Restoring authorship annotation for <orivej@yandex-team.ru>. Commit 1 of 2.

1 files changed, 1195 insertions, 1195 deletions

diff --git a/contrib/libs/llvm12/include/llvm/ADT/ImmutableSet.h b/contrib/libs/llvm12/include/llvm/ADT/ImmutableSet.h
index dfbf8b0156..8c2deb5f32 100644
--- a/contrib/libs/llvm12/include/llvm/ADT/ImmutableSet.h
+++ b/contrib/libs/llvm12/include/llvm/ADT/ImmutableSet.h
@@ -1,1195 +1,1195 @@
-#pragma once
-
-#ifdef __GNUC__
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunused-parameter"
-#endif
-
-//===--- ImmutableSet.h - Immutable (functional) set interface --*- C++ -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines the ImutAVLTree and ImmutableSet classes.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_ADT_IMMUTABLESET_H
-#define LLVM_ADT_IMMUTABLESET_H
-
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/FoldingSet.h"
-#include "llvm/ADT/IntrusiveRefCntPtr.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/iterator.h"
-#include "llvm/Support/Allocator.h"
-#include "llvm/Support/ErrorHandling.h"
-#include <cassert>
-#include <cstdint>
-#include <functional>
-#include <iterator>
-#include <new>
-#include <vector>
-
-namespace llvm {
-
-//===----------------------------------------------------------------------===//
-// Immutable AVL-Tree Definition.
-//===----------------------------------------------------------------------===//
-
-template <typename ImutInfo> class ImutAVLFactory;
-template <typename ImutInfo> class ImutIntervalAVLFactory;
-template <typename ImutInfo> class ImutAVLTreeInOrderIterator;
-template <typename ImutInfo> class ImutAVLTreeGenericIterator;
-
-template <typename ImutInfo >
-class ImutAVLTree {
-public:
-  using key_type_ref = typename ImutInfo::key_type_ref;
-  using value_type = typename ImutInfo::value_type;
-  using value_type_ref = typename ImutInfo::value_type_ref;
-  using Factory = ImutAVLFactory<ImutInfo>;
-  using iterator = ImutAVLTreeInOrderIterator<ImutInfo>;
-
-  friend class ImutAVLFactory<ImutInfo>;
-  friend class ImutIntervalAVLFactory<ImutInfo>;
-  friend class ImutAVLTreeGenericIterator<ImutInfo>;
-
-  //===----------------------------------------------------===//
-  // Public Interface.
-  //===----------------------------------------------------===//
-
-  /// Return a pointer to the left subtree.  This value
-  ///  is NULL if there is no left subtree.
-  ImutAVLTree *getLeft() const { return left; }
-
-  /// Return a pointer to the right subtree.  This value is
-  ///  NULL if there is no right subtree.
-  ImutAVLTree *getRight() const { return right; }
-
-  /// getHeight - Returns the height of the tree.  A tree with no subtrees
-  ///  has a height of 1.
-  unsigned getHeight() const { return height; }
-
-  /// getValue - Returns the data value associated with the tree node.
-  const value_type& getValue() const { return value; }
-
-  /// find - Finds the subtree associated with the specified key value.
-  ///  This method returns NULL if no matching subtree is found.
-  ImutAVLTree* find(key_type_ref K) {
-    ImutAVLTree *T = this;
-    while (T) {
-      key_type_ref CurrentKey = ImutInfo::KeyOfValue(T->getValue());
-      if (ImutInfo::isEqual(K,CurrentKey))
-        return T;
-      else if (ImutInfo::isLess(K,CurrentKey))
-        T = T->getLeft();
-      else
-        T = T->getRight();
-    }
-    return nullptr;
-  }
-
-  /// getMaxElement - Find the subtree associated with the highest ranged
-  ///  key value.
-  ImutAVLTree* getMaxElement() {
-    ImutAVLTree *T = this;
-    ImutAVLTree *Right = T->getRight();
-    while (Right) { T = Right; Right = T->getRight(); }
-    return T;
-  }
-
-  /// size - Returns the number of nodes in the tree, which includes
-  ///  both leaves and non-leaf nodes.
-  unsigned size() const {
-    unsigned n = 1;
-    if (const ImutAVLTree* L = getLeft())
-      n += L->size();
-    if (const ImutAVLTree* R = getRight())
-      n += R->size();
-    return n;
-  }
-
-  /// begin - Returns an iterator that iterates over the nodes of the tree
-  ///  in an inorder traversal.  The returned iterator thus refers to the
-  ///  the tree node with the minimum data element.
-  iterator begin() const { return iterator(this); }
-
-  /// end - Returns an iterator for the tree that denotes the end of an
-  ///  inorder traversal.
-  iterator end() const { return iterator(); }
-
-  bool isElementEqual(value_type_ref V) const {
-    // Compare the keys.
-    if (!ImutInfo::isEqual(ImutInfo::KeyOfValue(getValue()),
-                           ImutInfo::KeyOfValue(V)))
-      return false;
-
-    // Also compare the data values.
-    if (!ImutInfo::isDataEqual(ImutInfo::DataOfValue(getValue()),
-                               ImutInfo::DataOfValue(V)))
-      return false;
-
-    return true;
-  }
-
-  bool isElementEqual(const ImutAVLTree* RHS) const {
-    return isElementEqual(RHS->getValue());
-  }
-
-  /// isEqual - Compares two trees for structural equality and returns true
-  ///   if they are equal.  This worst case performance of this operation is
-  //    linear in the sizes of the trees.
-  bool isEqual(const ImutAVLTree& RHS) const {
-    if (&RHS == this)
-      return true;
-
-    iterator LItr = begin(), LEnd = end();
-    iterator RItr = RHS.begin(), REnd = RHS.end();
-
-    while (LItr != LEnd && RItr != REnd) {
-      if (&*LItr == &*RItr) {
-        LItr.skipSubTree();
-        RItr.skipSubTree();
-        continue;
-      }
-
-      if (!LItr->isElementEqual(&*RItr))
-        return false;
-
-      ++LItr;
-      ++RItr;
-    }
-
-    return LItr == LEnd && RItr == REnd;
-  }
-
-  /// isNotEqual - Compares two trees for structural inequality.  Performance
-  ///  is the same is isEqual.
-  bool isNotEqual(const ImutAVLTree& RHS) const { return !isEqual(RHS); }
-
-  /// contains - Returns true if this tree contains a subtree (node) that
-  ///  has an data element that matches the specified key.  Complexity
-  ///  is logarithmic in the size of the tree.
-  bool contains(key_type_ref K) { return (bool) find(K); }
-
-  /// foreach - A member template the accepts invokes operator() on a functor
-  ///  object (specified by Callback) for every node/subtree in the tree.
-  ///  Nodes are visited using an inorder traversal.
-  template <typename Callback>
-  void foreach(Callback& C) {
-    if (ImutAVLTree* L = getLeft())
-      L->foreach(C);
-
-    C(value);
-
-    if (ImutAVLTree* R = getRight())
-      R->foreach(C);
-  }
-
-  /// validateTree - A utility method that checks that the balancing and
-  ///  ordering invariants of the tree are satisfied.  It is a recursive
-  ///  method that returns the height of the tree, which is then consumed
-  ///  by the enclosing validateTree call.  External callers should ignore the
-  ///  return value.  An invalid tree will cause an assertion to fire in
-  ///  a debug build.
-  unsigned validateTree() const {
-    unsigned HL = getLeft() ? getLeft()->validateTree() : 0;
-    unsigned HR = getRight() ? getRight()->validateTree() : 0;
-    (void) HL;
-    (void) HR;
-
-    assert(getHeight() == ( HL > HR ? HL : HR ) + 1
-            && "Height calculation wrong");
-
-    assert((HL > HR ? HL-HR : HR-HL) <= 2
-           && "Balancing invariant violated");
-
-    assert((!getLeft() ||
-            ImutInfo::isLess(ImutInfo::KeyOfValue(getLeft()->getValue()),
-                             ImutInfo::KeyOfValue(getValue()))) &&
-           "Value in left child is not less that current value");
-
-    assert((!getRight() ||
-             ImutInfo::isLess(ImutInfo::KeyOfValue(getValue()),
-                              ImutInfo::KeyOfValue(getRight()->getValue()))) &&
-           "Current value is not less that value of right child");
-
-    return getHeight();
-  }
-
-  //===----------------------------------------------------===//
-  // Internal values.
-  //===----------------------------------------------------===//
-
-private:
-  Factory *factory;
-  ImutAVLTree *left;
-  ImutAVLTree *right;
-  ImutAVLTree *prev = nullptr;
-  ImutAVLTree *next = nullptr;
-
-  unsigned height : 28;
-  bool IsMutable : 1;
-  bool IsDigestCached : 1;
-  bool IsCanonicalized : 1;
-
-  value_type value;
-  uint32_t digest = 0;
-  uint32_t refCount = 0;
-
-  //===----------------------------------------------------===//
-  // Internal methods (node manipulation; used by Factory).
-  //===----------------------------------------------------===//
-
-private:
-  /// ImutAVLTree - Internal constructor that is only called by
-  ///   ImutAVLFactory.
-  ImutAVLTree(Factory *f, ImutAVLTree* l, ImutAVLTree* r, value_type_ref v,
-              unsigned height)
-    : factory(f), left(l), right(r), height(height), IsMutable(true),
-      IsDigestCached(false), IsCanonicalized(false), value(v)
-  {
-    if (left) left->retain();
-    if (right) right->retain();
-  }
-
-  /// isMutable - Returns true if the left and right subtree references
-  ///  (as well as height) can be changed.  If this method returns false,
-  ///  the tree is truly immutable.  Trees returned from an ImutAVLFactory
-  ///  object should always have this method return true.  Further, if this
-  ///  method returns false for an instance of ImutAVLTree, all subtrees
-  ///  will also have this method return false.  The converse is not true.
-  bool isMutable() const { return IsMutable; }
-
-  /// hasCachedDigest - Returns true if the digest for this tree is cached.
-  ///  This can only be true if the tree is immutable.
-  bool hasCachedDigest() const { return IsDigestCached; }
-
-  //===----------------------------------------------------===//
-  // Mutating operations.  A tree root can be manipulated as
-  // long as its reference has not "escaped" from internal
-  // methods of a factory object (see below).  When a tree
-  // pointer is externally viewable by client code, the
-  // internal "mutable bit" is cleared to mark the tree
-  // immutable.  Note that a tree that still has its mutable
-  // bit set may have children (subtrees) that are themselves
-  // immutable.
-  //===----------------------------------------------------===//
-
-  /// markImmutable - Clears the mutable flag for a tree.  After this happens,
-  ///   it is an error to call setLeft(), setRight(), and setHeight().
-  void markImmutable() {
-    assert(isMutable() && "Mutable flag already removed.");
-    IsMutable = false;
-  }
-
-  /// markedCachedDigest - Clears the NoCachedDigest flag for a tree.
-  void markedCachedDigest() {
-    assert(!hasCachedDigest() && "NoCachedDigest flag already removed.");
-    IsDigestCached = true;
-  }
-
-  /// setHeight - Changes the height of the tree.  Used internally by
-  ///  ImutAVLFactory.
