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 KeyT key_type;
109 typedef ValueT mapped_type;
110 typedef BucketT value_type;
112 DenseMap(const DenseMap& other) {
117 explicit DenseMap(unsigned NumInitBuckets = 64) {
118 init(NumInitBuckets);
122 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
123 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
124 if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
125 !KeyInfoT::isEqual(P->first, TombstoneKey))
129 operator delete(Buckets);
132 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
133 typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
134 inline iterator begin() {
135 return iterator(Buckets, Buckets+NumBuckets);
137 inline iterator end() {
138 return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
140 inline const_iterator begin() const {
141 return const_iterator(Buckets, Buckets+NumBuckets);
143 inline const_iterator end() const {
144 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
147 bool empty() const { return NumEntries == 0; }
148 unsigned size() const { return NumEntries; }
150 /// Grow the densemap so that it has at least Size buckets. Does not shrink
151 void resize(size_t Size) { grow(Size); }
154 // If the capacity of the array is huge, and the # elements used is small,
156 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
161 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
162 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
163 if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
164 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
171 assert(NumEntries == 0 && "Node count imbalance!");
175 /// count - Return true if the specified key is in the map.
176 bool count(const KeyT &Val) const {
178 return LookupBucketFor(Val, TheBucket);
181 iterator find(const KeyT &Val) {
183 if (LookupBucketFor(Val, TheBucket))
184 return iterator(TheBucket, Buckets+NumBuckets);
187 const_iterator find(const KeyT &Val) const {
189 if (LookupBucketFor(Val, TheBucket))
190 return const_iterator(TheBucket, Buckets+NumBuckets);
194 /// lookup - Return the entry for the specified key, or a default
195 /// constructed value if no such entry exists.
196 ValueT lookup(const KeyT &Val) const {
198 if (LookupBucketFor(Val, TheBucket))
199 return TheBucket->second;
203 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
205 if (LookupBucketFor(KV.first, TheBucket))
206 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
207 false); // Already in map.
209 // Otherwise, insert the new element.
210 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
211 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
215 bool erase(const KeyT &Val) {
217 if (!LookupBucketFor(Val, TheBucket))
218 return false; // not in map.
220 TheBucket->second.~ValueT();
221 TheBucket->first = getTombstoneKey();
226 bool erase(iterator I) {
227 BucketT *TheBucket = &*I;
228 TheBucket->second.~ValueT();
229 TheBucket->first = getTombstoneKey();
235 value_type& FindAndConstruct(const KeyT &Key) {
237 if (LookupBucketFor(Key, TheBucket))
240 return *InsertIntoBucket(Key, ValueT(), TheBucket);
243 ValueT &operator[](const KeyT &Key) {
244 return FindAndConstruct(Key).second;
247 DenseMap& operator=(const DenseMap& other) {
253 void CopyFrom(const DenseMap& other) {
254 if (NumBuckets != 0 && (!KeyInfoT::isPod() || !ValueInfoT::isPod())) {
255 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
256 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
257 if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
258 !KeyInfoT::isEqual(P->first, TombstoneKey))
264 NumEntries = other.NumEntries;
265 NumTombstones = other.NumTombstones;
268 operator delete(Buckets);
269 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) *
272 if (KeyInfoT::isPod() && ValueInfoT::isPod())
273 memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT));
275 for (size_t i = 0; i < other.NumBuckets; ++i) {
276 new (&Buckets[i].first) KeyT(other.Buckets[i].first);
277 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
278 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
279 new (&Buckets[i].second) ValueT(other.Buckets[i].second);
281 NumBuckets = other.NumBuckets;
284 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
285 BucketT *TheBucket) {
286 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
287 // the buckets are empty (meaning that many are filled with tombstones),
290 // The later case is tricky. For example, if we had one empty bucket with
291 // tons of tombstones, failing lookups (e.g. for insertion) would have to
292 // probe almost the entire table until it found the empty bucket. If the
293 // table completely filled with tombstones, no lookup would ever succeed,
294 // causing infinite loops in lookup.
295 if (NumEntries*4 >= NumBuckets*3 ||
296 NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
297 this->grow(NumBuckets * 2);
298 LookupBucketFor(Key, TheBucket);
302 // If we are writing over a tombstone, remember this.
303 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
306 TheBucket->first = Key;
307 new (&TheBucket->second) ValueT(Value);
311 static unsigned getHashValue(const KeyT &Val) {
312 return KeyInfoT::getHashValue(Val);
314 static const KeyT getEmptyKey() {
315 return KeyInfoT::getEmptyKey();
317 static const KeyT getTombstoneKey() {
318 return KeyInfoT::getTombstoneKey();
321 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
322 /// FoundBucket. If the bucket contains the key and a value, this returns
323 /// true, otherwise it returns a bucket with an empty marker or tombstone and
325 bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
326 unsigned BucketNo = getHashValue(Val);
327 unsigned ProbeAmt = 1;
328 BucketT *BucketsPtr = Buckets;
330 // FoundTombstone - Keep track of whether we find a tombstone while probing.
