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/ADT/EpochTracker.h"
19#include "llvm/Support/AlignOf.h"
20#include "llvm/Support/Compiler.h"
21#include "llvm/Support/MathExtras.h"
22#include "llvm/Support/PointerLikeTypeTraits.h"
23#include "llvm/Support/type_traits.h"
24#include <algorithm>
25#include <cassert>
26#include <climits>
27#include <cstddef>
28#include <cstring>
29#include <iterator>
30#include <new>
31#include <utility>
32
33namespace llvm {
34
35namespace detail {
36// We extend a pair to allow users to override the bucket type with their own
37// implementation without requiring two members.
38template <typename KeyT, typename ValueT>
39struct DenseMapPair : public std::pair<KeyT, ValueT> {
40  KeyT &getFirst() { return std::pair<KeyT, ValueT>::first; }
41  const KeyT &getFirst() const { return std::pair<KeyT, ValueT>::first; }
42  ValueT &getSecond() { return std::pair<KeyT, ValueT>::second; }
43  const ValueT &getSecond() const { return std::pair<KeyT, ValueT>::second; }
44};
45}
46
47template <
48    typename KeyT, typename ValueT, typename KeyInfoT = DenseMapInfo<KeyT>,
49    typename Bucket = detail::DenseMapPair<KeyT, ValueT>, bool IsConst = false>
50class DenseMapIterator;
51
52template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
53          typename BucketT>
54class DenseMapBase : public DebugEpochBase {
55public:
56  typedef unsigned size_type;
57  typedef KeyT key_type;
58  typedef ValueT mapped_type;
59  typedef BucketT value_type;
60
61  typedef DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT> iterator;
62  typedef DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT, true>
63      const_iterator;
64  inline iterator begin() {
65    // When the map is empty, avoid the overhead of AdvancePastEmptyBuckets().
66    return empty() ? end() : iterator(getBuckets(), getBucketsEnd(), *this);
67  }
68  inline iterator end() {
69    return iterator(getBucketsEnd(), getBucketsEnd(), *this, true);
70  }
71  inline const_iterator begin() const {
72    return empty() ? end()
73                   : const_iterator(getBuckets(), getBucketsEnd(), *this);
74  }
75  inline const_iterator end() const {
76    return const_iterator(getBucketsEnd(), getBucketsEnd(), *this, true);
77  }
78
79  bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
80    return getNumEntries() == 0;
81  }
82  unsigned size() const { return getNumEntries(); }
83
84  /// Grow the densemap so that it can contain at least \p NumEntries items
85  /// before resizing again.
86  void reserve(size_type NumEntries) {
87    auto NumBuckets = getMinBucketToReserveForEntries(NumEntries);
88    incrementEpoch();
89    if (NumBuckets > getNumBuckets())
90      grow(NumBuckets);
91  }
92
93  void clear() {
94    incrementEpoch();
95    if (getNumEntries() == 0 && getNumTombstones() == 0) return;
96
97    // If the capacity of the array is huge, and the # elements used is small,
98    // shrink the array.
99    if (getNumEntries() * 4 < getNumBuckets() && getNumBuckets() > 64) {
100      shrink_and_clear();
101      return;
102    }
103
104    const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
105    unsigned NumEntries = getNumEntries();
106    for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
107      if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey)) {
108        if (!KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
109          P->getSecond().~ValueT();
110          --NumEntries;
111        }
112        P->getFirst() = EmptyKey;
113      }
114    }
115    assert(NumEntries == 0 && "Node count imbalance!");
116    setNumEntries(0);
117    setNumTombstones(0);
118  }
119
120  /// Return 1 if the specified key is in the map, 0 otherwise.
