//===- 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 #include #include #include #include #include #include namespace llvm { template, typename ValueInfoT = DenseMapInfo, bool IsConst = false> class DenseMapIterator; template, typename ValueInfoT = DenseMapInfo > class DenseMap { typedef std::pair 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 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 iterator; typedef DenseMapIterator 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 insert(const std::pair &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 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::value || !isPodLike::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(operator new(sizeof(BucketT) * NumBuckets)); if (isPodLike::value && isPodLike::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(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(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(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 class DenseMapIterator { typedef std::pair Bucket; typedef DenseMapIterator ConstIterator; friend class DenseMapIterator; public: typedef ptrdiff_t difference_type; typedef typename conditional::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& 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; } }; } // end namespace llvm #endif