DenseMap.h revision bdd376ccb25f251e115fff24b526b4e65e03a1d3
1//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the DenseMap class. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_ADT_DENSEMAP_H 15#define LLVM_ADT_DENSEMAP_H 16 17#include "llvm/Support/PointerLikeTypeTraits.h" 18#include "llvm/Support/MathExtras.h" 19#include <cassert> 20#include <utility> 21 22namespace llvm { 23 24template<typename T> 25struct DenseMapInfo { 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); 30 //static bool isPod() 31}; 32 33// Provide DenseMapInfo for all pointers. 34template<typename T> 35struct DenseMapInfo<T*> { 36 static inline T* getEmptyKey() { 37 intptr_t Val = -1; 38 Val <<= PointerLikeTypeTraits<T*>::NumLowBitsAvailable; 39 return reinterpret_cast<T*>(Val); 40 } 41 static inline T* getTombstoneKey() { 42 intptr_t Val = -2; 43 Val <<= PointerLikeTypeTraits<T*>::NumLowBitsAvailable; 44 return reinterpret_cast<T*>(Val); 45 } 46 static unsigned getHashValue(const T *PtrVal) { 47 return (unsigned((uintptr_t)PtrVal) >> 4) ^ 48 (unsigned((uintptr_t)PtrVal) >> 9); 49 } 50 static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; } 51 static bool isPod() { return true; } 52}; 53 54// Provide DenseMapInfo for unsigned ints. 55template<> struct DenseMapInfo<unsigned> { 56 static inline unsigned getEmptyKey() { return ~0; } 57 static inline unsigned getTombstoneKey() { return ~0 - 1; } 58 static unsigned getHashValue(const unsigned& Val) { return Val * 37; } 59 static bool isPod() { return true; } 60 static bool isEqual(const unsigned& LHS, const unsigned& RHS) { 61 return LHS == RHS; 62 } 63}; 64 65// Provide DenseMapInfo for unsigned longs. 66template<> struct DenseMapInfo<unsigned long> { 67 static inline unsigned long getEmptyKey() { return ~0L; } 68 static inline unsigned long getTombstoneKey() { return ~0L - 1L; } 69 static unsigned getHashValue(const unsigned long& Val) { 70 return (unsigned)(Val * 37L); 71 } 72 static bool isPod() { return true; } 73 static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) { 74 return LHS == RHS; 75 } 76}; 77 78// Provide DenseMapInfo for all pairs whose members have info. 79template<typename T, typename U> 80struct DenseMapInfo<std::pair<T, U> > { 81 typedef std::pair<T, U> Pair; 82 typedef DenseMapInfo<T> FirstInfo; 83 typedef DenseMapInfo<U> SecondInfo; 84 85 static inline Pair getEmptyKey() { 86 return std::make_pair(FirstInfo::getEmptyKey(), 87 SecondInfo::getEmptyKey()); 88 } 89 static inline Pair getTombstoneKey() { 90 return std::make_pair(FirstInfo::getTombstoneKey(), 91 SecondInfo::getEmptyKey()); 92 } 93 static unsigned getHashValue(const Pair& PairVal) { 94 uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32 95 | (uint64_t)SecondInfo::getHashValue(PairVal.second); 96 key += ~(key << 32); 97 key ^= (key >> 22); 98 key += ~(key << 13); 99 key ^= (key >> 8); 100 key += (key << 3); 101 key ^= (key >> 15); 102 key += ~(key << 27); 103 key ^= (key >> 31); 104 return (unsigned)key; 105 } 106 static bool isEqual(const Pair& LHS, const Pair& RHS) { return LHS == RHS; } 107 static bool isPod() { return FirstInfo::isPod() && SecondInfo::isPod(); } 108}; 109 110template<typename KeyT, typename ValueT, 111 typename KeyInfoT = DenseMapInfo<KeyT>, 112 typename ValueInfoT = DenseMapInfo<ValueT> > 113class DenseMapIterator; 114template<typename KeyT, typename ValueT, 115 typename KeyInfoT = DenseMapInfo<KeyT>, 116 typename ValueInfoT = DenseMapInfo<ValueT> > 117class DenseMapConstIterator; 118 119template<typename KeyT, typename ValueT, 120 typename KeyInfoT = DenseMapInfo<KeyT>, 121 typename ValueInfoT = DenseMapInfo<ValueT> > 122class DenseMap { 123 typedef std::pair<KeyT, ValueT> BucketT; 124 unsigned NumBuckets; 125 BucketT *Buckets; 126 127 unsigned NumEntries; 128 unsigned NumTombstones; 129public: 130 typedef KeyT key_type; 131 typedef ValueT mapped_type; 132 typedef BucketT value_type; 133 134 DenseMap(const DenseMap& other) { 135 NumBuckets = 0; 136 CopyFrom(other); 137 } 138 139 explicit DenseMap(unsigned NumInitBuckets = 64) { 140 init(NumInitBuckets); 141 } 142 143 ~DenseMap() { 144 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 145 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 146 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 147 !KeyInfoT::isEqual(P->first, TombstoneKey)) 148 P->second.~ValueT(); 149 P->first.