DenseMap.h revision babd5980d8a8b4aad9814212a269f6197ebf1f2e
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/MathExtras.h" 18#include "llvm/Support/PointerLikeTypeTraits.h" 19#include "llvm/Support/type_traits.h" 20#include "llvm/ADT/DenseMapInfo.h" 21#include <algorithm> 22#include <iterator> 23#include <new> 24#include <utility> 25#include <cassert> 26#include <cstddef> 27#include <cstring> 28 29namespace llvm { 30 31template<typename KeyT, typename ValueT, 32 typename KeyInfoT = DenseMapInfo<KeyT>, 33 typename ValueInfoT = DenseMapInfo<ValueT>, bool IsConst = false> 34class DenseMapIterator; 35 36template<typename KeyT, typename ValueT, 37 typename KeyInfoT = DenseMapInfo<KeyT>, 38 typename ValueInfoT = DenseMapInfo<ValueT> > 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 explicit DenseMap(unsigned NumInitBuckets = 0) { 57 init(NumInitBuckets); 58 } 59 60 template<typename InputIt> 61 DenseMap(const InputIt &I, const InputIt &E) { 62 init(NextPowerOf2(std::distance(I, E))); 63 insert(I, E); 64 } 65 66 ~DenseMap() { 67 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 68 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 69 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 70 !KeyInfoT::isEqual(P->first, TombstoneKey)) 71 P->second.~ValueT(); 72 P->first.~KeyT(); 73 } 74#ifndef NDEBUG 75 if (NumBuckets) 76 memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets); 77#endif 78 operator delete(Buckets); 79 } 80 81 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator; 82 typedef DenseMapIterator<KeyT, ValueT, 83 KeyInfoT, ValueInfoT, true> const_iterator; 84 inline iterator begin() { 85 // When the map is empty, avoid the overhead of AdvancePastEmptyBuckets(). 86 return empty() ? end() : iterator(Buckets, Buckets+NumBuckets); 87 } 88 inline iterator end() { 89 return iterator(Buckets+NumBuckets, Buckets+NumBuckets, true); 90 } 91 inline const_iterator begin() const { 92 return empty() ? end() : const_iterator(Buckets, Buckets+NumBuckets); 93 } 94 inline const_iterator end() const { 95 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets, true); 96 } 97 98 bool empty() const { return NumEntries == 0; } 99 unsigned size() const { return NumEntries; } 100 101 /// Grow the densemap so that it has at least Size buckets. Does not shrink 102 void resize(size_t Size) { 103 if (Size > NumBuckets) 104 grow(Size); 105 } 106 107 void clear() { 108 if (NumEntries == 0 && NumTombstones == 0) return; 109 110 // If the capacity of the array is huge, and the # elements used is small, 111 // shrink the array. 112 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) { 113 shrink_and_clear(); 114 return; 115 } 116 117 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 118 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 119 if (!KeyInfoT::isEqual(P->first, EmptyKey)) { 120 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) { 121 P->second.~ValueT(); 122 --NumEntries; 123 } 124 P->first = EmptyKey; 125 } 126 } 127 assert(NumEntries == 0 && "Node count imbalance!"); 128 NumTombstones = 0; 129 } 130 131 /// count - Return true if the specified key is in the map. 132 bool count(const KeyT &Val) const { 133 BucketT *TheBucket; 134 return LookupBucketFor(Val, TheBucket); 135 } 136 137 iterator find(const KeyT &Val) { 138 BucketT *TheBucket; 139 if (LookupBucketFor(Val, TheBucket)) 140 return iterator(TheBucket, Buckets+NumBuckets, true); 141 return end(); 142 } 143 const_iterator find(const KeyT &Val) const { 144 BucketT *TheBucket; 145 if (LookupBucketFor(Val, TheBucket)) 146 return const_iterator(TheBucket, Buckets+NumBuckets, true); 147 return end(); 148 } 149 150 /// Alternate version of find() which allows a different, and possibly 151 /// less expensive, key type. 152 /// The DenseMapInfo is responsible for supplying methods 153 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key 154 /// type used. 155 template<class LookupKeyT> 156 iterator find_as(const LookupKeyT &Val) { 157 BucketT *TheBucket; 158 if (LookupBucketFor(Val, TheBucket)) 159 return iterator(TheBucket, Buckets+NumBuckets, true); 160 return end(); 161 } 162 template<class LookupKeyT> 163 const_iterator find_as(const LookupKeyT &Val) const { 164 BucketT *TheBucket; 165 if (LookupBucketFor(Val, TheBucket)) 166 return const_iterator(TheBucket, Buckets+NumBuckets, true); 167 return end(); 168 } 169 170 /// lookup - Return the entry for the specified key, or a default 171 /// constructed value if no such entry exists. 