DenseMap.h revision aee60d4d42b913bd3e4958f32ec9e7f2cf28b0ff
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/Compiler.h" 18#include "llvm/Support/MathExtras.h" 19#include "llvm/Support/PointerLikeTypeTraits.h" 20#include "llvm/Support/type_traits.h" 21#include "llvm/ADT/DenseMapInfo.h" 22#include <algorithm> 23#include <iterator> 24#include <new> 25#include <utility> 26#include <cassert> 27#include <cstddef> 28#include <cstring> 29 30namespace llvm { 31 32template<typename KeyT, typename ValueT, 33 typename KeyInfoT = DenseMapInfo<KeyT>, 34 bool IsConst = false> 35class DenseMapIterator; 36 37template<typename KeyT, typename ValueT, 38 typename KeyInfoT = DenseMapInfo<KeyT> > 39class DenseMap { 40 typedef std::pair<KeyT, ValueT> BucketT; 41 unsigned NumBuckets; 42 BucketT *Buckets; 43 44 unsigned NumEntries; 45 unsigned NumTombstones; 46public: 47 typedef KeyT key_type; 48 typedef ValueT mapped_type; 49 typedef BucketT value_type; 50 51 DenseMap(const DenseMap &other) { 52 NumBuckets = 0; 53 CopyFrom(other); 54 } 55 56#if LLVM_USE_RVALUE_REFERENCES 57 DenseMap(DenseMap &&other) { 58 init(0); 59 swap(other); 60 } 61#endif 62 63 explicit DenseMap(unsigned NumInitBuckets = 0) { 64 init(NumInitBuckets); 65 } 66 67 template<typename InputIt> 68 DenseMap(const InputIt &I, const InputIt &E) { 69 init(NextPowerOf2(std::distance(I, E))); 70 insert(I, E); 71 } 72 73 ~DenseMap() { 74 DestroyAll(); 75 } 76 77 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator; 78 typedef DenseMapIterator<KeyT, ValueT, 79 KeyInfoT, true> const_iterator; 80 inline iterator begin() { 81 // When the map is empty, avoid the overhead of AdvancePastEmptyBuckets(). 82 return empty() ? end() : iterator(Buckets, Buckets+NumBuckets); 83 } 84 inline iterator end() { 85 return iterator(Buckets+NumBuckets, Buckets+NumBuckets, true); 86 } 87 inline const_iterator begin() const { 88 return empty() ? end() : const_iterator(Buckets, Buckets+NumBuckets); 89 } 90 inline const_iterator end() const { 91 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets, true); 92 } 93 94 bool empty() const { return NumEntries == 0; } 95 unsigned size() const { return NumEntries; } 96 97 /// Grow the densemap so that it has at least Size buckets. Does not shrink 98 void resize(size_t Size) { 99 if (Size > NumBuckets) 100 grow(Size); 101 } 102 103 void clear() { 104 if (NumEntries == 0 && NumTombstones == 0) return; 105 106 // If the capacity of the array is huge, and the # elements used is small, 107 // shrink the array. 108 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) { 109 shrink_and_clear(); 110 return; 111 } 112 113 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 114 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 115 if (!KeyInfoT::isEqual(P->first, EmptyKey)) { 116 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) { 117 P->second.~ValueT(); 118 --NumEntries; 119 } 120 P->first = EmptyKey; 121 } 122 } 123 assert(NumEntries == 0 && "Node count imbalance!"); 124 NumTombstones = 0; 125 } 126 127 /// count - Return true if the specified key is in the map. 128 bool count(const KeyT &Val) const { 129 BucketT *TheBucket; 130 return LookupBucketFor(Val, TheBucket); 131 } 132 133 iterator find(const KeyT &Val) { 134 BucketT *TheBucket; 135 if (LookupBucketFor(Val, TheBucket)) 136 return iterator(TheBucket, Buckets+NumBuckets, true); 137 return end(); 138 } 139 const_iterator find(const KeyT &Val) const { 140 BucketT *TheBucket; 141 if (LookupBucketFor(Val, TheBucket)) 142 return const_iterator(TheBucket, Buckets+NumBuckets, true); 143 return end(); 144 } 145 146 /// Alternate