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+//===- ValueMap.h - Safe map from Values to data ----------------*- 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 the ValueMap class.  ValueMap maps Value* or any subclass
+// to an arbitrary other type.  It provides the DenseMap interface but updates
+// itself to remain safe when keys are RAUWed or deleted.  By default, when a
+// key is RAUWed from V1 to V2, the old mapping V1->target is removed, and a new
+// mapping V2->target is added.  If V2 already existed, its old target is
+// overwritten.  When a key is deleted, its mapping is removed.
+//
+// You can override a ValueMap's Config parameter to control exactly what
+// happens on RAUW and destruction and to get called back on each event.  It's
+// legal to call back into the ValueMap from a Config's callbacks.  Config
+// parameters should inherit from ValueMapConfig<KeyT> to get default
+// implementations of all the methods ValueMap uses.  See ValueMapConfig for
+// documentation of the functions you can override.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_VALUEMAP_H
+#define LLVM_IR_VALUEMAP_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/IR/TrackingMDRef.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/Mutex.h"
+#include "llvm/Support/UniqueLock.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+namespace llvm {
+
+template<typename KeyT, typename ValueT, typename Config>
+class ValueMapCallbackVH;
+template<typename DenseMapT, typename KeyT>
+class ValueMapIterator;
+template<typename DenseMapT, typename KeyT>
+class ValueMapConstIterator;
+
+/// This class defines the default behavior for configurable aspects of
+/// ValueMap<>.  User Configs should inherit from this class to be as compatible
+/// as possible with future versions of ValueMap.
+template<typename KeyT, typename MutexT = sys::Mutex>
+struct ValueMapConfig {
+  using mutex_type = MutexT;
+
+  /// If FollowRAUW is true, the ValueMap will update mappings on RAUW. If it's
+  /// false, the ValueMap will leave the original mapping in place.
+  enum { FollowRAUW = true };
+
+  // All methods will be called with a first argument of type ExtraData.  The
+  // default implementations in this class take a templated first argument so
+  // that users' subclasses can use any type they want without having to
+  // override all the defaults.
+  struct ExtraData {};
+
+  template<typename ExtraDataT>
+  static void onRAUW(const ExtraDataT & /*Data*/, KeyT /*Old*/, KeyT /*New*/) {}
+  template<typename ExtraDataT>
+  static void onDelete(const ExtraDataT &/*Data*/, KeyT /*Old*/) {}
+
+  /// Returns a mutex that should be acquired around any changes to the map.
+  /// This is only acquired from the CallbackVH (and held around calls to onRAUW
+  /// and onDelete) and not inside other ValueMap methods.  NULL means that no
+  /// mutex is necessary.
+  template<typename ExtraDataT>
+  static mutex_type *getMutex(const ExtraDataT &/*Data*/) { return nullptr; }
+};
+
+/// See the file comment.
+template<typename KeyT, typename ValueT, typename Config =ValueMapConfig<KeyT>>
+class ValueMap {
+  friend class ValueMapCallbackVH<KeyT, ValueT, Config>;
+
+  using ValueMapCVH = ValueMapCallbackVH<KeyT, ValueT, Config>;
+  using MapT = DenseMap<ValueMapCVH, ValueT, DenseMapInfo<ValueMapCVH>>;
+  using MDMapT = DenseMap<const Metadata *, TrackingMDRef>;
+  using ExtraData = typename Config::ExtraData;
+
+  MapT Map;
+  Optional<MDMapT> MDMap;
+  ExtraData Data;
+  bool MayMapMetadata = true;
+
+public:
+  using key_type = KeyT;
+  using mapped_type = ValueT;
+  using value_type = std::pair<KeyT, ValueT>;
+  using size_type = unsigned;
+
+  explicit ValueMap(unsigned NumInitBuckets = 64)
+      : Map(NumInitBuckets), Data() {}
+  explicit ValueMap(const ExtraData &Data, unsigned NumInitBuckets = 64)
+      : Map(NumInitBuckets), Data(Data) {}
+  ValueMap(const ValueMap &) = delete;
+  ValueMap &operator=(const ValueMap &) = delete;
+
+  bool hasMD() const { return bool(MDMap); }
+  MDMapT &MD() {
+    if (!MDMap)
+      MDMap.emplace();
+    return *MDMap;
+  }
+  Optional<MDMapT> &getMDMap() { return MDMap; }
+
+  bool mayMapMetadata() const { return MayMapMetadata; }
+  void enableMapMetadata() { MayMapMetadata = true; }
+  void disableMapMetadata() { MayMapMetadata = false; }
+
+  /// Get the mapped metadata, if it's in the map.
