src/llvm/include/llvm/ADT/DenseMap.h

   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/ADT/DenseMapInfo.h"
  18 #include "llvm/Support/AlignOf.h"
  19 #include "llvm/Support/Compiler.h"
  20 #include "llvm/Support/MathExtras.h"
  21 #include "llvm/Support/PointerLikeTypeTraits.h"
  22 #include "llvm/Support/type_traits.h"
  23 #include <algorithm>
  24 #include <cassert>
  25 #include <climits>
  26 #include <cstddef>
  27 #include <cstring>
  28 #include <iterator>
  29 #include <new>
  30 #include <utility>
  31
  32 namespace llvm {
  33
  34 template<typename KeyT, typename ValueT,
  35          typename KeyInfoT = DenseMapInfo<KeyT>,
  36          bool IsConst = false>
  37 class DenseMapIterator;
  38
  39 template<typename DerivedT,
  40          typename KeyT, typename ValueT, typename KeyInfoT>
  41 class DenseMapBase {
  42 protected:
  43   typedef std::pair<KeyT, ValueT> BucketT;
  44
  45 public:
  46   typedef KeyT key_type;
  47   typedef ValueT mapped_type;
  48   typedef BucketT value_type;
  49
  50   typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
  51   typedef DenseMapIterator<KeyT, ValueT,
  52                            KeyInfoT, true> const_iterator;
  53   inline iterator begin() {
  54     // When the map is empty, avoid the overhead of AdvancePastEmptyBuckets().
  55     return empty() ? end() : iterator(getBuckets(), getBucketsEnd());
  56   }
  57   inline iterator end() {
  58     return iterator(getBucketsEnd(), getBucketsEnd(), true);
  59   }
  60   inline const_iterator begin() const {
  61     return empty() ? end() : const_iterator(getBuckets(), getBucketsEnd());
  62   }
  63   inline const_iterator end() const {
  64     return const_iterator(getBucketsEnd(), getBucketsEnd(), true);
  65   }
  66
  67   bool empty() const { return getNumEntries() == 0; }
  68   unsigned size() const { return getNumEntries(); }
  69
  70   /// Grow the densemap so that it has at least Size buckets. Does not shrink
  71   void resize(size_t Size) {
  72     if (Size > getNumBuckets())
  73       grow(Size);
  74   }
  75
  76   void clear() {
  77     if (getNumEntries() == 0 && getNumTombstones() == 0) return;
  78
  79     // If the capacity of the array is huge, and the # elements used is small,
  80     // shrink the array.
  81     if (getNumEntries() * 4 < getNumBuckets() && getNumBuckets() > 64) {
  82       shrink_and_clear();
  83       return;
  84     }
  85
  86     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
  87     for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
  88       if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
  89         if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
  90           P->second.~ValueT();
  91           decrementNumEntries();
  92         }
  93         P->first = EmptyKey;
  94       }
  95     }
  96     assert(getNumEntries() == 0 && "Node count imbalance!");
  97     setNumTombstones(0);
  98   }
  99
 100   /// count - Return true if the specified key is in the map.
 101   bool count(const KeyT &Val) const {
 102     const BucketT *TheBucket;
 103     return LookupBucketFor(Val, TheBucket);
 104   }
 105
 106   iterator find(const KeyT &Val) {
 107     BucketT *TheBucket;
 108     if (LookupBucketFor(Val, TheBucket))
 109       return iterator(TheBucket, getBucketsEnd(), true);
 110     return end();
 111   }
 112   const_iterator find(const KeyT &Val) const {
 113     const BucketT *TheBucket;
 114     if (LookupBucketFor(Val, TheBucket))
 115       return const_iterator(TheBucket, getBucketsEnd(), true);
 116     return end();
 117   }
 118
 119   /// Alternate version of find() which allows a different, and possibly
 120   /// less expensive, key type.
 121   /// The DenseMapInfo is responsible for supplying methods
 122   /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
 123   /// type used.
 124   template<class LookupKeyT>
 125   iterator find_as(const LookupKeyT &Val) {
 126     BucketT *TheBucket;
 127     if (LookupBucketFor(Val, TheBucket))
 128       return iterator(TheBucket, getBucketsEnd(), true);
 129     return end();
 130   }
 131   template<class LookupKeyT>
 132   const_iterator find_as(const LookupKeyT &Val) const {
 133     const BucketT *TheBucket;
 134     if (LookupBucketFor(Val, TheBucket))
 135       return const_iterator(TheBucket, getBucketsEnd(), true);
 136     return end();
 137   }
 138
 139   /// lookup - Return the entry for the specified key, or a default
 140   /// constructed value if no such entry exists.
 141   ValueT lookup(const KeyT &Val) const {
 142     const BucketT *TheBucket;
 143     if (LookupBucketFor(Val, TheBucket))
 144       return TheBucket->second;
 145     return ValueT();
 146   }
 147
 148   // Inserts key,value pair into the map if the key isn't already in the map.
 149   // If the key is already in the map, it returns false and doesn't update the
 150   // value.