version of find() which allows a different, and possibly 147 /// less expensive, key type. 148 /// The DenseMapInfo is responsible for supplying methods 149 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key 150 /// type used. 151 template<class LookupKeyT> 152 iterator find_as(const LookupKeyT &Val) { 153 BucketT *TheBucket; 154 if (LookupBucketFor(Val, TheBucket)) 155 return iterator(TheBucket, Buckets+NumBuckets, true); 156 return end(); 157 } 158 template<class LookupKeyT> 159 const_iterator find_as(const LookupKeyT &Val) const { 160 BucketT *TheBucket; 161 if (LookupBucketFor(Val, TheBucket)) 162 return const_iterator(TheBucket, Buckets+NumBuckets, true); 163 return end(); 164 } 165 166 /// lookup - Return the entry for the specified key, or a default 167 /// constructed value if no such entry exists. 168 ValueT lookup(const KeyT &Val) const { 169 BucketT *TheBucket; 170 if (LookupBucketFor(Val, TheBucket)) 171 return TheBucket->second; 172 return ValueT(); 173 } 174 175 // Inserts key,value pair into the map if the key isn't already in the map. 176 // If the key is already in the map, it returns false and doesn't update the 177 // value. 178 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) { 179 BucketT *TheBucket; 180 if (LookupBucketFor(KV.first, TheBucket)) 181 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), 182 false); // Already in map. 183 184 // Otherwise, insert the new element. 185 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket); 186 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), true); 187 } 188 189 /// insert - Range insertion of pairs. 190 template<typename InputIt> 191 void insert(InputIt I, InputIt E) { 192 for (; I != E; ++I) 193 insert(*I); 194 } 195 196 197 bool erase(const KeyT &Val) { 198 BucketT *TheBucket; 199 if (!LookupBucketFor(Val, TheBucket)) 200 return false; // not in map. 201 202 TheBucket->second.~ValueT(); 203 TheBucket->first = getTombstoneKey(); 204 --NumEntries; 205 ++NumTombstones; 206 return true; 207 } 208 void erase(iterator I) { 209 BucketT *TheBucket = &*I; 210 TheBucket->second.~ValueT(); 211 TheBucket->first = getTombstoneKey(); 212 --NumEntries; 213 ++NumTombstones; 214 } 215 216 void swap(DenseMap& RHS) { 217 std::swap(NumBuckets, RHS.NumBuckets); 218 std::swap(Buckets, RHS.Buckets); 219 std::swap(NumEntries, RHS.NumEntries); 220 std::swap(NumTombstones, RHS.NumTombstones); 221 } 222 223 value_type& FindAndConstruct(const KeyT &Key) { 224 BucketT *TheBucket; 225 if (LookupBucketFor(Key, TheBucket)) 226 return *TheBucket; 227 228 return *InsertIntoBucket(Key, ValueT(), TheBucket); 229 } 230 231 ValueT &operator[](const KeyT &Key) { 232 return FindAndConstruct(Key).second; 233 } 234 235#if LLVM_USE_RVALUE_REFERENCES 236 value_type& FindAndConstruct(KeyT &&Key) { 237 BucketT *TheBucket; 238 if (LookupBucketFor(Key, TheBucket)) 239 return *TheBucket; 240 241 return *InsertIntoBucket(Key, ValueT(), TheBucket); 242 } 243 244 ValueT &operator[](KeyT &&Key) { 245 return FindAndConstruct(Key).second; 246 } 247#endif 248 249 DenseMap& operator=(const DenseMap& other) { 250 CopyFrom(other); 251 return *this; 252 } 253 254#if LLVM_USE_RVALUE_REFERENCES 255 DenseMap& operator=(DenseMap &&other) { 256 DestroyAll(); 257 init(0); 258 swap(other); 259 } 260#endif 261 262 /// isPointerIntoBucketsArray - Return true if the specified pointer points 263 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or 264 /// value in the DenseMap). 