DenseMap.h revision 4e58263459d7f9ae862b52adafe585b66411272f
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 bool IsConst = false> 34class DenseMapIterator; 35 36template<typename KeyT, typename ValueT, 37 typename KeyInfoT = DenseMapInfo<KeyT> > 38class DenseMap { 39 typedef std::pair<KeyT, ValueT> BucketT; 40 unsigned NumBuckets; 41 BucketT *Buckets; 42 43 unsigned NumEntries; 44 unsigned NumTombstones; 45public: 46 typedef KeyT key_type; 47 typedef ValueT mapped_type; 48 typedef BucketT value_type; 49 50 DenseMap(const DenseMap &other) { 51 NumBuckets = 0; 52 CopyFrom(other); 53 } 54 55 explicit DenseMap(unsigned NumInitBuckets = 0) { 56 init(NumInitBuckets); 57 } 58 59 template<typename InputIt> 60 DenseMap(const InputIt &I, const InputIt &E) { 61 init(NextPowerOf2(std::distance(I, E))); 62 insert(I, E); 63 } 64 65 ~DenseMap() { 66 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 67 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 68 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 69 !KeyInfoT::isEqual(P->first, TombstoneKey)) 70 P->second.~ValueT(); 71 P->first.~KeyT(); 72 } 73#ifndef NDEBUG 74 if (NumBuckets) 75 memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets); 76#endif 77 operator delete(Buckets); 78 } 79 80 typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator; 81 typedef DenseMapIterator<KeyT, ValueT, 82 KeyInfoT, true> const_iterator; 83 inline iterator begin() { 84 // When the map is empty, avoid the overhead of AdvancePastEmptyBuckets(). 85 return empty() ? end() : iterator(Buckets, Buckets+NumBuckets); 86 } 87 inline iterator end() { 88 return iterator(Buckets+NumBuckets, Buckets+NumBuckets, true); 89 } 90 inline const_iterator begin() const { 91 return empty() ? end() : const_iterator(Buckets, Buckets+NumBuckets); 92 } 93 inline const_iterator end() const { 94 return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets, true); 95 } 96 97 bool empty() const { return NumEntries == 0; } 98 unsigned size() const { return NumEntries; } 99 100 /// Grow the densemap so that it has at least Size buckets. Does not shrink 101 void resize(size_t Size) { 102 if (Size > NumBuckets) 103 grow(Size); 104 } 105 106 void clear() { 107 if (NumEntries == 0 && NumTombstones == 0) return; 108 109 // If the capacity of the array is huge, and the # elements used is small, 110 // shrink the array. 111 if (NumEntries * 4 < NumBuckets && NumBuckets > 64) { 112 shrink_and_clear(); 113 return; 114 } 115 116 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 117 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 118 if (!KeyInfoT::isEqual(P->first, EmptyKey)) { 119 if (!KeyInfoT::isEqual(P->first, TombstoneKey)) { 120 P->second.~ValueT(); 121 --NumEntries; 122 } 123 P->first = EmptyKey; 124 } 125 } 126 assert(NumEntries == 0 && "Node count imbalance!"); 127 NumTombstones = 0; 128 } 129 130 /// count - Return true if the specified key is in the map. 131 bool count(const KeyT &Val) const { 132 BucketT *TheBucket; 133 return LookupBucketFor(Val, TheBucket); 134 } 135 136 iterator find(const KeyT &Val) { 137 BucketT *TheBucket; 138 if (LookupBucketFor(Val, TheBucket)) 139 return iterator(TheBucket, Buckets+NumBuckets, true); 140 return end(); 141 } 142 const_iterator find(const KeyT &Val) const { 143 BucketT *TheBucket; 144 if (LookupBucketFor(Val, TheBucket)) 145 return const_iterator(TheBucket, Buckets+NumBuckets, true); 146 return end(); 147 } 148 149 /// Alternate version of find() which allows a different, and possibly 150 /// less expensive, key type. 151 /// The DenseMapInfo is responsible for supplying methods 152 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key 153 /// type used. 154 template<class LookupKeyT> 155 iterator find_as(const LookupKeyT &Val) { 156 BucketT *TheBucket; 157 if (LookupBucketFor(Val, TheBucket)) 158 return iterator(TheBucket, Buckets+NumBuckets, true); 159 return end(); 160 } 161 template<class LookupKeyT> 162 const_iterator find_as(const LookupKeyT &Val) const { 163 BucketT *TheBucket; 164 if (LookupBucketFor(Val, TheBucket)) 165 return const_iterator(TheBucket, Buckets+NumBuckets, true); 166 return end(); 167 } 168 169 /// lookup - Return the entry for the specified key, or a default 170 /// constructed value if no such entry exists. 