121  size_type count(const KeyT &Val) const {
122    const BucketT *TheBucket;
123    return LookupBucketFor(Val, TheBucket) ? 1 : 0;
124  }
125
126  iterator find(const KeyT &Val) {
127    BucketT *TheBucket;
128    if (LookupBucketFor(Val, TheBucket))
129      return iterator(TheBucket, getBucketsEnd(), *this, true);
130    return end();
131  }
132  const_iterator find(const KeyT &Val) const {
133    const BucketT *TheBucket;
134    if (LookupBucketFor(Val, TheBucket))
135      return const_iterator(TheBucket, getBucketsEnd(), *this, true);
136    return end();
137  }
138
139  /// Alternate version of find() which allows a different, and possibly
140  /// less expensive, key type.
141  /// The DenseMapInfo is responsible for supplying methods
142  /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
143  /// type used.
144  template<class LookupKeyT>
145  iterator find_as(const LookupKeyT &Val) {
146    BucketT *TheBucket;
147    if (LookupBucketFor(Val, TheBucket))
148      return iterator(TheBucket, getBucketsEnd(), *this, true);
149    return end();
150  }
151  template<class LookupKeyT>
152  const_iterator find_as(const LookupKeyT &Val) const {
153    const BucketT *TheBucket;
154    if (LookupBucketFor(Val, TheBucket))
155      return const_iterator(TheBucket, getBucketsEnd(), *this, true);
156    return end();
157  }
158
159  /// lookup - Return the entry for the specified key, or a default
160  /// constructed value if no such entry exists.
161  ValueT lookup(const KeyT &Val) const {
162    const BucketT *TheBucket;
163    if (LookupBucketFor(Val, TheBucket))
164      return TheBucket->getSecond();
165    return ValueT();
166  }
167
168  // Inserts key,value pair into the map if the key isn't already in the map.
169  // If the key is already in the map, it returns false and doesn't update the
170  // value.
171  std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
172    BucketT *TheBucket;
173    if (LookupBucketFor(KV.first, TheBucket))
174      return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
175                            false); // Already in map.
176
177    // Otherwise, insert the new element.
178    TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
179    return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
180                          true);
181  }
182
183  // Inserts key,value pair into the map if the key isn't already in the map.
184  // If the key is already in the map, it returns false and doesn't update the
185  // value.
186  std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
187    BucketT *TheBucket;
188    if (LookupBucketFor(KV.first, TheBucket))
189      return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
190                            false); // Already in map.
191
192    // Otherwise, insert the new element.
193    TheBucket = InsertIntoBucket(std::move(KV.first),
194                                 std::move(KV.second),
195                                 TheBucket);
196    return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
197                          true);
198  }
199
200  /// Alternate version of insert() which allows a different, and possibly
201  /// less expensive, key type.
202  /// The DenseMapInfo is responsible for supplying methods
203  /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
204  /// type used.
205  template <typename LookupKeyT>
206  std::pair<iterator, bool> insert_as(std::pair<KeyT, ValueT> &&KV,
207                                      const LookupKeyT &Val) {
208    BucketT *TheBucket;
209    if (LookupBucketFor(Val, TheBucket))
210      return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
211                            false); // Already in map.
212
213    // Otherwise, insert the new element.
214    TheBucket = InsertIntoBucket(std::move(KV.first), std::move(KV.second), Val,
215                                 TheBucket);
216    return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
217                          true);
218  }
219
220  /// insert - Range insertion of pairs.
221  template<typename InputIt>
222  void insert(InputIt I, InputIt E) {
223    for (; I != E; ++I)
224      insert(*I);
225  }
226
227
228  bool erase(const KeyT &Val) {
229    BucketT *TheBucket;
230    if (!LookupBucketFor(Val, TheBucket))
231      return false; // not in map.