265 bool isPointerIntoBucketsArray(const void *Ptr) const { 266 return Ptr >= Buckets && Ptr < Buckets+NumBuckets; 267 } 268 269 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets 270 /// array. In conjunction with the previous method, this can be used to 271 /// determine whether an insertion caused the DenseMap to reallocate. 272 const void *getPointerIntoBucketsArray() const { return Buckets; } 273 274private: 275 void DestroyAll() { 276 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 277 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 278 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 279 !KeyInfoT::isEqual(P->first, TombstoneKey)) 280 P->second.~ValueT(); 281 P->first.~KeyT(); 282 } 283 284 if (NumBuckets) { 285#ifndef NDEBUG 286 memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets); 287#endif 288 operator delete(Buckets); 289 } 290 } 291 292 void CopyFrom(const DenseMap& other) { 293 DestroyAll(); 294 295 NumEntries = other.NumEntries; 296 NumTombstones = other.NumTombstones; 297 NumBuckets = other.NumBuckets; 298 299 if (NumBuckets == 0) { 300 Buckets = 0; 301 return; 302 } 303 304 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets)); 305 306 if (isPodLike<KeyT>::value && isPodLike<ValueT>::value) 307 memcpy(Buckets, other.Buckets, NumBuckets * sizeof(BucketT)); 308 else 309 for (size_t i = 0; i < NumBuckets; ++i) { 310 new (&Buckets[i].first) KeyT(other.Buckets[i].first); 311 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) && 312 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey())) 313 new (&Buckets[i].second) ValueT(other.Buckets[i].second); 314 } 315 } 316 317 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value, 318 BucketT *TheBucket) { 319 TheBucket = InsertIntoBucketImpl(Key, TheBucket); 320 321 TheBucket->first = Key; 322 new (&TheBucket->second) ValueT(Value); 323 return TheBucket; 324 } 325 326#if LLVM_USE_RVALUE_REFERENCES 327 BucketT *InsertIntoBucket(const KeyT &Key, ValueT &&Value, 328 BucketT *TheBucket) { 329 TheBucket = InsertIntoBucketImpl(Key, TheBucket); 330 331 TheBucket->first = Key; 332 new (&TheBucket->second) ValueT(std::move(Value)); 333 return TheBucket; 334 } 335 336 BucketT *InsertIntoBucket(KeyT &&Key, ValueT &&Value, BucketT *TheBucket) { 337 TheBucket = InsertIntoBucketImpl(Key, TheBucket); 338 339 TheBucket->first = std::move(Key); 340 new (&TheBucket->second) ValueT(std::move(Value)); 341 return TheBucket; 342 } 343#endif 344 345 BucketT *InsertIntoBucketImpl(const KeyT &Key, BucketT *TheBucket) { 346 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of 347 // the buckets are empty (meaning that many are filled with tombstones), 348 // grow the table. 349 // 350 // The later case is tricky. For example, if we had one empty bucket with 351 // tons of tombstones, failing lookups (e.g. for insertion) would have to 352 // probe almost the entire table until it found the empty bucket. If the 353 // table completely filled with tombstones, no lookup would ever succeed, 354 // causing infinite loops in lookup. 355 ++NumEntries; 356 if (NumEntries*4 >= NumBuckets*3) { 357 this->grow(NumBuckets * 2); 358 LookupBucketFor(Key, TheBucket); 359 } 360 if (NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) { 361 this->grow(NumBuckets); 362 LookupBucketFor(Key, TheBucket); 363 } 364 365 // If we are writing over a tombstone, remember this. 366 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey())) 367 --NumTombstones; 368 369 return TheBucket; 370 } 371 372 static unsigned getHashValue(const KeyT &Val) { 373 return KeyInfoT::getHashValue(Val); 374 } 375 template<typename LookupKeyT> 376 static unsigned getHashValue(const LookupKeyT &Val) { 377 return KeyInfoT::getHashValue(Val); 378 } 379 static const KeyT getEmptyKey() { 380 return KeyInfoT::getEmptyKey(); 381 } 382 static const KeyT getTombstoneKey() { 383 return KeyInfoT::getTombstoneKey(); 384 } 385 386 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in 387 /// FoundBucket. If the bucket contains the key and a value, this returns 388 /// true, otherwise it returns a bucket with an empty marker or tombstone and 389 /// returns false. 