~KeyT(); 150 } 151 operator delete(Buckets); 152 } 153 154 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator; 155 typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator; 156 inline iterator begin() { 157 return iterator(Buckets, Buckets+NumBuckets); 158 } 159 inline iterator end() { 160 return iterator(Buckets+NumBuckets, Buckets+NumBuckets); 161 } 162 inline const_iterator begin() const { 163 return const_iterator(Buckets, Buckets+NumBuckets); 164 } 165 inline const_iterator end() const { 166 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets); 167 } 168 169 bool empty() const { return NumEntries == 0; } 170 unsigned size() const { return NumEntries; } 171 172 /// Grow the densemap so that it has at least Size buckets. Does not shrink 173 void resize(size_t Size) { grow(Size); } 174 175 void clear() { 176 // If the capacity of the array is huge, and the # elements used is small, 177 // shrink the array. 178 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) { 179 shrink_and_clear(); 180 return; 181 } 182 183 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 184 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 185 if (!KeyInfoT::isEqual(P->first, EmptyKey)) { 186 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) { 187 P->second.~ValueT(); 188 --NumEntries; 189 } 190 P->first = EmptyKey; 191 } 192 } 193 assert(NumEntries == 0 && "Node count imbalance!"); 194 NumTombstones = 0; 195 } 196 197 /// count - Return true if the specified key is in the map. 198 bool count(const KeyT &Val) const { 199 BucketT *TheBucket; 200 return LookupBucketFor(Val, TheBucket); 201 } 202 203 iterator find(const KeyT &Val) { 204 BucketT *TheBucket; 205 if (LookupBucketFor(Val, TheBucket)) 206 return iterator(TheBucket, Buckets+NumBuckets); 207 return end(); 208 } 209 const_iterator find(const KeyT &Val) const { 210 BucketT *TheBucket; 211 if (LookupBucketFor(Val, TheBucket)) 212 return const_iterator(TheBucket, Buckets+NumBuckets); 213 return end(); 214 } 215 216 /// lookup - Return the entry for the specified key, or a default 217 /// constructed value if no such entry exists. 218 ValueT lookup(const KeyT &Val) const { 219 BucketT *TheBucket; 220 if (LookupBucketFor(Val, TheBucket)) 221 return TheBucket->second; 222 return ValueT(); 223 } 224 225 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) { 226 BucketT *TheBucket; 227 if (LookupBucketFor(KV.first, TheBucket)) 228 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets), 229 false); // Already in map. 230 231 // Otherwise, insert the new element. 232 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket); 233 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets), 234 true); 235 } 236 237 /// insert - Range insertion of pairs. 238 template<typename InputIt> 239 void insert(InputIt I, InputIt E) { 240 for (; I != E; ++I) 241 insert(*I); 242 } 243 244 245 bool erase(const KeyT &Val) { 246 BucketT *TheBucket; 247 if (!LookupBucketFor(Val, TheBucket)) 248 return false; // not in map. 249 250 TheBucket->second.~ValueT(); 251 TheBucket->first = getTombstoneKey(); 252 --NumEntries; 253 ++NumTombstones; 254 return true; 255 } 256 bool erase(iterator I) { 257 BucketT *TheBucket = &*I; 258 TheBucket->second.~ValueT(); 259 TheBucket->first = getTombstoneKey(); 260 --NumEntries; 261 ++NumTombstones; 262 return true; 263 } 264 265 value_type& FindAndConstruct(const KeyT &Key) { 266 BucketT *TheBucket; 267 if (LookupBucketFor(Key, TheBucket)) 268 return *TheBucket; 269 270 return *InsertIntoBucket(Key, ValueT(), TheBucket); 271 } 272 273 ValueT &operator[](const KeyT &Key) { 274 return FindAndConstruct(Key).second; 275 } 276 277 DenseMap& operator=(const DenseMap& other) { 278 CopyFrom(other); 279 return *this; 280 } 281 282 /// isPointerIntoBucketsArray - Return true if the specified pointer points 283 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or 284 /// value in the DenseMap). 285 bool isPointerIntoBucketsArray(const void *Ptr) const { 286 return Ptr >= Buckets && Ptr < Buckets+NumBuckets; 287 } 288 289 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets 290 /// array. In conjunction with the previous method, this can be used to 291 /// determine whether an insertion caused the DenseMap to reallocate. 