-  void setHeight(unsigned h) {
-    assert(isMutable() && "Only a mutable tree can have its height changed.");
-    height = h;
-  }
-
-  static uint32_t computeDigest(ImutAVLTree *L, ImutAVLTree *R,
-                                value_type_ref V) {
-    uint32_t digest = 0;
-
-    if (L)
-      digest += L->computeDigest();
-
-    // Compute digest of stored data.
-    FoldingSetNodeID ID;
-    ImutInfo::Profile(ID,V);
-    digest += ID.ComputeHash();
-
-    if (R)
-      digest += R->computeDigest();
-
-    return digest;
-  }
-
-  uint32_t computeDigest() {
-    // Check the lowest bit to determine if digest has actually been
-    // pre-computed.
-    if (hasCachedDigest())
-      return digest;
-
-    uint32_t X = computeDigest(getLeft(), getRight(), getValue());
-    digest = X;
-    markedCachedDigest();
-    return X;
-  }
-
-  //===----------------------------------------------------===//
-  // Reference count operations.
-  //===----------------------------------------------------===//
-
-public:
-  void retain() { ++refCount; }
-
-  void release() {
-    assert(refCount > 0);
-    if (--refCount == 0)
-      destroy();
-  }
-
-  void destroy() {
-    if (left)
-      left->release();
-    if (right)
-      right->release();
-    if (IsCanonicalized) {
-      if (next)
-        next->prev = prev;
-
-      if (prev)
-        prev->next = next;
-      else
-        factory->Cache[factory->maskCacheIndex(computeDigest())] = next;
-    }
-
-    // We need to clear the mutability bit in case we are
-    // destroying the node as part of a sweep in ImutAVLFactory::recoverNodes().
-    IsMutable = false;
-    factory->freeNodes.push_back(this);
-  }
-};
-
-template <typename ImutInfo>
-struct IntrusiveRefCntPtrInfo<ImutAVLTree<ImutInfo>> {
-  static void retain(ImutAVLTree<ImutInfo> *Tree) { Tree->retain(); }
-  static void release(ImutAVLTree<ImutInfo> *Tree) { Tree->release(); }
-};
-
-//===----------------------------------------------------------------------===//
-// Immutable AVL-Tree Factory class.
-//===----------------------------------------------------------------------===//
-
-template <typename ImutInfo >
-class ImutAVLFactory {
-  friend class ImutAVLTree<ImutInfo>;
-
-  using TreeTy = ImutAVLTree<ImutInfo>;
-  using value_type_ref = typename TreeTy::value_type_ref;
-  using key_type_ref = typename TreeTy::key_type_ref;
-  using CacheTy = DenseMap<unsigned, TreeTy*>;
-
-  CacheTy Cache;
-  uintptr_t Allocator;
-  std::vector<TreeTy*> createdNodes;
-  std::vector<TreeTy*> freeNodes;
-
-  bool ownsAllocator() const {
-    return (Allocator & 0x1) == 0;
-  }
-
-  BumpPtrAllocator& getAllocator() const {
-    return *reinterpret_cast<BumpPtrAllocator*>(Allocator & ~0x1);
-  }
-
-  //===--------------------------------------------------===//
-  // Public interface.
-  //===--------------------------------------------------===//
-
-public:
-  ImutAVLFactory()
-    : Allocator(reinterpret_cast<uintptr_t>(new BumpPtrAllocator())) {}
-
-  ImutAVLFactory(BumpPtrAllocator& Alloc)
-    : Allocator(reinterpret_cast<uintptr_t>(&Alloc) | 0x1) {}
-
-  ~ImutAVLFactory() {
-    if (ownsAllocator()) delete &getAllocator();
-  }
-
-  TreeTy* add(TreeTy* T, value_type_ref V) {
-    T = add_internal(V,T);
-    markImmutable(T);
-    recoverNodes();
-    return T;
-  }
-
-  TreeTy* remove(TreeTy* T, key_type_ref V) {
-    T = remove_internal(V,T);
-    markImmutable(T);
-    recoverNodes();
-    return T;
-  }
-
-  TreeTy* getEmptyTree() const { return nullptr; }
-
-protected:
-  //===--------------------------------------------------===//
-  // A bunch of quick helper functions used for reasoning
-  // about the properties of trees and their children.
-  // These have succinct names so that the balancing code
-  // is as terse (and readable) as possible.
-  //===--------------------------------------------------===//
-
-  bool            isEmpty(TreeTy* T) const { return !T; }
-  unsigned        getHeight(TreeTy* T) const { return T ? T->getHeight() : 0; }
-  TreeTy*         getLeft(TreeTy* T) const { return T->getLeft(); }
-  TreeTy*         getRight(TreeTy* T) const { return T->getRight(); }
-  value_type_ref  getValue(TreeTy* T) const { return T->value; }
-
-  // Make sure the index is not the Tombstone or Entry key of the DenseMap.
-  static unsigned maskCacheIndex(unsigned I) { return (I & ~0x02); }
-
-  unsigned incrementHeight(TreeTy* L, TreeTy* R) const {
-    unsigned hl = getHeight(L);
-    unsigned hr = getHeight(R);
-    return (hl > hr ? hl : hr) + 1;
-  }
-
-  static bool compareTreeWithSection(TreeTy* T,
-                                     typename TreeTy::iterator& TI,
-                                     typename TreeTy::iterator& TE) {
-    typename TreeTy::iterator I = T->begin(), E = T->end();
-    for ( ; I!=E ; ++I, ++TI) {
-      if (TI == TE || !I->isElementEqual(&*TI))
-        return false;
-    }
-    return true;
-  }
-
-  //===--------------------------------------------------===//
-  // "createNode" is used to generate new tree roots that link
-  // to other trees.  The function may also simply move links
-  // in an existing root if that root is still marked mutable.
-  // This is necessary because otherwise our balancing code
-  // would leak memory as it would create nodes that are
-  // then discarded later before the finished tree is
-  // returned to the caller.
-  //===--------------------------------------------------===//
-
-  TreeTy* createNode(TreeTy* L, value_type_ref V, TreeTy* R) {
-    BumpPtrAllocator& A = getAllocator();
-    TreeTy* T;
-    if (!freeNodes.empty()) {
-      T = freeNodes.back();
-      freeNodes.pop_back();
-      assert(T != L);
-      assert(T != R);
-    } else {
-      T = (TreeTy*) A.Allocate<TreeTy>();
-    }
-    new (T) TreeTy(this, L, R, V, incrementHeight(L,R));
-    createdNodes.push_back(T);
-    return T;
-  }
-
-  TreeTy* createNode(TreeTy* newLeft, TreeTy* oldTree, TreeTy* newRight) {
-    return createNode(newLeft, getValue(oldTree), newRight);
-  }
-
-  void recoverNodes() {
-    for (unsigned i = 0, n = createdNodes.size(); i < n; ++i) {
-      TreeTy *N = createdNodes[i];
-      if (N->isMutable() && N->refCount == 0)
-        N->destroy();
-    }
-    createdNodes.clear();
-  }
-
-  /// balanceTree - Used by add_internal and remove_internal to
-  ///  balance a newly created tree.
-  TreeTy* balanceTree(TreeTy* L, value_type_ref V, TreeTy* R) {
-    unsigned hl = getHeight(L);
-    unsigned hr = getHeight(R);
-
-    if (hl > hr + 2) {
-      assert(!isEmpty(L) && "Left tree cannot be empty to have a height >= 2");
-
-      TreeTy *LL = getLeft(L);
-      TreeTy *LR = getRight(L);
-
-      if (getHeight(LL) >= getHeight(LR))
-        return createNode(LL, L, createNode(LR,V,R));
-
-      assert(!isEmpty(LR) && "LR cannot be empty because it has a height >= 1");
-
-      TreeTy *LRL = getLeft(LR);
-      TreeTy *LRR = getRight(LR);
-
-      return createNode(createNode(LL,L,LRL), LR, createNode(LRR,V,R));
-    }
-
-    if (hr > hl + 2) {
-      assert(!isEmpty(R) && "Right tree cannot be empty to have a height >= 2");
-
-      TreeTy *RL = getLeft(R);
-      TreeTy *RR = getRight(R);
-
-      if (getHeight(RR) >= getHeight(RL))
-        return createNode(createNode(L,V,RL), R, RR);
-
-      assert(!isEmpty(RL) && "RL cannot be empty because it has a height >= 1");
-
-      TreeTy *RLL = getLeft(RL);
-      TreeTy *RLR = getRight(RL);
-
-      return createNode(createNode(L,V,RLL), RL, createNode(RLR,R,RR));
-    }
-
-    return createNode(L,V,R);
-  }
-
-  /// add_internal - Creates a new tree that includes the specified
-  ///  data and the data from the original tree.  If the original tree
-  ///  already contained the data item, the original tree is returned.
-  TreeTy* add_internal(value_type_ref V, TreeTy* T) {
-    if (isEmpty(T))
-      return createNode(T, V, T);
-    assert(!T->isMutable());
-
-    key_type_ref K = ImutInfo::KeyOfValue(V);
-    key_type_ref KCurrent = ImutInfo::KeyOfValue(getValue(T));
-
-    if (ImutInfo::isEqual(K,KCurrent))
-      return createNode(getLeft(T), V, getRight(T));
-    else if (ImutInfo::isLess(K,KCurrent))
-      return balanceTree(add_internal(V, getLeft(T)), getValue(T), getRight(T));
-    else
-      return balanceTree(getLeft(T), getValue(T), add_internal(V, getRight(T)));
-  }
-
-  /// remove_internal - Creates a new tree that includes all the data
-  ///  from the original tree except the specified data.  If the
-  ///  specified data did not exist in the original tree, the original
-  ///  tree is returned.
-  TreeTy* remove_internal(key_type_ref K, TreeTy* T) {
-    if (isEmpty(T))
-      return T;
-
-    assert(!T->isMutable());
-
-    key_type_ref KCurrent = ImutInfo::KeyOfValue(getValue(T));
-
-    if (ImutInfo::isEqual(K,KCurrent)) {
-      return combineTrees(getLeft(T), getRight(T));
-    } else if (ImutInfo::isLess(K,KCurrent)) {
-      return balanceTree(remove_internal(K, getLeft(T)),
-                                            getValue(T), getRight(T));
-    } else {
-      return balanceTree(getLeft(T), getValue(T),
-                         remove_internal(K, getRight(T)));
-    }
-  }
-
-  TreeTy* combineTrees(TreeTy* L, TreeTy* R) {
-    if (isEmpty(L))
-      return R;
-    if (isEmpty(R))
-      return L;
-    TreeTy* OldNode;
-    TreeTy* newRight = removeMinBinding(R,OldNode);
-    return balanceTree(L, getValue(OldNode), newRight);
-  }
-
-  TreeTy* removeMinBinding(TreeTy* T, TreeTy*& Noderemoved) {
-    assert(!isEmpty(T));
-    if (isEmpty(getLeft(T))) {
-      Noderemoved = T;
-      return getRight(T);
-    }
-    return balanceTree(removeMinBinding(getLeft(T), Noderemoved),
-                       getValue(T), getRight(T));
-  }
-
-  /// markImmutable - Clears the mutable bits of a root and all of its
-  ///  descendants.