171 ValueT lookup(const KeyT &Val) const { 172 BucketT *TheBucket; 173 if (LookupBucketFor(Val, TheBucket)) 174 return TheBucket->second; 175 return ValueT(); 176 } 177 178 // Inserts key,value pair into the map if the key isn't already in the map. 179 // If the key is already in the map, it returns false and doesn't update the 180 // value. 181 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) { 182 BucketT *TheBucket; 183 if (LookupBucketFor(KV.first, TheBucket)) 184 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), 185 false); // Already in map. 186 187 // Otherwise, insert the new element. 188 TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket); 189 return std::make_pair(iterator(TheBucket, Buckets+NumBuckets, true), true); 190 } 191 192 /// insert - Range insertion of pairs. 193 template<typename InputIt> 194 void insert(InputIt I, InputIt E) { 195 for (; I != E; ++I) 196 insert(*I); 197 } 198 199 200 bool erase(const KeyT &Val) { 201 BucketT *TheBucket; 202 if (!LookupBucketFor(Val, TheBucket)) 203 return false; // not in map. 204 205 TheBucket->second.~ValueT(); 206 TheBucket->first = getTombstoneKey(); 207 --NumEntries; 208 ++NumTombstones; 209 return true; 210 } 211 void erase(iterator I) { 212 BucketT *TheBucket = &*I; 213 TheBucket->second.~ValueT(); 214 TheBucket->first = getTombstoneKey(); 215 --NumEntries; 216 ++NumTombstones; 217 } 218 219 void swap(DenseMap& RHS) { 220 std::swap(NumBuckets, RHS.NumBuckets); 221 std::swap(Buckets, RHS.Buckets); 222 std::swap(NumEntries, RHS.NumEntries); 223 std::swap(NumTombstones, RHS.NumTombstones); 224 } 225 226 value_type& FindAndConstruct(const KeyT &Key) { 227 BucketT *TheBucket; 228 if (LookupBucketFor(Key, TheBucket)) 229 return *TheBucket; 230 231 return *InsertIntoBucket(Key, ValueT(), TheBucket); 232 } 233 234 ValueT &operator[](const KeyT &Key) { 235 return FindAndConstruct(Key).second; 236 } 237 238 DenseMap& operator=(const DenseMap& other) { 239 CopyFrom(other); 240 return *this; 241 } 242 243 /// isPointerIntoBucketsArray - Return true if the specified pointer points 244 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or 245 /// value in the DenseMap). 246 bool isPointerIntoBucketsArray(const void *Ptr) const { 247 return Ptr >= Buckets && Ptr < Buckets+NumBuckets; 248 } 249 250 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets 251 /// array. In conjunction with the previous method, this can be used to 252 /// determine whether an insertion caused the DenseMap to reallocate. 253 const void *getPointerIntoBucketsArray() const { return Buckets; } 254 255private: 256 void CopyFrom(const DenseMap& other) { 257 if (NumBuckets != 0 && 258 (!isPodLike<KeyT>::value || !isPodLike<ValueT>::value)) { 259 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey(); 260 for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) { 261 if (!KeyInfoT::isEqual(P->first, EmptyKey) && 262 !KeyInfoT::isEqual(P->first, TombstoneKey)) 263 P->second.~ValueT(); 264 P->first.~KeyT(); 265 } 266 } 267 268 NumEntries = other.NumEntries; 269 NumTombstones = other.NumTombstones; 270 271 if (NumBuckets) { 272#ifndef NDEBUG 273 memset((void*)Buckets, 0x5a, sizeof(BucketT)*NumBuckets); 274#endif 275 operator delete(Buckets); 276 } 277 278 NumBuckets = other.NumBuckets; 279 280 if (NumBuckets == 0) { 281 Buckets = 0; 282 return; 283 } 284 285 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets)); 286 287 if (isPodLike<KeyT>::value && isPodLike<ValueT>::value) 288 memcpy(Buckets, other.Buckets, NumBuckets * sizeof(BucketT)); 289 else 290 for (size_t i = 0; i < NumBuckets; ++i) { 291 new (&Buckets[i].first) KeyT(other.Buckets[i].first); 292 if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) && 293 !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey())) 294 new (&Buckets[i].second) ValueT(other.Buckets[i].second); 295 } 296 } 297 298 BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value, 299 BucketT *TheBucket) { 300 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of 301 // the buckets are empty (meaning that many are filled with tombstones), 302 // grow the table. 