390 template<typename LookupKeyT> 391 bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) const { 392 unsigned BucketNo = getHashValue(Val); 393 unsigned ProbeAmt = 1; 394 BucketT *BucketsPtr = Buckets; 395 396 if (NumBuckets == 0) { 397 FoundBucket = 0; 398 return false; 399 } 400 401 // FoundTombstone - Keep track of whether we find a tombstone while probing. 402 BucketT *FoundTombstone = 0; 403 const KeyT EmptyKey = getEmptyKey(); 404 const KeyT TombstoneKey = getTombstoneKey(); 405 assert(!KeyInfoT::isEqual(Val, EmptyKey) && 406 !KeyInfoT::isEqual(Val, TombstoneKey) && 407 "Empty/Tombstone value shouldn't be inserted into map!"); 408 409 while (1) { 410 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1)); 411 // Found Val's bucket? If so, return it. 412 if (KeyInfoT::isEqual(Val, ThisBucket->first)) { 413 FoundBucket = ThisBucket; 414 return true; 415 } 416 417 // If we found an empty bucket, the key doesn't exist in the set. 418 // Insert it and return the default value. 419 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) { 420 // If we've already seen a tombstone while probing, fill it in instead 421 // of the empty bucket we eventually probed to. 422 if (FoundTombstone) ThisBucket = FoundTombstone; 423 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket; 424 return false; 425 } 426 427 // If this is a tombstone, remember it. If Val ends up not in the map, we 428 // prefer to return it than something that would require more probing. 429 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone) 430 FoundTombstone = ThisBucket; // Remember the first tombstone found. 431 432 // Otherwise, it's a hash collision or a tombstone, continue quadratic 433 // probing. 434 BucketNo += ProbeAmt++; 435 } 436 } 437 438 void init(unsigned InitBuckets) { 439 NumEntries = 0; 440 NumTombstones = 0; 441 NumBuckets = InitBuckets; 442 443 if (InitBuckets == 0) { 444 Buckets = 0; 445 return; 446 } 447 448 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 && 449 "# initial buckets must be a power of two!"); 450 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets)); 451 // Initialize all the keys to EmptyKey. 452 const KeyT EmptyKey = getEmptyKey(); 453 for (unsigned i = 0; i != InitBuckets; ++i) 454 new (&Buckets[i].first) KeyT(EmptyKey); 455 } 456 457 void grow(unsigned AtLeast) { 458 unsigned OldNumBuckets = NumBuckets; 459 BucketT *OldBuckets = Buckets; 460 461 if (NumBuckets < 64) 462 NumBuckets = 64; 463 464 // Double the number of buckets. 465 while (NumBuckets < AtLeast) 466 NumBuckets <<= 1; 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 // Insert all the old elements. 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 // Insert the key/value into the new table. 481 BucketT *DestBucket; 482 bool FoundVal = LookupBucketFor(B->first, DestBucket); 483 (void)FoundVal; // silence warning. 484 assert(!FoundVal && "Key already in new map?"); 485 DestBucket->first = llvm_move(B->first); 486 new (&DestBucket->second) ValueT(llvm_move(B->second)); 487 488 // Free the value. 489 B->second.~ValueT(); 490 } 491 B->first.~KeyT(); 492 } 493 494#ifndef NDEBUG 495 if (OldNumBuckets) 496 memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets); 497#endif 498 // Free the old table. 