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());
72 static unsigned getHashValue(const Pair& PairVal) {
73 uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32
74 | (uint64_t)SecondInfo::getHashValue(PairVal.second);
85 static bool isEqual(const Pair& LHS, const Pair& RHS) { return LHS == RHS; }
86 static bool isPod() { return FirstInfo::isPod() && SecondInfo::isPod(); }
89 template<typename KeyT, typename ValueT,
90 typename KeyInfoT = DenseMapInfo<KeyT>,
91 typename ValueInfoT = DenseMapInfo<ValueT> >
92 class DenseMapIterator;
93 template<typename KeyT, typename ValueT,
94 typename KeyInfoT = DenseMapInfo<KeyT>,
95 typename ValueInfoT = DenseMapInfo<ValueT> >
96 class DenseMapConstIterator;
98 template<typename KeyT, typename ValueT,
99 typename KeyInfoT = DenseMapInfo<KeyT>,
100 typename ValueInfoT = DenseMapInfo<ValueT> >
102 typedef std::pair<KeyT, ValueT> BucketT;
107 unsigned NumTombstones;
109 typedef KeyT key_type;
110 typedef ValueT mapped_type;
111 typedef BucketT value_type;
113 DenseMap(const DenseMap& other) {
118 explicit DenseMap(unsigned NumInitBuckets = 64) {
119 init(NumInitBuckets);
123 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
124 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
125 if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
126 !KeyInfoT::isEqual(P->first, TombstoneKey))
130 operator delete(Buckets);
133 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
134 typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
135 inline iterator begin() {
136 return iterator(Buckets, Buckets+NumBuckets);
138 inline iterator end() {
139 return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
141 inline const_iterator begin() const {
142 return const_iterator(Buckets, Buckets+NumBuckets);
144 inline const_iterator end() const {
145 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
148 bool empty() const { return NumEntries == 0; }
149 unsigned size() const { return NumEntries; }
151 /// Grow the densemap so that it has at least Size buckets. Does not shrink
152 void resize(size_t Size) { grow(Size); }
155 // If the capacity of the array is huge, and the # elements used is small,
157 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
162 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
163 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
164 if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
165 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
172 assert(NumEntries == 0 && "Node count imbalance!");
176 /// count - Return true if the specified key is in the map.
177 bool count(const KeyT &Val) const {
179 return LookupBucketFor(Val, TheBucket);
182 iterator find(const KeyT &Val) {
184 if (LookupBucketFor(Val, TheBucket))
185 return iterator(TheBucket, Buckets+NumBuckets);
188 const_iterator find(const KeyT &Val) const {
190 if (LookupBucketFor(Val, TheBucket))
191 return const_iterator(TheBucket, Buckets+NumBuckets);
195 /// lookup - Return the entry for the specified key, or a default
196 /// constructed value if no such entry exists.
197 ValueT lookup(const KeyT &Val) const {
199 if (LookupBucketFor(Val, TheBucket))
200 return TheBucket->second;
204 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
206 if (LookupBucketFor(KV.first, TheBucket))
207 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
208 false); // Already in map.
210 // Otherwise, insert the new element.
211 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
212 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
216 bool erase(const KeyT &Val) {
218 if (!LookupBucketFor(Val, TheBucket))
219 return false; // not in map.
221 TheBucket->second.~ValueT();
222 TheBucket->first = getTombstoneKey();
227 bool erase(iterator I) {
228 BucketT *TheBucket = &*I;
229 TheBucket->second.~ValueT();
230 TheBucket->first = getTombstoneKey();
236 value_type& FindAndConstruct(const KeyT &Key) {
238 if (LookupBucketFor(Key, TheBucket))
241 return *InsertIntoBucket(Key, ValueT(), TheBucket);
244 ValueT &operator[](const KeyT &Key) {
245 return FindAndConstruct(Key).second;
248 DenseMap& operator=(const DenseMap& other) {
254 void CopyFrom(const DenseMap& other) {
255 if (NumBuckets != 0 && (!KeyInfoT::isPod() || !ValueInfoT::isPod())) {
256 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
257 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
258 if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
259 !KeyInfoT::isEqual(P->first, TombstoneKey))
265 NumEntries = other.NumEntries;
266 NumTombstones = other.NumTombstones;
269 operator delete(Buckets);
270 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) *
273 if (KeyInfoT::isPod() && ValueInfoT::isPod())
274 memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT));
276 for (size_t i = 0; i < other.NumBuckets; ++i) {
277 new (&Buckets[i].first) KeyT(other.Buckets[i].first);
278 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
279 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
280 new (&Buckets[i].second) ValueT(other.Buckets[i].second);
282 NumBuckets = other.NumBuckets;
285 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
286 BucketT *TheBucket) {
287 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
288 // the buckets are empty (meaning that many are filled with tombstones),
291 // The later case is tricky. For example, if we had one empty bucket with
292 // tons of tombstones, failing lookups (e.g. for insertion) would have to
293 // probe almost the entire table until it found the empty bucket. If the
294 // table completely filled with tombstones, no lookup would ever succeed,
295 // causing infinite loops in lookup.
296 if (NumEntries*4 >= NumBuckets*3 ||
297 NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
298 this->grow(NumBuckets * 2);
299 LookupBucketFor(Key, TheBucket);
303 // If we are writing over a tombstone, remember this.