-  void markImmutable(TreeTy* T) {
-    if (!T || !T->isMutable())
-      return;
-    T->markImmutable();
-    markImmutable(getLeft(T));
-    markImmutable(getRight(T));
-  }
-
-public:
-  TreeTy *getCanonicalTree(TreeTy *TNew) {
-    if (!TNew)
-      return nullptr;
-
-    if (TNew->IsCanonicalized)
-      return TNew;
-
-    // Search the hashtable for another tree with the same digest, and
-    // if find a collision compare those trees by their contents.
-    unsigned digest = TNew->computeDigest();
-    TreeTy *&entry = Cache[maskCacheIndex(digest)];
-    do {
-      if (!entry)
-        break;
-      for (TreeTy *T = entry ; T != nullptr; T = T->next) {
-        // Compare the Contents('T') with Contents('TNew')
-        typename TreeTy::iterator TI = T->begin(), TE = T->end();
-        if (!compareTreeWithSection(TNew, TI, TE))
-          continue;
-        if (TI != TE)
-          continue; // T has more contents than TNew.
-        // Trees did match!  Return 'T'.
-        if (TNew->refCount == 0)
-          TNew->destroy();
-        return T;
-      }
-      entry->prev = TNew;
-      TNew->next = entry;
-    }
-    while (false);
-
-    entry = TNew;
-    TNew->IsCanonicalized = true;
-    return TNew;
-  }
-};
-
-//===----------------------------------------------------------------------===//
-// Immutable AVL-Tree Iterators.
-//===----------------------------------------------------------------------===//
-
-template <typename ImutInfo>
-class ImutAVLTreeGenericIterator
-    : public std::iterator<std::bidirectional_iterator_tag,
-                           ImutAVLTree<ImutInfo>> {
-  SmallVector<uintptr_t,20> stack;
-
-public:
-  enum VisitFlag { VisitedNone=0x0, VisitedLeft=0x1, VisitedRight=0x3,
-                   Flags=0x3 };
-
-  using TreeTy = ImutAVLTree<ImutInfo>;
-
-  ImutAVLTreeGenericIterator() = default;
-  ImutAVLTreeGenericIterator(const TreeTy *Root) {
-    if (Root) stack.push_back(reinterpret_cast<uintptr_t>(Root));
-  }
-
-  TreeTy &operator*() const {
-    assert(!stack.empty());
-    return *reinterpret_cast<TreeTy *>(stack.back() & ~Flags);
-  }
-  TreeTy *operator->() const { return &*this; }
-
-  uintptr_t getVisitState() const {
-    assert(!stack.empty());
-    return stack.back() & Flags;
-  }
-
-  bool atEnd() const { return stack.empty(); }
-
-  bool atBeginning() const {
-    return stack.size() == 1 && getVisitState() == VisitedNone;
-  }
-
-  void skipToParent() {
-    assert(!stack.empty());
-    stack.pop_back();
-    if (stack.empty())
-      return;
-    switch (getVisitState()) {
-      case VisitedNone:
-        stack.back() |= VisitedLeft;
-        break;
-      case VisitedLeft:
-        stack.back() |= VisitedRight;
-        break;
-      default:
-        llvm_unreachable("Unreachable.");
-    }
-  }
-
-  bool operator==(const ImutAVLTreeGenericIterator &x) const {
-    return stack == x.stack;
-  }
-
-  bool operator!=(const ImutAVLTreeGenericIterator &x) const {
-    return !(*this == x);
-  }
-
-  ImutAVLTreeGenericIterator &operator++() {
-    assert(!stack.empty());
-    TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
-    assert(Current);
-    switch (getVisitState()) {
-      case VisitedNone:
-        if (TreeTy* L = Current->getLeft())
-          stack.push_back(reinterpret_cast<uintptr_t>(L));
-        else
-          stack.back() |= VisitedLeft;
-        break;
-      case VisitedLeft:
-        if (TreeTy* R = Current->getRight())
-          stack.push_back(reinterpret_cast<uintptr_t>(R));
-        else
-          stack.back() |= VisitedRight;
-        break;
-      case VisitedRight:
-        skipToParent();
-        break;
-      default:
-        llvm_unreachable("Unreachable.");
-    }
-    return *this;
-  }
-
-  ImutAVLTreeGenericIterator &operator--() {
-    assert(!stack.empty());
-    TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
-    assert(Current);
-    switch (getVisitState()) {
-      case VisitedNone:
-        stack.pop_back();
-        break;
-      case VisitedLeft:
-        stack.back() &= ~Flags; // Set state to "VisitedNone."
-        if (TreeTy* L = Current->getLeft())
-          stack.push_back(reinterpret_cast<uintptr_t>(L) | VisitedRight);
-        break;
-      case VisitedRight:
-        stack.back() &= ~Flags;
-        stack.back() |= VisitedLeft;
-        if (TreeTy* R = Current->getRight())
-          stack.push_back(reinterpret_cast<uintptr_t>(R) | VisitedRight);
-        break;
-      default:
-        llvm_unreachable("Unreachable.");
-    }
-    return *this;
-  }
-};
-
-template <typename ImutInfo>
-class ImutAVLTreeInOrderIterator
-    : public std::iterator<std::bidirectional_iterator_tag,
-                           ImutAVLTree<ImutInfo>> {
-  using InternalIteratorTy = ImutAVLTreeGenericIterator<ImutInfo>;
-
-  InternalIteratorTy InternalItr;
-
-public:
-  using TreeTy = ImutAVLTree<ImutInfo>;
-
-  ImutAVLTreeInOrderIterator(const TreeTy* Root) : InternalItr(Root) {
-    if (Root)
-      ++*this; // Advance to first element.
-  }
-
-  ImutAVLTreeInOrderIterator() : InternalItr() {}
-
-  bool operator==(const ImutAVLTreeInOrderIterator &x) const {
-    return InternalItr == x.InternalItr;
-  }
-
-  bool operator!=(const ImutAVLTreeInOrderIterator &x) const {
-    return !(*this == x);
-  }
-
-  TreeTy &operator*() const { return *InternalItr; }
-  TreeTy *operator->() const { return &*InternalItr; }
-
-  ImutAVLTreeInOrderIterator &operator++() {
-    do ++InternalItr;
-    while (!InternalItr.atEnd() &&
-           InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
-
-    return *this;
-  }
-
-  ImutAVLTreeInOrderIterator &operator--() {
-    do --InternalItr;
-    while (!InternalItr.atBeginning() &&
-           InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
-
-    return *this;
-  }
-
-  void skipSubTree() {
-    InternalItr.skipToParent();
-
-    while (!InternalItr.atEnd() &&
-           InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft)
-      ++InternalItr;
-  }
-};
-
-/// Generic iterator that wraps a T::TreeTy::iterator and exposes
-/// iterator::getValue() on dereference.
-template <typename T>
-struct ImutAVLValueIterator
-    : iterator_adaptor_base<
-          ImutAVLValueIterator<T>, typename T::TreeTy::iterator,
-          typename std::iterator_traits<
-              typename T::TreeTy::iterator>::iterator_category,
-          const typename T::value_type> {
-  ImutAVLValueIterator() = default;
-  explicit ImutAVLValueIterator(typename T::TreeTy *Tree)
-      : ImutAVLValueIterator::iterator_adaptor_base(Tree) {}
-
-  typename ImutAVLValueIterator::reference operator*() const {
-    return this->I->getValue();
-  }
-};
-
-//===----------------------------------------------------------------------===//
-// Trait classes for Profile information.
-//===----------------------------------------------------------------------===//
-
-/// Generic profile template.  The default behavior is to invoke the
-/// profile method of an object.  Specializations for primitive integers
-/// and generic handling of pointers is done below.
-template <typename T>
-struct ImutProfileInfo {
-  using value_type = const T;
-  using value_type_ref = const T&;
-
-  static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
-    FoldingSetTrait<T>::Profile(X,ID);
-  }
-};
-
-/// Profile traits for integers.
-template <typename T>
-struct ImutProfileInteger {
-  using value_type = const T;
-  using value_type_ref = const T&;
-
-  static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
-    ID.AddInteger(X);
-  }
-};
-
-#define PROFILE_INTEGER_INFO(X)\
-template<> struct ImutProfileInfo<X> : ImutProfileInteger<X> {};
-
-PROFILE_INTEGER_INFO(char)
-PROFILE_INTEGER_INFO(unsigned char)
-PROFILE_INTEGER_INFO(short)
-PROFILE_INTEGER_INFO(unsigned short)
-PROFILE_INTEGER_INFO(unsigned)
-PROFILE_INTEGER_INFO(signed)
-PROFILE_INTEGER_INFO(long)
-PROFILE_INTEGER_INFO(unsigned long)
-PROFILE_INTEGER_INFO(long long)
-PROFILE_INTEGER_INFO(unsigned long long)
-
-#undef PROFILE_INTEGER_INFO
-
-/// Profile traits for booleans.
-template <>
-struct ImutProfileInfo<bool> {
-  using value_type = const bool;
-  using value_type_ref = const bool&;
-
-  static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
-    ID.AddBoolean(X);
-  }
-};
-
-/// Generic profile trait for pointer types.  We treat pointers as
-/// references to unique objects.
-template <typename T>
-struct ImutProfileInfo<T*> {
-  using value_type = const T*;
-  using value_type_ref = value_type;
-
-  static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
-    ID.AddPointer(X);
-  }
-};
-
-//===----------------------------------------------------------------------===//
-// Trait classes that contain element comparison operators and type
-//  definitions used by ImutAVLTree, ImmutableSet, and ImmutableMap.  These
-//  inherit from the profile traits (ImutProfileInfo) to include operations
-//  for element profiling.
-//===----------------------------------------------------------------------===//
-
-/// ImutContainerInfo - Generic definition of comparison operations for
-///   elements of immutable containers that defaults to using
-///   std::equal_to<> and std::less<> to perform comparison of elements.
-template <typename T>
-struct ImutContainerInfo : public ImutProfileInfo<T> {
-  using value_type = typename ImutProfileInfo<T>::value_type;
-  using value_type_ref = typename ImutProfileInfo<T>::value_type_ref;
-  using key_type = value_type;
-  using key_type_ref = value_type_ref;
-  using data_type = bool;
-  using data_type_ref = bool;
-
-  static key_type_ref KeyOfValue(value_type_ref D) { return D; }
-  static data_type_ref DataOfValue(value_type_ref) { return true; }
-
-  static bool isEqual(key_type_ref LHS, key_type_ref RHS) {
-    return std::equal_to<key_type>()(LHS,RHS);
-  }
-
-  static bool isLess(key_type_ref LHS, key_type_ref RHS) {
-    return std::less<key_type>()(LHS,RHS);
-  }
-
-  static bool isDataEqual(data_type_ref, data_type_ref) { return true; }
-};
-
-/// ImutContainerInfo - Specialization for pointer values to treat pointers
-///  as references to unique objects.  Pointers are thus compared by
-///  their addresses.