499 operator delete(OldBuckets); 500 } 501 502 void shrink_and_clear() { 503 unsigned OldNumBuckets = NumBuckets; 504 BucketT *OldBuckets = Buckets; 505 506 // Reduce the number of buckets. 507 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1) 508 : 64; 509 NumTombstones = 0; 510 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 511 512 // Initialize all the keys to EmptyKey. 513 const KeyT EmptyKey = getEmptyKey(); 514 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 515 new (&Buckets[i].first) KeyT(EmptyKey); 516 517 // Free the old buckets. 518 const KeyT TombstoneKey = getTombstoneKey(); 519 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 520 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 521 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 522 // Free the value. 523 B->second.~ValueT(); 524 } 525 B->first.~KeyT(); 526 } 527 528#ifndef NDEBUG 529 memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets); 530#endif 531 // Free the old table. 532 operator delete(OldBuckets); 533 534 NumEntries = 0; 535 } 536 537public: 538 /// Return the approximate size (in bytes) of the actual map. 539 /// This is just the raw memory used by DenseMap. 540 /// If entries are pointers to objects, the size of the referenced objects 541 /// are not included. 542 size_t getMemorySize() const { 543 return NumBuckets * sizeof(BucketT); 544 } 545}; 546 547template<typename KeyT, typename ValueT, 548 typename KeyInfoT, bool IsConst> 549class DenseMapIterator { 550 typedef std::pair<KeyT, ValueT> Bucket; 551 typedef DenseMapIterator<KeyT, ValueT, 552 KeyInfoT, true> ConstIterator; 553 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, true>; 554public: 555 typedef ptrdiff_t difference_type; 556 typedef typename conditional<IsConst, const Bucket, Bucket>::type value_type; 557 typedef value_type *pointer; 558 typedef value_type &reference; 559 typedef std::forward_iterator_tag iterator_category; 560private: 561 pointer Ptr, End; 562public: 563 DenseMapIterator() : Ptr(0), End(0) {} 564 565 DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false) 566 : Ptr(Pos), End(E) { 567 if (!NoAdvance) AdvancePastEmptyBuckets(); 568 } 569 570 // If IsConst is true this is a converting constructor from iterator to 571 // const_iterator and the default copy constructor is used. 572 // Otherwise this is a copy constructor for iterator. 573 DenseMapIterator(const DenseMapIterator<KeyT, ValueT, 574 KeyInfoT, false>& I) 575 : Ptr(I.Ptr), End(I.End) {} 576 577 reference operator*() const { 578 return *Ptr; 579 } 580 pointer operator->() const { 581 return Ptr; 582 } 583 584 bool operator==(const ConstIterator &RHS) const { 585 return Ptr == RHS.operator->(); 586 } 587 bool operator!=(const ConstIterator &RHS) const { 588 return Ptr != RHS.operator->(); 589 } 590 591 inline DenseMapIterator& operator++() { // Preincrement 592 ++Ptr; 593 AdvancePastEmptyBuckets(); 594 return *this; 595 } 596 DenseMapIterator operator++(int) { // Postincrement 597 DenseMapIterator tmp = *this; ++*this; return tmp; 598 } 599 600private: 601 void AdvancePastEmptyBuckets() { 602 const KeyT Empty = KeyInfoT::getEmptyKey(); 603 const KeyT Tombstone = KeyInfoT::getTombstoneKey(); 604 605 while (Ptr != End && 606 (KeyInfoT::isEqual(Ptr->first, Empty) || 607 KeyInfoT::isEqual(Ptr->first, Tombstone))) 608 ++Ptr; 609 } 610}; 611 612template<typename KeyT, typename ValueT, typename KeyInfoT> 613static inline size_t 614capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) { 615 return X.getMemorySize(); 616} 617 618} // end namespace llvm 619 620#endif 621