+  Optional<Metadata *> getMappedMD(const Metadata *MD) const {
+    if (!MDMap)
+      return None;
+    auto Where = MDMap->find(MD);
+    if (Where == MDMap->end())
+      return None;
+    return Where->second.get();
+  }
+
+  using iterator = ValueMapIterator<MapT, KeyT>;
+  using const_iterator = ValueMapConstIterator<MapT, KeyT>;
+
+  inline iterator begin() { return iterator(Map.begin()); }
+  inline iterator end() { return iterator(Map.end()); }
+  inline const_iterator begin() const { return const_iterator(Map.begin()); }
+  inline const_iterator end() const { return const_iterator(Map.end()); }
+
+  bool empty() const { return Map.empty(); }
+  size_type size() const { return Map.size(); }
+
+  /// Grow the map so that it has at least Size buckets. Does not shrink
+  void resize(size_t Size) { Map.resize(Size); }
+
+  void clear() {
+    Map.clear();
+    MDMap.reset();
+  }
+
+  /// Return 1 if the specified key is in the map, 0 otherwise.
+  size_type count(const KeyT &Val) const {
+    return Map.find_as(Val) == Map.end() ? 0 : 1;
+  }
+
+  iterator find(const KeyT &Val) {
+    return iterator(Map.find_as(Val));
+  }
+  const_iterator find(const KeyT &Val) const {
+    return const_iterator(Map.find_as(Val));
+  }
+
+  /// lookup - Return the entry for the specified key, or a default
+  /// constructed value if no such entry exists.
+  ValueT lookup(const KeyT &Val) const {
+    typename MapT::const_iterator I = Map.find_as(Val);
+    return I != Map.end() ? I->second : ValueT();
+  }
+
+  // Inserts key,value pair into the map if the key isn't already in the map.
+  // If the key is already in the map, it returns false and doesn't update the
+  // value.
+  std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
+    auto MapResult = Map.insert(std::make_pair(Wrap(KV.first), KV.second));
+    return std::make_pair(iterator(MapResult.first), MapResult.second);
+  }
+
+  std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
+    auto MapResult =
+        Map.insert(std::make_pair(Wrap(KV.first), std::move(KV.second)));
+    return std::make_pair(iterator(MapResult.first), MapResult.second);
+  }
+
+  /// insert - Range insertion of pairs.
+  template<typename InputIt>
+  void insert(InputIt I, InputIt E) {
+    for (; I != E; ++I)
+      insert(*I);
+  }
+
+  bool erase(const KeyT &Val) {
+    typename MapT::iterator I = Map.find_as(Val);
+    if (I == Map.end())
+      return false;
+
+    Map.erase(I);
+    return true;
+  }
+  void erase(iterator I) {
+    return Map.erase(I.base());
+  }
+
+  value_type& FindAndConstruct(const KeyT &Key) {
+    return Map.FindAndConstruct(Wrap(Key));
+  }
+
+  ValueT &operator[](const KeyT &Key) {
+    return Map[Wrap(Key)];
+  }
+
+  /// isPointerIntoBucketsArray - Return true if the specified pointer points
+  /// somewhere into the ValueMap's array of buckets (i.e. either to a key or
+  /// value in the ValueMap).
+  bool isPointerIntoBucketsArray(const void *Ptr) const {
+    return Map.isPointerIntoBucketsArray(Ptr);
+  }
+
+  /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
+  /// array.  In conjunction with the previous method, this can be used to
+  /// determine whether an insertion caused the ValueMap to reallocate.