172 ValueT lookup(const KeyT &Val) const { 173 BucketT *TheBucket; 174 if (LookupBucketFor(Val, TheBucket)) 175 return TheBucket->second; 176 return ValueT(); 177 } 178 179 // Inserts key,value pair into the map if the key isn't already in the map. 180 // If the key is already in the map, it returns false and doesn't update the 181 // value. 182 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) { 183 BucketT *TheBucket; 184 if (LookupBucketFor(KV.first, TheBucket)) 185 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), 186 false); // Already in map. 187 188 // Otherwise, insert the new element. 189 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket); 190 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), true); 191 } 192 193 /// insert - Range insertion of pairs. 194 template<typename InputIt> 195 void insert(InputIt I, InputIt E) { 196 for (; I != E; ++I) 197 insert(*I); 198 } 199 200 201 bool erase(const KeyT &Val) { 202 BucketT *TheBucket; 203 if (!LookupBucketFor(Val, TheBucket)) 204 return false; // not in map. 205 206 TheBucket->second.~ValueT(); 207 TheBucket->first = getTombstoneKey(); 208 --NumEntries; 209 ++NumTombstones; 210 return true; 211 } 212 void erase(iterator I) { 213 BucketT *TheBucket = &*I; 214 TheBucket->second.~ValueT(); 215 TheBucket->first = getTombstoneKey(); 216 --NumEntries; 217 ++NumTombstones; 218 } 219 220 void swap(DenseMap& RHS) { 221 std::swap(NumBuckets, RHS.NumBuckets); 222 std::swap(Buckets, RHS.Buckets); 223 std::swap(NumEntries, RHS.NumEntries); 224 std::swap(NumTombstones, RHS.NumTombstones); 225 } 226 227 value_type& FindAndConstruct(const KeyT &Key) { 228 BucketT *TheBucket; 229 if (LookupBucketFor(Key, TheBucket)) 230 return *TheBucket; 231 232 return *InsertIntoBucket(Key, ValueT(), TheBucket); 233 } 234 235 ValueT &operator[](const KeyT &Key) { 236 return FindAndConstruct(Key).second; 237 } 238 239 DenseMap& operator=(const DenseMap& other) { 240 CopyFrom(other); 241 return *this; 242 } 243 244 /// isPointerIntoBucketsArray - Return true if the specified pointer points 245 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or 246 /// value in the DenseMap). 247 bool isPointerIntoBucketsArray(const void *Ptr) const { 248 return Ptr >= Buckets && Ptr < Buckets+NumBuckets; 249 } 250 251 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets 252 /// array. In conjunction with the previous method, this can be used to 253 /// determine whether an insertion caused the DenseMap to reallocate. 254 const void *getPointerIntoBucketsArray() const { return Buckets; } 255 256private: 257 void CopyFrom(const DenseMap& other) { 258 if (NumBuckets != 0 && 259 (!isPodLike<KeyInfoT>::value || !isPodLike<ValueInfoT>::value)) { 260 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 261 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 262 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 263 !KeyInfoT::isEqual(P->first, TombstoneKey)) 264 P->second.~ValueT(); 265 P->first.~KeyT(); 266 } 267 } 268 269 NumEntries = other.NumEntries; 270 NumTombstones = other.NumTombstones; 271 272 if (NumBuckets) { 273#ifndef NDEBUG 274 memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets); 275#endif 276 operator delete(Buckets); 277 } 278 279 NumBuckets = other.NumBuckets; 280 281 if (NumBuckets == 0) { 282 Buckets = 0; 283 return; 284 } 285 286 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets)); 287 288 if (isPodLike<KeyInfoT>::value && isPodLike<ValueInfoT>::value) 289 memcpy(Buckets, other.Buckets, NumBuckets * sizeof(BucketT)); 290 else 291 for (size_t i = 0; i < NumBuckets; ++i) { 292 new (&Buckets[i].first) KeyT(other.Buckets[i].first); 293 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) && 294 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey())) 295 new (&Buckets[i].second) ValueT(other.Buckets[i].second); 296 } 297 } 298 299 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value, 300 BucketT *TheBucket) { 301 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of 302 // the buckets are empty (meaning that many are filled with tombstones), 303 // grow the table. 