include/llvm/ADT/DenseMap.h - llvm - Git at Google

 //===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- 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 DenseMap class.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_ADT_DENSEMAP_H
 #define LLVM_ADT_DENSEMAP_H

 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
 #include "llvm/Support/type_traits.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include <algorithm>
 #include <iterator>
 #include <new>
 #include <utility>
 #include <cassert>
 #include <cstddef>
 #include <cstring>

 namespace llvm {

 template<typename KeyT, typename ValueT,
          typename KeyInfoT = DenseMapInfo<KeyT>,
          typename ValueInfoT = DenseMapInfo<ValueT>, bool IsConst = false>
 class DenseMapIterator;

 template<typename KeyT, typename ValueT,
          typename KeyInfoT = DenseMapInfo<KeyT>,
          typename ValueInfoT = DenseMapInfo<ValueT> >
 class DenseMap {
   typedef std::pair<KeyT, ValueT> BucketT;
   unsigned NumBuckets;
   BucketT *Buckets;

   unsigned NumEntries;
   unsigned NumTombstones;
 public:
   typedef KeyT key_type;
   typedef ValueT mapped_type;
   typedef BucketT value_type;

   DenseMap(const DenseMap &other) {
     NumBuckets = 0;
     CopyFrom(other);
   }

   explicit DenseMap(unsigned NumInitBuckets = 0) {
     init(NumInitBuckets);
   }

   template<typename InputIt>
   DenseMap(const InputIt &I, const InputIt &E) {
     init(NextPowerOf2(std::distance(I, E)));
     insert(I, E);
   }

   ~DenseMap() {
     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
     for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
       if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
           !KeyInfoT::isEqual(P->first, TombstoneKey))
         P->second.~ValueT();
       P->first.~KeyT();
     }
 #ifndef NDEBUG
     if (NumBuckets)
       memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets);
 #endif
     operator delete(Buckets);
   }

   typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
   typedef DenseMapIterator<KeyT, ValueT,
                            KeyInfoT, ValueInfoT, true> const_iterator;
   inline iterator begin() {
     // When the map is empty, avoid the overhead of AdvancePastEmptyBuckets().
     return empty() ? end() : iterator(Buckets, Buckets+NumBuckets);
   }
   inline iterator end() {
     return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
   }
   inline const_iterator begin() const {
     return empty() ? end() : const_iterator(Buckets, Buckets+NumBuckets);
   }
   inline const_iterator end() const {
     return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
   }

   bool empty() const { return NumEntries == 0; }
   unsigned size() const { return NumEntries; }

   /// Grow the densemap so that it has at least Size buckets. Does not shrink
   void resize(size_t Size) {
     if (Size > NumBuckets)
       grow(Size);
   }

   void clear() {
     if (NumEntries == 0 && NumTombstones == 0) return;

     // If the capacity of the array is huge, and the # elements used is small,
     // shrink the array.
     if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
       shrink_and_clear();
       return;
     }

     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
     for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
       if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
         if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
           P->second.~ValueT();
           --NumEntries;
         }
         P->first = EmptyKey;
       }
     }
     assert(NumEntries == 0 && "Node count imbalance!");
     NumTombstones = 0;
   }

   /// count - Return true if the specified key is in the map.
   bool count(const KeyT &Val) const {
     BucketT *TheBucket;
     return LookupBucketFor(Val, TheBucket);
   }

   iterator find(const KeyT &Val) {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
       return iterator(TheBucket, Buckets+NumBuckets);
     return end();
   }
   const_iterator find(const KeyT &Val) const {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
       return const_iterator(TheBucket, Buckets+NumBuckets);
     return end();
   }

   /// lookup - Return the entry for the specified key, or a default
   /// constructed value if no such entry exists.
   ValueT lookup(const KeyT &Val) const {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
       return TheBucket->second;
     return 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) {
     BucketT *TheBucket;
     if (LookupBucketFor(KV.first, TheBucket))
       return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
                             false); // Already in map.

