1 //===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the DenseMap class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_DENSEMAP_H
15 #define LLVM_ADT_DENSEMAP_H
17 #include "llvm/Support/DataTypes.h"
18 #include "llvm/Support/MathExtras.h"
26 //static inline T getEmptyKey();
27 //static inline T getTombstoneKey();
28 //static unsigned getHashValue(const T &Val);
29 //static bool isEqual(const T &LHS, const T &RHS);
33 // Provide DenseMapInfo for all pointers.
35 struct DenseMapInfo<T*> {
36 static inline T* getEmptyKey() { return reinterpret_cast<T*>(-1); }
37 static inline T* getTombstoneKey() { return reinterpret_cast<T*>(-2); }
38 static unsigned getHashValue(const T *PtrVal) {
39 return (unsigned((uintptr_t)PtrVal) >> 4) ^
40 (unsigned((uintptr_t)PtrVal) >> 9);
42 static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
43 static bool isPod() { return true; }
46 // Provide DenseMapInfo for unsigned ints.
47 template<> struct DenseMapInfo<uint32_t> {
48 static inline uint32_t getEmptyKey() { return ~0; }
49 static inline uint32_t getTombstoneKey() { return ~0 - 1; }
50 static unsigned getHashValue(const uint32_t& Val) { return Val * 37; }
51 static bool isPod() { return true; }
52 static bool isEqual(const uint32_t& LHS, const uint32_t& RHS) {
57 // Provide DenseMapInfo for all pairs whose members have info.
58 template<typename T, typename U>
59 struct DenseMapInfo<std::pair<T, U> > {
60 typedef std::pair<T, U> Pair;
61 typedef DenseMapInfo<T> FirstInfo;
62 typedef DenseMapInfo<U> SecondInfo;
64 static inline Pair getEmptyKey() {
65 return std::make_pair(FirstInfo::getEmptyKey(),
66 SecondInfo::getEmptyKey());
68 static inline Pair getTombstoneKey() {
69 return std::make_pair(FirstInfo::getTombstoneKey(),
70 SecondInfo::getEmptyKey()); }
71 static unsigned getHashValue(const Pair& PairVal) {
72 uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32
73 | (uint64_t)SecondInfo::getHashValue(PairVal.second);
84 static bool isEqual(const Pair& LHS, const Pair& RHS) { return LHS == RHS; }
85 static bool isPod() { return false; }
88 template<typename KeyT, typename ValueT,
89 typename KeyInfoT = DenseMapInfo<KeyT>,
90 typename ValueInfoT = DenseMapInfo<ValueT> >
91 class DenseMapIterator;
92 template<typename KeyT, typename ValueT,
93 typename KeyInfoT = DenseMapInfo<KeyT>,
94 typename ValueInfoT = DenseMapInfo<ValueT> >
95 class DenseMapConstIterator;
97 template<typename KeyT, typename ValueT,
98 typename KeyInfoT = DenseMapInfo<KeyT>,
99 typename ValueInfoT = DenseMapInfo<ValueT> >
101 typedef std::pair<KeyT, ValueT> BucketT;
106 unsigned NumTombstones;
108 typedef BucketT value_type;
110 DenseMap(const DenseMap& other) {
115 explicit DenseMap(unsigned NumInitBuckets = 64) {
116 init(NumInitBuckets);
120 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
121 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
122 if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
123 !KeyInfoT::isEqual(P->first, TombstoneKey))
127 operator delete(Buckets);
130 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
131 typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
132 inline iterator begin() {
133 return iterator(Buckets, Buckets+NumBuckets);
135 inline iterator end() {
136 return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
138 inline const_iterator begin() const {
139 return const_iterator(Buckets, Buckets+NumBuckets);
141 inline const_iterator end() const {
142 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
145 bool empty() const { return NumEntries == 0; }
146 unsigned size() const { return NumEntries; }
148 /// Grow the densemap so that it has at least Size buckets. Does not shrink
149 void resize(size_t Size) { grow(Size); }
152 // If the capacity of the array is huge, and the # elements used is small,
154 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
159 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
160 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
161 if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
162 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
169 assert(NumEntries == 0 && "Node count imbalance!");
173 /// count - Return true if the specified key is in the map.