+  const void *getPointerIntoBucketsArray() const {
+    return Map.getPointerIntoBucketsArray();
+  }
+
+private:
+  // Takes a key being looked up in the map and wraps it into a
+  // ValueMapCallbackVH, the actual key type of the map.  We use a helper
+  // function because ValueMapCVH is constructed with a second parameter.
+  ValueMapCVH Wrap(KeyT key) const {
+    // The only way the resulting CallbackVH could try to modify *this (making
+    // the const_cast incorrect) is if it gets inserted into the map.  But then
+    // this function must have been called from a non-const method, making the
+    // const_cast ok.
+    return ValueMapCVH(key, const_cast<ValueMap*>(this));
+  }
+};
+
+// This CallbackVH updates its ValueMap when the contained Value changes,
+// according to the user's preferences expressed through the Config object.
+template <typename KeyT, typename ValueT, typename Config>
+class ValueMapCallbackVH final : public CallbackVH {
+  friend class ValueMap<KeyT, ValueT, Config>;
+  friend struct DenseMapInfo<ValueMapCallbackVH>;
+
+  using ValueMapT = ValueMap<KeyT, ValueT, Config>;
+  using KeySansPointerT = typename std::remove_pointer<KeyT>::type;
+
+  ValueMapT *Map;
+
+  ValueMapCallbackVH(KeyT Key, ValueMapT *Map)
+      : CallbackVH(const_cast<Value*>(static_cast<const Value*>(Key))),
+        Map(Map) {}
+
+  // Private constructor used to create empty/tombstone DenseMap keys.
+  ValueMapCallbackVH(Value *V) : CallbackVH(V), Map(nullptr) {}
+
+public:
+  KeyT Unwrap() const { return cast_or_null<KeySansPointerT>(getValPtr()); }
+
+  void deleted() override {
+    // Make a copy that won't get changed even when *this is destroyed.
+    ValueMapCallbackVH Copy(*this);
+    typename Config::mutex_type *M = Config::getMutex(Copy.Map->Data);
+    unique_lock<typename Config::mutex_type> Guard;
+    if (M)
+      Guard = unique_lock<typename Config::mutex_type>(*M);
+    Config::onDelete(Copy.Map->Data, Copy.Unwrap());  // May destroy *this.
+    Copy.Map->Map.erase(Copy);  // Definitely destroys *this.
+  }
+
+  void allUsesReplacedWith(Value *new_key) override {
+    assert(isa<KeySansPointerT>(new_key) &&
+           "Invalid RAUW on key of ValueMap<>");
+    // Make a copy that won't get changed even when *this is destroyed.
+    ValueMapCallbackVH Copy(*this);
+    typename Config::mutex_type *M = Config::getMutex(Copy.Map->Data);
+    unique_lock<typename Config::mutex_type> Guard;
+    if (M)
+      Guard = unique_lock<typename Config::mutex_type>(*M);
+
+    KeyT typed_new_key = cast<KeySansPointerT>(new_key);
+    // Can destroy *this:
+    Config::onRAUW(Copy.Map->Data, Copy.Unwrap(), typed_new_key);
+    if (Config::FollowRAUW) {
+      typename ValueMapT::MapT::iterator I = Copy.Map->Map.find(Copy);
+      // I could == Copy.Map->Map.end() if the onRAUW callback already
+      // removed the old mapping.
+      if (I != Copy.Map->Map.end()) {
+        ValueT Target(std::move(I->second));
+        Copy.Map->Map.erase(I);  // Definitely destroys *this.