     // Otherwise, insert the new element.
     TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
     return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
                           true);
   }

   /// 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) {
     BucketT *TheBucket;
     if (!LookupBucketFor(Val, TheBucket))
       return false; // not in map.

     TheBucket->second.~ValueT();
     TheBucket->first = getTombstoneKey();
     --NumEntries;
     ++NumTombstones;
     return true;
   }
   void erase(iterator I) {
     BucketT *TheBucket = &*I;
     TheBucket->second.~ValueT();
     TheBucket->first = getTombstoneKey();
     --NumEntries;
     ++NumTombstones;
   }

   void swap(DenseMap& RHS) {
     std::swap(NumBuckets, RHS.NumBuckets);
     std::swap(Buckets, RHS.Buckets);
     std::swap(NumEntries, RHS.NumEntries);
     std::swap(NumTombstones, RHS.NumTombstones);
   }

   value_type& FindAndConstruct(const KeyT &Key) {
     BucketT *TheBucket;
     if (LookupBucketFor(Key, TheBucket))
       return *TheBucket;

     return *InsertIntoBucket(Key, ValueT(), TheBucket);
   }

   ValueT &operator[](const KeyT &Key) {
     return FindAndConstruct(Key).second;
   }

   DenseMap& operator=(const DenseMap& other) {
     CopyFrom(other);
     return *this;
   }

   /// isPointerIntoBucketsArray - Return true if the specified pointer points
   /// somewhere into the DenseMap's array of buckets (i.e. either to a key or
   /// value in the DenseMap).
   bool isPointerIntoBucketsArray(const void *Ptr) const {
     return Ptr >= Buckets && Ptr < Buckets+NumBuckets;
   }

   /// 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 DenseMap to reallocate.
   const void *getPointerIntoBucketsArray() const { return Buckets; }

 private:
   void CopyFrom(const DenseMap& other) {
     if (NumBuckets != 0 &&
         (!isPodLike<KeyInfoT>::value || !isPodLike<ValueInfoT>::value)) {
       const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
       for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
         if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
             !KeyInfoT::isEqual(P->first, TombstoneKey))
           P->second.~ValueT();
         P->first.~KeyT();
       }
     }

     NumEntries = other.NumEntries;
     NumTombstones = other.NumTombstones;

     if (NumBuckets) {
 #ifndef NDEBUG
       memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets);
 #endif
       operator delete(Buckets);
     }

     NumBuckets = other.NumBuckets;

     if (NumBuckets == 0) {
       Buckets = 0;
       return;
     }

     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets));

     if (isPodLike<KeyInfoT>::value && isPodLike<ValueInfoT>::value)
       memcpy(Buckets, other.Buckets, NumBuckets * sizeof(BucketT));
     else
       for (size_t i = 0; i < NumBuckets; ++i) {
         new (&Buckets[i].first) KeyT(other.Buckets[i].first);
         if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
             !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
           new (&Buckets[i].second) ValueT(other.Buckets[i].second);
       }
   }

   BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
                             BucketT *TheBucket) {
     // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
     // the buckets are empty (meaning that many are filled with tombstones),
     // grow the table.
     //
     // The later case is tricky.  For example, if we had one empty bucket with
     // tons of tombstones, failing lookups (e.g. for insertion) would have to
     // probe almost the entire table until it found the empty bucket.  If the
     // table completely filled with tombstones, no lookup would ever succeed,
     // causing infinite loops in lookup.
     ++NumEntries;
     if (NumEntries*4 >= NumBuckets*3) {
       this->grow(NumBuckets * 2);
       LookupBucketFor(Key, TheBucket);
     }
     if (NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
       this->grow(NumBuckets);
       LookupBucketFor(Key, TheBucket);
     }

     // If we are writing over a tombstone, remember this.
     if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
       --NumTombstones;