 151   std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
 152     BucketT *TheBucket;
 153     if (LookupBucketFor(KV.first, TheBucket))
 154       return std::make_pair(iterator(TheBucket, getBucketsEnd(), true),
 155                             false); // Already in map.
 156
 157     // Otherwise, insert the new element.
 158     TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
 159     return std::make_pair(iterator(TheBucket, getBucketsEnd(), true), true);
 160   }
 161
 162 #if LLVM_HAS_RVALUE_REFERENCES
 163   // Inserts key,value pair into the map if the key isn't already in the map.
 164   // If the key is already in the map, it returns false and doesn't update the
 165   // value.
 166   std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
 167     BucketT *TheBucket;
 168     if (LookupBucketFor(KV.first, TheBucket))
 169       return std::make_pair(iterator(TheBucket, getBucketsEnd(), true),
 170                             false); // Already in map.
 171
 172     // Otherwise, insert the new element.
 173     TheBucket = InsertIntoBucket(std::move(KV.first),
 174                                  std::move(KV.second),
 175                                  TheBucket);
 176     return std::make_pair(iterator(TheBucket, getBucketsEnd(), true), true);
 177   }
 178 #endif
 179
 180   /// insert - Range insertion of pairs.
 181   template<typename InputIt>
 182   void insert(InputIt I, InputIt E) {
 183     for (; I != E; ++I)
 184       insert(*I);
 185   }
 186
 187
 188   bool erase(const KeyT &Val) {
 189     BucketT *TheBucket;
 190     if (!LookupBucketFor(Val, TheBucket))
 191       return false; // not in map.
 192
 193     TheBucket->second.~ValueT();
 194     TheBucket->first = getTombstoneKey();
 195     decrementNumEntries();
 196     incrementNumTombstones();
 197     return true;
 198   }
 199   void erase(iterator I) {
 200     BucketT *TheBucket = &*I;
 201     TheBucket->second.~ValueT();
 202     TheBucket->first = getTombstoneKey();
 203     decrementNumEntries();
 204     incrementNumTombstones();
 205   }
 206
 207   value_type& FindAndConstruct(const KeyT &Key) {
 208     BucketT *TheBucket;
 209     if (LookupBucketFor(Key, TheBucket))
 210       return *TheBucket;
 211
 212     return *InsertIntoBucket(Key, ValueT(), TheBucket);
 213   }
 214
 215   ValueT &operator[](const KeyT &Key) {
 216     return FindAndConstruct(Key).second;
 217   }
 218
 219 #if LLVM_HAS_RVALUE_REFERENCES
 220   value_type& FindAndConstruct(KeyT &&Key) {
 221     BucketT *TheBucket;
 222     if (LookupBucketFor(Key, TheBucket))
 223       return *TheBucket;
 224
 225     return *InsertIntoBucket(Key, ValueT(), TheBucket);
 226   }
 227
 228   ValueT &operator[](KeyT &&Key) {
 229     return FindAndConstruct(Key).second;
 230   }
 231 #endif
 232
 233   /// isPointerIntoBucketsArray - Return true if the specified pointer points
 234   /// somewhere into the DenseMap's array of buckets (i.e. either to a key or
 235   /// value in the DenseMap).
 236   bool isPointerIntoBucketsArray(const void *Ptr) const {
 237     return Ptr >= getBuckets() && Ptr < getBucketsEnd();
 238   }
 239
 240   /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
 241   /// array.  In conjunction with the previous method, this can be used to
 242   /// determine whether an insertion caused the DenseMap to reallocate.
 243   const void *getPointerIntoBucketsArray() const { return getBuckets(); }
 244
 245 protected:
 246   DenseMapBase() {}
 247
 248   void destroyAll() {
 249     if (getNumBuckets() == 0) // Nothing to do.
 250       return;
 251
 252     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
 253     for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
 254       if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
 255           !KeyInfoT::isEqual(P->first, TombstoneKey))
 256         P->second.~ValueT();
 257       P->first.~KeyT();
 258     }
 259
 260 #ifndef NDEBUG
 261     memset((void*)getBuckets(), 0x5a, sizeof(BucketT)*getNumBuckets());
 262 #endif
 263   }
 264
 265   void initEmpty() {
 266     setNumEntries(0);
 267     setNumTombstones(0);
 268
 269     assert((getNumBuckets() & (getNumBuckets()-1)) == 0 &&
 270            "# initial buckets must be a power of two!");
 271     const KeyT EmptyKey = getEmptyKey();
 272     for (BucketT *B = getBuckets(), *E = getBucketsEnd(); B != E; ++B)
 273       new (&B->first) KeyT(EmptyKey);
 274   }
 275
 276   void moveFromOldBuckets(BucketT *OldBucketsBegin, BucketT *OldBucketsEnd) {
 277     initEmpty();
 278
 279     // Insert all the old elements.
 280     const KeyT EmptyKey = getEmptyKey();
 281     const KeyT TombstoneKey = getTombstoneKey();
 282     for (BucketT *B = OldBucketsBegin, *E = OldBucketsEnd; B != E; ++B) {
 283       if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
 284           !KeyInfoT::isEqual(B->first, TombstoneKey)) {
 285         // Insert the key/value into the new table.
