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Merge pull request #76759 from slavapestov/cstrail-part-0
Unify ConstraintGraph change tracking with SavedTypeVariableBindings
2 parents b24a810 + 4548880 commit f563de5

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14 files changed

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14 files changed

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‎include/swift/Sema/CSTrail.h‎

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//===--- CSTrail.h - Constraint Solver Trail --------------------*- C++ -*-===//
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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 - 2024 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 defines the \c SolverTrail class, which records the decisions taken
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// while attempting to find a solution.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SEMA_CSTRAIL_H
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#define SWIFT_SEMA_CSTRAIL_H
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#include <vector>
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namespace llvm {
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class raw_ostream;
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}
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namespace swift {
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class TypeBase;
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class TypeVariableType;
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namespace constraints {
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class Constraint;
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class SolverTrail {
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public:
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/// The kind of change made to the graph.
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enum class ChangeKind {
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/// Added a type variable to the constraint graph.
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AddedTypeVariable,
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/// Added a new constraint to the constraint graph.
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AddedConstraint,
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/// Removed an existing constraint from the constraint graph.
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RemovedConstraint,
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/// Extended the equivalence class of a type variable in the constraint graph.
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ExtendedEquivalenceClass,
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/// Added a fixed binding for a type variable in the constraint graph.
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BoundTypeVariable,
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/// Introduced a type variable's fixed type to inference.
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IntroducedToInference,
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/// Set the fixed type or parent and flags for a type variable.
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UpdatedTypeVariable,
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};
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/// A change made to the constraint system.
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///
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/// Each change can be undone (once, and in reverse order) by calling the
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/// undo() method.
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class Change {
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public:
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/// The kind of change.
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ChangeKind Kind;
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union {
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TypeVariableType *TypeVar;
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Constraint *TheConstraint;
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struct {
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/// The type variable whose equivalence class was extended.
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TypeVariableType *TypeVar;
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/// The previous size of the equivalence class.
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unsigned PrevSize;
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} EquivClass;
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struct {
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/// The type variable being bound to a fixed type.
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TypeVariableType *TypeVar;
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/// The fixed type to which the type variable was bound.
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TypeBase *FixedType;
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} Binding;
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struct {
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/// The type variable being updated.
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TypeVariableType *TypeVar;
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/// The representative of the equivalence class, or the fixed type.
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llvm::PointerUnion<TypeVariableType *, TypeBase *> ParentOrFixed;
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/// The saved value of TypeVariableType::Implementation::getRawOptions().
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unsigned Options;
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} Update;
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};
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Change() : Kind(ChangeKind::AddedTypeVariable), TypeVar(nullptr) { }
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/// Create a change that added a type variable.
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static Change addedTypeVariable(TypeVariableType *typeVar);
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/// Create a change that added a constraint.
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static Change addedConstraint(Constraint *constraint);
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/// Create a change that removed a constraint.
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static Change removedConstraint(Constraint *constraint);
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/// Create a change that extended an equivalence class.
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static Change extendedEquivalenceClass(TypeVariableType *typeVar,
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unsigned prevSize);
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/// Create a change that bound a type variable to a fixed type.
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static Change boundTypeVariable(TypeVariableType *typeVar, Type fixed);
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/// Create a change that introduced a type variable to inference.
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static Change introducedToInference(TypeVariableType *typeVar, Type fixed);
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/// Create a change that updated a type variable.
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static Change updatedTypeVariable(
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TypeVariableType *typeVar,
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llvm::PointerUnion<TypeVariableType *, TypeBase *> parentOrFixed,
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unsigned options);
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/// Undo this change, reverting the constraint graph to the state it
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/// had prior to this change.
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///
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/// Changes must be undone in stack order.
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void undo(ConstraintSystem &cs) const;
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void dump(llvm::raw_ostream &out, ConstraintSystem &cs,
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unsigned indent = 0) const;
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};
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SolverTrail(ConstraintSystem &cs) : CS(cs) {}
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~SolverTrail();
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SolverTrail(const SolverTrail &) = delete;
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SolverTrail &operator=(const SolverTrail &) = delete;
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bool isUndoActive() const { return UndoActive; }
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void recordChange(Change change);
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void dumpActiveScopeChanges(llvm::raw_ostream &out,
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unsigned fromIndex,
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unsigned indent = 0) const;
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unsigned size() const {
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return Changes.size();
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}
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void undo(unsigned toIndex);
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private:
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ConstraintSystem &CS;
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/// The list of changes made to this constraint system.
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std::vector<Change> Changes;
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bool UndoActive = false;
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unsigned Total = 0;
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unsigned Max = 0;
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};
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} // namespace constraints
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} // namespace swift
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#endif // SWIFT_SEMA_CSTRAIL_H