331 BucketT *FoundTombstone = 0;
332 const KeyT EmptyKey = getEmptyKey();
333 const KeyT TombstoneKey = getTombstoneKey();
334 assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
335 !KeyInfoT::isEqual(Val, TombstoneKey) &&
336 "Empty/Tombstone value shouldn't be inserted into map!");
339 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
340 // Found Val's bucket? If so, return it.
341 if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
342 FoundBucket = ThisBucket;
346 // If we found an empty bucket, the key doesn't exist in the set.
347 // Insert it and return the default value.
348 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
349 // If we've already seen a tombstone while probing, fill it in instead
350 // of the empty bucket we eventually probed to.
351 if (FoundTombstone) ThisBucket = FoundTombstone;
352 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
356 // If this is a tombstone, remember it. If Val ends up not in the map, we
357 // prefer to return it than something that would require more probing.
358 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
359 FoundTombstone = ThisBucket; // Remember the first tombstone found.
361 // Otherwise, it's a hash collision or a tombstone, continue quadratic
363 BucketNo += ProbeAmt++;
367 void init(unsigned InitBuckets) {
370 NumBuckets = InitBuckets;
371 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
372 "# initial buckets must be a power of two!");
373 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets));
374 // Initialize all the keys to EmptyKey.
375 const KeyT EmptyKey = getEmptyKey();
376 for (unsigned i = 0; i != InitBuckets; ++i)
377 new (&Buckets[i].first) KeyT(EmptyKey);
380 void grow(unsigned AtLeast) {
381 unsigned OldNumBuckets = NumBuckets;
382 BucketT *OldBuckets = Buckets;
384 // Double the number of buckets.
385 while (NumBuckets <= AtLeast)
388 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));
390 // Initialize all the keys to EmptyKey.
391 const KeyT EmptyKey = getEmptyKey();
392 for (unsigned i = 0, e = NumBuckets; i != e; ++i)
393 new (&Buckets[i].first) KeyT(EmptyKey);
395 // Insert all the old elements.
396 const KeyT TombstoneKey = getTombstoneKey();
397 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
398 if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
399 !KeyInfoT::isEqual(B->first, TombstoneKey)) {
400 // Insert the key/value into the new table.
402 bool FoundVal = LookupBucketFor(B->first, DestBucket);
403 FoundVal = FoundVal; // silence warning.
404 assert(!FoundVal && "Key already in new map?");
405 DestBucket->first = B->first;
406 new (&DestBucket->second) ValueT(B->second);
414 // Free the old table.
415 operator delete(OldBuckets);
418 void shrink_and_clear() {
419 unsigned OldNumBuckets = NumBuckets;
420 BucketT *OldBuckets = Buckets;
422 // Reduce the number of buckets.
423 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
426 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));
428 // Initialize all the keys to EmptyKey.
429 const KeyT EmptyKey = getEmptyKey();
430 for (unsigned i = 0, e = NumBuckets; i != e; ++i)
431 new (&Buckets[i].first) KeyT(EmptyKey);
433 // Free the old buckets.
434 const KeyT TombstoneKey = getTombstoneKey();
435 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
436 if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
437 !KeyInfoT::isEqual(B->first, TombstoneKey)) {
444 // Free the old table.
445 operator delete(OldBuckets);
451 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
452 class DenseMapIterator {
453 typedef std::pair<KeyT, ValueT> BucketT;
455 const BucketT *Ptr, *End;
457 DenseMapIterator(void) : Ptr(0), End(0) {}
459 DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) {
460 AdvancePastEmptyBuckets();
463 std::pair<KeyT, ValueT> &operator*() const {
464 return *const_cast<BucketT*>(Ptr);
466 std::pair<KeyT, ValueT> *operator->() const {
467 return const_cast<BucketT*>(Ptr);
470 bool operator==(const DenseMapIterator &RHS) const {
471 return Ptr == RHS.Ptr;
473 bool operator!=(const DenseMapIterator &RHS) const {
474 return Ptr != RHS.Ptr;
477 inline DenseMapIterator& operator++() { // Preincrement
479 AdvancePastEmptyBuckets();
482 DenseMapIterator operator++(int) { // Postincrement
483 DenseMapIterator tmp = *this; ++*this; return tmp;
487 void AdvancePastEmptyBuckets() {
488 const KeyT Empty = KeyInfoT::getEmptyKey();
489 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
492 (KeyInfoT::isEqual(Ptr->first, Empty) ||
493 KeyInfoT::isEqual(Ptr->first, Tombstone)))
498 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
499 class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
501 DenseMapConstIterator(void) : DenseMapIterator<KeyT, ValueT, KeyInfoT>() {}
502 DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
503 const std::pair<KeyT, ValueT> *E)
504 : DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
506 const std::pair<KeyT, ValueT> &operator*() const {
509 const std::pair<KeyT, ValueT> *operator->() const {
514 } // end namespace llvm