     TheBucket->first = Key;
     new (&TheBucket->second) ValueT(Value);
     return TheBucket;
   }

   static unsigned getHashValue(const KeyT &Val) {
     return KeyInfoT::getHashValue(Val);
   }
   static const KeyT getEmptyKey() {
     return KeyInfoT::getEmptyKey();
   }
   static const KeyT getTombstoneKey() {
     return KeyInfoT::getTombstoneKey();
   }

   /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
   /// FoundBucket.  If the bucket contains the key and a value, this returns
   /// true, otherwise it returns a bucket with an empty marker or tombstone and
   /// returns false.
   bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
     unsigned BucketNo = getHashValue(Val);
     unsigned ProbeAmt = 1;
     BucketT *BucketsPtr = Buckets;

     if (NumBuckets == 0) {
       FoundBucket = 0;
       return false;
     }

     // FoundTombstone - Keep track of whether we find a tombstone while probing.
     BucketT *FoundTombstone = 0;
     const KeyT EmptyKey = getEmptyKey();
     const KeyT TombstoneKey = getTombstoneKey();
     assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
            !KeyInfoT::isEqual(Val, TombstoneKey) &&
            "Empty/Tombstone value shouldn't be inserted into map!");

     while (1) {
       BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
       // Found Val's bucket?  If so, return it.
       if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
         FoundBucket = ThisBucket;
         return true;
       }

       // If we found an empty bucket, the key doesn't exist in the set.
       // Insert it and return the default value.
       if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
         // If we've already seen a tombstone while probing, fill it in instead
         // of the empty bucket we eventually probed to.
         if (FoundTombstone) ThisBucket = FoundTombstone;
         FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
         return false;
       }

       // If this is a tombstone, remember it.  If Val ends up not in the map, we
       // prefer to return it than something that would require more probing.
       if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
         FoundTombstone = ThisBucket;  // Remember the first tombstone found.

       // Otherwise, it's a hash collision or a tombstone, continue quadratic
       // probing.
       BucketNo += ProbeAmt++;
     }
   }

   void init(unsigned InitBuckets) {
     NumEntries = 0;
     NumTombstones = 0;
     NumBuckets = InitBuckets;

     if (InitBuckets == 0) {
       Buckets = 0;
       return;
     }

     assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
            "# initial buckets must be a power of two!");
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets));
     // Initialize all the keys to EmptyKey.
     const KeyT EmptyKey = getEmptyKey();
     for (unsigned i = 0; i != InitBuckets; ++i)
       new (&Buckets[i].first) KeyT(EmptyKey);
   }

   void grow(unsigned AtLeast) {
     unsigned OldNumBuckets = NumBuckets;
     BucketT *OldBuckets = Buckets;

     if (NumBuckets < 64)
       NumBuckets = 64;

     // Double the number of buckets.
     while (NumBuckets < AtLeast)
       NumBuckets <<= 1;
     NumTombstones = 0;
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));

     // Initialize all the keys to EmptyKey.
     const KeyT EmptyKey = getEmptyKey();
     for (unsigned i = 0, e = NumBuckets; i != e; ++i)
       new (&Buckets[i].first) KeyT(EmptyKey);

     // Insert all the old elements.
     const KeyT TombstoneKey = getTombstoneKey();
     for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
       if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
           !KeyInfoT::isEqual(B->first, TombstoneKey)) {
         // Insert the key/value into the new table.
         BucketT *DestBucket;
         bool FoundVal = LookupBucketFor(B->first, DestBucket);
         (void)FoundVal; // silence warning.
         assert(!FoundVal && "Key already in new map?");
         DestBucket->first = B->first;
         new (&DestBucket->second) ValueT(B->second);

         // Free the value.
         B->second.~ValueT();
       }
       B->first.~KeyT();
     }

 #ifndef NDEBUG
     if (OldNumBuckets)
       memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets);
 #endif
     // Free the old table.
     operator delete(OldBuckets);
   }

   void shrink_and_clear() {
     unsigned OldNumBuckets = NumBuckets;
     BucketT *OldBuckets = Buckets;

     // Reduce the number of buckets.
     NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
                                  : 64;
     NumTombstones = 0;
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));