292 const void *getPointerIntoBucketsArray() const { return Buckets; } 293 294private: 295 void CopyFrom(const DenseMap& other) { 296 if (NumBuckets != 0 && (!KeyInfoT::isPod() || !ValueInfoT::isPod())) { 297 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 298 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 299 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 300 !KeyInfoT::isEqual(P->first, TombstoneKey)) 301 P->second.~ValueT(); 302 P->first.~KeyT(); 303 } 304 } 305 306 NumEntries = other.NumEntries; 307 NumTombstones = other.NumTombstones; 308 309 if (NumBuckets) 310 operator delete(Buckets); 311 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * 312 other.NumBuckets)); 313 314 if (KeyInfoT::isPod() && ValueInfoT::isPod()) 315 memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT)); 316 else 317 for (size_t i = 0; i < other.NumBuckets; ++i) { 318 new (&Buckets[i].first) KeyT(other.Buckets[i].first); 319 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) && 320 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey())) 321 new (&Buckets[i].second) ValueT(other.Buckets[i].second); 322 } 323 NumBuckets = other.NumBuckets; 324 } 325 326 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value, 327 BucketT *TheBucket) { 328 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of 329 // the buckets are empty (meaning that many are filled with tombstones), 330 // grow the table. 331 // 332 // The later case is tricky. For example, if we had one empty bucket with 333 // tons of tombstones, failing lookups (e.g. for insertion) would have to 334 // probe almost the entire table until it found the empty bucket. If the 335 // table completely filled with tombstones, no lookup would ever succeed, 336 // causing infinite loops in lookup. 337 if (NumEntries*4 >= NumBuckets*3 || 338 NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) { 339 this->grow(NumBuckets * 2); 340 LookupBucketFor(Key, TheBucket); 341 } 342 ++NumEntries; 343 344 // If we are writing over a tombstone, remember this. 345 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey())) 346 --NumTombstones; 347 348 TheBucket->first = Key; 349 new (&TheBucket->second) ValueT(Value); 350 return TheBucket; 351 } 352 353 static unsigned getHashValue(const KeyT &Val) { 354 return KeyInfoT::getHashValue(Val); 355 } 356 static const KeyT getEmptyKey() { 357 return KeyInfoT::getEmptyKey(); 358 } 359 static const KeyT getTombstoneKey() { 360 return KeyInfoT::getTombstoneKey(); 361 } 362 363 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in 364 /// FoundBucket. If the bucket contains the key and a value, this returns 365 /// true, otherwise it returns a bucket with an empty marker or tombstone and 366 /// returns false. 367 bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const { 368 unsigned BucketNo = getHashValue(Val); 369 unsigned ProbeAmt = 1; 370 BucketT *BucketsPtr = Buckets; 371 372 // FoundTombstone - Keep track of whether we find a tombstone while probing. 373 BucketT *FoundTombstone = 0; 374 const KeyT EmptyKey = getEmptyKey(); 375 const KeyT TombstoneKey = getTombstoneKey(); 376 assert(!KeyInfoT::isEqual(Val, EmptyKey) && 377 !KeyInfoT::isEqual(Val, TombstoneKey) && 378 "Empty/Tombstone value shouldn't be inserted into map!"); 379 380 while (1) { 381 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1)); 382 // Found Val's bucket? If so, return it. 383 if (KeyInfoT::isEqual(ThisBucket->first, Val)) { 384 FoundBucket = ThisBucket; 385 return true; 386 } 387 388 // If we found an empty bucket, the key doesn't exist in the set. 389 // Insert it and return the default value. 390 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) { 391 // If we've already seen a tombstone while probing, fill it in instead 392 // of the empty bucket we eventually probed to. 393 if (FoundTombstone) ThisBucket = FoundTombstone; 394 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket; 395 return false; 396 } 397 398 // If this is a tombstone, remember it. If Val ends up not in the map, we 399 // prefer to return it than something that would require more probing. 400 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone) 401 FoundTombstone = ThisBucket; // Remember the first tombstone found. 402 403 // Otherwise, it's a hash collision or a tombstone, continue quadratic 404 // probing. 