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+//===- llvm/ADT/FoldingSet.h - Uniquing Hash Set ----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a hash set that can be used to remove duplication of nodes
+// in a graph.  This code was originally created by Chris Lattner for use with
+// SelectionDAGCSEMap, but was isolated to provide use across the llvm code set.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_FOLDINGSET_H
+#define LLVM_ADT_FOLDINGSET_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/Support/Allocator.h"
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <utility>
+
+namespace llvm {
+
+/// This folding set used for two purposes:
+///   1. Given information about a node we want to create, look up the unique
+///      instance of the node in the set.  If the node already exists, return
+///      it, otherwise return the bucket it should be inserted into.
+///   2. Given a node that has already been created, remove it from the set.
+///
+/// This class is implemented as a single-link chained hash table, where the
+/// "buckets" are actually the nodes themselves (the next pointer is in the
+/// node).  The last node points back to the bucket to simplify node removal.
+///
+/// Any node that is to be included in the folding set must be a subclass of
+/// FoldingSetNode.  The node class must also define a Profile method used to
+/// establish the unique bits of data for the node.  The Profile method is
+/// passed a FoldingSetNodeID object which is used to gather the bits.  Just
+/// call one of the Add* functions defined in the FoldingSetBase::NodeID class.
+/// NOTE: That the folding set does not own the nodes and it is the
+/// responsibility of the user to dispose of the nodes.
+///
+/// Eg.
+///    class MyNode : public FoldingSetNode {
+///    private:
+///      std::string Name;
+///      unsigned Value;
+///    public:
+///      MyNode(const char *N, unsigned V) : Name(N), Value(V) {}
+///       ...
+///      void Profile(FoldingSetNodeID &ID) const {
+///        ID.AddString(Name);
+///        ID.AddInteger(Value);
+///      }
+///      ...
+///    };
+///
+/// To define the folding set itself use the FoldingSet template;
+///
+/// Eg.
+///    FoldingSet<MyNode> MyFoldingSet;
+///
+/// Four public methods are available to manipulate the folding set;
+///
+/// 1) If you have an existing node that you want add to the set but unsure
+/// that the node might already exist then call;
+///
+///    MyNode *M = MyFoldingSet.GetOrInsertNode(N);
+///
+/// If The result is equal to the input then the node has been inserted.
+/// Otherwise, the result is the node existing in the folding set, and the
+/// input can be discarded (use the result instead.)
+///
+/// 2) If you are ready to construct a node but want to check if it already
+/// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to
+/// check;
+///
+///   FoldingSetNodeID ID;
+///   ID.AddString(Name);
+///   ID.AddInteger(Value);
+///   void *InsertPoint;
+///
+///    MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint);
+///
+/// If found then M with be non-NULL, else InsertPoint will point to where it
+/// should be inserted using InsertNode.
+///
+/// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new
+/// node with FindNodeOrInsertPos;
+///
+///    InsertNode(N, InsertPoint);
+///
+/// 4) Finally, if you want to remove a node from the folding set call;
+///
+///    bool WasRemoved = RemoveNode(N);
+///
+/// The result indicates whether the node existed in the folding set.
+
+class FoldingSetNodeID;
+class StringRef;
+
+//===----------------------------------------------------------------------===//
+/// FoldingSetBase - Implements the folding set functionality.  The main
+/// structure is an array of buckets.  Each bucket is indexed by the hash of
+/// the nodes it contains.  The bucket itself points to the nodes contained
+/// in the bucket via a singly linked list.  The last node in the list points
+/// back to the bucket to facilitate node removal.
+///
+class FoldingSetBase {
+  virtual void anchor(); // Out of line virtual method.
+
+protected:
+  /// Buckets - Array of bucket chains.
+  void **Buckets;
+
+  /// NumBuckets - Length of the Buckets array.  Always a power of 2.
+  unsigned NumBuckets;
+
+  /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes
+  /// is greater than twice the number of buckets.
+  unsigned NumNodes;
+
+  explicit FoldingSetBase(unsigned Log2InitSize = 6);
+  FoldingSetBase(FoldingSetBase &&Arg);
+  FoldingSetBase &operator=(FoldingSetBase &&RHS);
+  ~FoldingSetBase();
+
+public:
+  //===--------------------------------------------------------------------===//
+  /// Node - This class is used to maintain the singly linked bucket list in
+  /// a folding set.