-template <typename T>
-struct ImutContainerInfo<T*> : public ImutProfileInfo<T*> {
-  using value_type = typename ImutProfileInfo<T*>::value_type;
-  using value_type_ref = typename ImutProfileInfo<T*>::value_type_ref;
-  using key_type = value_type;
-  using key_type_ref = value_type_ref;
-  using data_type = bool;
-  using data_type_ref = bool;
-
-  static key_type_ref KeyOfValue(value_type_ref D) { return D; }
-  static data_type_ref DataOfValue(value_type_ref) { return true; }
-
-  static bool isEqual(key_type_ref LHS, key_type_ref RHS) { return LHS == RHS; }
-
-  static bool isLess(key_type_ref LHS, key_type_ref RHS) { return LHS < RHS; }
-
-  static bool isDataEqual(data_type_ref, data_type_ref) { return true; }
-};
-
-//===----------------------------------------------------------------------===//
-// Immutable Set
-//===----------------------------------------------------------------------===//
-
-template <typename ValT, typename ValInfo = ImutContainerInfo<ValT>>
-class ImmutableSet {
-public:
-  using value_type = typename ValInfo::value_type;
-  using value_type_ref = typename ValInfo::value_type_ref;
-  using TreeTy = ImutAVLTree<ValInfo>;
-
-private:
-  IntrusiveRefCntPtr<TreeTy> Root;
-
-public:
-  /// Constructs a set from a pointer to a tree root.  In general one
-  /// should use a Factory object to create sets instead of directly
-  /// invoking the constructor, but there are cases where make this
-  /// constructor public is useful.
-  explicit ImmutableSet(TreeTy *R) : Root(R) {}
-
-  class Factory {
-    typename TreeTy::Factory F;
-    const bool Canonicalize;
-
-  public:
-    Factory(bool canonicalize = true)
-      : Canonicalize(canonicalize) {}
-
-    Factory(BumpPtrAllocator& Alloc, bool canonicalize = true)
-      : F(Alloc), Canonicalize(canonicalize) {}
-
-    Factory(const Factory& RHS) = delete;
-    void operator=(const Factory& RHS) = delete;
-
-    /// getEmptySet - Returns an immutable set that contains no elements.
-    ImmutableSet getEmptySet() {
-      return ImmutableSet(F.getEmptyTree());
-    }
-
-    /// add - Creates a new immutable set that contains all of the values
-    ///  of the original set with the addition of the specified value.  If
-    ///  the original set already included the value, then the original set is
-    ///  returned and no memory is allocated.  The time and space complexity
-    ///  of this operation is logarithmic in the size of the original set.
-    ///  The memory allocated to represent the set is released when the
-    ///  factory object that created the set is destroyed.
-    LLVM_NODISCARD ImmutableSet add(ImmutableSet Old, value_type_ref V) {
-      TreeTy *NewT = F.add(Old.Root.get(), V);
-      return ImmutableSet(Canonicalize ? F.getCanonicalTree(NewT) : NewT);
-    }
-
-    /// remove - Creates a new immutable set that contains all of the values
-    ///  of the original set with the exception of the specified value.  If
-    ///  the original set did not contain the value, the original set is
-    ///  returned and no memory is allocated.  The time and space complexity
-    ///  of this operation is logarithmic in the size of the original set.
-    ///  The memory allocated to represent the set is released when the
-    ///  factory object that created the set is destroyed.
-    LLVM_NODISCARD ImmutableSet remove(ImmutableSet Old, value_type_ref V) {
-      TreeTy *NewT = F.remove(Old.Root.get(), V);
-      return ImmutableSet(Canonicalize ? F.getCanonicalTree(NewT) : NewT);
-    }
-
-    BumpPtrAllocator& getAllocator() { return F.getAllocator(); }
-
-    typename TreeTy::Factory *getTreeFactory() const {
-      return const_cast<typename TreeTy::Factory *>(&F);
-    }
-  };
-
-  friend class Factory;
-
-  /// Returns true if the set contains the specified value.
-  bool contains(value_type_ref V) const {
-    return Root ? Root->contains(V) : false;
-  }
-
-  bool operator==(const ImmutableSet &RHS) const {
-    return Root && RHS.Root ? Root->isEqual(*RHS.Root.get()) : Root == RHS.Root;
-  }
-
-  bool operator!=(const ImmutableSet &RHS) const {
-    return Root && RHS.Root ? Root->isNotEqual(*RHS.Root.get())
-                            : Root != RHS.Root;
-  }
-
-  TreeTy *getRoot() {
-    if (Root) { Root->retain(); }
-    return Root.get();
-  }
-
-  TreeTy *getRootWithoutRetain() const { return Root.get(); }
-
-  /// isEmpty - Return true if the set contains no elements.
-  bool isEmpty() const { return !Root; }
-
-  /// isSingleton - Return true if the set contains exactly one element.
-  ///   This method runs in constant time.
-  bool isSingleton() const { return getHeight() == 1; }
-
-  template <typename Callback>
-  void foreach(Callback& C) { if (Root) Root->foreach(C); }
-
-  template <typename Callback>
-  void foreach() { if (Root) { Callback C; Root->foreach(C); } }
-
-  //===--------------------------------------------------===//
-  // Iterators.
-  //===--------------------------------------------------===//
-
-  using iterator = ImutAVLValueIterator<ImmutableSet>;
-
-  iterator begin() const { return iterator(Root.get()); }
-  iterator end() const { return iterator(); }
-
-  //===--------------------------------------------------===//
-  // Utility methods.
-  //===--------------------------------------------------===//
-
-  unsigned getHeight() const { return Root ? Root->getHeight() : 0; }
-
-  static void Profile(FoldingSetNodeID &ID, const ImmutableSet &S) {
-    ID.AddPointer(S.Root.get());
-  }
-
-  void Profile(FoldingSetNodeID &ID) const { return Profile(ID, *this); }
-
-  //===--------------------------------------------------===//
-  // For testing.
-  //===--------------------------------------------------===//
-
-  void validateTree() const { if (Root) Root->validateTree(); }
-};
-
-// NOTE: This may some day replace the current ImmutableSet.
-template <typename ValT, typename ValInfo = ImutContainerInfo<ValT>>
-class ImmutableSetRef {
-public:
-  using value_type = typename ValInfo::value_type;
-  using value_type_ref = typename ValInfo::value_type_ref;
-  using TreeTy = ImutAVLTree<ValInfo>;
-  using FactoryTy = typename TreeTy::Factory;
-
-private:
-  IntrusiveRefCntPtr<TreeTy> Root;
-  FactoryTy *Factory;
-
-public:
-  /// Constructs a set from a pointer to a tree root.  In general one
-  /// should use a Factory object to create sets instead of directly
-  /// invoking the constructor, but there are cases where make this
-  /// constructor public is useful.
-  ImmutableSetRef(TreeTy *R, FactoryTy *F) : Root(R), Factory(F) {}
-
-  static ImmutableSetRef getEmptySet(FactoryTy *F) {
-    return ImmutableSetRef(0, F);
-  }
-
-  ImmutableSetRef add(value_type_ref V) {
-    return ImmutableSetRef(Factory->add(Root.get(), V), Factory);
-  }
-
-  ImmutableSetRef remove(value_type_ref V) {
-    return ImmutableSetRef(Factory->remove(Root.get(), V), Factory);
-  }
-
-  /// Returns true if the set contains the specified value.
-  bool contains(value_type_ref V) const {
-    return Root ? Root->contains(V) : false;
-  }
-
-  ImmutableSet<ValT> asImmutableSet(bool canonicalize = true) const {
-    return ImmutableSet<ValT>(
-        canonicalize ? Factory->getCanonicalTree(Root.get()) : Root.get());
-  }
-
-  TreeTy *getRootWithoutRetain() const { return Root.get(); }
-
-  bool operator==(const ImmutableSetRef &RHS) const {
-    return Root && RHS.Root ? Root->isEqual(*RHS.Root.get()) : Root == RHS.Root;
-  }
-
-  bool operator!=(const ImmutableSetRef &RHS) const {
-    return Root && RHS.Root ? Root->isNotEqual(*RHS.Root.get())
-                            : Root != RHS.Root;
-  }
-
-  /// isEmpty - Return true if the set contains no elements.
-  bool isEmpty() const { return !Root; }
-
-  /// isSingleton - Return true if the set contains exactly one element.
-  ///   This method runs in constant time.
-  bool isSingleton() const { return getHeight() == 1; }
-
-  //===--------------------------------------------------===//
-  // Iterators.
-  //===--------------------------------------------------===//
-
-  using iterator = ImutAVLValueIterator<ImmutableSetRef>;
-
-  iterator begin() const { return iterator(Root.get()); }
-  iterator end() const { return iterator(); }
-
-  //===--------------------------------------------------===//
-  // Utility methods.
-  //===--------------------------------------------------===//
-
-  unsigned getHeight() const { return Root ? Root->getHeight() : 0; }
-
-  static void Profile(FoldingSetNodeID &ID, const ImmutableSetRef &S) {
-    ID.AddPointer(S.Root.get());
-  }
-
-  void Profile(FoldingSetNodeID &ID) const { return Profile(ID, *this); }
-
-  //===--------------------------------------------------===//
-  // For testing.
-  //===--------------------------------------------------===//
-
-  void validateTree() const { if (Root) Root->validateTree(); }
-};
-
-} // end namespace llvm
-
-#endif // LLVM_ADT_IMMUTABLESET_H
-
-#ifdef __GNUC__
-#pragma GCC diagnostic pop
-#endif
+#pragma once 
+ 
+#ifdef __GNUC__ 
+#pragma GCC diagnostic push 
+#pragma GCC diagnostic ignored "-Wunused-parameter" 
+#endif 
+ 
+//===--- ImmutableSet.h - Immutable (functional) set interface --*- C++ -*-===// 
+// 
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 
+// See https://llvm.org/LICENSE.txt for license information. 
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 
+// 
+//===----------------------------------------------------------------------===// 
+// 
+// This file defines the ImutAVLTree and ImmutableSet classes. 
+// 
+//===----------------------------------------------------------------------===// 
+ 
+#ifndef LLVM_ADT_IMMUTABLESET_H 
+#define LLVM_ADT_IMMUTABLESET_H 
+ 
+#include "llvm/ADT/DenseMap.h" 
+#include "llvm/ADT/FoldingSet.h" 
+#include "llvm/ADT/IntrusiveRefCntPtr.h" 
+#include "llvm/ADT/SmallVector.h" 
+#include "llvm/ADT/iterator.h" 
+#include "llvm/Support/Allocator.h" 
+#include "llvm/Support/ErrorHandling.h" 
+#include <cassert> 
+#include <cstdint> 
+#include <functional> 
+#include <iterator> 
+#include <new> 
+#include <vector> 
+ 
+namespace llvm { 
+ 
+//===----------------------------------------------------------------------===// 
+// Immutable AVL-Tree Definition. 
+//===----------------------------------------------------------------------===// 
+ 
+template <typename ImutInfo> class ImutAVLFactory; 
+template <typename ImutInfo> class ImutIntervalAVLFactory; 
+template <typename ImutInfo> class ImutAVLTreeInOrderIterator; 
+template <typename ImutInfo> class ImutAVLTreeGenericIterator; 
+ 
+template <typename ImutInfo > 
+class ImutAVLTree { 
+public: 
+  using key_type_ref = typename ImutInfo::key_type_ref; 
+  using value_type = typename ImutInfo::value_type; 
+  using value_type_ref = typename ImutInfo::value_type_ref; 
+  using Factory = ImutAVLFactory<ImutInfo>; 
+  using iterator = ImutAVLTreeInOrderIterator<ImutInfo>; 
+ 
+  friend class ImutAVLFactory<ImutInfo>; 
+  friend class ImutIntervalAVLFactory<ImutInfo>; 
+  friend class ImutAVLTreeGenericIterator<ImutInfo>; 
+ 
+  //===----------------------------------------------------===// 
+  // Public Interface. 