 286         BucketT *DestBucket;
 287         bool FoundVal = LookupBucketFor(B->first, DestBucket);
 288         (void)FoundVal; // silence warning.
 289         assert(!FoundVal && "Key already in new map?");
 290         DestBucket->first = llvm_move(B->first);
 291         new (&DestBucket->second) ValueT(llvm_move(B->second));
 292         incrementNumEntries();
 293
 294         // Free the value.
 295         B->second.~ValueT();
 296       }
 297       B->first.~KeyT();
 298     }
 299
 300 #ifndef NDEBUG
 301     if (OldBucketsBegin != OldBucketsEnd)
 302       memset((void*)OldBucketsBegin, 0x5a,
 303              sizeof(BucketT) * (OldBucketsEnd - OldBucketsBegin));
 304 #endif
 305   }
 306
 307   template <typename OtherBaseT>
 308   void copyFrom(const DenseMapBase<OtherBaseT, KeyT, ValueT, KeyInfoT>& other) {
 309     assert(getNumBuckets() == other.getNumBuckets());
 310
 311     setNumEntries(other.getNumEntries());
 312     setNumTombstones(other.getNumTombstones());
 313
 314     if (isPodLike<KeyT>::value && isPodLike<ValueT>::value)
 315       memcpy(getBuckets(), other.getBuckets(),
 316              getNumBuckets() * sizeof(BucketT));
 317     else
 318       for (size_t i = 0; i < getNumBuckets(); ++i) {
 319         new (&getBuckets()[i].first) KeyT(other.getBuckets()[i].first);
 320         if (!KeyInfoT::isEqual(getBuckets()[i].first, getEmptyKey()) &&
 321             !KeyInfoT::isEqual(getBuckets()[i].first, getTombstoneKey()))
 322           new (&getBuckets()[i].second) ValueT(other.getBuckets()[i].second);
 323       }
 324   }
 325
 326   void swap(DenseMapBase& RHS) {
 327     std::swap(getNumEntries(), RHS.getNumEntries());
 328     std::swap(getNumTombstones(), RHS.getNumTombstones());
 329   }
 330
 331   static unsigned getHashValue(const KeyT &Val) {
 332     return KeyInfoT::getHashValue(Val);
 333   }
 334   template<typename LookupKeyT>
 335   static unsigned getHashValue(const LookupKeyT &Val) {
 336     return KeyInfoT::getHashValue(Val);
 337   }
 338   static const KeyT getEmptyKey() {
 339     return KeyInfoT::getEmptyKey();
 340   }
 341   static const KeyT getTombstoneKey() {
 342     return KeyInfoT::getTombstoneKey();
 343   }
 344
 345 private:
 346   unsigned getNumEntries() const {
 347     return static_cast<const DerivedT *>(this)->getNumEntries();
 348   }
 349   void setNumEntries(unsigned Num) {
 350     static_cast<DerivedT *>(this)->setNumEntries(Num);
 351   }
 352   void incrementNumEntries() {
 353     setNumEntries(getNumEntries() + 1);
 354   }
 355   void decrementNumEntries() {
 356     setNumEntries(getNumEntries() - 1);
 357   }
 358   unsigned getNumTombstones() const {
 359     return static_cast<const DerivedT *>(this)->getNumTombstones();
 360   }
 361   void setNumTombstones(unsigned Num) {
 362     static_cast<DerivedT *>(this)->setNumTombstones(Num);
 363   }
 364   void incrementNumTombstones() {
 365     setNumTombstones(getNumTombstones() + 1);
 366   }
 367   void decrementNumTombstones() {
 368     setNumTombstones(getNumTombstones() - 1);
 369   }
 370   const BucketT *getBuckets() const {
 371     return static_cast<const DerivedT *>(this)->getBuckets();
 372   }
 373   BucketT *getBuckets() {
 374     return static_cast<DerivedT *>(this)->getBuckets();
 375   }
 376   unsigned getNumBuckets() const {
 377     return static_cast<const DerivedT *>(this)->getNumBuckets();
 378   }
 379   BucketT *getBucketsEnd() {
 380     return getBuckets() + getNumBuckets();
 381   }
 382   const BucketT *getBucketsEnd() const {
 383     return getBuckets() + getNumBuckets();
 384   }
 385
 386   void grow(unsigned AtLeast) {
 387     static_cast<DerivedT *>(this)->grow(AtLeast);
 388   }
 389
 390   void shrink_and_clear() {
 391     static_cast<DerivedT *>(this)->shrink_and_clear();
 392   }
 393
 394
 395   BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
 396                             BucketT *TheBucket) {
 397     TheBucket = InsertIntoBucketImpl(Key, TheBucket);
 398
 399     TheBucket->first = Key;
 400     new (&TheBucket->second) ValueT(Value);
 401     return TheBucket;
 402   }
 403
 404 #if LLVM_HAS_RVALUE_REFERENCES
 405   BucketT *InsertIntoBucket(const KeyT &Key, ValueT &&Value,
 406                             BucketT *TheBucket) {
 407     TheBucket = InsertIntoBucketImpl(Key, TheBucket);
 408
 409     TheBucket->first = Key;
 410     new (&TheBucket->second) ValueT(std::move(Value));
 411     return TheBucket;
 412   }
 413
 414   BucketT *InsertIntoBucket(KeyT &&Key, ValueT &&Value, BucketT *TheBucket) {
 415     TheBucket = InsertIntoBucketImpl(Key, TheBucket);
 416
 417     TheBucket->first = std::move(Key);
 418     new (&TheBucket->second) ValueT(std::move(Value));
 419     return TheBucket;
 420   }
 421 #endif
 422
 423   BucketT *InsertIntoBucketImpl(const KeyT &Key, BucketT *TheBucket) {
 424     // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
 425     // the buckets are empty (meaning that many are filled with tombstones),
 426     // grow the table.