232
233    TheBucket->getSecond().~ValueT();
234    TheBucket->getFirst() = getTombstoneKey();
235    decrementNumEntries();
236    incrementNumTombstones();
237    return true;
238  }
239  void erase(iterator I) {
240    BucketT *TheBucket = &*I;
241    TheBucket->getSecond().~ValueT();
242    TheBucket->getFirst() = getTombstoneKey();
243    decrementNumEntries();
244    incrementNumTombstones();
245  }
246
247  value_type& FindAndConstruct(const KeyT &Key) {
248    BucketT *TheBucket;
249    if (LookupBucketFor(Key, TheBucket))
250      return *TheBucket;
251
252    return *InsertIntoBucket(Key, ValueT(), TheBucket);
253  }
254
255  ValueT &operator[](const KeyT &Key) {
256    return FindAndConstruct(Key).second;
257  }
258
259  value_type& FindAndConstruct(KeyT &&Key) {
260    BucketT *TheBucket;
261    if (LookupBucketFor(Key, TheBucket))
262      return *TheBucket;
263
264    return *InsertIntoBucket(std::move(Key), ValueT(), TheBucket);
265  }
266
267  ValueT &operator[](KeyT &&Key) {
268    return FindAndConstruct(std::move(Key)).second;
269  }
270
271  /// isPointerIntoBucketsArray - Return true if the specified pointer points
272  /// somewhere into the DenseMap's array of buckets (i.e. either to a key or
273  /// value in the DenseMap).
274  bool isPointerIntoBucketsArray(const void *Ptr) const {
275    return Ptr >= getBuckets() && Ptr < getBucketsEnd();
276  }
277
278  /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
279  /// array.  In conjunction with the previous method, this can be used to
280  /// determine whether an insertion caused the DenseMap to reallocate.
281  const void *getPointerIntoBucketsArray() const { return getBuckets(); }
282
283protected:
284  DenseMapBase() = default;
285
286  void destroyAll() {
287    if (getNumBuckets() == 0) // Nothing to do.
288      return;
289
290    const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
291    for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
292      if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
293          !KeyInfoT::isEqual(P->getFirst(), TombstoneKey))
294        P->getSecond().~ValueT();
295      P->getFirst().~KeyT();
296    }
297  }
298
299  void initEmpty() {
300    setNumEntries(0);
301    setNumTombstones(0);
302
303    assert((getNumBuckets() & (getNumBuckets()-1)) == 0 &&
304           "# initial buckets must be a power of two!");
305    const KeyT EmptyKey = getEmptyKey();
306    for (BucketT *B = getBuckets(), *E = getBucketsEnd(); B != E; ++B)
307      ::new (&B->getFirst()) KeyT(EmptyKey);
308  }
309
310  /// Returns the number of buckets to allocate to ensure that the DenseMap can
311  /// accommodate \p NumEntries without need to grow().
312  unsigned getMinBucketToReserveForEntries(unsigned NumEntries) {
313    // Ensure that "NumEntries * 4 < NumBuckets * 3"
314    if (NumEntries == 0)
315      return 0;
316    // +1 is required because of the strict equality.
317    // For example if NumEntries is 48, we need to return 401.
318    return NextPowerOf2(NumEntries * 4 / 3 + 1);
319  }
320
321  void moveFromOldBuckets(BucketT *OldBucketsBegin, BucketT *OldBucketsEnd) {
322    initEmpty();
323
324    // Insert all the old elements.
325    const KeyT EmptyKey = getEmptyKey();
326    const KeyT TombstoneKey = getTombstoneKey();
327    for (BucketT *B = OldBucketsBegin, *E = OldBucketsEnd; B != E; ++B) {
328      if (!KeyInfoT::isEqual(B->getFirst(), EmptyKey) &&
329          !KeyInfoT::isEqual(B->getFirst(), TombstoneKey)) {
330        // Insert the key/value into the new table.
331        BucketT *DestBucket;
332        bool FoundVal = LookupBucketFor(B->getFirst(), DestBucket);
333        (void)FoundVal; // silence warning.
334        assert(!FoundVal && "Key already in new map?");
335        DestBucket->getFirst() = std::move(B->getFirst());
336        ::new (&DestBucket->getSecond()) ValueT(std::move(B->getSecond()));
337        incrementNumEntries();
338
339        // Free the value.