+  class Node {
+  private:
+    // NextInFoldingSetBucket - next link in the bucket list.
+    void *NextInFoldingSetBucket = nullptr;
+
+  public:
+    Node() = default;
+
+    // Accessors
+    void *getNextInBucket() const { return NextInFoldingSetBucket; }
+    void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; }
+  };
+
+  /// clear - Remove all nodes from the folding set.
+  void clear();
+
+  /// size - Returns the number of nodes in the folding set.
+  unsigned size() const { return NumNodes; }
+
+  /// empty - Returns true if there are no nodes in the folding set.
+  bool empty() const { return NumNodes == 0; }
+
+  /// reserve - Increase the number of buckets such that adding the
+  /// EltCount-th node won't cause a rebucket operation. reserve is permitted
+  /// to allocate more space than requested by EltCount.
+  void reserve(unsigned EltCount);
+
+  /// capacity - Returns the number of nodes permitted in the folding set
+  /// before a rebucket operation is performed.
+  unsigned capacity() {
+    // We allow a load factor of up to 2.0,
+    // so that means our capacity is NumBuckets * 2
+    return NumBuckets * 2;
+  }
+
+private:
+  /// GrowHashTable - Double the size of the hash table and rehash everything.
+  void GrowHashTable();
+
+  /// GrowBucketCount - resize the hash table and rehash everything.
+  /// NewBucketCount must be a power of two, and must be greater than the old
+  /// bucket count.
+  void GrowBucketCount(unsigned NewBucketCount);
+
+protected:
+  /// GetNodeProfile - Instantiations of the FoldingSet template implement
+  /// this function to gather data bits for the given node.
+  virtual void GetNodeProfile(Node *N, FoldingSetNodeID &ID) const = 0;
+
+  /// NodeEquals - Instantiations of the FoldingSet template implement
+  /// this function to compare the given node with the given ID.
+  virtual bool NodeEquals(Node *N, const FoldingSetNodeID &ID, unsigned IDHash,
+                          FoldingSetNodeID &TempID) const=0;
+
+  /// ComputeNodeHash - Instantiations of the FoldingSet template implement
+  /// this function to compute a hash value for the given node.
+  virtual unsigned ComputeNodeHash(Node *N, FoldingSetNodeID &TempID) const = 0;
+
+  // The below methods are protected to encourage subclasses to provide a more
+  // type-safe API.
+
+  /// RemoveNode - Remove a node from the folding set, returning true if one
+  /// was removed or false if the node was not in the folding set.
+  bool RemoveNode(Node *N);
+
+  /// GetOrInsertNode - If there is an existing simple Node exactly
+  /// equal to the specified node, return it.  Otherwise, insert 'N' and return
+  /// it instead.
+  Node *GetOrInsertNode(Node *N);
+
+  /// FindNodeOrInsertPos - Look up the node specified by ID.  If it exists,
+  /// return it.  If not, return the insertion token that will make insertion
+  /// faster.
+  Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos);
+
+  /// InsertNode - Insert the specified node into the folding set, knowing that
+  /// it is not already in the folding set.  InsertPos must be obtained from
+  /// FindNodeOrInsertPos.
+  void InsertNode(Node *N, void *InsertPos);
+};
+
+//===----------------------------------------------------------------------===//
+
+/// DefaultFoldingSetTrait - This class provides default implementations
+/// for FoldingSetTrait implementations.
+template<typename T> struct DefaultFoldingSetTrait {
+  static void Profile(const T &X, FoldingSetNodeID &ID) {
+    X.Profile(ID);
+  }
+  static void Profile(T &X, FoldingSetNodeID &ID) {
+    X.Profile(ID);
+  }
+
+  // Equals - Test if the profile for X would match ID, using TempID
+  // to compute a temporary ID if necessary. The default implementation
+  // just calls Profile and does a regular comparison. Implementations
+  // can override this to provide more efficient implementations.
+  static inline bool Equals(T &X, const FoldingSetNodeID &ID, unsigned IDHash,
+                            FoldingSetNodeID &TempID);
+
+  // ComputeHash - Compute a hash value for X, using TempID to
+  // compute a temporary ID if necessary. The default implementation
+  // just calls Profile and does a regular hash computation.