 427     //
 428     // The later case is tricky.  For example, if we had one empty bucket with
 429     // tons of tombstones, failing lookups (e.g. for insertion) would have to
 430     // probe almost the entire table until it found the empty bucket.  If the
 431     // table completely filled with tombstones, no lookup would ever succeed,
 432     // causing infinite loops in lookup.
 433     unsigned NewNumEntries = getNumEntries() + 1;
 434     unsigned NumBuckets = getNumBuckets();
 435     if (NewNumEntries*4 >= NumBuckets*3) {
 436       this->grow(NumBuckets * 2);
 437       LookupBucketFor(Key, TheBucket);
 438       NumBuckets = getNumBuckets();
 439     }
 440     if (NumBuckets-(NewNumEntries+getNumTombstones()) <= NumBuckets/8) {
 441       this->grow(NumBuckets * 2);
 442       LookupBucketFor(Key, TheBucket);
 443     }
 444     assert(TheBucket);
 445
 446     // Only update the state after we've grown our bucket space appropriately
 447     // so that when growing buckets we have self-consistent entry count.
 448     incrementNumEntries();
 449
 450     // If we are writing over a tombstone, remember this.
 451     const KeyT EmptyKey = getEmptyKey();
 452     if (!KeyInfoT::isEqual(TheBucket->first, EmptyKey))
 453       decrementNumTombstones();
 454
 455     return TheBucket;
 456   }
 457
 458   /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
 459   /// FoundBucket.  If the bucket contains the key and a value, this returns
 460   /// true, otherwise it returns a bucket with an empty marker or tombstone and
 461   /// returns false.
 462   template<typename LookupKeyT>
 463   bool LookupBucketFor(const LookupKeyT &Val,
 464                        const BucketT *&FoundBucket) const {
 465     const BucketT *BucketsPtr = getBuckets();
 466     const unsigned NumBuckets = getNumBuckets();
 467
 468     if (NumBuckets == 0) {
 469       FoundBucket = 0;
 470       return false;
 471     }
 472
 473     // FoundTombstone - Keep track of whether we find a tombstone while probing.
 474     const BucketT *FoundTombstone = 0;
 475     const KeyT EmptyKey = getEmptyKey();
 476     const KeyT TombstoneKey = getTombstoneKey();
 477     assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
 478            !KeyInfoT::isEqual(Val, TombstoneKey) &&
 479            "Empty/Tombstone value shouldn't be inserted into map!");
 480
 481     unsigned BucketNo = getHashValue(Val) & (NumBuckets-1);
 482     unsigned ProbeAmt = 1;
 483     while (1) {
 484       const BucketT *ThisBucket = BucketsPtr + BucketNo;
 485       // Found Val's bucket?  If so, return it.
 486       if (KeyInfoT::isEqual(Val, ThisBucket->first)) {
 487         FoundBucket = ThisBucket;
 488         return true;
 489       }
 490
 491       // If we found an empty bucket, the key doesn't exist in the set.
 492       // Insert it and return the default value.
 493       if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
 494         // If we've already seen a tombstone while probing, fill it in instead
 495         // of the empty bucket we eventually probed to.
 496         FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
 497         return false;
 498       }
 499
 500       // If this is a tombstone, remember it.  If Val ends up not in the map, we
 501       // prefer to return it than something that would require more probing.
 502       if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
 503         FoundTombstone = ThisBucket;  // Remember the first tombstone found.
 504
 505       // Otherwise, it's a hash collision or a tombstone, continue quadratic
 506       // probing.
 507       BucketNo += ProbeAmt++;
 508       BucketNo &= (NumBuckets-1);
 509     }
 510   }
 511
 512   template <typename LookupKeyT>
 513   bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) {
 514     const BucketT *ConstFoundBucket;
 515     bool Result = const_cast<const DenseMapBase *>(this)
 516       ->LookupBucketFor(Val, ConstFoundBucket);
 517     FoundBucket = const_cast<BucketT *>(ConstFoundBucket);
 518     return Result;
 519   }
 520
 521 public:
 522   /// Return the approximate size (in bytes) of the actual map.