     // Initialize all the keys to EmptyKey.
     const KeyT EmptyKey = getEmptyKey();
     for (unsigned i = 0, e = NumBuckets; i != e; ++i)
       new (&Buckets[i].first) KeyT(EmptyKey);

     // Free the old buckets.
     const KeyT TombstoneKey = getTombstoneKey();
     for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
       if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
           !KeyInfoT::isEqual(B->first, TombstoneKey)) {
         // Free the value.
         B->second.~ValueT();
       }
       B->first.~KeyT();
     }

 #ifndef NDEBUG
     memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets);
 #endif
     // Free the old table.
     operator delete(OldBuckets);

     NumEntries = 0;
   }

 public:
   /// Return the approximate size (in bytes) of the actual map.
   /// This is just the raw memory used by DenseMap.
   /// If entries are pointers to objects, the size of the referenced objects
   /// are not included.
   size_t getMemorySize() const {
     return NumBuckets * sizeof(BucketT);
   }
 };

 template<typename KeyT, typename ValueT,
          typename KeyInfoT, typename ValueInfoT, bool IsConst>
 class DenseMapIterator {
   typedef std::pair<KeyT, ValueT> Bucket;
   typedef DenseMapIterator<KeyT, ValueT,
                            KeyInfoT, ValueInfoT, true> ConstIterator;
   friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, ValueInfoT, true>;
 public:
   typedef ptrdiff_t difference_type;
   typedef typename conditional<IsConst, const Bucket, Bucket>::type value_type;
   typedef value_type *pointer;
   typedef value_type &reference;
   typedef std::forward_iterator_tag iterator_category;
 private:
   pointer Ptr, End;
 public:
   DenseMapIterator() : Ptr(0), End(0) {}

   DenseMapIterator(pointer Pos, pointer E) : Ptr(Pos), End(E) {
     AdvancePastEmptyBuckets();
   }

   // If IsConst is true this is a converting constructor from iterator to
   // const_iterator and the default copy constructor is used.
   // Otherwise this is a copy constructor for iterator.
   DenseMapIterator(const DenseMapIterator<KeyT, ValueT,
                                           KeyInfoT, ValueInfoT, false>& I)
     : Ptr(I.Ptr), End(I.End) {}

   reference operator*() const {
     return *Ptr;
   }
   pointer operator->() const {
     return Ptr;
   }

   bool operator==(const ConstIterator &RHS) const {
     return Ptr == RHS.operator->();
   }
   bool operator!=(const ConstIterator &RHS) const {
     return Ptr != RHS.operator->();
   }

   inline DenseMapIterator& operator++() {  // Preincrement
     ++Ptr;
     AdvancePastEmptyBuckets();
     return *this;
   }
   DenseMapIterator operator++(int) {  // Postincrement
     DenseMapIterator tmp = *this; ++*this; return tmp;
   }

 private:
   void AdvancePastEmptyBuckets() {
     const KeyT Empty = KeyInfoT::getEmptyKey();
     const KeyT Tombstone = KeyInfoT::getTombstoneKey();

     while (Ptr != End &&
            (KeyInfoT::isEqual(Ptr->first, Empty) ||
             KeyInfoT::isEqual(Ptr->first, Tombstone)))
       ++Ptr;
   }
 };

 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
 static inline size_t
 capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT, ValueInfoT> &X) {
   return X.getMemorySize();
 }

 } // end namespace llvm

 #endif
	//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------- 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 DenseMap class.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_ADT_DENSEMAP_H
	#define LLVM_ADT_DENSEMAP_H