+  // Implementations can override this to provide more efficient
+  // implementations.
+  static inline unsigned ComputeHash(T &X, FoldingSetNodeID &TempID);
+};
+
+/// FoldingSetTrait - This trait class is used to define behavior of how
+/// to "profile" (in the FoldingSet parlance) an object of a given type.
+/// The default behavior is to invoke a 'Profile' method on an object, but
+/// through template specialization the behavior can be tailored for specific
+/// types.  Combined with the FoldingSetNodeWrapper class, one can add objects
+/// to FoldingSets that were not originally designed to have that behavior.
+template<typename T> struct FoldingSetTrait
+  : public DefaultFoldingSetTrait<T> {};
+
+/// DefaultContextualFoldingSetTrait - Like DefaultFoldingSetTrait, but
+/// for ContextualFoldingSets.
+template<typename T, typename Ctx>
+struct DefaultContextualFoldingSetTrait {
+  static void Profile(T &X, FoldingSetNodeID &ID, Ctx Context) {
+    X.Profile(ID, Context);
+  }
+
+  static inline bool Equals(T &X, const FoldingSetNodeID &ID, unsigned IDHash,
+                            FoldingSetNodeID &TempID, Ctx Context);
+  static inline unsigned ComputeHash(T &X, FoldingSetNodeID &TempID,
+                                     Ctx Context);
+};
+
+/// ContextualFoldingSetTrait - Like FoldingSetTrait, but for
+/// ContextualFoldingSets.
+template<typename T, typename Ctx> struct ContextualFoldingSetTrait
+  : public DefaultContextualFoldingSetTrait<T, Ctx> {};
+
+//===--------------------------------------------------------------------===//
+/// FoldingSetNodeIDRef - This class describes a reference to an interned
+/// FoldingSetNodeID, which can be a useful to store node id data rather
+/// than using plain FoldingSetNodeIDs, since the 32-element SmallVector
+/// is often much larger than necessary, and the possibility of heap
+/// allocation means it requires a non-trivial destructor call.
+class FoldingSetNodeIDRef {
+  const unsigned *Data = nullptr;
+  size_t Size = 0;
+
+public:
+  FoldingSetNodeIDRef() = default;
+  FoldingSetNodeIDRef(const unsigned *D, size_t S) : Data(D), Size(S) {}
+
+  /// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef,
+  /// used to lookup the node in the FoldingSetBase.
+  unsigned ComputeHash() const;
+
+  bool operator==(FoldingSetNodeIDRef) const;
+
+  bool operator!=(FoldingSetNodeIDRef RHS) const { return !(*this == RHS); }
+
+  /// Used to compare the "ordering" of two nodes as defined by the
+  /// profiled bits and their ordering defined by memcmp().
+  bool operator<(FoldingSetNodeIDRef) const;
+
+  const unsigned *getData() const { return Data; }
+  size_t getSize() const { return Size; }
+};
+
+//===--------------------------------------------------------------------===//
+/// FoldingSetNodeID - This class is used to gather all the unique data bits of
+/// a node.  When all the bits are gathered this class is used to produce a
+/// hash value for the node.
+class FoldingSetNodeID {
+  /// Bits - Vector of all the data bits that make the node unique.
+  /// Use a SmallVector to avoid a heap allocation in the common case.
+  SmallVector<unsigned, 32> Bits;
+
+public:
+  FoldingSetNodeID() = default;
+
+  FoldingSetNodeID(FoldingSetNodeIDRef Ref)
+    : Bits(Ref.getData(), Ref.getData() + Ref.getSize()) {}
+
+  /// Add* - Add various data types to Bit data.
+  void AddPointer(const void *Ptr);
+  void AddInteger(signed I);
+  void AddInteger(unsigned I);
+  void AddInteger(long I);
+  void AddInteger(unsigned long I);
+  void AddInteger(long long I);
+  void AddInteger(unsigned long long I);
+  void AddBoolean(bool B) { AddInteger(B ? 1U : 0U); }
+  void AddString(StringRef String);
+  void AddNodeID(const FoldingSetNodeID &ID);
+
+  template <typename T>
+  inline void Add(const T &x) { FoldingSetTrait<T>::Profile(x, *this); }
+
+  /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID
+  /// object to be used to compute a new profile.