174 bool count(const KeyT &Val) const {
176 return LookupBucketFor(Val, TheBucket);
179 iterator find(const KeyT &Val) {
181 if (LookupBucketFor(Val, TheBucket))
182 return iterator(TheBucket, Buckets+NumBuckets);
185 const_iterator find(const KeyT &Val) const {
187 if (LookupBucketFor(Val, TheBucket))
188 return const_iterator(TheBucket, Buckets+NumBuckets);
192 /// lookup - Return the entry for the specified key, or a default
193 /// constructed value if no such entry exists.
194 ValueT lookup(const KeyT &Val) const {
196 if (LookupBucketFor(Val, TheBucket))
197 return TheBucket->second;
201 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
203 if (LookupBucketFor(KV.first, TheBucket))
204 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
205 false); // Already in map.
207 // Otherwise, insert the new element.
208 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
209 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
213 bool erase(const KeyT &Val) {
215 if (!LookupBucketFor(Val, TheBucket))
216 return false; // not in map.
218 TheBucket->second.~ValueT();
219 TheBucket->first = getTombstoneKey();
224 bool erase(iterator I) {
225 BucketT *TheBucket = &*I;
226 TheBucket->second.~ValueT();
227 TheBucket->first = getTombstoneKey();
233 value_type& FindAndConstruct(const KeyT &Key) {
235 if (LookupBucketFor(Key, TheBucket))
238 return *InsertIntoBucket(Key, ValueT(), TheBucket);
241 ValueT &operator[](const KeyT &Key) {
242 return FindAndConstruct(Key).second;
245 DenseMap& operator=(const DenseMap& other) {
251 void CopyFrom(const DenseMap& other) {
252 if (NumBuckets != 0 && (!KeyInfoT::isPod() || !ValueInfoT::isPod())) {
253 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
254 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
255 if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
256 !KeyInfoT::isEqual(P->first, TombstoneKey))
262 NumEntries = other.NumEntries;
263 NumTombstones = other.NumTombstones;
266 operator delete(Buckets);
267 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) *
270 if (KeyInfoT::isPod() && ValueInfoT::isPod())
271 memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT));
273 for (size_t i = 0; i < other.NumBuckets; ++i) {
274 new (&Buckets[i].first) KeyT(other.Buckets[i].first);
275 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
276 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
277 new (&Buckets[i].second) ValueT(other.Buckets[i].second);
279 NumBuckets = other.NumBuckets;
282 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
283 BucketT *TheBucket) {
284 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
285 // the buckets are empty (meaning that many are filled with tombstones),
288 // The later case is tricky. For example, if we had one empty bucket with
289 // tons of tombstones, failing lookups (e.g. for insertion) would have to
290 // probe almost the entire table until it found the empty bucket. If the
291 // table completely filled with tombstones, no lookup would ever succeed,
292 // causing infinite loops in lookup.
293 if (NumEntries*4 >= NumBuckets*3 ||
294 NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
295 this->grow(NumBuckets * 2);
296 LookupBucketFor(Key, TheBucket);
300 // If we are writing over a tombstone, remember this.
301 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
304 TheBucket->first = Key;
305 new (&TheBucket->second) ValueT(Value);
309 static unsigned getHashValue(const KeyT &Val) {
310 return KeyInfoT::getHashValue(Val);
312 static const KeyT getEmptyKey() {
313 return KeyInfoT::getEmptyKey();
315 static const KeyT getTombstoneKey() {
316 return KeyInfoT::getTombstoneKey();
319 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
320 /// FoundBucket. If the bucket contains the key and a value, this returns
321 /// true, otherwise it returns a bucket with an empty marker or tombstone and
323 bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
324 unsigned BucketNo = getHashValue(Val);
325 unsigned ProbeAmt = 1;
326 BucketT *BucketsPtr = Buckets;
328 // FoundTombstone - Keep track of whether we find a tombstone while probing.
329 BucketT *FoundTombstone = 0;
330 const KeyT EmptyKey = getEmptyKey();
331 const KeyT TombstoneKey = getTombstoneKey();
332 assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
333 !KeyInfoT::isEqual(Val, TombstoneKey) &&
334 "Empty/Tombstone value shouldn't be inserted into map!");
337 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
338 // Found Val's bucket? If so, return it.
339 if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
340 FoundBucket = ThisBucket;
344 // If we found an empty bucket, the key doesn't exist in the set.