303 // 304 // The later case is tricky. For example, if we had one empty bucket with 305 // tons of tombstones, failing lookups (e.g. for insertion) would have to 306 // probe almost the entire table until it found the empty bucket. If the 307 // table completely filled with tombstones, no lookup would ever succeed, 308 // causing infinite loops in lookup. 309 ++NumEntries; 310 if (NumEntries*4 >= NumBuckets*3) { 311 this->grow(NumBuckets * 2); 312 LookupBucketFor(Key, TheBucket); 313 } 314 if (NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) { 315 this->grow(NumBuckets); 316 LookupBucketFor(Key, TheBucket); 317 } 318 319 // If we are writing over a tombstone, remember this. 320 if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey())) 321 --NumTombstones; 322 323 TheBucket->first = Key; 324 new (&TheBucket->second) ValueT(Value); 325 return TheBucket; 326 } 327 328 static unsigned getHashValue(const KeyT &Val) { 329 return KeyInfoT::getHashValue(Val); 330 } 331 template<typename LookupKeyT> 332 static unsigned getHashValue(const LookupKeyT &Val) { 333 return KeyInfoT::getHashValue(Val); 334 } 335 static const KeyT getEmptyKey() { 336 return KeyInfoT::getEmptyKey(); 337 } 338 static const KeyT getTombstoneKey() { 339 return KeyInfoT::getTombstoneKey(); 340 } 341 342 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in 343 /// FoundBucket. If the bucket contains the key and a value, this returns 344 /// true, otherwise it returns a bucket with an empty marker or tombstone and 345 /// returns false. 346 template<typename LookupKeyT> 347 bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) const { 348 unsigned BucketNo = getHashValue(Val); 349 unsigned ProbeAmt = 1; 350 BucketT *BucketsPtr = Buckets; 351 352 if (NumBuckets == 0) { 353 FoundBucket = 0; 354 return false; 355 } 356 357 // FoundTombstone - Keep track of whether we find a tombstone while probing. 358 BucketT *FoundTombstone = 0; 359 const KeyT EmptyKey = getEmptyKey(); 360 const KeyT TombstoneKey = getTombstoneKey(); 361 assert(!KeyInfoT::isEqual(Val, EmptyKey) && 362 !KeyInfoT::isEqual(Val, TombstoneKey) && 363 "Empty/Tombstone value shouldn't be inserted into map!"); 364 365 while (1) { 366 BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1)); 367 // Found Val's bucket? If so, return it. 368 if (KeyInfoT::isEqual(Val, ThisBucket->first)) { 369 FoundBucket = ThisBucket; 370 return true; 371 } 372 373 // If we found an empty bucket, the key doesn't exist in the set. 374 // Insert it and return the default value. 375 if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) { 376 // If we've already seen a tombstone while probing, fill it in instead 377 // of the empty bucket we eventually probed to. 378 if (FoundTombstone) ThisBucket = FoundTombstone; 379 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket; 380 return false; 381 } 382 383 // If this is a tombstone, remember it. If Val ends up not in the map, we 384 // prefer to return it than something that would require more probing. 385 if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone) 386 FoundTombstone = ThisBucket; // Remember the first tombstone found. 387 388 // Otherwise, it's a hash collision or a tombstone, continue quadratic 389 // probing. 390 BucketNo += ProbeAmt++; 391 } 392 } 393 394 void init(unsigned InitBuckets) { 395 NumEntries = 0; 396 NumTombstones = 0; 397 NumBuckets = InitBuckets; 398 399 if (InitBuckets == 0) { 400 Buckets = 0; 401 return; 402 } 403 404 assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 && 405 "# initial buckets must be a power of two!"); 406 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets)); 407 // Initialize all the keys to EmptyKey. 408 const KeyT EmptyKey = getEmptyKey(); 409 for (unsigned i = 0; i != InitBuckets; ++i) 410 new (&Buckets[i].first) KeyT(EmptyKey); 411 } 412 413 void grow(unsigned AtLeast) { 414 unsigned OldNumBuckets = NumBuckets; 415 BucketT *OldBuckets = Buckets; 416 417 if (NumBuckets < 64) 418 NumBuckets = 64; 419 420 // Double the number of buckets. 421 while (NumBuckets < AtLeast) 422 NumBuckets <<= 1; 423 NumTombstones = 0; 424 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 425 426 // Initialize all the keys to EmptyKey. 427 const KeyT EmptyKey = getEmptyKey(); 428 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 429 new (&Buckets[i].first) KeyT(EmptyKey); 430 431 // Insert all the old elements. 