304 // 305 // The later case is tricky. For example, if we had one empty bucket with 306 // tons of tombstones, failing lookups (e.g. for insertion) would have to 307 // probe almost the entire table until it found the empty bucket. If the 308 // table completely filled with tombstones, no lookup would ever succeed, 309 // causing infinite loops in lookup. 310 ++NumEntries; 311 if (NumEntries*4 >= NumBuckets*3) { 312 this->grow(NumBuckets * 2); 313 LookupBucketFor(Key, TheBucket); 314 } 315 if (NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) { 316 this->grow(NumBuckets); 317 LookupBucketFor(Key, TheBucket); 318 } 319 320 // If we are writing over a tombstone, remember this. 321 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey())) 322 --NumTombstones; 323 324 TheBucket->first = Key; 325 new (&TheBucket->second) ValueT(Value); 326 return TheBucket; 327 } 328 329 static unsigned getHashValue(const KeyT &Val) { 330 return KeyInfoT::getHashValue(Val); 331 } 332 template<typename LookupKeyT> 333 static unsigned getHashValue(const LookupKeyT &Val) { 334 return KeyInfoT::getHashValue(Val); 335 } 336 static const KeyT getEmptyKey() { 337 return KeyInfoT::getEmptyKey(); 338 } 339 static const KeyT getTombstoneKey() { 340 return KeyInfoT::getTombstoneKey(); 341 } 342 343 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in 344 /// FoundBucket. If the bucket contains the key and a value, this returns 345 /// true, otherwise it returns a bucket with an empty marker or tombstone and 346 /// returns false. 347 template<typename LookupKeyT> 348 bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) const { 349 unsigned BucketNo = getHashValue(Val); 350 unsigned ProbeAmt = 1; 351 BucketT *BucketsPtr = Buckets; 352 353 if (NumBuckets == 0) { 354 FoundBucket = 0; 355 return false; 356 } 357 358 // FoundTombstone - Keep track of whether we find a tombstone while probing. 359 BucketT *FoundTombstone = 0; 360 const KeyT EmptyKey = getEmptyKey(); 361 const KeyT TombstoneKey = getTombstoneKey(); 362 assert(!KeyInfoT::isEqual(Val, EmptyKey) && 363 !KeyInfoT::isEqual(Val, TombstoneKey) && 364 "Empty/Tombstone value shouldn't be inserted into map!"); 365 366 while (1) { 367 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1)); 368 // Found Val's bucket? If so, return it. 369 if (KeyInfoT::isEqual(Val, ThisBucket->first)) { 370 FoundBucket = ThisBucket; 371 return true; 372 } 373 374 // If we found an empty bucket, the key doesn't exist in the set. 375 // Insert it and return the default value. 376 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) { 377 // If we've already seen a tombstone while probing, fill it in instead 378 // of the empty bucket we eventually probed to. 379 if (FoundTombstone) ThisBucket = FoundTombstone; 380 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket; 381 return false; 382 } 383 384 // If this is a tombstone, remember it. If Val ends up not in the map, we 385 // prefer to return it than something that would require more probing. 386 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone) 387 FoundTombstone = ThisBucket; // Remember the first tombstone found. 388 389 // Otherwise, it's a hash collision or a tombstone, continue quadratic 390 // probing. 391 BucketNo += ProbeAmt++; 392 } 393 } 394 395 void init(unsigned InitBuckets) { 396 NumEntries = 0; 397 NumTombstones = 0; 398 NumBuckets = InitBuckets; 399 400 if (InitBuckets == 0) { 401 Buckets = 0; 402 return; 403 } 404 405 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 && 406 "# initial buckets must be a power of two!"); 407 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets)); 408 // Initialize all the keys to EmptyKey. 409 const KeyT EmptyKey = getEmptyKey(); 410 for (unsigned i = 0; i != InitBuckets; ++i) 411 new (&Buckets[i].first) KeyT(EmptyKey); 412 } 413 414 void grow(unsigned AtLeast) { 415 unsigned OldNumBuckets = NumBuckets; 416 BucketT *OldBuckets = Buckets; 417 418 if (NumBuckets < 64) 419 NumBuckets = 64; 420 421 // Double the number of buckets. 422 while (NumBuckets < AtLeast) 423 NumBuckets <<= 1; 424 NumTombstones = 0; 425 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 426 427 // Initialize all the keys to EmptyKey. 428 const KeyT EmptyKey = getEmptyKey(); 429 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 430 new (&Buckets[i].first) KeyT(EmptyKey); 431 432 // Insert all the old elements. 