304 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
307 TheBucket->first = Key;
308 new (&TheBucket->second) ValueT(Value);
312 static unsigned getHashValue(const KeyT &Val) {
313 return KeyInfoT::getHashValue(Val);
315 static const KeyT getEmptyKey() {
316 return KeyInfoT::getEmptyKey();
318 static const KeyT getTombstoneKey() {
319 return KeyInfoT::getTombstoneKey();
322 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
323 /// FoundBucket. If the bucket contains the key and a value, this returns
324 /// true, otherwise it returns a bucket with an empty marker or tombstone and
326 bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
327 unsigned BucketNo = getHashValue(Val);
328 unsigned ProbeAmt = 1;
329 BucketT *BucketsPtr = Buckets;
331 // FoundTombstone - Keep track of whether we find a tombstone while probing.
332 BucketT *FoundTombstone = 0;
333 const KeyT EmptyKey = getEmptyKey();
334 const KeyT TombstoneKey = getTombstoneKey();
335 assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
336 !KeyInfoT::isEqual(Val, TombstoneKey) &&
337 "Empty/Tombstone value shouldn't be inserted into map!");
340 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
341 // Found Val's bucket? If so, return it.
342 if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
343 FoundBucket = ThisBucket;
347 // If we found an empty bucket, the key doesn't exist in the set.
348 // Insert it and return the default value.
349 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
350 // If we've already seen a tombstone while probing, fill it in instead
351 // of the empty bucket we eventually probed to.
352 if (FoundTombstone) ThisBucket = FoundTombstone;
353 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
357 // If this is a tombstone, remember it. If Val ends up not in the map, we
358 // prefer to return it than something that would require more probing.
359 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
360 FoundTombstone = ThisBucket; // Remember the first tombstone found.
362 // Otherwise, it's a hash collision or a tombstone, continue quadratic
364 BucketNo += ProbeAmt++;
368 void init(unsigned InitBuckets) {
371 NumBuckets = InitBuckets;
372 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
373 "# initial buckets must be a power of two!");
374 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets));
375 // Initialize all the keys to EmptyKey.
376 const KeyT EmptyKey = getEmptyKey();
377 for (unsigned i = 0; i != InitBuckets; ++i)
378 new (&Buckets[i].first) KeyT(EmptyKey);
381 void grow(unsigned AtLeast) {
382 unsigned OldNumBuckets = NumBuckets;
383 BucketT *OldBuckets = Buckets;
385 // Double the number of buckets.
386 while (NumBuckets <= AtLeast)
389 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));
391 // Initialize all the keys to EmptyKey.
392 const KeyT EmptyKey = getEmptyKey();
393 for (unsigned i = 0, e = NumBuckets; i != e; ++i)
394 new (&Buckets[i].first) KeyT(EmptyKey);
396 // Insert all the old elements.
397 const KeyT TombstoneKey = getTombstoneKey();
398 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
399 if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
400 !KeyInfoT::isEqual(B->first, TombstoneKey)) {
401 // Insert the key/value into the new table.
403 bool FoundVal = LookupBucketFor(B->first, DestBucket);
404 FoundVal = FoundVal; // silence warning.
405 assert(!FoundVal && "Key already in new map?");
406 DestBucket->first = B->first;
407 new (&DestBucket->second) ValueT(B->second);
415 // Free the old table.
416 operator delete(OldBuckets);
419 void shrink_and_clear() {
420 unsigned OldNumBuckets = NumBuckets;
421 BucketT *OldBuckets = Buckets;
423 // Reduce the number of buckets.
424 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
427 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));
429 // Initialize all the keys to EmptyKey.
430 const KeyT EmptyKey = getEmptyKey();
431 for (unsigned i = 0, e = NumBuckets; i != e; ++i)
432 new (&Buckets[i].first) KeyT(EmptyKey);
434 // Free the old buckets.
435 const KeyT TombstoneKey = getTombstoneKey();
436 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
437 if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
438 !KeyInfoT::isEqual(B->first, TombstoneKey)) {
445 // Free the old table.
446 operator delete(OldBuckets);
452 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
453 class DenseMapIterator {
454 typedef std::pair<KeyT, ValueT> BucketT;
456 const BucketT *Ptr, *End;
458 DenseMapIterator(void) : Ptr(0), End(0) {}
460 DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) {
461 AdvancePastEmptyBuckets();
464 std::pair<KeyT, ValueT> &operator*() const {
465 return *const_cast<BucketT*>(Ptr);
467 std::pair<KeyT, ValueT> *operator->() const {
468 return const_cast<BucketT*>(Ptr);
471 bool operator==(const DenseMapIterator &RHS) const {
472 return Ptr == RHS.Ptr;
474 bool operator!=(const DenseMapIterator &RHS) const {
475 return Ptr != RHS.Ptr;
478 inline DenseMapIterator& operator++() { // Preincrement
480 AdvancePastEmptyBuckets();
483 DenseMapIterator operator++(int) { // Postincrement
484 DenseMapIterator tmp = *this; ++*this; return tmp;
488 void AdvancePastEmptyBuckets() {
489 const KeyT Empty = KeyInfoT::getEmptyKey();
490 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
493 (KeyInfoT::isEqual(Ptr->first, Empty) ||
494 KeyInfoT::isEqual(Ptr->first, Tombstone)))
499 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
500 class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
502 DenseMapConstIterator(void) : DenseMapIterator<KeyT, ValueT, KeyInfoT>() {}
503 DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
504 const std::pair<KeyT, ValueT> *E)
505 : DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
507 const std::pair<KeyT, ValueT> &operator*() const {
510 const std::pair<KeyT, ValueT> *operator->() const {
515 } // end namespace llvm