432 const KeyT TombstoneKey = getTombstoneKey(); 433 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 434 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 435 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 436 // Insert the key/value into the new table. 437 BucketT *DestBucket; 438 bool FoundVal = LookupBucketFor(B->first, DestBucket); 439 (void)FoundVal; // silence warning. 440 assert(!FoundVal && "Key already in new map?"); 441 DestBucket->first = B->first; 442 new (&DestBucket->second) ValueT(B->second); 443 444 // Free the value. 445 B->second.~ValueT(); 446 } 447 B->first.~KeyT(); 448 } 449 450#ifndef NDEBUG 451 if (OldNumBuckets) 452 memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets); 453#endif 454 // Free the old table. 455 operator delete(OldBuckets); 456 } 457 458 void shrink_and_clear() { 459 unsigned OldNumBuckets = NumBuckets; 460 BucketT *OldBuckets = Buckets; 461 462 // Reduce the number of buckets. 463 NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1) 464 : 64; 465 NumTombstones = 0; 466 Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets)); 467 468 // Initialize all the keys to EmptyKey. 469 const KeyT EmptyKey = getEmptyKey(); 470 for (unsigned i = 0, e = NumBuckets; i != e; ++i) 471 new (&Buckets[i].first) KeyT(EmptyKey); 472 473 // Free the old buckets. 474 const KeyT TombstoneKey = getTombstoneKey(); 475 for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) { 476 if (!KeyInfoT::isEqual(B->first, EmptyKey) && 477 !KeyInfoT::isEqual(B->first, TombstoneKey)) { 478 // Free the value. 479 B->second.~ValueT(); 480 } 481 B->first.~KeyT(); 482 } 483 484#ifndef NDEBUG 485 memset((void*)OldBuckets, 0x5a, sizeof(BucketT)*OldNumBuckets); 486#endif 487 // Free the old table. 488 operator delete(OldBuckets); 489 490 NumEntries = 0; 491 } 492 493public: 494 /// Return the approximate size (in bytes) of the actual map. 495 /// This is just the raw memory used by DenseMap. 496 /// If entries are pointers to objects, the size of the referenced objects 497 /// are not included. 498 size_t getMemorySize() const { 499 return NumBuckets * sizeof(BucketT); 500 } 501}; 502 503template<typename KeyT, typename ValueT, 504 typename KeyInfoT, bool IsConst> 505class DenseMapIterator { 506 typedef std::pair<KeyT, ValueT> Bucket; 507 typedef DenseMapIterator<KeyT, ValueT, 508 KeyInfoT, true> ConstIterator; 509 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, true>; 510public: 511 typedef ptrdiff_t difference_type; 512 typedef typename conditional<IsConst, const Bucket, Bucket>::type value_type; 513 typedef value_type *pointer; 514 typedef value_type &reference; 515 typedef std::forward_iterator_tag iterator_category; 516private: 517 pointer Ptr, End; 518public: 519 DenseMapIterator() : Ptr(0), End(0) {} 520 521 DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false) 522 : Ptr(Pos), End(E) { 523 if (!NoAdvance) AdvancePastEmptyBuckets(); 524 } 525 526 // If IsConst is true this is a converting constructor from iterator to 527 // const_iterator and the default copy constructor is used. 528 // Otherwise this is a copy constructor for iterator. 529 DenseMapIterator(const DenseMapIterator<KeyT, ValueT, 530 KeyInfoT, false>& I) 531 : Ptr(I.Ptr), End(I.End) {} 532 533 reference operator*() const { 534 return *Ptr; 535 } 536 pointer operator->() const { 537 return Ptr; 538 } 539 540 bool operator==(const ConstIterator &RHS) const { 541 return Ptr == RHS.operator->(); 542 } 543 bool operator!=(const ConstIterator &RHS) const { 544 return Ptr != RHS.operator->(); 545 } 546 547 inline DenseMapIterator& operator++() { // Preincrement 548 ++Ptr; 549 AdvancePastEmptyBuckets(); 550 return *this; 551 } 552 DenseMapIterator operator++(int) { // Postincrement 553 DenseMapIterator tmp = *this; ++*this; return tmp; 554 } 555 556private: 557 void AdvancePastEmptyBuckets() { 558 const KeyT Empty = KeyInfoT::getEmptyKey(); 559 const KeyT Tombstone = KeyInfoT::getTombstoneKey(); 560 561 while (Ptr != End && 562 (KeyInfoT::isEqual(Ptr->first, Empty) || 563 KeyInfoT::isEqual(Ptr->first, Tombstone))) 564 ++Ptr; 565 } 566}; 567 568template<typename KeyT, typename ValueT, typename KeyInfoT> 569static inline size_t 570capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) { 571 return X.getMemorySize(); 572} 573 574} // end namespace llvm 575 576#endif 577