+  inline void clear() { Bits.clear(); }
+
+  /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used
+  /// to lookup the node in the FoldingSetBase.
+  unsigned ComputeHash() const;
+
+  /// operator== - Used to compare two nodes to each other.
+  bool operator==(const FoldingSetNodeID &RHS) const;
+  bool operator==(const FoldingSetNodeIDRef RHS) const;
+
+  bool operator!=(const FoldingSetNodeID &RHS) const { return !(*this == RHS); }
+  bool operator!=(const FoldingSetNodeIDRef RHS) const { return !(*this ==RHS);}
+
+  /// Used to compare the "ordering" of two nodes as defined by the
+  /// profiled bits and their ordering defined by memcmp().
+  bool operator<(const FoldingSetNodeID &RHS) const;
+  bool operator<(const FoldingSetNodeIDRef RHS) const;
+
+  /// Intern - Copy this node's data to a memory region allocated from the
+  /// given allocator and return a FoldingSetNodeIDRef describing the
+  /// interned data.
+  FoldingSetNodeIDRef Intern(BumpPtrAllocator &Allocator) const;
+};
+
+// Convenience type to hide the implementation of the folding set.
+using FoldingSetNode = FoldingSetBase::Node;
+template<class T> class FoldingSetIterator;
+template<class T> class FoldingSetBucketIterator;
+
+// Definitions of FoldingSetTrait and ContextualFoldingSetTrait functions, which
+// require the definition of FoldingSetNodeID.
+template<typename T>
+inline bool
+DefaultFoldingSetTrait<T>::Equals(T &X, const FoldingSetNodeID &ID,
+                                  unsigned /*IDHash*/,
+                                  FoldingSetNodeID &TempID) {
+  FoldingSetTrait<T>::Profile(X, TempID);
+  return TempID == ID;
+}
+template<typename T>
+inline unsigned
+DefaultFoldingSetTrait<T>::ComputeHash(T &X, FoldingSetNodeID &TempID) {
+  FoldingSetTrait<T>::Profile(X, TempID);
+  return TempID.ComputeHash();
+}
+template<typename T, typename Ctx>
+inline bool
+DefaultContextualFoldingSetTrait<T, Ctx>::Equals(T &X,
+                                                 const FoldingSetNodeID &ID,
+                                                 unsigned /*IDHash*/,
+                                                 FoldingSetNodeID &TempID,
+                                                 Ctx Context) {
+  ContextualFoldingSetTrait<T, Ctx>::Profile(X, TempID, Context);
+  return TempID == ID;
+}
+template<typename T, typename Ctx>
+inline unsigned
+DefaultContextualFoldingSetTrait<T, Ctx>::ComputeHash(T &X,
+                                                      FoldingSetNodeID &TempID,
+                                                      Ctx Context) {
+  ContextualFoldingSetTrait<T, Ctx>::Profile(X, TempID, Context);
+  return TempID.ComputeHash();
+}
+
+//===----------------------------------------------------------------------===//
+/// FoldingSetImpl - An implementation detail that lets us share code between
+/// FoldingSet and ContextualFoldingSet.
+template <class T> class FoldingSetImpl : public FoldingSetBase {
+protected:
+  explicit FoldingSetImpl(unsigned Log2InitSize)
+      : FoldingSetBase(Log2InitSize) {}
+
+  FoldingSetImpl(FoldingSetImpl &&Arg) = default;
+  FoldingSetImpl &operator=(FoldingSetImpl &&RHS) = default;
+  ~FoldingSetImpl() = default;
+
+public:
+  using iterator = FoldingSetIterator<T>;
+
+  iterator begin() { return iterator(Buckets); }
+  iterator end() { return iterator(Buckets+NumBuckets); }
+
+  using const_iterator = FoldingSetIterator<const T>;
+
+  const_iterator begin() const { return const_iterator(Buckets); }
+  const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
+
+  using bucket_iterator = FoldingSetBucketIterator<T>;
+
+  bucket_iterator bucket_begin(unsigned hash) {
+    return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
+  }
+
+  bucket_iterator bucket_end(unsigned hash) {
+    return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
+  }
+
+  /// RemoveNode - Remove a node from the folding set, returning true if one
+  /// was removed or false if the node was not in the folding set.