 523   /// This is just the raw memory used by DenseMap.
 524   /// If entries are pointers to objects, the size of the referenced objects
 525   /// are not included.
 526   size_t getMemorySize() const {
 527     return getNumBuckets() * sizeof(BucketT);
 528   }
 529 };
 530
 531 template<typename KeyT, typename ValueT,
 532          typename KeyInfoT = DenseMapInfo<KeyT> >
 533 class DenseMap
 534     : public DenseMapBase<DenseMap<KeyT, ValueT, KeyInfoT>,
 535                           KeyT, ValueT, KeyInfoT> {
 536   // Lift some types from the dependent base class into this class for
 537   // simplicity of referring to them.
 538   typedef DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT> BaseT;
 539   typedef typename BaseT::BucketT BucketT;
 540   friend class DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT>;
 541
 542   BucketT *Buckets;
 543   unsigned NumEntries;
 544   unsigned NumTombstones;
 545   unsigned NumBuckets;
 546
 547 public:
 548   explicit DenseMap(unsigned NumInitBuckets = 0) {
 549     init(NumInitBuckets);
 550   }
 551
 552   DenseMap(const DenseMap &other) : BaseT() {
 553     init(0);
 554     copyFrom(other);
 555   }
 556
 557 #if LLVM_HAS_RVALUE_REFERENCES
 558   DenseMap(DenseMap &&other) : BaseT() {
 559     init(0);
 560     swap(other);
 561   }
 562 #endif
 563
 564   template<typename InputIt>
 565   DenseMap(const InputIt &I, const InputIt &E) {
 566     init(NextPowerOf2(std::distance(I, E)));
 567     this->insert(I, E);
 568   }
 569
 570   ~DenseMap() {
 571     this->destroyAll();
 572     operator delete(Buckets);
 573   }
 574
 575   void swap(DenseMap& RHS) {
 576     std::swap(Buckets, RHS.Buckets);
 577     std::swap(NumEntries, RHS.NumEntries);
 578     std::swap(NumTombstones, RHS.NumTombstones);
 579     std::swap(NumBuckets, RHS.NumBuckets);
 580   }
 581
 582   DenseMap& operator=(const DenseMap& other) {
 583     copyFrom(other);
 584     return *this;
 585   }
 586
 587 #if LLVM_HAS_RVALUE_REFERENCES
 588   DenseMap& operator=(DenseMap &&other) {
 589     this->destroyAll();
 590     operator delete(Buckets);
 591     init(0);
 592     swap(other);
 593     return *this;
 594   }
 595 #endif
 596
 597   void copyFrom(const DenseMap& other) {
 598     this->destroyAll();
 599     operator delete(Buckets);
 600     if (allocateBuckets(other.NumBuckets)) {
 601       this->BaseT::copyFrom(other);
 602     } else {
 603       NumEntries = 0;
 604       NumTombstones = 0;
 605     }
 606   }
 607
 608   void init(unsigned InitBuckets) {
 609     if (allocateBuckets(InitBuckets)) {
 610       this->BaseT::initEmpty();
 611     } else {
 612       NumEntries = 0;
 613       NumTombstones = 0;
 614     }
 615   }
 616
 617   void grow(unsigned AtLeast) {
 618     unsigned OldNumBuckets = NumBuckets;
 619     BucketT *OldBuckets = Buckets;
 620
 621     allocateBuckets(std::max<unsigned>(64, NextPowerOf2(AtLeast-1)));
 622     assert(Buckets);
 623     if (!OldBuckets) {
 624       this->BaseT::initEmpty();
 625       return;
 626     }
 627
 628     this->moveFromOldBuckets(OldBuckets, OldBuckets+OldNumBuckets);
 629
 630     // Free the old table.
 631     operator delete(OldBuckets);
 632   }
 633
 634   void shrink_and_clear() {
 635     unsigned OldNumEntries = NumEntries;
 636     this->destroyAll();
 637
 638     // Reduce the number of buckets.
 639     unsigned NewNumBuckets = 0;
 640     if (OldNumEntries)
 641       NewNumBuckets = std::max(64, 1 << (Log2_32_Ceil(OldNumEntries) + 1));
 642     if (NewNumBuckets == NumBuckets) {
 643       this->BaseT::initEmpty();
 644       return;
 645     }
 646
 647     operator delete(Buckets);
 648     init(NewNumBuckets);
 649   }
 650
 651 private:
 652   unsigned getNumEntries() const {
 653     return NumEntries;
 654   }
 655   void setNumEntries(unsigned Num) {
 656     NumEntries = Num;
 657   }
 658
 659   unsigned getNumTombstones() const {
 660     return NumTombstones;
 661   }
 662   void setNumTombstones(unsigned Num) {
 663     NumTombstones = Num;
 664   }
 665
 666   BucketT *getBuckets() const {
 667     return Buckets;
 668   }
 669
 670   unsigned getNumBuckets() const {
 671     return NumBuckets;
 672   }
 673
 674   bool allocateBuckets(unsigned Num) {
 675     NumBuckets = Num;
 676     if (NumBuckets == 0) {
 677       Buckets = 0;
 678       return false;
 679     }
 680
 681     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets));
 682     return true;
 683   }
 684 };
 685
 686 template<typename KeyT, typename ValueT,
 687          unsigned InlineBuckets = 4,
 688          typename KeyInfoT = DenseMapInfo<KeyT> >
 689 class SmallDenseMap
 690     : public DenseMapBase<SmallDenseMap<KeyT, ValueT, InlineBuckets, KeyInfoT>,
 691                           KeyT, ValueT, KeyInfoT> {
 692   // Lift some types from the dependent base class into this class for
 693   // simplicity of referring to them.