	#include "llvm/Support/MathExtras.h"
	#include "llvm/Support/PointerLikeTypeTraits.h"
	#include "llvm/Support/type_traits.h"
	#include "llvm/ADT/DenseMapInfo.h"
	#include <algorithm>
	#include <iterator>
	#include <new>
	#include <utility>
	#include <cassert>
	#include <cstddef>
	#include <cstring>

	namespace llvm {

	template<typename KeyT, typename ValueT,
	typename KeyInfoT = DenseMapInfo<KeyT>,
	typename ValueInfoT = DenseMapInfo<ValueT>, bool IsConst = false>
	class DenseMapIterator;

	template<typename KeyT, typename ValueT,
	typename KeyInfoT = DenseMapInfo<KeyT>,
	typename ValueInfoT = DenseMapInfo<ValueT> >
	class DenseMap {
	typedef std::pair<KeyT, ValueT> BucketT;
	unsigned NumBuckets;
	BucketT *Buckets;

	unsigned NumEntries;
	unsigned NumTombstones;
	public:
	typedef KeyT key_type;
	typedef ValueT mapped_type;
	typedef BucketT value_type;

	DenseMap(const DenseMap &other) {
	NumBuckets = 0;
	CopyFrom(other);
	}

	explicit DenseMap(unsigned NumInitBuckets = 0) {
	init(NumInitBuckets);
	}

	template<typename InputIt>
	DenseMap(const InputIt &I, const InputIt &E) {
	init(NextPowerOf2(std::distance(I, E)));
	insert(I, E);
	}

	~DenseMap() {
	const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
	for (BucketT P = Buckets, E = Buckets+NumBuckets; P != E; ++P) {
	if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
	!KeyInfoT::isEqual(P->first, TombstoneKey))
	P->second.~ValueT();
	P->first.~KeyT();
	}
	#ifndef NDEBUG
	if (NumBuckets)
	memset((void)Buckets, 0x5a, sizeof(BucketT)NumBuckets);
	#endif
	operator delete(Buckets);
	}

	typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
	typedef DenseMapIterator<KeyT, ValueT,
	KeyInfoT, ValueInfoT, true> const_iterator;
	inline iterator begin() {
	// When the map is empty, avoid the overhead of AdvancePastEmptyBuckets().
	return empty() ? end() : iterator(Buckets, Buckets+NumBuckets);
	}
	inline iterator end() {
	return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
	}
	inline const_iterator begin() const {
	return empty() ? end() : const_iterator(Buckets, Buckets+NumBuckets);
	}
	inline const_iterator end() const {
	return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
	}

	bool empty() const { return NumEntries == 0; }
	unsigned size() const { return NumEntries; }

	/// Grow the densemap so that it has at least Size buckets. Does not shrink
	void resize(size_t Size) {
	if (Size > NumBuckets)
	grow(Size);
	}

	void clear() {
	if (NumEntries == 0 && NumTombstones == 0) return;

	// If the capacity of the array is huge, and the # elements used is small,
	// shrink the array.
	if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
	shrink_and_clear();
	return;
	}

	const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
	for (BucketT P = Buckets, E = Buckets+NumBuckets; P != E; ++P) {
	if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
	if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
	P->second.~ValueT();
	--NumEntries;
	}
	P->first = EmptyKey;
	}
	}
	assert(NumEntries == 0 && "Node count imbalance!");
	NumTombstones = 0;
	}

	/// count - Return true if the specified key is in the map.
	bool count(const KeyT &Val) const {
	BucketT *TheBucket;
	return LookupBucketFor(Val, TheBucket);
	}

	iterator find(const KeyT &Val) {
	BucketT *TheBucket;
	if (LookupBucketFor(Val, TheBucket))
	return iterator(TheBucket, Buckets+NumBuckets);
	return end();
	}
	const_iterator find(const KeyT &Val) const {
	BucketT *TheBucket;
	if (LookupBucketFor(Val, TheBucket))
	return const_iterator(TheBucket, Buckets+NumBuckets);
	return end();
	}

	/// lookup - Return the entry for the specified key, or a default
	/// constructed value if no such entry exists.
	ValueT lookup(const KeyT &Val) const {
	BucketT *TheBucket;
	if (LookupBucketFor(Val, TheBucket))
	return TheBucket->second;
	return 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) {
	BucketT *TheBucket;
	if (LookupBucketFor(KV.first, TheBucket))
	return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
	false); // Already in map.