+  //===----------------------------------------------------===// 
+ 
+  /// Return a pointer to the left subtree.  This value 
+  ///  is NULL if there is no left subtree. 
+  ImutAVLTree *getLeft() const { return left; } 
+ 
+  /// Return a pointer to the right subtree.  This value is 
+  ///  NULL if there is no right subtree. 
+  ImutAVLTree *getRight() const { return right; } 
+ 
+  /// getHeight - Returns the height of the tree.  A tree with no subtrees 
+  ///  has a height of 1. 
+  unsigned getHeight() const { return height; } 
+ 
+  /// getValue - Returns the data value associated with the tree node. 
+  const value_type& getValue() const { return value; } 
+ 
+  /// find - Finds the subtree associated with the specified key value. 
+  ///  This method returns NULL if no matching subtree is found. 
+  ImutAVLTree* find(key_type_ref K) { 
+    ImutAVLTree *T = this; 
+    while (T) { 
+      key_type_ref CurrentKey = ImutInfo::KeyOfValue(T->getValue()); 
+      if (ImutInfo::isEqual(K,CurrentKey)) 
+        return T; 
+      else if (ImutInfo::isLess(K,CurrentKey)) 
+        T = T->getLeft(); 
+      else 
+        T = T->getRight(); 
+    } 
+    return nullptr; 
+  } 
+ 
+  /// getMaxElement - Find the subtree associated with the highest ranged 
+  ///  key value. 
+  ImutAVLTree* getMaxElement() { 
+    ImutAVLTree *T = this; 
+    ImutAVLTree *Right = T->getRight(); 
+    while (Right) { T = Right; Right = T->getRight(); } 
+    return T; 
+  } 
+ 
+  /// size - Returns the number of nodes in the tree, which includes 
+  ///  both leaves and non-leaf nodes. 
+  unsigned size() const { 
+    unsigned n = 1; 
+    if (const ImutAVLTree* L = getLeft()) 
+      n += L->size(); 
+    if (const ImutAVLTree* R = getRight()) 
+      n += R->size(); 
+    return n; 
+  } 
+ 
+  /// begin - Returns an iterator that iterates over the nodes of the tree 
+  ///  in an inorder traversal.  The returned iterator thus refers to the 
+  ///  the tree node with the minimum data element. 
+  iterator begin() const { return iterator(this); } 
+ 
+  /// end - Returns an iterator for the tree that denotes the end of an 
+  ///  inorder traversal. 
+  iterator end() const { return iterator(); } 
+ 
+  bool isElementEqual(value_type_ref V) const { 
+    // Compare the keys. 
+    if (!ImutInfo::isEqual(ImutInfo::KeyOfValue(getValue()), 
+                           ImutInfo::KeyOfValue(V))) 
+      return false; 
+ 
+    // Also compare the data values. 
+    if (!ImutInfo::isDataEqual(ImutInfo::DataOfValue(getValue()), 
+                               ImutInfo::DataOfValue(V))) 
+      return false; 
+ 
+    return true; 
+  } 
+ 
+  bool isElementEqual(const ImutAVLTree* RHS) const { 
+    return isElementEqual(RHS->getValue()); 
+  } 
+ 
+  /// isEqual - Compares two trees for structural equality and returns true 
+  ///   if they are equal.  This worst case performance of this operation is 
+  //    linear in the sizes of the trees. 
+  bool isEqual(const ImutAVLTree& RHS) const { 
+    if (&RHS == this) 
+      return true; 
+ 
+    iterator LItr = begin(), LEnd = end(); 
+    iterator RItr = RHS.begin(), REnd = RHS.end(); 
+ 
+    while (LItr != LEnd && RItr != REnd) { 
+      if (&*LItr == &*RItr) { 
+        LItr.skipSubTree(); 
+        RItr.skipSubTree(); 
+        continue; 
+      } 
+ 
+      if (!LItr->isElementEqual(&*RItr)) 
+        return false; 
+ 
+      ++LItr; 
+      ++RItr; 
+    } 
+ 
+    return LItr == LEnd && RItr == REnd; 
+  } 
+ 
+  /// isNotEqual - Compares two trees for structural inequality.  Performance 
+  ///  is the same is isEqual. 
+  bool isNotEqual(const ImutAVLTree& RHS) const { return !isEqual(RHS); } 
+ 
+  /// contains - Returns true if this tree contains a subtree (node) that 
+  ///  has an data element that matches the specified key.  Complexity 
+  ///  is logarithmic in the size of the tree. 
+  bool contains(key_type_ref K) { return (bool) find(K); } 
+ 
+  /// foreach - A member template the accepts invokes operator() on a functor 
+  ///  object (specified by Callback) for every node/subtree in the tree. 
+  ///  Nodes are visited using an inorder traversal. 
+  template <typename Callback> 
+  void foreach(Callback& C) { 
+    if (ImutAVLTree* L = getLeft()) 
+      L->foreach(C); 
+ 
+    C(value); 
+ 
+    if (ImutAVLTree* R = getRight()) 
+      R->foreach(C); 
+  } 
+ 
+  /// validateTree - A utility method that checks that the balancing and 
+  ///  ordering invariants of the tree are satisfied.  It is a recursive 
+  ///  method that returns the height of the tree, which is then consumed 
+  ///  by the enclosing validateTree call.  External callers should ignore the 
+  ///  return value.  An invalid tree will cause an assertion to fire in 
+  ///  a debug build. 
+  unsigned validateTree() const { 
+    unsigned HL = getLeft() ? getLeft()->validateTree() : 0; 
+    unsigned HR = getRight() ? getRight()->validateTree() : 0; 
+    (void) HL; 
+    (void) HR; 
+ 
+    assert(getHeight() == ( HL > HR ? HL : HR ) + 1 
+            && "Height calculation wrong"); 
+ 
+    assert((HL > HR ? HL-HR : HR-HL) <= 2 
+           && "Balancing invariant violated"); 
+ 
+    assert((!getLeft() || 
+            ImutInfo::isLess(ImutInfo::KeyOfValue(getLeft()->getValue()), 
+                             ImutInfo::KeyOfValue(getValue()))) && 
+           "Value in left child is not less that current value"); 
+ 
+    assert((!getRight() || 
+             ImutInfo::isLess(ImutInfo::KeyOfValue(getValue()), 
+                              ImutInfo::KeyOfValue(getRight()->getValue()))) && 
+           "Current value is not less that value of right child"); 
+ 
+    return getHeight(); 
+  } 
+ 
+  //===----------------------------------------------------===// 
+  // Internal values. 
+  //===----------------------------------------------------===// 
+ 
+private: 
+  Factory *factory; 
+  ImutAVLTree *left; 
+  ImutAVLTree *right; 
+  ImutAVLTree *prev = nullptr; 
+  ImutAVLTree *next = nullptr; 
+ 
+  unsigned height : 28; 
+  bool IsMutable : 1; 
+  bool IsDigestCached : 1; 
+  bool IsCanonicalized : 1; 
+ 
+  value_type value; 
+  uint32_t digest = 0; 
+  uint32_t refCount = 0; 
+ 
+  //===----------------------------------------------------===// 
+  // Internal methods (node manipulation; used by Factory). 
+  //===----------------------------------------------------===// 
+ 
+private: 
+  /// ImutAVLTree - Internal constructor that is only called by 
+  ///   ImutAVLFactory. 
+  ImutAVLTree(Factory *f, ImutAVLTree* l, ImutAVLTree* r, value_type_ref v, 
+              unsigned height) 
+    : factory(f), left(l), right(r), height(height), IsMutable(true), 
+      IsDigestCached(false), IsCanonicalized(false), value(v) 
+  { 
+    if (left) left->retain(); 
+    if (right) right->retain(); 
+  } 
+ 
+  /// isMutable - Returns true if the left and right subtree references 
+  ///  (as well as height) can be changed.  If this method returns false, 
+  ///  the tree is truly immutable.  Trees returned from an ImutAVLFactory 
+  ///  object should always have this method return true.  Further, if this 
+  ///  method returns false for an instance of ImutAVLTree, all subtrees 
+  ///  will also have this method return false.  The converse is not true. 
+  bool isMutable() const { return IsMutable; } 
+ 
+  /// hasCachedDigest - Returns true if the digest for this tree is cached. 
+  ///  This can only be true if the tree is immutable. 
+  bool hasCachedDigest() const { return IsDigestCached; } 
+ 
+  //===----------------------------------------------------===// 
+  // Mutating operations.  A tree root can be manipulated as 
+  // long as its reference has not "escaped" from internal 
+  // methods of a factory object (see below).  When a tree 
+  // pointer is externally viewable by client code, the 
+  // internal "mutable bit" is cleared to mark the tree 
+  // immutable.  Note that a tree that still has its mutable 
+  // bit set may have children (subtrees) that are themselves 
+  // immutable. 
+  //===----------------------------------------------------===// 
+ 
+  /// markImmutable - Clears the mutable flag for a tree.  After this happens, 
+  ///   it is an error to call setLeft(), setRight(), and setHeight(). 
+  void markImmutable() { 
+    assert(isMutable() && "Mutable flag already removed."); 
+    IsMutable = false; 
+  } 
+ 
+  /// markedCachedDigest - Clears the NoCachedDigest flag for a tree. 
+  void markedCachedDigest() { 
+    assert(!hasCachedDigest() && "NoCachedDigest flag already removed."); 
+    IsDigestCached = true; 
+  } 
+ 
+  /// setHeight - Changes the height of the tree.  Used internally by 
+  ///  ImutAVLFactory. 
+  void setHeight(unsigned h) { 
+    assert(isMutable() && "Only a mutable tree can have its height changed."); 
+    height = h; 
+  } 
+ 
+  static uint32_t computeDigest(ImutAVLTree *L, ImutAVLTree *R, 
+                                value_type_ref V) { 
+    uint32_t digest = 0; 
+ 
+    if (L) 
+      digest += L->computeDigest(); 
+ 
+    // Compute digest of stored data. 
+    FoldingSetNodeID ID; 
+    ImutInfo::Profile(ID,V); 
+    digest += ID.ComputeHash(); 
+ 
+    if (R) 
+      digest += R->computeDigest(); 
+ 
+    return digest; 
+  } 
+ 
+  uint32_t computeDigest() { 
+    // Check the lowest bit to determine if digest has actually been 
+    // pre-computed. 
+    if (hasCachedDigest()) 
+      return digest; 
+ 
+    uint32_t X = computeDigest(getLeft(), getRight(), getValue()); 
+    digest = X; 
+    markedCachedDigest(); 
+    return X; 
+  } 
+ 
+  //===----------------------------------------------------===// 
+  // Reference count operations. 