+  bool RemoveNode(T *N) { return FoldingSetBase::RemoveNode(N); }
+
+  /// GetOrInsertNode - If there is an existing simple Node exactly
+  /// equal to the specified node, return it.  Otherwise, insert 'N' and
+  /// return it instead.
+  T *GetOrInsertNode(T *N) {
+    return static_cast<T *>(FoldingSetBase::GetOrInsertNode(N));
+  }
+
+  /// FindNodeOrInsertPos - Look up the node specified by ID.  If it exists,
+  /// return it.  If not, return the insertion token that will make insertion
+  /// faster.
+  T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
+    return static_cast<T *>(FoldingSetBase::FindNodeOrInsertPos(ID, InsertPos));
+  }
+
+  /// InsertNode - Insert the specified node into the folding set, knowing that
+  /// it is not already in the folding set.  InsertPos must be obtained from
+  /// FindNodeOrInsertPos.
+  void InsertNode(T *N, void *InsertPos) {
+    FoldingSetBase::InsertNode(N, InsertPos);
+  }
+
+  /// InsertNode - Insert the specified node into the folding set, knowing that
+  /// it is not already in the folding set.
+  void InsertNode(T *N) {
+    T *Inserted = GetOrInsertNode(N);
+    (void)Inserted;
+    assert(Inserted == N && "Node already inserted!");
+  }
+};
+
+//===----------------------------------------------------------------------===//
+/// FoldingSet - This template class is used to instantiate a specialized
+/// implementation of the folding set to the node class T.  T must be a
+/// subclass of FoldingSetNode and implement a Profile function.
+///
+/// Note that this set type is movable and move-assignable. However, its
+/// moved-from state is not a valid state for anything other than
+/// move-assigning and destroying. This is primarily to enable movable APIs
+/// that incorporate these objects.
+template <class T> class FoldingSet final : public FoldingSetImpl<T> {
+  using Super = FoldingSetImpl<T>;
+  using Node = typename Super::Node;
+
+  /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
+  /// way to convert nodes into a unique specifier.
+  void GetNodeProfile(Node *N, FoldingSetNodeID &ID) const override {
+    T *TN = static_cast<T *>(N);
+    FoldingSetTrait<T>::Profile(*TN, ID);
+  }
+
+  /// NodeEquals - Instantiations may optionally provide a way to compare a
+  /// node with a specified ID.
+  bool NodeEquals(Node *N, const FoldingSetNodeID &ID, unsigned IDHash,
+                  FoldingSetNodeID &TempID) const override {
+    T *TN = static_cast<T *>(N);
+    return FoldingSetTrait<T>::Equals(*TN, ID, IDHash, TempID);
+  }
+
+  /// ComputeNodeHash - Instantiations may optionally provide a way to compute a
+  /// hash value directly from a node.
+  unsigned ComputeNodeHash(Node *N, FoldingSetNodeID &TempID) const override {
+    T *TN = static_cast<T *>(N);
+    return FoldingSetTrait<T>::ComputeHash(*TN, TempID);
+  }
+
+public:
+  explicit FoldingSet(unsigned Log2InitSize = 6) : Super(Log2InitSize) {}
+  FoldingSet(FoldingSet &&Arg) = default;
+  FoldingSet &operator=(FoldingSet &&RHS) = default;
+};
+
+//===----------------------------------------------------------------------===//
+/// ContextualFoldingSet - This template class is a further refinement
+/// of FoldingSet which provides a context argument when calling
+/// Profile on its nodes.  Currently, that argument is fixed at
+/// initialization time.
+///
+/// T must be a subclass of FoldingSetNode and implement a Profile
+/// function with signature
+///   void Profile(FoldingSetNodeID &, Ctx);
+template <class T, class Ctx>
+class ContextualFoldingSet final : public FoldingSetImpl<T> {
+  // Unfortunately, this can't derive from FoldingSet<T> because the
+  // construction of the vtable for FoldingSet<T> requires
+  // FoldingSet<T>::GetNodeProfile to be instantiated, which in turn
+  // requires a single-argument T::Profile().