	// Otherwise, insert the new element.
	TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
	return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
	true);
	}

	/// 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) {
	BucketT *TheBucket;
	if (!LookupBucketFor(Val, TheBucket))
	return false; // not in map.

	TheBucket->second.~ValueT();
	TheBucket->first = getTombstoneKey();
	--NumEntries;
	++NumTombstones;
	return true;
	}
	void erase(iterator I) {
	BucketT TheBucket = &I;
	TheBucket->second.~ValueT();
	TheBucket->first = getTombstoneKey();
	--NumEntries;
	++NumTombstones;
	}

	void swap(DenseMap& RHS) {
	std::swap(NumBuckets, RHS.NumBuckets);
	std::swap(Buckets, RHS.Buckets);
	std::swap(NumEntries, RHS.NumEntries);
	std::swap(NumTombstones, RHS.NumTombstones);
	}

	value_type& FindAndConstruct(const KeyT &Key) {
	BucketT *TheBucket;
	if (LookupBucketFor(Key, TheBucket))
	return *TheBucket;

	return *InsertIntoBucket(Key, ValueT(), TheBucket);
	}

	ValueT &operator[](const KeyT &Key) {
	return FindAndConstruct(Key).second;
	}

	DenseMap& operator=(const DenseMap& other) {
	CopyFrom(other);
	return *this;
	}

	/// isPointerIntoBucketsArray - Return true if the specified pointer points
	/// somewhere into the DenseMap's array of buckets (i.e. either to a key or
	/// value in the DenseMap).
	bool isPointerIntoBucketsArray(const void *Ptr) const {
	return Ptr >= Buckets && Ptr < Buckets+NumBuckets;
	}

	/// 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 DenseMap to reallocate.
	const void *getPointerIntoBucketsArray() const { return Buckets; }

	private:
	void CopyFrom(const DenseMap& other) {
	if (NumBuckets != 0 &&
	(!isPodLike<KeyInfoT>::value \|\| !isPodLike<ValueInfoT>::value)) {
	const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
	for (BucketT P = Buckets, E = Buckets+NumBuckets; P != E; ++P) {
	if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
	!KeyInfoT::isEqual(P->first, TombstoneKey))
	P->second.~ValueT();
	P->first.~KeyT();
	}
	}

	NumEntries = other.NumEntries;
	NumTombstones = other.NumTombstones;

	if (NumBuckets) {
	#ifndef NDEBUG
	memset((void)Buckets, 0x5a, sizeof(BucketT)NumBuckets);
	#endif
	operator delete(Buckets);
	}

	NumBuckets = other.NumBuckets;

	if (NumBuckets == 0) {
	Buckets = 0;
	return;
	}

	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT) NumBuckets));

	if (isPodLike<KeyInfoT>::value && isPodLike<ValueInfoT>::value)
	memcpy(Buckets, other.Buckets, NumBuckets * sizeof(BucketT));
	else
	for (size_t i = 0; i < NumBuckets; ++i) {
	new (&Buckets[i].first) KeyT(other.Buckets[i].first);
	if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
	!KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
	new (&Buckets[i].second) ValueT(other.Buckets[i].second);
	}
	}

	BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
	BucketT *TheBucket) {
	// If the load of the hash table is more than 3/4, or if fewer than 1/8 of
	// the buckets are empty (meaning that many are filled with tombstones),
	// grow the table.
	//
	// The later case is tricky. For example, if we had one empty bucket with
	// tons of tombstones, failing lookups (e.g. for insertion) would have to
	// probe almost the entire table until it found the empty bucket. If the
	// table completely filled with tombstones, no lookup would ever succeed,
	// causing infinite loops in lookup.
	++NumEntries;
	if (NumEntries4 >= NumBuckets3) {
	this->grow(NumBuckets * 2);
	LookupBucketFor(Key, TheBucket);
	}
	if (NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
	this->grow(NumBuckets);
	LookupBucketFor(Key, TheBucket);
	}

	// If we are writing over a tombstone, remember this.
	if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
	--NumTombstones;