+  //===----------------------------------------------------===// 
+ 
+public: 
+  void retain() { ++refCount; } 
+ 
+  void release() { 
+    assert(refCount > 0); 
+    if (--refCount == 0) 
+      destroy(); 
+  } 
+ 
+  void destroy() { 
+    if (left) 
+      left->release(); 
+    if (right) 
+      right->release(); 
+    if (IsCanonicalized) { 
+      if (next) 
+        next->prev = prev; 
+ 
+      if (prev) 
+        prev->next = next; 
+      else 
+        factory->Cache[factory->maskCacheIndex(computeDigest())] = next; 
+    } 
+ 
+    // We need to clear the mutability bit in case we are 
+    // destroying the node as part of a sweep in ImutAVLFactory::recoverNodes(). 
+    IsMutable = false; 
+    factory->freeNodes.push_back(this); 
+  } 
+}; 
+ 
+template <typename ImutInfo> 
+struct IntrusiveRefCntPtrInfo<ImutAVLTree<ImutInfo>> { 
+  static void retain(ImutAVLTree<ImutInfo> *Tree) { Tree->retain(); } 
+  static void release(ImutAVLTree<ImutInfo> *Tree) { Tree->release(); } 
+}; 
+ 
+//===----------------------------------------------------------------------===// 
+// Immutable AVL-Tree Factory class. 
+//===----------------------------------------------------------------------===// 
+ 
+template <typename ImutInfo > 
+class ImutAVLFactory { 
+  friend class ImutAVLTree<ImutInfo>; 
+ 
+  using TreeTy = ImutAVLTree<ImutInfo>; 
+  using value_type_ref = typename TreeTy::value_type_ref; 
+  using key_type_ref = typename TreeTy::key_type_ref; 
+  using CacheTy = DenseMap<unsigned, TreeTy*>; 
+ 
+  CacheTy Cache; 
+  uintptr_t Allocator; 
+  std::vector<TreeTy*> createdNodes; 
+  std::vector<TreeTy*> freeNodes; 
+ 
+  bool ownsAllocator() const { 
+    return (Allocator & 0x1) == 0; 
+  } 
+ 
+  BumpPtrAllocator& getAllocator() const { 
+    return *reinterpret_cast<BumpPtrAllocator*>(Allocator & ~0x1); 
+  } 
+ 
+  //===--------------------------------------------------===// 
+  // Public interface. 
+  //===--------------------------------------------------===// 
+ 
+public: 
+  ImutAVLFactory() 
+    : Allocator(reinterpret_cast<uintptr_t>(new BumpPtrAllocator())) {} 
+ 
+  ImutAVLFactory(BumpPtrAllocator& Alloc) 
+    : Allocator(reinterpret_cast<uintptr_t>(&Alloc) | 0x1) {} 
+ 
+  ~ImutAVLFactory() { 
+    if (ownsAllocator()) delete &getAllocator(); 
+  } 
+ 
+  TreeTy* add(TreeTy* T, value_type_ref V) { 
+    T = add_internal(V,T); 
+    markImmutable(T); 
+    recoverNodes(); 
+    return T; 
+  } 
+ 
+  TreeTy* remove(TreeTy* T, key_type_ref V) { 
+    T = remove_internal(V,T); 
+    markImmutable(T); 
+    recoverNodes(); 
+    return T; 
+  } 
+ 
+  TreeTy* getEmptyTree() const { return nullptr; } 
+ 
+protected: 
+  //===--------------------------------------------------===// 
+  // A bunch of quick helper functions used for reasoning 
+  // about the properties of trees and their children. 
+  // These have succinct names so that the balancing code 
+  // is as terse (and readable) as possible. 
+  //===--------------------------------------------------===// 
+ 
+  bool            isEmpty(TreeTy* T) const { return !T; } 
+  unsigned        getHeight(TreeTy* T) const { return T ? T->getHeight() : 0; } 
+  TreeTy*         getLeft(TreeTy* T) const { return T->getLeft(); } 
+  TreeTy*         getRight(TreeTy* T) const { return T->getRight(); } 
+  value_type_ref  getValue(TreeTy* T) const { return T->value; } 
+ 
+  // Make sure the index is not the Tombstone or Entry key of the DenseMap. 
+  static unsigned maskCacheIndex(unsigned I) { return (I & ~0x02); } 
+ 
+  unsigned incrementHeight(TreeTy* L, TreeTy* R) const { 
+    unsigned hl = getHeight(L); 
+    unsigned hr = getHeight(R); 
+    return (hl > hr ? hl : hr) + 1; 
+  } 
+ 
+  static bool compareTreeWithSection(TreeTy* T, 
+                                     typename TreeTy::iterator& TI, 
+                                     typename TreeTy::iterator& TE) { 
+    typename TreeTy::iterator I = T->begin(), E = T->end(); 
+    for ( ; I!=E ; ++I, ++TI) { 
+      if (TI == TE || !I->isElementEqual(&*TI)) 
+        return false; 
+    } 
+    return true; 
+  } 
+ 
+  //===--------------------------------------------------===// 
+  // "createNode" is used to generate new tree roots that link 
+  // to other trees.  The function may also simply move links 
+  // in an existing root if that root is still marked mutable. 
+  // This is necessary because otherwise our balancing code 
+  // would leak memory as it would create nodes that are 
+  // then discarded later before the finished tree is 
+  // returned to the caller. 
+  //===--------------------------------------------------===// 
+ 
+  TreeTy* createNode(TreeTy* L, value_type_ref V, TreeTy* R) { 
+    BumpPtrAllocator& A = getAllocator(); 
+    TreeTy* T; 
+    if (!freeNodes.empty()) { 
+      T = freeNodes.back(); 
+      freeNodes.pop_back(); 
+      assert(T != L); 
+      assert(T != R); 
+    } else { 
+      T = (TreeTy*) A.Allocate<TreeTy>(); 
+    } 
+    new (T) TreeTy(this, L, R, V, incrementHeight(L,R)); 
+    createdNodes.push_back(T); 
+    return T; 
+  } 
+ 
+  TreeTy* createNode(TreeTy* newLeft, TreeTy* oldTree, TreeTy* newRight) { 
+    return createNode(newLeft, getValue(oldTree), newRight); 
+  } 
+ 
+  void recoverNodes() { 
+    for (unsigned i = 0, n = createdNodes.size(); i < n; ++i) { 
+      TreeTy *N = createdNodes[i]; 
+      if (N->isMutable() && N->refCount == 0) 
+        N->destroy(); 
+    } 
+    createdNodes.clear(); 
+  } 
+ 
+  /// balanceTree - Used by add_internal and remove_internal to 
+  ///  balance a newly created tree. 
+  TreeTy* balanceTree(TreeTy* L, value_type_ref V, TreeTy* R) { 
+    unsigned hl = getHeight(L); 
+    unsigned hr = getHeight(R); 
+ 
+    if (hl > hr + 2) { 
+      assert(!isEmpty(L) && "Left tree cannot be empty to have a height >= 2"); 
+ 
+      TreeTy *LL = getLeft(L); 
+      TreeTy *LR = getRight(L); 
+ 
+      if (getHeight(LL) >= getHeight(LR)) 
+        return createNode(LL, L, createNode(LR,V,R)); 
+ 
+      assert(!isEmpty(LR) && "LR cannot be empty because it has a height >= 1"); 
+ 
+      TreeTy *LRL = getLeft(LR); 
+      TreeTy *LRR = getRight(LR); 
+ 
+      return createNode(createNode(LL,L,LRL), LR, createNode(LRR,V,R)); 
+    } 
+ 
+    if (hr > hl + 2) { 
+      assert(!isEmpty(R) && "Right tree cannot be empty to have a height >= 2"); 
+ 
+      TreeTy *RL = getLeft(R); 
+      TreeTy *RR = getRight(R); 
+ 
+      if (getHeight(RR) >= getHeight(RL)) 
+        return createNode(createNode(L,V,RL), R, RR); 
+ 
+      assert(!isEmpty(RL) && "RL cannot be empty because it has a height >= 1"); 
+ 
+      TreeTy *RLL = getLeft(RL); 
+      TreeTy *RLR = getRight(RL); 
+ 
+      return createNode(createNode(L,V,RLL), RL, createNode(RLR,R,RR)); 
+    } 
+ 
+    return createNode(L,V,R); 
+  } 
+ 
+  /// add_internal - Creates a new tree that includes the specified 
+  ///  data and the data from the original tree.  If the original tree 
+  ///  already contained the data item, the original tree is returned. 
+  TreeTy* add_internal(value_type_ref V, TreeTy* T) { 
+    if (isEmpty(T)) 
+      return createNode(T, V, T); 
+    assert(!T->isMutable()); 
+ 
+    key_type_ref K = ImutInfo::KeyOfValue(V); 
+    key_type_ref KCurrent = ImutInfo::KeyOfValue(getValue(T)); 
+ 
+    if (ImutInfo::isEqual(K,KCurrent)) 
+      return createNode(getLeft(T), V, getRight(T)); 
+    else if (ImutInfo::isLess(K,KCurrent)) 
+      return balanceTree(add_internal(V, getLeft(T)), getValue(T), getRight(T)); 
+    else 
+      return balanceTree(getLeft(T), getValue(T), add_internal(V, getRight(T))); 
+  } 
+ 
+  /// remove_internal - Creates a new tree that includes all the data 
+  ///  from the original tree except the specified data.  If the 
+  ///  specified data did not exist in the original tree, the original 
+  ///  tree is returned. 
+  TreeTy* remove_internal(key_type_ref K, TreeTy* T) { 
+    if (isEmpty(T)) 
+      return T; 
+ 
+    assert(!T->isMutable()); 
+ 
+    key_type_ref KCurrent = ImutInfo::KeyOfValue(getValue(T)); 
+ 
+    if (ImutInfo::isEqual(K,KCurrent)) { 
+      return combineTrees(getLeft(T), getRight(T)); 
+    } else if (ImutInfo::isLess(K,KCurrent)) { 
+      return balanceTree(remove_internal(K, getLeft(T)), 
+                                            getValue(T), getRight(T)); 
+    } else { 
+      return balanceTree(getLeft(T), getValue(T), 
+                         remove_internal(K, getRight(T))); 
+    } 
+  } 
+ 
+  TreeTy* combineTrees(TreeTy* L, TreeTy* R) { 
+    if (isEmpty(L)) 
+      return R; 
+    if (isEmpty(R)) 
+      return L; 
+    TreeTy* OldNode; 
+    TreeTy* newRight = removeMinBinding(R,OldNode); 
+    return balanceTree(L, getValue(OldNode), newRight); 
+  } 
+ 
+  TreeTy* removeMinBinding(TreeTy* T, TreeTy*& Noderemoved) { 
+    assert(!isEmpty(T)); 
+    if (isEmpty(getLeft(T))) { 
+      Noderemoved = T; 
+      return getRight(T); 
+    } 
+    return balanceTree(removeMinBinding(getLeft(T), Noderemoved), 
+                       getValue(T), getRight(T)); 
+  } 
+ 
+  /// markImmutable - Clears the mutable bits of a root and all of its 
+  ///  descendants. 