340        B->getSecond().~ValueT();
341      }
342      B->getFirst().~KeyT();
343    }
344  }
345
346  template <typename OtherBaseT>
347  void copyFrom(
348      const DenseMapBase<OtherBaseT, KeyT, ValueT, KeyInfoT, BucketT> &other) {
349    assert(&other != this);
350    assert(getNumBuckets() == other.getNumBuckets());
351
352    setNumEntries(other.getNumEntries());
353    setNumTombstones(other.getNumTombstones());
354
355    if (isPodLike<KeyT>::value && isPodLike<ValueT>::value)
356      memcpy(getBuckets(), other.getBuckets(),
357             getNumBuckets() * sizeof(BucketT));
358    else
359      for (size_t i = 0; i < getNumBuckets(); ++i) {
360        ::new (&getBuckets()[i].getFirst())
361            KeyT(other.getBuckets()[i].getFirst());
362        if (!KeyInfoT::isEqual(getBuckets()[i].getFirst(), getEmptyKey()) &&
363            !KeyInfoT::isEqual(getBuckets()[i].getFirst(), getTombstoneKey()))
364          ::new (&getBuckets()[i].getSecond())
365              ValueT(other.getBuckets()[i].getSecond());
366      }
367  }
368
369  static unsigned getHashValue(const KeyT &Val) {
370    return KeyInfoT::getHashValue(Val);
371  }
372  template<typename LookupKeyT>
373  static unsigned getHashValue(const LookupKeyT &Val) {
374    return KeyInfoT::getHashValue(Val);
375  }
376  static const KeyT getEmptyKey() {
377    return KeyInfoT::getEmptyKey();
378  }
379  static const KeyT getTombstoneKey() {
380    return KeyInfoT::getTombstoneKey();
381  }
382
383private:
384  unsigned getNumEntries() const {
385    return static_cast<const DerivedT *>(this)->getNumEntries();
386  }
387  void setNumEntries(unsigned Num) {
388    static_cast<DerivedT *>(this)->setNumEntries(Num);
389  }
390  void incrementNumEntries() {
391    setNumEntries(getNumEntries() + 1);
392  }
393  void decrementNumEntries() {
394    setNumEntries(getNumEntries() - 1);
395  }
396  unsigned getNumTombstones() const {
397    return static_cast<const DerivedT *>(this)->getNumTombstones();
398  }
399  void setNumTombstones(unsigned Num) {
400    static_cast<DerivedT *>(this)->setNumTombstones(Num);
401  }
402  void incrementNumTombstones() {
403    setNumTombstones(getNumTombstones() + 1);
404  }
405  void decrementNumTombstones() {
406    setNumTombstones(getNumTombstones() - 1);
407  }
408  const BucketT *getBuckets() const {
409    return static_cast<const DerivedT *>(this)->getBuckets();
410  }
411  BucketT *getBuckets() {
412    return static_cast<DerivedT *>(this)->getBuckets();
413  }
414  unsigned getNumBuckets() const {
415    return static_cast<const DerivedT *>(this)->getNumBuckets();
416  }
417  BucketT *getBucketsEnd() {
418    return getBuckets() + getNumBuckets();
419  }
420  const BucketT *getBucketsEnd() const {
421    return getBuckets() + getNumBuckets();
422  }
423
424  void grow(unsigned AtLeast) {
425    static_cast<DerivedT *>(this)->grow(AtLeast);
426  }
427
428  void shrink_and_clear() {
429    static_cast<DerivedT *>(this)->shrink_and_clear();
430  }
431
432
433  BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
434                            BucketT *TheBucket) {
435    TheBucket = InsertIntoBucketImpl(Key, Key, TheBucket);
436
437    TheBucket->getFirst() = Key;
438    ::new (&TheBucket->getSecond()) ValueT(Value);
439    return TheBucket;
440  }
441
442  BucketT *InsertIntoBucket(const KeyT &Key, ValueT &&Value,
443                            BucketT *TheBucket) {
444    TheBucket = InsertIntoBucketImpl(Key, Key, TheBucket);
445
446    TheBucket->getFirst() = Key;
447    ::new (&TheBucket->getSecond()) ValueT(std::move(Value));