345 // Insert it and return the default value.
346 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
347 // If we've already seen a tombstone while probing, fill it in instead
348 // of the empty bucket we eventually probed to.
349 if (FoundTombstone) ThisBucket = FoundTombstone;
350 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
354 // If this is a tombstone, remember it. If Val ends up not in the map, we
355 // prefer to return it than something that would require more probing.
356 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
357 FoundTombstone = ThisBucket; // Remember the first tombstone found.
359 // Otherwise, it's a hash collision or a tombstone, continue quadratic
361 BucketNo += ProbeAmt++;
365 void init(unsigned InitBuckets) {
368 NumBuckets = InitBuckets;
369 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
370 "# initial buckets must be a power of two!");
371 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets));
372 // Initialize all the keys to EmptyKey.
373 const KeyT EmptyKey = getEmptyKey();
374 for (unsigned i = 0; i != InitBuckets; ++i)
375 new (&Buckets[i].first) KeyT(EmptyKey);
378 void grow(unsigned AtLeast) {
379 unsigned OldNumBuckets = NumBuckets;
380 BucketT *OldBuckets = Buckets;
382 // Double the number of buckets.
383 while (NumBuckets <= AtLeast)
386 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));
388 // Initialize all the keys to EmptyKey.
389 const KeyT EmptyKey = getEmptyKey();
390 for (unsigned i = 0, e = NumBuckets; i != e; ++i)
391 new (&Buckets[i].first) KeyT(EmptyKey);
393 // Insert all the old elements.
394 const KeyT TombstoneKey = getTombstoneKey();
395 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
396 if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
397 !KeyInfoT::isEqual(B->first, TombstoneKey)) {
398 // Insert the key/value into the new table.
400 bool FoundVal = LookupBucketFor(B->first, DestBucket);
401 FoundVal = FoundVal; // silence warning.
402 assert(!FoundVal && "Key already in new map?");
403 DestBucket->first = B->first;
404 new (&DestBucket->second) ValueT(B->second);
412 // Free the old table.
413 operator delete(OldBuckets);
416 void shrink_and_clear() {
417 unsigned OldNumBuckets = NumBuckets;
418 BucketT *OldBuckets = Buckets;
420 // Reduce the number of buckets.
421 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
424 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));
426 // Initialize all the keys to EmptyKey.
427 const KeyT EmptyKey = getEmptyKey();
428 for (unsigned i = 0, e = NumBuckets; i != e; ++i)
429 new (&Buckets[i].first) KeyT(EmptyKey);
431 // Free the old buckets.
432 const KeyT TombstoneKey = getTombstoneKey();
433 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
434 if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
435 !KeyInfoT::isEqual(B->first, TombstoneKey)) {
442 // Free the old table.
443 operator delete(OldBuckets);
449 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
450 class DenseMapIterator {
451 typedef std::pair<KeyT, ValueT> BucketT;
453 const BucketT *Ptr, *End;
455 DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) {
456 AdvancePastEmptyBuckets();
459 std::pair<KeyT, ValueT> &operator*() const {
460 return *const_cast<BucketT*>(Ptr);
462 std::pair<KeyT, ValueT> *operator->() const {
463 return const_cast<BucketT*>(Ptr);
466 bool operator==(const DenseMapIterator &RHS) const {
467 return Ptr == RHS.Ptr;
469 bool operator!=(const DenseMapIterator &RHS) const {
470 return Ptr != RHS.Ptr;
473 inline DenseMapIterator& operator++() { // Preincrement
475 AdvancePastEmptyBuckets();
478 DenseMapIterator operator++(int) { // Postincrement
479 DenseMapIterator tmp = *this; ++*this; return tmp;
483 void AdvancePastEmptyBuckets() {
484 const KeyT Empty = KeyInfoT::getEmptyKey();
485 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
488 (KeyInfoT::isEqual(Ptr->first, Empty) ||
489 KeyInfoT::isEqual(Ptr->first, Tombstone)))
494 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
495 class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
497 DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
498 const std::pair<KeyT, ValueT> *E)
499 : DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
501 const std::pair<KeyT, ValueT> &operator*() const {
504 const std::pair<KeyT, ValueT> *operator->() const {
509 } // end namespace llvm