+
+  using Super = FoldingSetImpl<T>;
+  using Node = typename Super::Node;
+
+  Ctx Context;
+
+  /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
+  /// way to convert nodes into a unique specifier.
+  void GetNodeProfile(Node *N, FoldingSetNodeID &ID) const override {
+    T *TN = static_cast<T *>(N);
+    ContextualFoldingSetTrait<T, Ctx>::Profile(*TN, ID, Context);
+  }
+
+  bool NodeEquals(Node *N, const FoldingSetNodeID &ID, unsigned IDHash,
+                  FoldingSetNodeID &TempID) const override {
+    T *TN = static_cast<T *>(N);
+    return ContextualFoldingSetTrait<T, Ctx>::Equals(*TN, ID, IDHash, TempID,
+                                                     Context);
+  }
+
+  unsigned ComputeNodeHash(Node *N, FoldingSetNodeID &TempID) const override {
+    T *TN = static_cast<T *>(N);
+    return ContextualFoldingSetTrait<T, Ctx>::ComputeHash(*TN, TempID, Context);
+  }
+
+public:
+  explicit ContextualFoldingSet(Ctx Context, unsigned Log2InitSize = 6)
+      : Super(Log2InitSize), Context(Context) {}
+
+  Ctx getContext() const { return Context; }
+};
+
+//===----------------------------------------------------------------------===//
+/// FoldingSetVector - This template class combines a FoldingSet and a vector
+/// to provide the interface of FoldingSet but with deterministic iteration
+/// order based on the insertion order. T must be a subclass of FoldingSetNode
+/// and implement a Profile function.
+template <class T, class VectorT = SmallVector<T*, 8>>
+class FoldingSetVector {
+  FoldingSet<T> Set;
+  VectorT Vector;
+
+public:
+  explicit FoldingSetVector(unsigned Log2InitSize = 6) : Set(Log2InitSize) {}
+
+  using iterator = pointee_iterator<typename VectorT::iterator>;
+
+  iterator begin() { return Vector.begin(); }
+  iterator end()   { return Vector.end(); }
+
+  using const_iterator = pointee_iterator<typename VectorT::const_iterator>;
+
+  const_iterator begin() const { return Vector.begin(); }
+  const_iterator end()   const { return Vector.end(); }
+
+  /// clear - Remove all nodes from the folding set.
+  void clear() { Set.clear(); Vector.clear(); }
+
+  /// FindNodeOrInsertPos - Look up the node specified by ID.  If it exists,
+  /// return it.  If not, return the insertion token that will make insertion
+  /// faster.
+  T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
+    return Set.FindNodeOrInsertPos(ID, InsertPos);
+  }
+
+  /// GetOrInsertNode - If there is an existing simple Node exactly
+  /// equal to the specified node, return it.  Otherwise, insert 'N' and
+  /// return it instead.
+  T *GetOrInsertNode(T *N) {
+    T *Result = Set.GetOrInsertNode(N);
+    if (Result == N) Vector.push_back(N);
+    return Result;
+  }
+
+  /// InsertNode - Insert the specified node into the folding set, knowing that
+  /// it is not already in the folding set.  InsertPos must be obtained from
+  /// FindNodeOrInsertPos.
+  void InsertNode(T *N, void *InsertPos) {
+    Set.InsertNode(N, InsertPos);
+    Vector.push_back(N);
+  }
+
+  /// InsertNode - Insert the specified node into the folding set, knowing that
+  /// it is not already in the folding set.
+  void InsertNode(T *N) {
+    Set.InsertNode(N);
+    Vector.push_back(N);
+  }
+
+  /// size - Returns the number of nodes in the folding set.
+  unsigned size() const { return Set.size(); }
+
+  /// empty - Returns true if there are no nodes in the folding set.
+  bool empty() const { return Set.empty(); }
+};
+
+//===----------------------------------------------------------------------===//
+/// FoldingSetIteratorImpl - This is the common iterator support shared by all
+/// folding sets, which knows how to walk the folding set hash table.