+  void markImmutable(TreeTy* T) { 
+    if (!T || !T->isMutable()) 
+      return; 
+    T->markImmutable(); 
+    markImmutable(getLeft(T)); 
+    markImmutable(getRight(T)); 
+  } 
+ 
+public: 
+  TreeTy *getCanonicalTree(TreeTy *TNew) { 
+    if (!TNew) 
+      return nullptr; 
+ 
+    if (TNew->IsCanonicalized) 
+      return TNew; 
+ 
+    // Search the hashtable for another tree with the same digest, and 
+    // if find a collision compare those trees by their contents. 
+    unsigned digest = TNew->computeDigest(); 
+    TreeTy *&entry = Cache[maskCacheIndex(digest)]; 
+    do { 
+      if (!entry) 
+        break; 
+      for (TreeTy *T = entry ; T != nullptr; T = T->next) { 
+        // Compare the Contents('T') with Contents('TNew') 
+        typename TreeTy::iterator TI = T->begin(), TE = T->end(); 
+        if (!compareTreeWithSection(TNew, TI, TE)) 
+          continue; 
+        if (TI != TE) 
+          continue; // T has more contents than TNew. 
+        // Trees did match!  Return 'T'. 
+        if (TNew->refCount == 0) 
+          TNew->destroy(); 
+        return T; 
+      } 
+      entry->prev = TNew; 
+      TNew->next = entry; 
+    } 
+    while (false); 
+ 
+    entry = TNew; 
+    TNew->IsCanonicalized = true; 
+    return TNew; 
+  } 
+}; 
+ 
+//===----------------------------------------------------------------------===// 
+// Immutable AVL-Tree Iterators. 
+//===----------------------------------------------------------------------===// 
+ 
+template <typename ImutInfo> 
+class ImutAVLTreeGenericIterator 
+    : public std::iterator<std::bidirectional_iterator_tag, 
+                           ImutAVLTree<ImutInfo>> { 
+  SmallVector<uintptr_t,20> stack; 
+ 
+public: 
+  enum VisitFlag { VisitedNone=0x0, VisitedLeft=0x1, VisitedRight=0x3, 
+                   Flags=0x3 }; 
+ 
+  using TreeTy = ImutAVLTree<ImutInfo>; 
+ 
+  ImutAVLTreeGenericIterator() = default; 
+  ImutAVLTreeGenericIterator(const TreeTy *Root) { 
+    if (Root) stack.push_back(reinterpret_cast<uintptr_t>(Root)); 
+  } 
+ 
+  TreeTy &operator*() const { 
+    assert(!stack.empty()); 
+    return *reinterpret_cast<TreeTy *>(stack.back() & ~Flags); 
+  } 
+  TreeTy *operator->() const { return &*this; } 
+ 
+  uintptr_t getVisitState() const { 
+    assert(!stack.empty()); 
+    return stack.back() & Flags; 
+  } 
+ 
+  bool atEnd() const { return stack.empty(); } 
+ 
+  bool atBeginning() const { 
+    return stack.size() == 1 && getVisitState() == VisitedNone; 
+  } 
+ 
+  void skipToParent() { 
+    assert(!stack.empty()); 
+    stack.pop_back(); 
+    if (stack.empty()) 
+      return; 
+    switch (getVisitState()) { 
+      case VisitedNone: 
+        stack.back() |= VisitedLeft; 
+        break; 
+      case VisitedLeft: 
+        stack.back() |= VisitedRight; 
+        break; 
+      default: 
+        llvm_unreachable("Unreachable."); 
+    } 
+  } 
+ 
+  bool operator==(const ImutAVLTreeGenericIterator &x) const { 
+    return stack == x.stack; 
+  } 
+ 
+  bool operator!=(const ImutAVLTreeGenericIterator &x) const { 
+    return !(*this == x); 
+  } 
+ 
+  ImutAVLTreeGenericIterator &operator++() { 
+    assert(!stack.empty()); 
+    TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags); 
+    assert(Current); 
+    switch (getVisitState()) { 
+      case VisitedNone: 
+        if (TreeTy* L = Current->getLeft()) 
+          stack.push_back(reinterpret_cast<uintptr_t>(L)); 
+        else 
+          stack.back() |= VisitedLeft; 
+        break; 
+      case VisitedLeft: 
+        if (TreeTy* R = Current->getRight()) 
+          stack.push_back(reinterpret_cast<uintptr_t>(R)); 
+        else 
+          stack.back() |= VisitedRight; 
+        break; 
+      case VisitedRight: 
+        skipToParent(); 
+        break; 
+      default: 
+        llvm_unreachable("Unreachable."); 
+    } 
+    return *this; 
+  } 
+ 
+  ImutAVLTreeGenericIterator &operator--() { 
+    assert(!stack.empty()); 
+    TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags); 
+    assert(Current); 
+    switch (getVisitState()) { 
+      case VisitedNone: 
+        stack.pop_back(); 
+        break; 
+      case VisitedLeft: 
+        stack.back() &= ~Flags; // Set state to "VisitedNone." 
+        if (TreeTy* L = Current->getLeft()) 
+          stack.push_back(reinterpret_cast<uintptr_t>(L) | VisitedRight); 
+        break; 
+      case VisitedRight: 
+        stack.back() &= ~Flags; 
+        stack.back() |= VisitedLeft; 
+        if (TreeTy* R = Current->getRight()) 
+          stack.push_back(reinterpret_cast<uintptr_t>(R) | VisitedRight); 
+        break; 
+      default: 
+        llvm_unreachable("Unreachable."); 
+    } 
+    return *this; 
+  } 
+}; 
+ 
+template <typename ImutInfo> 
+class ImutAVLTreeInOrderIterator 
+    : public std::iterator<std::bidirectional_iterator_tag, 
+                           ImutAVLTree<ImutInfo>> { 
+  using InternalIteratorTy = ImutAVLTreeGenericIterator<ImutInfo>; 
+ 
+  InternalIteratorTy InternalItr; 
+ 
+public: 
+  using TreeTy = ImutAVLTree<ImutInfo>; 
+ 
+  ImutAVLTreeInOrderIterator(const TreeTy* Root) : InternalItr(Root) { 
+    if (Root) 
+      ++*this; // Advance to first element. 
+  } 
+ 
+  ImutAVLTreeInOrderIterator() : InternalItr() {} 
+ 
+  bool operator==(const ImutAVLTreeInOrderIterator &x) const { 
+    return InternalItr == x.InternalItr; 
+  } 
+ 
+  bool operator!=(const ImutAVLTreeInOrderIterator &x) const { 
+    return !(*this == x); 
+  } 
+ 
+  TreeTy &operator*() const { return *InternalItr; } 
+  TreeTy *operator->() const { return &*InternalItr; } 
+ 
+  ImutAVLTreeInOrderIterator &operator++() { 
+    do ++InternalItr; 
+    while (!InternalItr.atEnd() && 
+           InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft); 
+ 
+    return *this; 
+  } 
+ 
+  ImutAVLTreeInOrderIterator &operator--() { 
+    do --InternalItr; 
+    while (!InternalItr.atBeginning() && 
+           InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft); 
+ 
+    return *this; 
+  } 
+ 
+  void skipSubTree() { 
+    InternalItr.skipToParent(); 
+ 
+    while (!InternalItr.atEnd() && 
+           InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft) 
+      ++InternalItr; 
+  } 
+}; 
+ 
+/// Generic iterator that wraps a T::TreeTy::iterator and exposes 
+/// iterator::getValue() on dereference. 
+template <typename T> 
+struct ImutAVLValueIterator 
+    : iterator_adaptor_base< 
+          ImutAVLValueIterator<T>, typename T::TreeTy::iterator, 
+          typename std::iterator_traits< 
+              typename T::TreeTy::iterator>::iterator_category, 
+          const typename T::value_type> { 
+  ImutAVLValueIterator() = default; 
+  explicit ImutAVLValueIterator(typename T::TreeTy *Tree) 
+      : ImutAVLValueIterator::iterator_adaptor_base(Tree) {} 
+ 
+  typename ImutAVLValueIterator::reference operator*() const { 
+    return this->I->getValue(); 
+  } 
+}; 
+ 
+//===----------------------------------------------------------------------===// 
+// Trait classes for Profile information. 
+//===----------------------------------------------------------------------===// 
+ 
+/// Generic profile template.  The default behavior is to invoke the 
+/// profile method of an object.  Specializations for primitive integers 
+/// and generic handling of pointers is done below. 
+template <typename T> 
+struct ImutProfileInfo { 
+  using value_type = const T; 
+  using value_type_ref = const T&; 
+ 
+  static void Profile(FoldingSetNodeID &ID, value_type_ref X) { 
+    FoldingSetTrait<T>::Profile(X,ID); 
+  } 
+}; 
+ 
+/// Profile traits for integers. 
+template <typename T> 
+struct ImutProfileInteger { 
+  using value_type = const T; 
+  using value_type_ref = const T&; 
+ 
+  static void Profile(FoldingSetNodeID &ID, value_type_ref X) { 
+    ID.AddInteger(X); 
+  } 
+}; 
+ 
+#define PROFILE_INTEGER_INFO(X)\ 
+template<> struct ImutProfileInfo<X> : ImutProfileInteger<X> {}; 
+ 
+PROFILE_INTEGER_INFO(char) 
+PROFILE_INTEGER_INFO(unsigned char) 
+PROFILE_INTEGER_INFO(short) 
+PROFILE_INTEGER_INFO(unsigned short) 
+PROFILE_INTEGER_INFO(unsigned) 
+PROFILE_INTEGER_INFO(signed) 
+PROFILE_INTEGER_INFO(long) 
+PROFILE_INTEGER_INFO(unsigned long) 
+PROFILE_INTEGER_INFO(long long) 
+PROFILE_INTEGER_INFO(unsigned long long) 
+ 
+#undef PROFILE_INTEGER_INFO 
+ 
+/// Profile traits for booleans. 
+template <> 
+struct ImutProfileInfo<bool> { 
+  using value_type = const bool; 
+  using value_type_ref = const bool&; 
+ 
+  static void Profile(FoldingSetNodeID &ID, value_type_ref X) { 
+    ID.AddBoolean(X); 
+  } 
+}; 
+ 
+/// Generic profile trait for pointer types.  We treat pointers as 
+/// references to unique objects. 
+template <typename T> 
+struct ImutProfileInfo<T*> { 
+  using value_type = const T*; 
+  using value_type_ref = value_type; 
+ 
+  static void Profile(FoldingSetNodeID &ID, value_type_ref X) { 
+    ID.AddPointer(X); 
+  } 
+}; 
+ 
+//===----------------------------------------------------------------------===// 
+// Trait classes that contain element comparison operators and type 
+//  definitions used by ImutAVLTree, ImmutableSet, and ImmutableMap.  These 
+//  inherit from the profile traits (ImutProfileInfo) to include operations 
+//  for element profiling. 
+//===----------------------------------------------------------------------===// 
+ 
+/// ImutContainerInfo - Generic definition of comparison operations for 
+///   elements of immutable containers that defaults to using 
+///   std::equal_to<> and std::less<> to perform comparison of elements. 