 694   typedef DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT> BaseT;
 695   typedef typename BaseT::BucketT BucketT;
 696   friend class DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT>;
 697
 698   unsigned Small : 1;
 699   unsigned NumEntries : 31;
 700   unsigned NumTombstones;
 701
 702   struct LargeRep {
 703     BucketT *Buckets;
 704     unsigned NumBuckets;
 705   };
 706
 707   /// A "union" of an inline bucket array and the struct representing
 708   /// a large bucket. This union will be discriminated by the 'Small' bit.
 709   AlignedCharArrayUnion<BucketT[InlineBuckets], LargeRep> storage;
 710
 711 public:
 712   explicit SmallDenseMap(unsigned NumInitBuckets = 0) {
 713     init(NumInitBuckets);
 714   }
 715
 716   SmallDenseMap(const SmallDenseMap &other) {
 717     init(0);
 718     copyFrom(other);
 719   }
 720
 721 #if LLVM_HAS_RVALUE_REFERENCES
 722   SmallDenseMap(SmallDenseMap &&other) {
 723     init(0);
 724     swap(other);
 725   }
 726 #endif
 727
 728   template<typename InputIt>
 729   SmallDenseMap(const InputIt &I, const InputIt &E) {
 730     init(NextPowerOf2(std::distance(I, E)));
 731     this->insert(I, E);
 732   }
 733
 734   ~SmallDenseMap() {
 735     this->destroyAll();
 736     deallocateBuckets();
 737   }
 738
 739   void swap(SmallDenseMap& RHS) {
 740     unsigned TmpNumEntries = RHS.NumEntries;
 741     RHS.NumEntries = NumEntries;
 742     NumEntries = TmpNumEntries;
 743     std::swap(NumTombstones, RHS.NumTombstones);
 744
 745     const KeyT EmptyKey = this->getEmptyKey();
 746     const KeyT TombstoneKey = this->getTombstoneKey();
 747     if (Small && RHS.Small) {
 748       // If we're swapping inline bucket arrays, we have to cope with some of
 749       // the tricky bits of DenseMap's storage system: the buckets are not
 750       // fully initialized. Thus we swap every key, but we may have
 751       // a one-directional move of the value.
 752       for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
 753         BucketT *LHSB = &getInlineBuckets()[i],
 754                 *RHSB = &RHS.getInlineBuckets()[i];
 755         bool hasLHSValue = (!KeyInfoT::isEqual(LHSB->first, EmptyKey) &&
 756                             !KeyInfoT::isEqual(LHSB->first, TombstoneKey));
 757         bool hasRHSValue = (!KeyInfoT::isEqual(RHSB->first, EmptyKey) &&
 758                             !KeyInfoT::isEqual(RHSB->first, TombstoneKey));
 759         if (hasLHSValue && hasRHSValue) {
 760           // Swap together if we can...
 761           std::swap(*LHSB, *RHSB);
 762           continue;
 763         }
 764         // Swap separately and handle any assymetry.
 765         std::swap(LHSB->first, RHSB->first);
 766         if (hasLHSValue) {
 767           new (&RHSB->second) ValueT(llvm_move(LHSB->second));
 768           LHSB->second.~ValueT();
 769         } else if (hasRHSValue) {
 770           new (&LHSB->second) ValueT(llvm_move(RHSB->second));
 771           RHSB->second.~ValueT();
 772         }
 773       }
 774       return;
 775     }
 776     if (!Small && !RHS.Small) {
 777       std::swap(getLargeRep()->Buckets, RHS.getLargeRep()->Buckets);
 778       std::swap(getLargeRep()->NumBuckets, RHS.getLargeRep()->NumBuckets);
 779       return;
 780     }
 781
 782     SmallDenseMap &SmallSide = Small ? *this : RHS;
 783     SmallDenseMap &LargeSide = Small ? RHS : *this;
 784
 785     // First stash the large side's rep and move the small side across.
 786     LargeRep TmpRep = llvm_move(*LargeSide.getLargeRep());
 787     LargeSide.getLargeRep()->~LargeRep();
 788     LargeSide.Small = true;
 789     // This is similar to the standard move-from-old-buckets, but the bucket
 790     // count hasn't actually rotated in this case. So we have to carefully
 791     // move construct the keys and values into their new locations, but there
 792     // is no need to re-hash things.