405 BucketNo += ProbeAmt++; 406 } 407 } 408 409 void init(unsigned InitBuckets) { 410 NumEntries = 0; 411 NumTombstones = 0; 412 NumBuckets = InitBuckets; 413 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 && 414 "# initial buckets must be a power of two!"); 415 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets)); 416 // Initialize all the keys to EmptyKey. 417 const KeyT EmptyKey = getEmptyKey(); 418 for (unsigned i = 0; i != InitBuckets; ++i) 419 new (&Buckets[i].first) KeyT(EmptyKey); 420 } 421 422 void grow(unsigned AtLeast) { 423 unsigned OldNumBuckets = NumBuckets; 424 BucketT *OldBuckets = Buckets; 425 426 // Double the number of buckets. 427 while (NumBuckets <= AtLeast) 428 NumBuckets <<= 1; 429 NumTombstones = 0; 430 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 431 432 // Initialize all the keys to EmptyKey. 433 const KeyT EmptyKey = getEmptyKey(); 434 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 435 new (&Buckets[i].first) KeyT(EmptyKey); 436 437 // Insert all the old elements. 438 const KeyT TombstoneKey = getTombstoneKey(); 439 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 440 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 441 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 442 // Insert the key/value into the new table. 443 BucketT *DestBucket; 444 bool FoundVal = LookupBucketFor(B->first, DestBucket); 445 FoundVal = FoundVal; // silence warning. 446 assert(!FoundVal && "Key already in new map?"); 447 DestBucket->first = B->first; 448 new (&DestBucket->second) ValueT(B->second); 449 450 // Free the value. 451 B->second.~ValueT(); 452 } 453 B->first.~KeyT(); 454 } 455 456 // Free the old table. 457 operator delete(OldBuckets); 458 } 459 460 void shrink_and_clear() { 461 unsigned OldNumBuckets = NumBuckets; 462 BucketT *OldBuckets = Buckets; 463 464 // Reduce the number of buckets. 465 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1) 466 : 64; 467 NumTombstones = 0; 468 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 469 470 // Initialize all the keys to EmptyKey. 471 const KeyT EmptyKey = getEmptyKey(); 472 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 473 new (&Buckets[i].first) KeyT(EmptyKey); 474 475 // Free the old buckets. 476 const KeyT TombstoneKey = getTombstoneKey(); 477 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 478 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 479 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 480 // Free the value. 481 B->second.~ValueT(); 482 } 483 B->first.~KeyT(); 484 } 485 486 // Free the old table. 487 operator delete(OldBuckets); 488 489 NumEntries = 0; 490 } 491}; 492 493template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT> 494class DenseMapIterator { 495 typedef std::pair<KeyT, ValueT> BucketT; 496protected: 497 const BucketT *Ptr, *End; 498public: 499 DenseMapIterator(void) : Ptr(0), End(0) {} 500 501 DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) { 502 AdvancePastEmptyBuckets(); 503 } 504 505 std::pair<KeyT, ValueT> &operator*() const { 506 return *const_cast<BucketT*>(Ptr); 507 } 508 std::pair<KeyT, ValueT> *operator->() const { 509 return const_cast<BucketT*>(Ptr); 510 } 511 512 bool operator==(const DenseMapIterator &RHS) const { 513 return Ptr == RHS.Ptr; 514 } 515 bool operator!=(const DenseMapIterator &RHS) const { 516 return Ptr != RHS.Ptr; 517 } 518 519 inline DenseMapIterator& operator++() { // Preincrement 520 ++Ptr; 521 AdvancePastEmptyBuckets(); 522 return *this; 523 } 524 DenseMapIterator operator++(int) { // Postincrement 525 DenseMapIterator tmp = *this; ++*this; return tmp; 526 } 527 528private: 529 void AdvancePastEmptyBuckets() { 530 const KeyT Empty = KeyInfoT::getEmptyKey(); 531 const KeyT Tombstone = KeyInfoT::getTombstoneKey(); 532 533 while (Ptr != End && 534 (KeyInfoT::isEqual(Ptr->first, Empty) || 535 KeyInfoT::isEqual(Ptr->first, Tombstone))) 536 ++Ptr; 537 } 538}; 539 540template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT> 541class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> { 542public: 543 DenseMapConstIterator(void) : DenseMapIterator<KeyT, ValueT, KeyInfoT>() {} 544 DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos, 545 const std::pair<KeyT, ValueT> *E) 546 : DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) { 547 } 548 const std::pair<KeyT, ValueT> &operator*() const { 549 return *this->Ptr; 550 } 551 const std::pair<KeyT, ValueT> *operator->() const { 552 return this->Ptr; 553 } 554}; 555 556} // end namespace llvm 557 558#endif 559