+template <typename T> 
+struct ImutContainerInfo : public ImutProfileInfo<T> { 
+  using value_type = typename ImutProfileInfo<T>::value_type; 
+  using value_type_ref = typename ImutProfileInfo<T>::value_type_ref; 
+  using key_type = value_type; 
+  using key_type_ref = value_type_ref; 
+  using data_type = bool; 
+  using data_type_ref = bool; 
+ 
+  static key_type_ref KeyOfValue(value_type_ref D) { return D; } 
+  static data_type_ref DataOfValue(value_type_ref) { return true; } 
+ 
+  static bool isEqual(key_type_ref LHS, key_type_ref RHS) { 
+    return std::equal_to<key_type>()(LHS,RHS); 
+  } 
+ 
+  static bool isLess(key_type_ref LHS, key_type_ref RHS) { 
+    return std::less<key_type>()(LHS,RHS); 
+  } 
+ 
+  static bool isDataEqual(data_type_ref, data_type_ref) { return true; } 
+}; 
+ 
+/// ImutContainerInfo - Specialization for pointer values to treat pointers 
+///  as references to unique objects.  Pointers are thus compared by 
+///  their addresses. 
+template <typename T> 
+struct ImutContainerInfo<T*> : public ImutProfileInfo<T*> { 
+  using value_type = typename ImutProfileInfo<T*>::value_type; 
+  using value_type_ref = typename ImutProfileInfo<T*>::value_type_ref; 
+  using key_type = value_type; 
+  using key_type_ref = value_type_ref; 
+  using data_type = bool; 
+  using data_type_ref = bool; 
+ 
+  static key_type_ref KeyOfValue(value_type_ref D) { return D; } 
+  static data_type_ref DataOfValue(value_type_ref) { return true; } 
+ 
+  static bool isEqual(key_type_ref LHS, key_type_ref RHS) { return LHS == RHS; } 
+ 
+  static bool isLess(key_type_ref LHS, key_type_ref RHS) { return LHS < RHS; } 
+ 
+  static bool isDataEqual(data_type_ref, data_type_ref) { return true; } 
+}; 
+ 
+//===----------------------------------------------------------------------===// 
+// Immutable Set 
+//===----------------------------------------------------------------------===// 
+ 
+template <typename ValT, typename ValInfo = ImutContainerInfo<ValT>> 
+class ImmutableSet { 
+public: 
+  using value_type = typename ValInfo::value_type; 
+  using value_type_ref = typename ValInfo::value_type_ref; 
+  using TreeTy = ImutAVLTree<ValInfo>; 
+ 
+private: 
+  IntrusiveRefCntPtr<TreeTy> Root; 
+ 
+public: 
+  /// Constructs a set from a pointer to a tree root.  In general one 
+  /// should use a Factory object to create sets instead of directly 
+  /// invoking the constructor, but there are cases where make this 
+  /// constructor public is useful. 
+  explicit ImmutableSet(TreeTy *R) : Root(R) {} 
+ 
+  class Factory { 
+    typename TreeTy::Factory F; 
+    const bool Canonicalize; 
+ 
+  public: 
+    Factory(bool canonicalize = true) 
+      : Canonicalize(canonicalize) {} 
+ 
+    Factory(BumpPtrAllocator& Alloc, bool canonicalize = true) 
+      : F(Alloc), Canonicalize(canonicalize) {} 
+ 
+    Factory(const Factory& RHS) = delete; 
+    void operator=(const Factory& RHS) = delete; 
+ 
+    /// getEmptySet - Returns an immutable set that contains no elements. 
+    ImmutableSet getEmptySet() { 
+      return ImmutableSet(F.getEmptyTree()); 
+    } 
+ 
+    /// add - Creates a new immutable set that contains all of the values 
+    ///  of the original set with the addition of the specified value.  If 
+    ///  the original set already included the value, then the original set is 
+    ///  returned and no memory is allocated.  The time and space complexity 
+    ///  of this operation is logarithmic in the size of the original set. 
+    ///  The memory allocated to represent the set is released when the 
+    ///  factory object that created the set is destroyed. 
+    LLVM_NODISCARD ImmutableSet add(ImmutableSet Old, value_type_ref V) { 
+      TreeTy *NewT = F.add(Old.Root.get(), V); 
+      return ImmutableSet(Canonicalize ? F.getCanonicalTree(NewT) : NewT); 
+    } 
+ 
+    /// remove - Creates a new immutable set that contains all of the values 
+    ///  of the original set with the exception of the specified value.  If 
+    ///  the original set did not contain the value, the original set is 
+    ///  returned and no memory is allocated.  The time and space complexity 
+    ///  of this operation is logarithmic in the size of the original set. 
+    ///  The memory allocated to represent the set is released when the 
+    ///  factory object that created the set is destroyed. 
+    LLVM_NODISCARD ImmutableSet remove(ImmutableSet Old, value_type_ref V) { 
+      TreeTy *NewT = F.remove(Old.Root.get(), V); 
+      return ImmutableSet(Canonicalize ? F.getCanonicalTree(NewT) : NewT); 
+    } 
+ 
+    BumpPtrAllocator& getAllocator() { return F.getAllocator(); } 
+ 
+    typename TreeTy::Factory *getTreeFactory() const { 
+      return const_cast<typename TreeTy::Factory *>(&F); 
+    } 
+  }; 
+ 
+  friend class Factory; 
+ 
+  /// Returns true if the set contains the specified value. 
+  bool contains(value_type_ref V) const { 
+    return Root ? Root->contains(V) : false; 
+  } 
+ 
+  bool operator==(const ImmutableSet &RHS) const { 
+    return Root && RHS.Root ? Root->isEqual(*RHS.Root.get()) : Root == RHS.Root; 
+  } 
+ 
+  bool operator!=(const ImmutableSet &RHS) const { 
+    return Root && RHS.Root ? Root->isNotEqual(*RHS.Root.get()) 
+                            : Root != RHS.Root; 
+  } 
+ 
+  TreeTy *getRoot() { 
+    if (Root) { Root->retain(); } 
+    return Root.get(); 
+  } 
+ 
+  TreeTy *getRootWithoutRetain() const { return Root.get(); } 
+ 
+  /// isEmpty - Return true if the set contains no elements. 
+  bool isEmpty() const { return !Root; } 
+ 
+  /// isSingleton - Return true if the set contains exactly one element. 
+  ///   This method runs in constant time. 
+  bool isSingleton() const { return getHeight() == 1; } 
+ 
+  template <typename Callback> 
+  void foreach(Callback& C) { if (Root) Root->foreach(C); } 
+ 
+  template <typename Callback> 
+  void foreach() { if (Root) { Callback C; Root->foreach(C); } } 
+ 
+  //===--------------------------------------------------===// 
+  // Iterators. 
+  //===--------------------------------------------------===// 
+ 
+  using iterator = ImutAVLValueIterator<ImmutableSet>; 
+ 
+  iterator begin() const { return iterator(Root.get()); } 
+  iterator end() const { return iterator(); } 
+ 
+  //===--------------------------------------------------===// 
+  // Utility methods. 
+  //===--------------------------------------------------===// 
+ 
+  unsigned getHeight() const { return Root ? Root->getHeight() : 0; } 
+ 
+  static void Profile(FoldingSetNodeID &ID, const ImmutableSet &S) { 
+    ID.AddPointer(S.Root.get()); 
+  } 
+ 
+  void Profile(FoldingSetNodeID &ID) const { return Profile(ID, *this); } 
+ 
+  //===--------------------------------------------------===// 
+  // For testing. 
+  //===--------------------------------------------------===// 
+ 
+  void validateTree() const { if (Root) Root->validateTree(); } 
+}; 
+ 
+// NOTE: This may some day replace the current ImmutableSet. 
+template <typename ValT, typename ValInfo = ImutContainerInfo<ValT>> 
+class ImmutableSetRef { 
+public: 
+  using value_type = typename ValInfo::value_type; 
+  using value_type_ref = typename ValInfo::value_type_ref; 
+  using TreeTy = ImutAVLTree<ValInfo>; 
+  using FactoryTy = typename TreeTy::Factory; 
+ 
+private: 
+  IntrusiveRefCntPtr<TreeTy> Root; 
+  FactoryTy *Factory; 
+ 
+public: 
+  /// Constructs a set from a pointer to a tree root.  In general one 
+  /// should use a Factory object to create sets instead of directly 
+  /// invoking the constructor, but there are cases where make this 
+  /// constructor public is useful. 
+  ImmutableSetRef(TreeTy *R, FactoryTy *F) : Root(R), Factory(F) {} 
+ 
+  static ImmutableSetRef getEmptySet(FactoryTy *F) { 
+    return ImmutableSetRef(0, F); 
+  } 
+ 
+  ImmutableSetRef add(value_type_ref V) { 
+    return ImmutableSetRef(Factory->add(Root.get(), V), Factory); 
+  } 
+ 
+  ImmutableSetRef remove(value_type_ref V) { 
+    return ImmutableSetRef(Factory->remove(Root.get(), V), Factory); 
+  } 
+ 
+  /// Returns true if the set contains the specified value. 
+  bool contains(value_type_ref V) const { 
+    return Root ? Root->contains(V) : false; 
+  } 
+ 
+  ImmutableSet<ValT> asImmutableSet(bool canonicalize = true) const { 
+    return ImmutableSet<ValT>( 
+        canonicalize ? Factory->getCanonicalTree(Root.get()) : Root.get()); 
+  } 
+ 
+  TreeTy *getRootWithoutRetain() const { return Root.get(); } 
+ 
+  bool operator==(const ImmutableSetRef &RHS) const { 
+    return Root && RHS.Root ? Root->isEqual(*RHS.Root.get()) : Root == RHS.Root; 
+  } 
+ 
+  bool operator!=(const ImmutableSetRef &RHS) const { 
+    return Root && RHS.Root ? Root->isNotEqual(*RHS.Root.get()) 
+                            : Root != RHS.Root; 
+  } 
+ 
+  /// isEmpty - Return true if the set contains no elements. 
+  bool isEmpty() const { return !Root; } 
+ 
+  /// isSingleton - Return true if the set contains exactly one element. 
+  ///   This method runs in constant time. 
+  bool isSingleton() const { return getHeight() == 1; } 
+ 
+  //===--------------------------------------------------===// 
+  // Iterators. 
+  //===--------------------------------------------------===// 
+ 
+  using iterator = ImutAVLValueIterator<ImmutableSetRef>; 
+ 
+  iterator begin() const { return iterator(Root.get()); } 
+  iterator end() const { return iterator(); } 
+ 
+  //===--------------------------------------------------===// 
+  // Utility methods. 
+  //===--------------------------------------------------===// 
+ 
+  unsigned getHeight() const { return Root ? Root->getHeight() : 0; } 
+ 
+  static void Profile(FoldingSetNodeID &ID, const ImmutableSetRef &S) { 
+    ID.AddPointer(S.Root.get()); 
+  } 
+ 
+  void Profile(FoldingSetNodeID &ID) const { return Profile(ID, *this); } 
+ 
+  //===--------------------------------------------------===// 
+  // For testing. 
+  //===--------------------------------------------------===// 
+ 
+  void validateTree() const { if (Root) Root->validateTree(); } 
+}; 
+ 
+} // end namespace llvm 
+ 
+#endif // LLVM_ADT_IMMUTABLESET_H 
+ 
+#ifdef __GNUC__ 
+#pragma GCC diagnostic pop 
+#endif