 793     for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
 794       BucketT *NewB = &LargeSide.getInlineBuckets()[i],
 795               *OldB = &SmallSide.getInlineBuckets()[i];
 796       new (&NewB->first) KeyT(llvm_move(OldB->first));
 797       OldB->first.~KeyT();
 798       if (!KeyInfoT::isEqual(NewB->first, EmptyKey) &&
 799           !KeyInfoT::isEqual(NewB->first, TombstoneKey)) {
 800         new (&NewB->second) ValueT(llvm_move(OldB->second));
 801         OldB->second.~ValueT();
 802       }
 803     }
 804
 805     // The hard part of moving the small buckets across is done, just move
 806     // the TmpRep into its new home.
 807     SmallSide.Small = false;
 808     new (SmallSide.getLargeRep()) LargeRep(llvm_move(TmpRep));
 809   }
 810
 811   SmallDenseMap& operator=(const SmallDenseMap& other) {
 812     copyFrom(other);
 813     return *this;
 814   }
 815
 816 #if LLVM_HAS_RVALUE_REFERENCES
 817   SmallDenseMap& operator=(SmallDenseMap &&other) {
 818     this->destroyAll();
 819     deallocateBuckets();
 820     init(0);
 821     swap(other);
 822     return *this;
 823   }
 824 #endif
 825
 826   void copyFrom(const SmallDenseMap& other) {
 827     this->destroyAll();
 828     deallocateBuckets();
 829     Small = true;
 830     if (other.getNumBuckets() > InlineBuckets) {
 831       Small = false;
 832       allocateBuckets(other.getNumBuckets());
 833     }
 834     this->BaseT::copyFrom(other);
 835   }
 836
 837   void init(unsigned InitBuckets) {
 838     Small = true;
 839     if (InitBuckets > InlineBuckets) {
 840       Small = false;
 841       new (getLargeRep()) LargeRep(allocateBuckets(InitBuckets));
 842     }
 843     this->BaseT::initEmpty();
 844   }
 845
 846   void grow(unsigned AtLeast) {
 847     if (AtLeast >= InlineBuckets)
 848       AtLeast = std::max<unsigned>(64, NextPowerOf2(AtLeast-1));
 849
 850     if (Small) {
 851       if (AtLeast < InlineBuckets)
 852         return; // Nothing to do.
 853
 854       // First move the inline buckets into a temporary storage.
 855       AlignedCharArrayUnion<BucketT[InlineBuckets]> TmpStorage;
 856       BucketT *TmpBegin = reinterpret_cast<BucketT *>(TmpStorage.buffer);
 857       BucketT *TmpEnd = TmpBegin;
 858
 859       // Loop over the buckets, moving non-empty, non-tombstones into the
 860       // temporary storage. Have the loop move the TmpEnd forward as it goes.
 861       const KeyT EmptyKey = this->getEmptyKey();
 862       const KeyT TombstoneKey = this->getTombstoneKey();
 863       for (BucketT *P = getBuckets(), *E = P + InlineBuckets; P != E; ++P) {
 864         if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
 865             !KeyInfoT::isEqual(P->first, TombstoneKey)) {
 866           assert(size_t(TmpEnd - TmpBegin) < InlineBuckets &&
 867                  "Too many inline buckets!");
 868           new (&TmpEnd->first) KeyT(llvm_move(P->first));
 869           new (&TmpEnd->second) ValueT(llvm_move(P->second));
 870           ++TmpEnd;
 871           P->second.~ValueT();
 872         }
 873         P->first.~KeyT();
 874       }
 875
 876       // Now make this map use the large rep, and move all the entries back
 877       // into it.
 878       Small = false;
 879       new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
 880       this->moveFromOldBuckets(TmpBegin, TmpEnd);
 881       return;
 882     }
 883
 884     LargeRep OldRep = llvm_move(*getLargeRep());
 885     getLargeRep()->~LargeRep();
 886     if (AtLeast <= InlineBuckets) {
 887       Small = true;
 888     } else {
 889       new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
 890     }
 891
 892     this->moveFromOldBuckets(OldRep.Buckets, OldRep.Buckets+OldRep.NumBuckets);
 893
 894     // Free the old table.
 895     operator delete(OldRep.Buckets);
 896   }
 897
 898   void shrink_and_clear() {
 899     unsigned OldSize = this->size();
 900     this->destroyAll();
 901
 902     // Reduce the number of buckets.
 903     unsigned NewNumBuckets = 0;
 904     if (OldSize) {
 905       NewNumBuckets = 1 << (Log2_32_Ceil(OldSize) + 1);
 906       if (NewNumBuckets > InlineBuckets && NewNumBuckets < 64u)
 907         NewNumBuckets = 64;
 908     }
 909     if ((Small && NewNumBuckets <= InlineBuckets) ||
 910         (!Small && NewNumBuckets == getLargeRep()->NumBuckets)) {
 911       this->BaseT::initEmpty();
 912       return;
 913     }
 914
 915     deallocateBuckets();
 916     init(NewNumBuckets);
 917   }
 918
 919 private:
 920   unsigned getNumEntries() const {
 921     return NumEntries;
 922   }
 923   void setNumEntries(unsigned Num) {
 924     assert(Num < INT_MAX && "Cannot support more than INT_MAX entries");
 925     NumEntries = Num;
 926   }
 927
 928   unsigned getNumTombstones() const {
 929     return NumTombstones;
 930   }
 931   void setNumTombstones(unsigned Num) {
 932     NumTombstones = Num;
 933   }
 934
 935   const BucketT *getInlineBuckets() const {
 936     assert(Small);
 937     // Note that this cast does not violate aliasing rules as we assert that
 938     // the memory's dynamic type is the small, inline bucket buffer, and the
 939     // 'storage.buffer' static type is 'char *'.
