.size()-1;
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if (index == lastIndex) {
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Adjacencies.pop_back();
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return;
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}
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// This adjacency is somewhere in the middle; swap it with the last
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// adjacency so we can remove the adjacency from the vector in O(1) time
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// rather than O(n) time.
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auto lastTypeVar = Adjacencies[lastIndex];
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Adjacencies[index] = lastTypeVar;
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AdjacencyInfo[lastTypeVar].Index = index;
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Adjacencies.pop_back();
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}
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void ConstraintGraphNode::addAdjacency(TypeVariableType *typeVar) {
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auto &adjacency = getAdjacency(typeVar);
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// Bump the degree of the adjacency.
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++adjacency.NumConstraints;
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}
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void ConstraintGraphNode::removeAdjacency(TypeVariableType *typeVar) {
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modifyAdjacency(typeVar, [](Adjacency &adj) {
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assert(adj.NumConstraints > 0 && "No adjacency to remove?");
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--adj.NumConstraints;
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});
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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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auto &adjacency = getAdjacency(typeVar);
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assert(!adjacency.FixedBinding && "Already marked as a fixed binding?");
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adjacency.FixedBinding = true;
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}
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void ConstraintGraphNode::removeFixedBinding(TypeVariableType *typeVar) {
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modifyAdjacency(typeVar, [](Adjacency &adj) {
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assert(adj.FixedBinding && "Not a fixed binding?");
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adj.FixedBinding = false;
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});
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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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// Record the adjacent type variables.
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// This is O(N^2) in the number of referenced type variables, because
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// we're updating all of the adjacent type variables eagerly.
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for (auto otherTypeVar : referencedTypeVars) {
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if (typeVar == otherTypeVar)
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continue;
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node.addAdjacency(otherTypeVar);
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}
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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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// Remove the adjacencies for all adjacent type variables.
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// This is O(N^2) in the number of referenced type variables, because
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// we're updating all of the adjacent type variables eagerly.
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for (auto otherTypeVar : referencedTypeVars) {
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if (typeVar == otherTypeVar)
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continue;
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node.removeAdjacency(otherTypeVar);
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}
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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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void ConstraintGraph::gatherConstraints(
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TypeVariableType *typeVar, SmallPtrSetImpl<Constraint *> &constraints,
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GatheringKind kind,
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llvm::function_ref<bool(Constraint *)> acceptConstraint) {
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auto &reprNode = (*this)[CS.getRepresentative(typeVar)];
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auto equivClass = reprNode.getEquivalenceClass();
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llvm::SmallPtrSet<TypeVariableType *, 4> typeVars;
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for (auto typeVar : equivClass) {
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if (!typeVars.insert(typeVar).second)
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continue;
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for (auto constraint : (*this)[typeVar].getConstraints()) {
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if (acceptConstraint(constraint))
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constraints.insert(constraint);
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}
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auto &node = (*this)[typeVar];
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// Retrieve the constraints from adjacent bindings.
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for (auto adjTypeVar : node.getAdjacencies()) {
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switch (kind) {
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case GatheringKind::EquivalenceClass:
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if (!node.getAdjacency(adjTypeVar).FixedBinding)
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continue;
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break;
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case GatheringKind::AllMentions:
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break;
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}
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ArrayRef<TypeVariableType *> adjTypeVarsToVisit;
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switch (kind) {
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case GatheringKind::EquivalenceClass:
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adjTypeVarsToVisit = adjTypeVar;
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break;
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case GatheringKind::AllMentions:
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adjTypeVarsToVisit
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= (*this)[CS.getRepresentative(adjTypeVar)].getEquivalenceClass();
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break;
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}
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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 (acceptConstraint(constraint))
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constraints.insert(constraint);
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}
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}
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}
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}
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}
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#pragma mark Algorithms
|
|
|
|
/// Depth-first search for connected components
|
|
static void connectedComponentsDFS(ConstraintGraph &cg,
|
|
ConstraintGraphNode &node,
|
|
unsigned component,
|
|
SmallVectorImpl<unsigned> &components) {
|
|
// Local function that recurses on the given set of type variables.
|
|
auto visitAdjacencies = [&](ArrayRef<TypeVariableType *> typeVars) {
|
|
for (auto adj : typeVars) {
|
|
auto nodeAndIndex = cg.lookupNode(adj);
|
|
// If we've already seen this node in this component, we're done.
|
|
unsigned &curComponent = components[nodeAndIndex.second];
|
|
if (curComponent == component)
|
|
continue;
|
|
|
|
// Mark this node as part of this connected component, then recurse.
|
|
assert(curComponent == components.size() && "Already in a component?");
|
|
curComponent = component;
|
|
connectedComponentsDFS(cg, nodeAndIndex.first, component, components);
|
|
}
|
|
};
|
|
|
|
// Recurse to mark adjacent nodes as part of this connected component.
|
|
visitAdjacencies(node.getAdjacencies());
|
|
|
|
// Figure out the representative for this type variable.
|
|
auto &cs = cg.getConstraintSystem();
|
|
auto typeVarRep = cs.getRepresentative(node.getTypeVariable());
|
|
if (typeVarRep == node.getTypeVariable()) {
|
|
// This type variable is the representative of its set; visit all of the
|
|
// other type variables in the same equivalence class.
|
|
visitAdjacencies(node.getEquivalenceClass().slice(1));
|
|
} else {
|
|
// Otherwise, visit the representative of the set.