+        Copy.Map->insert(std::make_pair(typed_new_key, std::move(Target)));
+      }
+    }
+  }
+};
+
+template<typename KeyT, typename ValueT, typename Config>
+struct DenseMapInfo<ValueMapCallbackVH<KeyT, ValueT, Config>> {
+  using VH = ValueMapCallbackVH<KeyT, ValueT, Config>;
+
+  static inline VH getEmptyKey() {
+    return VH(DenseMapInfo<Value *>::getEmptyKey());
+  }
+
+  static inline VH getTombstoneKey() {
+    return VH(DenseMapInfo<Value *>::getTombstoneKey());
+  }
+
+  static unsigned getHashValue(const VH &Val) {
+    return DenseMapInfo<KeyT>::getHashValue(Val.Unwrap());
+  }
+
+  static unsigned getHashValue(const KeyT &Val) {
+    return DenseMapInfo<KeyT>::getHashValue(Val);
+  }
+
+  static bool isEqual(const VH &LHS, const VH &RHS) {
+    return LHS == RHS;
+  }
+
+  static bool isEqual(const KeyT &LHS, const VH &RHS) {
+    return LHS == RHS.getValPtr();
+  }
+};
+
+template<typename DenseMapT, typename KeyT>
+class ValueMapIterator :
+    public std::iterator<std::forward_iterator_tag,
+                         std::pair<KeyT, typename DenseMapT::mapped_type>,
+                         ptrdiff_t> {
+  using BaseT = typename DenseMapT::iterator;
+  using ValueT = typename DenseMapT::mapped_type;
+
+  BaseT I;
+
+public:
+  ValueMapIterator() : I() {}
+  ValueMapIterator(BaseT I) : I(I) {}
+
+  BaseT base() const { return I; }
+
+  struct ValueTypeProxy {
+    const KeyT first;
+    ValueT& second;
+
+    ValueTypeProxy *operator->() { return this; }
+
+    operator std::pair<KeyT, ValueT>() const {
+      return std::make_pair(first, second);
+    }
+  };
+
+  ValueTypeProxy operator*() const {
+    ValueTypeProxy Result = {I->first.Unwrap(), I->second};
+    return Result;
+  }
+
+  ValueTypeProxy operator->() const {
+    return operator*();
+  }
+
+  bool operator==(const ValueMapIterator &RHS) const {
+    return I == RHS.I;
+  }
+  bool operator!=(const ValueMapIterator &RHS) const {
+    return I != RHS.I;
+  }
+
+  inline ValueMapIterator& operator++() {  // Preincrement
+    ++I;
+    return *this;
+  }
+  ValueMapIterator operator++(int) {  // Postincrement
+    ValueMapIterator tmp = *this; ++*this; return tmp;
+  }
+};
+
+template<typename DenseMapT, typename KeyT>
+class ValueMapConstIterator :
+    public std::iterator<std::forward_iterator_tag,
+                         std::pair<KeyT, typename DenseMapT::mapped_type>,
+                         ptrdiff_t> {
+  using BaseT = typename DenseMapT::const_iterator;
+  using ValueT = typename DenseMapT::mapped_type;
+
+  BaseT I;
+
+public:
+  ValueMapConstIterator() : I() {}
+  ValueMapConstIterator(BaseT I) : I(I) {}
+  ValueMapConstIterator(ValueMapIterator<DenseMapT, KeyT> Other)
+    : I(Other.base()) {}
+
+  BaseT base() const { return I; }
+
+  struct ValueTypeProxy {
+    const KeyT first;
+    const ValueT& second;
+    ValueTypeProxy *operator->() { return this; }
+    operator std::pair<KeyT, ValueT>() const {
+      return std::make_pair(first, second);
+    }
+  };
+
+  ValueTypeProxy operator*() const {
+    ValueTypeProxy Result = {I->first.Unwrap(), I->second};
+    return Result;
+  }
+
+  ValueTypeProxy operator->() const {
+    return operator*();
+  }
+
+  bool operator==(const ValueMapConstIterator &RHS) const {
+    return I == RHS.I;
+  }
+  bool operator!=(const ValueMapConstIterator &RHS) const {
+    return I != RHS.I;
+  }
+
+  inline ValueMapConstIterator& operator++() {  // Preincrement
+    ++I;
+    return *this;
+  }
+  ValueMapConstIterator operator++(int) {  // Postincrement
+    ValueMapConstIterator tmp = *this; ++*this; return tmp;
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_IR_VALUEMAP_H