	TheBucket->first = Key;
	new (&TheBucket->second) ValueT(Value);
	return TheBucket;
	}

	static unsigned getHashValue(const KeyT &Val) {
	return KeyInfoT::getHashValue(Val);
	}
	static const KeyT getEmptyKey() {
	return KeyInfoT::getEmptyKey();
	}
	static const KeyT getTombstoneKey() {
	return KeyInfoT::getTombstoneKey();
	}

	/// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
	/// FoundBucket. If the bucket contains the key and a value, this returns
	/// true, otherwise it returns a bucket with an empty marker or tombstone and
	/// returns false.
	bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
	unsigned BucketNo = getHashValue(Val);
	unsigned ProbeAmt = 1;
	BucketT *BucketsPtr = Buckets;

	if (NumBuckets == 0) {
	FoundBucket = 0;
	return false;
	}

	// FoundTombstone - Keep track of whether we find a tombstone while probing.
	BucketT *FoundTombstone = 0;
	const KeyT EmptyKey = getEmptyKey();
	const KeyT TombstoneKey = getTombstoneKey();
	assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
	!KeyInfoT::isEqual(Val, TombstoneKey) &&
	"Empty/Tombstone value shouldn't be inserted into map!");

	while (1) {
	BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
	// Found Val's bucket? If so, return it.
	if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
	FoundBucket = ThisBucket;
	return true;
	}

	// If we found an empty bucket, the key doesn't exist in the set.
	// Insert it and return the default value.
	if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
	// If we've already seen a tombstone while probing, fill it in instead
	// of the empty bucket we eventually probed to.
	if (FoundTombstone) ThisBucket = FoundTombstone;
	FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
	return false;
	}

	// If this is a tombstone, remember it. If Val ends up not in the map, we
	// prefer to return it than something that would require more probing.
	if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
	FoundTombstone = ThisBucket; // Remember the first tombstone found.

	// Otherwise, it's a hash collision or a tombstone, continue quadratic
	// probing.
	BucketNo += ProbeAmt++;
	}
	}

	void init(unsigned InitBuckets) {
	NumEntries = 0;
	NumTombstones = 0;
	NumBuckets = InitBuckets;

	if (InitBuckets == 0) {
	Buckets = 0;
	return;
	}

	assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
	"# initial buckets must be a power of two!");
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)InitBuckets));
	// Initialize all the keys to EmptyKey.
	const KeyT EmptyKey = getEmptyKey();
	for (unsigned i = 0; i != InitBuckets; ++i)
	new (&Buckets[i].first) KeyT(EmptyKey);
	}

	void grow(unsigned AtLeast) {
	unsigned OldNumBuckets = NumBuckets;
	BucketT *OldBuckets = Buckets;

	if (NumBuckets < 64)
	NumBuckets = 64;

	// Double the number of buckets.
	while (NumBuckets < AtLeast)
	NumBuckets <<= 1;
	NumTombstones = 0;
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)NumBuckets));

	// Initialize all the keys to EmptyKey.
	const KeyT EmptyKey = getEmptyKey();
	for (unsigned i = 0, e = NumBuckets; i != e; ++i)
	new (&Buckets[i].first) KeyT(EmptyKey);

	// Insert all the old elements.
	const KeyT TombstoneKey = getTombstoneKey();
	for (BucketT B = OldBuckets, E = OldBuckets+OldNumBuckets; B != E; ++B) {
	if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
	!KeyInfoT::isEqual(B->first, TombstoneKey)) {
	// Insert the key/value into the new table.
	BucketT *DestBucket;
	bool FoundVal = LookupBucketFor(B->first, DestBucket);
	(void)FoundVal; // silence warning.
	assert(!FoundVal && "Key already in new map?");
	DestBucket->first = B->first;
	new (&DestBucket->second) ValueT(B->second);