|
|
visitAdjacencies(typeVarRep);
|
|
}
|
|
}
|
|
|
|
unsigned ConstraintGraph::computeConnectedComponents(
|
|
SmallVectorImpl<TypeVariableType *> &typeVars,
|
|
SmallVectorImpl<unsigned> &components) {
|
|
// Track those type variables that the caller cares about.
|
|
llvm::SmallPtrSet<TypeVariableType *, 4> typeVarSubset(typeVars.begin(),
|
|
typeVars.end());
|
|
typeVars.clear();
|
|
|
|
// Initialize the components with component == # of type variables,
|
|
// a sentinel value indicating
|
|
unsigned numTypeVariables = TypeVariables.size();
|
|
components.assign(numTypeVariables, numTypeVariables);
|
|
|
|
// Perform a depth-first search from each type variable to identify
|
|
// what component it is in.
|
|
unsigned numComponents = 0;
|
|
for (unsigned i = 0; i != numTypeVariables; ++i) {
|
|
auto typeVar = TypeVariables[i];
|
|
|
|
// 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.
|
|
curComponent = component;
|
|
connectedComponentsDFS(*this, nodeAndIndex.first, component, components);
|
|
}
|
|
|
|
// 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 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) {
|
|
// 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.
|
|
unsigned outIndex = 0;
|
|
for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
|
|
// 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().mustBeMaterializable())
|
|
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 adjacencies.
|
|
if (!Adjacencies.empty()) {
|
|
out.indent(indent + 2);
|
|
out << "Adjacencies:";
|
|
SmallVector<TypeVariableType *, 4> sortedAdjacencies(Adjacencies.begin(),
|
|
Adjacencies.end());
|
|
std::sort(sortedAdjacencies.begin(), sortedAdjacencies.end(),
|
|
[&](TypeVariableType *typeVar1, TypeVariableType *typeVar2) {
|
|
return typeVar1->getID() < typeVar2->getID();
|
|
});
|
|
|
|
for (auto adj : sortedAdjacencies) {
|
|
out << ' ';
|
|
adj->print(out);
|
|
|
|
auto &info = AdjacencyInfo[adj];
|
|
auto degree = info.NumConstraints;
|
|
if (degree > 1 || info.FixedBinding) {
|
|
out << " (";
|
|
if (degree > 1) {
|
|
out << degree;
|
|
if (info.FixedBinding)
|
|
out << ", fixed";
|
|
} else {
|
|
out << "fixed";
|
|
}
|
|
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) {
|
|
SmallVector<TypeVariableType *, 16> typeVars;
|
|
typeVars.append(TypeVariables.begin(), TypeVariables.end());
|
|
SmallVector<unsigned, 16> 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/adjacency/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");
|
|
}
|
|
|
|
// Verify that the adjacency map/vector haven't gotten out of sync.
|
|
requireSameValue(Adjacencies.size(), AdjacencyInfo.size(),
|
|
"adjacency vector and map have different sizes");
|
|
for (auto info : AdjacencyInfo) {
|
|
require(info.second.Index < Adjacencies.size(),
|
|
"adjacency index out-of-range");
|
|
requireSameValue(info.first, Adjacencies[info.second.Index],
|
|
"adjacency map provides wrong index into vector");
|
|
require(!info.second.empty(),
|
|
"adjacency information should have been removed");
|
|
require(info.second.NumConstraints <= Constraints.size(),
|
|
"adjacency information has higher degree than # of constraints");
|
|
}
|
|
|
|
// Based on the constraints we have, build up a representation of what
|
|
// we expect the adjacencies to look like.
|
|
llvm::DenseMap<TypeVariableType *, unsigned> expectedAdjacencies;
|
|
for (auto constraint : Constraints) {
|
|
for (auto adjTypeVar : constraint->getTypeVariables()) {
|
|
if (adjTypeVar == TypeVar)
|
|
continue;
|
|
|
|
++expectedAdjacencies[adjTypeVar];
|
|
}
|
|
}
|
|
|
|
// Make sure that the adjacencies we expect are the adjacencies we have.
|
|
for (auto adj : expectedAdjacencies) {
|
|
auto knownAdj = AdjacencyInfo.find(adj.first);
|
|
requireWithContext(knownAdj != AdjacencyInfo.end(),
|
|
"missing adjacency information for type variable",
|
|
[&] {
|
|
llvm::dbgs() << " type variable=" << adj.first->getString() << 'n';
|
|
});
|
|
|
|
requireWithContext(adj.second == knownAdj->second.NumConstraints,
|
|
"wrong number of adjacencies for type variable",
|
|
[&] {
|
|
llvm::dbgs() << " type variable=" << adj.first->getString()
|
|
<< " (" << adj.second << " vs. "
|
|
<< knownAdj->second.NumConstraints
|
|
<< ")\n";
|
|
});
|
|
}
|
|
|
|
if (AdjacencyInfo.size() != expectedAdjacencies.size()) {
|
|
// The adjacency information has something extra in it. Find the
|
|
// extraneous type variable.
|
|
for (auto adj : AdjacencyInfo) {
|
|
requireWithContext(AdjacencyInfo.count(adj.first) > 0,
|
|
"extraneous adjacency info for type variable",
|
|
[&] {
|
|
llvm::dbgs() << " type variable=" << adj.first->getString() << '\n';
|
|
});
|
|
}
|
|
}
|
|
|
|
#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
|
|
}
|
|
|
|
|