 940     return reinterpret_cast<const BucketT *>(storage.buffer);
 941   }
 942   BucketT *getInlineBuckets() {
 943     return const_cast<BucketT *>(
 944       const_cast<const SmallDenseMap *>(this)->getInlineBuckets());
 945   }
 946   const LargeRep *getLargeRep() const {
 947     assert(!Small);
 948     // Note, same rule about aliasing as with getInlineBuckets.
 949     return reinterpret_cast<const LargeRep *>(storage.buffer);
 950   }
 951   LargeRep *getLargeRep() {
 952     return const_cast<LargeRep *>(
 953       const_cast<const SmallDenseMap *>(this)->getLargeRep());
 954   }
 955
 956   const BucketT *getBuckets() const {
 957     return Small ? getInlineBuckets() : getLargeRep()->Buckets;
 958   }
 959   BucketT *getBuckets() {
 960     return const_cast<BucketT *>(
 961       const_cast<const SmallDenseMap *>(this)->getBuckets());
 962   }
 963   unsigned getNumBuckets() const {
 964     return Small ? InlineBuckets : getLargeRep()->NumBuckets;
 965   }
 966
 967   void deallocateBuckets() {
 968     if (Small)
 969       return;
 970
 971     operator delete(getLargeRep()->Buckets);
 972     getLargeRep()->~LargeRep();
 973   }
 974
 975   LargeRep allocateBuckets(unsigned Num) {
 976     assert(Num > InlineBuckets && "Must allocate more buckets than are inline");
 977     LargeRep Rep = {
 978       static_cast<BucketT*>(operator new(sizeof(BucketT) * Num)), Num
 979     };
 980     return Rep;
 981   }
 982 };
 983
 984 template<typename KeyT, typename ValueT,
 985          typename KeyInfoT, bool IsConst>
 986 class DenseMapIterator {
 987   typedef std::pair<KeyT, ValueT> Bucket;
 988   typedef DenseMapIterator<KeyT, ValueT,
 989                            KeyInfoT, true> ConstIterator;
 990   friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, true>;
 991 public:
 992   typedef ptrdiff_t difference_type;
 993   typedef typename conditional<IsConst, const Bucket, Bucket>::type value_type;
 994   typedef value_type *pointer;
 995   typedef value_type &reference;
 996   typedef std::forward_iterator_tag iterator_category;
 997 private:
 998   pointer Ptr, End;
 999 public:
1000   DenseMapIterator() : Ptr(0), End(0) {}
1001
1002   DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false)
1003     : Ptr(Pos), End(E) {
1004     if (!NoAdvance) AdvancePastEmptyBuckets();
1005   }
1006
1007   // If IsConst is true this is a converting constructor from iterator to
1008   // const_iterator and the default copy constructor is used.
1009   // Otherwise this is a copy constructor for iterator.
1010   DenseMapIterator(const DenseMapIterator<KeyT, ValueT,
1011                                           KeyInfoT, false>& I)
1012     : Ptr(I.Ptr), End(I.End) {}
1013
1014   reference operator*() const {
1015     return *Ptr;
1016   }
1017   pointer operator->() const {
1018     return Ptr;
1019   }
1020
1021   bool operator==(const ConstIterator &RHS) const {
1022     return Ptr == RHS.operator->();
1023   }
1024   bool operator!=(const ConstIterator &RHS) const {
1025     return Ptr != RHS.operator->();
1026   }
1027
1028   inline DenseMapIterator& operator++() {  // Preincrement
1029     ++Ptr;
1030     AdvancePastEmptyBuckets();
1031     return *this;
1032   }
1033   DenseMapIterator operator++(int) {  // Postincrement
1034     DenseMapIterator tmp = *this; ++*this; return tmp;
1035   }
1036
1037 private:
1038   void AdvancePastEmptyBuckets() {
1039     const KeyT Empty = KeyInfoT::getEmptyKey();
1040     const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1041
1042     while (Ptr != End &&
1043            (KeyInfoT::isEqual(Ptr->first, Empty) ||
1044             KeyInfoT::isEqual(Ptr->first, Tombstone)))
1045       ++Ptr;
1046   }
1047 };
1048
1049 template<typename KeyT, typename ValueT, typename KeyInfoT>
1050 static inline size_t
1051 capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) {
1052   return X.getMemorySize();
1053 }
1054
1055 } // end namespace llvm
1056
1057 #endif