	// Free the value.
	B->second.~ValueT();
	}
	B->first.~KeyT();
	}

	#ifndef NDEBUG
	if (OldNumBuckets)
	memset((void)OldBuckets, 0x5a, sizeof(BucketT)OldNumBuckets);
	#endif
	// Free the old table.
	operator delete(OldBuckets);
	}

	void shrink_and_clear() {
	unsigned OldNumBuckets = NumBuckets;
	BucketT *OldBuckets = Buckets;

	// Reduce the number of buckets.
	NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
	: 64;
	NumTombstones = 0;
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)NumBuckets));

	// Initialize all the keys to EmptyKey.
	const KeyT EmptyKey = getEmptyKey();
	for (unsigned i = 0, e = NumBuckets; i != e; ++i)
	new (&Buckets[i].first) KeyT(EmptyKey);

	// Free the old buckets.
	const KeyT TombstoneKey = getTombstoneKey();
	for (BucketT B = OldBuckets, E = OldBuckets+OldNumBuckets; B != E; ++B) {
	if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
	!KeyInfoT::isEqual(B->first, TombstoneKey)) {
	// Free the value.
	B->second.~ValueT();
	}
	B->first.~KeyT();
	}

	#ifndef NDEBUG
	memset((void)OldBuckets, 0x5a, sizeof(BucketT)OldNumBuckets);
	#endif
	// Free the old table.
	operator delete(OldBuckets);

	NumEntries = 0;
	}

	public:
	/// Return the approximate size (in bytes) of the actual map.
	/// This is just the raw memory used by DenseMap.
	/// If entries are pointers to objects, the size of the referenced objects
	/// are not included.
	size_t getMemorySize() const {
	return NumBuckets * sizeof(BucketT);
	}
	};

	template<typename KeyT, typename ValueT,
	typename KeyInfoT, typename ValueInfoT, bool IsConst>
	class DenseMapIterator {
	typedef std::pair<KeyT, ValueT> Bucket;
	typedef DenseMapIterator<KeyT, ValueT,
	KeyInfoT, ValueInfoT, true> ConstIterator;
	friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, ValueInfoT, true>;
	public:
	typedef ptrdiff_t difference_type;
	typedef typename conditional<IsConst, const Bucket, Bucket>::type value_type;
	typedef value_type *pointer;
	typedef value_type &reference;
	typedef std::forward_iterator_tag iterator_category;
	private:
	pointer Ptr, End;
	public:
	DenseMapIterator() : Ptr(0), End(0) {}

	DenseMapIterator(pointer Pos, pointer E) : Ptr(Pos), End(E) {
	AdvancePastEmptyBuckets();
	}

	// If IsConst is true this is a converting constructor from iterator to
	// const_iterator and the default copy constructor is used.
	// Otherwise this is a copy constructor for iterator.
	DenseMapIterator(const DenseMapIterator<KeyT, ValueT,
	KeyInfoT, ValueInfoT, false>& I)
	: Ptr(I.Ptr), End(I.End) {}

	reference operator*() const {
	return *Ptr;
	}
	pointer operator->() const {
	return Ptr;
	}

	bool operator==(const ConstIterator &RHS) const {
	return Ptr == RHS.operator->();
	}
	bool operator!=(const ConstIterator &RHS) const {
	return Ptr != RHS.operator->();
	}

	inline DenseMapIterator& operator++() { // Preincrement
	++Ptr;
	AdvancePastEmptyBuckets();
	return *this;
	}
	DenseMapIterator operator++(int) { // Postincrement
	DenseMapIterator tmp = this; ++this; return tmp;
	}

	private:
	void AdvancePastEmptyBuckets() {
	const KeyT Empty = KeyInfoT::getEmptyKey();
	const KeyT Tombstone = KeyInfoT::getTombstoneKey();

	while (Ptr != End &&
	(KeyInfoT::isEqual(Ptr->first, Empty) \|\|
	KeyInfoT::isEqual(Ptr->first, Tombstone)))
	++Ptr;
	}
	};

	template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
	static inline size_t
	capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT, ValueInfoT> &X) {
	return X.getMemorySize();
	}

	} // end namespace llvm

	#endif