‎include/swift/Sema/ConstraintGraph.h‎

Lines changed: 22 additions & 85 deletions
Original file line numberDiff line numberDiff line change
@@ -42,7 +42,6 @@ namespace constraints {
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class Constraint;
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class ConstraintGraph;
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class ConstraintGraphScope;
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class ConstraintSystem;
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class TypeVariableBinding;
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@@ -58,6 +57,13 @@ class ConstraintGraphNode {
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/// Retrieve the type variable this node represents.
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TypeVariableType *getTypeVariable() const { return TypeVar; }
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void reset();
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void initTypeVariable(TypeVariableType *typeVar) {
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ASSERT(!TypeVar);
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TypeVar = typeVar;
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}
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/// Retrieve the set of constraints that mention this type variable.
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///
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/// These are the hyperedges of the graph, connecting this node to
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void introduceToInference(Type fixedType);
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/// Opposite of \c introduceToInference(Type)
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void
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retractFromInference(Type fixedType,
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SmallPtrSetImpl<TypeVariableType *> &referencedVars);
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void retractFromInference(Type fixedType);
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/// Drop all previously collected bindings and re-infer based on the
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/// current set constraints associated with this equivalence class.
@@ -216,6 +220,7 @@ class ConstraintGraphNode {
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friend class ConstraintGraph;
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friend class ConstraintSystem;
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friend class TypeVariableBinding;
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friend class SolverTrail;
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};
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/// A graph that describes the relationships among the various type variables
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/// Bind the given type variable to the given fixed type.
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void bindTypeVariable(TypeVariableType *typeVar, Type fixedType);
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/// Introduce the type variable's fixed type to inference.
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void introduceToInference(TypeVariableType *typeVar, Type fixedType);
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/// Describes which constraints \c gatherConstraints should gather.
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enum class GatheringKind {
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/// Gather constraints associated with all of the variables within the
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/// Print the graph.
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void print(ArrayRef<TypeVariableType *> typeVars, llvm::raw_ostream &out);
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void dump(llvm::raw_ostream &out);
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void dumpActiveScopeChanges(llvm::raw_ostream &out, unsigned indent = 0);
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// FIXME: Potentially side-effectful.
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SWIFT_DEBUG_HELPER(void dump());
@@ -423,6 +430,12 @@ class ConstraintGraph {
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/// caution.
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void unbindTypeVariable(TypeVariableType *typeVar, Type fixedType);
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/// Retract the given type variable from inference.
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///
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/// Note that this change is not recorded and cannot be undone. Use with
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/// caution.
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void retractFromInference(TypeVariableType *typeVar, Type fixedType);
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/// Perform edge contraction on the constraint graph, merging equivalence
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/// classes until a fixed point is reached.
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bool contractEdges();
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/// Constraints that are "orphaned" because they contain no type variables.
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SmallVector<Constraint *, 4> OrphanedConstraints;
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/// Unused nodes.
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SmallVector<ConstraintGraphNode *> FreeList;
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/// Increment the number of constraints considered per attempt
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/// to contract constraint graph edges.
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void incrementConstraintsPerContractionCounter();
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/// The kind of change made to the graph.
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enum class ChangeKind {
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/// Added a type variable.
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AddedTypeVariable,
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/// Added a new constraint.
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AddedConstraint,
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/// Removed an existing constraint
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RemovedConstraint,
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/// Extended the equivalence class of a type variable.
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ExtendedEquivalenceClass,
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/// Added a fixed binding for a type variable.
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BoundTypeVariable,
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};
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/// A change made to the constraint graph.
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///
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/// Each change can be undone (once, and in reverse order) by calling the
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/// undo() method.
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class Change {
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public:
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/// The kind of change.
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ChangeKind Kind;
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union {
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TypeVariableType *TypeVar;
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Constraint *TheConstraint;
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struct {
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/// The type variable whose equivalence class was extended.
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TypeVariableType *TypeVar;
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/// The previous size of the equivalence class.
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unsigned PrevSize;
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} EquivClass;
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struct {
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/// The type variable being bound to a fixed type.
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TypeVariableType *TypeVar;
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/// The fixed type to which the type variable was bound.
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TypeBase *FixedType;
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} Binding;
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};
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Change() : Kind(ChangeKind::AddedTypeVariable), TypeVar(nullptr) { }
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/// Create a change that added a type variable.
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static Change addedTypeVariable(TypeVariableType *typeVar);
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/// Create a change that added a constraint.
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static Change addedConstraint(Constraint *constraint);
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/// Create a change that removed a constraint.
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static Change removedConstraint(Constraint *constraint);
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/// Create a change that extended an equivalence class.
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static Change extendedEquivalenceClass(TypeVariableType *typeVar,
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unsigned prevSize);
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/// Create a change that bound a type variable to a fixed type.
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static Change boundTypeVariable(TypeVariableType *typeVar, Type fixed);
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/// Undo this change, reverting the constraint graph to the state it
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/// had prior to this change.
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///
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/// Changes must be undone in stack order.
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void undo(ConstraintGraph &cg);
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};
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/// The currently active scope, or null if we aren't tracking changes made
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/// to the constraint graph.
514-
ConstraintGraphScope *ActiveScope = nullptr;
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/// The set of changes made to this constraint graph.
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///
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/// As the constraint graph is extended and mutated, additional changes are
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/// introduced into this vector. Each scope
520-
llvm::SmallVector<Change, 4> Changes;
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friend class ConstraintGraphScope;
459+
friend class SolverTrail;
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};
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} // end namespace constraints

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