433 const KeyT TombstoneKey = getTombstoneKey(); 434 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 435 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 436 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 437 // Insert the key/value into the new table. 438 BucketT *DestBucket; 439 bool FoundVal = LookupBucketFor(B->first, DestBucket); 440 (void)FoundVal; // silence warning. 441 assert(!FoundVal && "Key already in new map?"); 442 DestBucket->first = B->first; 443 new (&DestBucket->second) ValueT(B->second); 444 445 // Free the value. 446 B->second.~ValueT(); 447 } 448 B->first.~KeyT(); 449 } 450 451#ifndef NDEBUG 452 if (OldNumBuckets) 453 memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets); 454#endif 455 // Free the old table. 456 operator delete(OldBuckets); 457 } 458 459 void shrink_and_clear() { 460 unsigned OldNumBuckets = NumBuckets; 461 BucketT *OldBuckets = Buckets; 462 463 // Reduce the number of buckets. 464 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1) 465 : 64; 466 NumTombstones = 0; 467 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 468 469 // Initialize all the keys to EmptyKey. 470 const KeyT EmptyKey = getEmptyKey(); 471 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 472 new (&Buckets[i].first) KeyT(EmptyKey); 473 474 // Free the old buckets. 475 const KeyT TombstoneKey = getTombstoneKey(); 476 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 477 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 478 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 479 // Free the value. 480 B->second.~ValueT(); 481 } 482 B->first.~KeyT(); 483 } 484 485#ifndef NDEBUG 486 memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets); 487#endif 488 // Free the old table. 489 operator delete(OldBuckets); 490 491 NumEntries = 0; 492 } 493 494public: 495 /// Return the approximate size (in bytes) of the actual map. 496 /// This is just the raw memory used by DenseMap. 497 /// If entries are pointers to objects, the size of the referenced objects 498 /// are not included. 499 size_t getMemorySize() const { 500 return NumBuckets * sizeof(BucketT); 501 } 502}; 503 504template<typename KeyT, typename ValueT, 505 typename KeyInfoT, typename ValueInfoT, bool IsConst> 506class DenseMapIterator { 507 typedef std::pair<KeyT, ValueT> Bucket; 508 typedef DenseMapIterator<KeyT, ValueT, 509 KeyInfoT, ValueInfoT, true> ConstIterator; 510 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, ValueInfoT, true>; 511public: 512 typedef ptrdiff_t difference_type; 513 typedef typename conditional<IsConst, const Bucket, Bucket>::type value_type; 514 typedef value_type *pointer; 515 typedef value_type &reference; 516 typedef std::forward_iterator_tag iterator_category; 517private: 518 pointer Ptr, End; 519public: 520 DenseMapIterator() : Ptr(0), End(0) {} 521 522 DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false) 523 : Ptr(Pos), End(E) { 524 if (!NoAdvance) AdvancePastEmptyBuckets(); 525 } 526 527 // If IsConst is true this is a converting constructor from iterator to 528 // const_iterator and the default copy constructor is used. 529 // Otherwise this is a copy constructor for iterator. 530 DenseMapIterator(const DenseMapIterator<KeyT, ValueT, 531 KeyInfoT, ValueInfoT, false>& I) 532 : Ptr(I.Ptr), End(I.End) {} 533 534 reference operator*() const { 535 return *Ptr; 536 } 537 pointer operator->() const { 538 return Ptr; 539 } 540 541 bool operator==(const ConstIterator &RHS) const { 542 return Ptr == RHS.operator->(); 543 } 544 bool operator!=(const ConstIterator &RHS) const { 545 return Ptr != RHS.operator->(); 546 } 547 548 inline DenseMapIterator& operator++() { // Preincrement 549 ++Ptr; 550 AdvancePastEmptyBuckets(); 551 return *this; 552 } 553 DenseMapIterator operator++(int) { // Postincrement 554 DenseMapIterator tmp = *this; ++*this; return tmp; 555 } 556 557private: 558 void AdvancePastEmptyBuckets() { 559 const KeyT Empty = KeyInfoT::getEmptyKey(); 560 const KeyT Tombstone = KeyInfoT::getTombstoneKey(); 561 562 while (Ptr != End && 563 (KeyInfoT::isEqual(Ptr->first, Empty) || 564 KeyInfoT::isEqual(Ptr->first, Tombstone))) 565 ++Ptr; 566 } 567}; 568 569template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT> 570static inline size_t 571capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT, ValueInfoT> &X) { 572 return X.getMemorySize(); 573} 574 575} // end namespace llvm 576 577#endif 578