+class FoldingSetIteratorImpl {
+protected:
+  FoldingSetNode *NodePtr;
+
+  FoldingSetIteratorImpl(void **Bucket);
+
+  void advance();
+
+public:
+  bool operator==(const FoldingSetIteratorImpl &RHS) const {
+    return NodePtr == RHS.NodePtr;
+  }
+  bool operator!=(const FoldingSetIteratorImpl &RHS) const {
+    return NodePtr != RHS.NodePtr;
+  }
+};
+
+template <class T> class FoldingSetIterator : public FoldingSetIteratorImpl {
+public:
+  explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
+
+  T &operator*() const {
+    return *static_cast<T*>(NodePtr);
+  }
+
+  T *operator->() const {
+    return static_cast<T*>(NodePtr);
+  }
+
+  inline FoldingSetIterator &operator++() {          // Preincrement
+    advance();
+    return *this;
+  }
+  FoldingSetIterator operator++(int) {        // Postincrement
+    FoldingSetIterator tmp = *this; ++*this; return tmp;
+  }
+};
+
+//===----------------------------------------------------------------------===//
+/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support
+/// shared by all folding sets, which knows how to walk a particular bucket
+/// of a folding set hash table.
+class FoldingSetBucketIteratorImpl {
+protected:
+  void *Ptr;
+
+  explicit FoldingSetBucketIteratorImpl(void **Bucket);
+
+  FoldingSetBucketIteratorImpl(void **Bucket, bool) : Ptr(Bucket) {}
+
+  void advance() {
+    void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket();
+    uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1;
+    Ptr = reinterpret_cast<void*>(x);
+  }
+
+public:
+  bool operator==(const FoldingSetBucketIteratorImpl &RHS) const {
+    return Ptr == RHS.Ptr;
+  }
+  bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const {
+    return Ptr != RHS.Ptr;
+  }
+};
+
+template <class T>
+class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl {
+public:
+  explicit FoldingSetBucketIterator(void **Bucket) :
+    FoldingSetBucketIteratorImpl(Bucket) {}
+
+  FoldingSetBucketIterator(void **Bucket, bool) :
+    FoldingSetBucketIteratorImpl(Bucket, true) {}
+
+  T &operator*() const { return *static_cast<T*>(Ptr); }
+  T *operator->() const { return static_cast<T*>(Ptr); }
+
+  inline FoldingSetBucketIterator &operator++() { // Preincrement
+    advance();
+    return *this;
+  }
+  FoldingSetBucketIterator operator++(int) {      // Postincrement
+    FoldingSetBucketIterator tmp = *this; ++*this; return tmp;
+  }
+};
+
+//===----------------------------------------------------------------------===//
+/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary
+/// types in an enclosing object so that they can be inserted into FoldingSets.
+template <typename T>
+class FoldingSetNodeWrapper : public FoldingSetNode {
+  T data;
+
+public:
+  template <typename... Ts>
+  explicit FoldingSetNodeWrapper(Ts &&... Args)
+      : data(std::forward<Ts>(Args)...) {}
+
+  void Profile(FoldingSetNodeID &ID) { FoldingSetTrait<T>::Profile(data, ID); }
+
+  T &getValue() { return data; }
+  const T &getValue() const { return data; }
+
+  operator T&() { return data; }
+  operator const T&() const { return data; }
+};
+
+//===----------------------------------------------------------------------===//
+/// FastFoldingSetNode - This is a subclass of FoldingSetNode which stores
+/// a FoldingSetNodeID value rather than requiring the node to recompute it
+/// each time it is needed. This trades space for speed (which can be
+/// significant if the ID is long), and it also permits nodes to drop
+/// information that would otherwise only be required for recomputing an ID.
+class FastFoldingSetNode : public FoldingSetNode {
+  FoldingSetNodeID FastID;
+
+protected:
+  explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {}
+
+public:
+  void Profile(FoldingSetNodeID &ID) const { ID.AddNodeID(FastID); }
+};
+
+//===----------------------------------------------------------------------===//
+// Partial specializations of FoldingSetTrait.
+
+template<typename T> struct FoldingSetTrait<T*> {
+  static inline void Profile(T *X, FoldingSetNodeID &ID) {
+    ID.AddPointer(X);
+  }
+};
+template <typename T1, typename T2>
+struct FoldingSetTrait<std::pair<T1, T2>> {
+  static inline void Profile(const std::pair<T1, T2> &P,
+                             FoldingSetNodeID &ID) {
+    ID.Add(P.first);
+    ID.Add(P.second);
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_ADT_FOLDINGSET_H