448    return TheBucket;
449  }
450
451  BucketT *InsertIntoBucket(KeyT &&Key, ValueT &&Value, BucketT *TheBucket) {
452    TheBucket = InsertIntoBucketImpl(Key, Key, TheBucket);
453
454    TheBucket->getFirst() = std::move(Key);
455    ::new (&TheBucket->getSecond()) ValueT(std::move(Value));
456    return TheBucket;
457  }
458
459  template <typename LookupKeyT>
460  BucketT *InsertIntoBucket(KeyT &&Key, ValueT &&Value, LookupKeyT &Lookup,
461                            BucketT *TheBucket) {
462    TheBucket = InsertIntoBucketImpl(Key, Lookup, TheBucket);
463
464    TheBucket->getFirst() = std::move(Key);
465    ::new (&TheBucket->getSecond()) ValueT(std::move(Value));
466    return TheBucket;
467  }
468
469  template <typename LookupKeyT>
470  BucketT *InsertIntoBucketImpl(const KeyT &Key, const LookupKeyT &Lookup,
471                                BucketT *TheBucket) {
472    incrementEpoch();
473
474    // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
475    // the buckets are empty (meaning that many are filled with tombstones),
476    // grow the table.
477    //
478    // The later case is tricky.  For example, if we had one empty bucket with
479    // tons of tombstones, failing lookups (e.g. for insertion) would have to
480    // probe almost the entire table until it found the empty bucket.  If the
481    // table completely filled with tombstones, no lookup would ever succeed,
482    // causing infinite loops in lookup.
483    unsigned NewNumEntries = getNumEntries() + 1;
484    unsigned NumBuckets = getNumBuckets();
485    if (LLVM_UNLIKELY(NewNumEntries * 4 >= NumBuckets * 3)) {
486      this->grow(NumBuckets * 2);
487      LookupBucketFor(Lookup, TheBucket);
488      NumBuckets = getNumBuckets();
489    } else if (LLVM_UNLIKELY(NumBuckets-(NewNumEntries+getNumTombstones()) <=
490                             NumBuckets/8)) {
491      this->grow(NumBuckets);
492      LookupBucketFor(Lookup, TheBucket);
493    }
494    assert(TheBucket);
495
496    // Only update the state after we've grown our bucket space appropriately
497    // so that when growing buckets we have self-consistent entry count.
498    incrementNumEntries();
499
500    // If we are writing over a tombstone, remember this.
501    const KeyT EmptyKey = getEmptyKey();
502    if (!KeyInfoT::isEqual(TheBucket->getFirst(), EmptyKey))
503      decrementNumTombstones();
504
505    return TheBucket;
506  }
507
508  /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
509  /// FoundBucket.  If the bucket contains the key and a value, this returns
510  /// true, otherwise it returns a bucket with an empty marker or tombstone and
511  /// returns false.
512  template<typename LookupKeyT>
513  bool LookupBucketFor(const LookupKeyT &Val,
514                       const BucketT *&FoundBucket) const {
515    const BucketT *BucketsPtr = getBuckets();
516    const unsigned NumBuckets = getNumBuckets();
517
518    if (NumBuckets == 0) {
519      FoundBucket = nullptr;
520      return false;
521    }
522
523    // FoundTombstone - Keep track of whether we find a tombstone while probing.
524    const BucketT *FoundTombstone = nullptr;
525    const KeyT EmptyKey = getEmptyKey();
526    const KeyT TombstoneKey = getTombstoneKey();
527    assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
528           !KeyInfoT::isEqual(Val, TombstoneKey) &&
529           "Empty/Tombstone value shouldn't be inserted into map!");
530
531    unsigned BucketNo = getHashValue(Val) & (NumBuckets-1);
532    unsigned ProbeAmt = 1;
533    while (1) {
534      const BucketT *ThisBucket = BucketsPtr + BucketNo;
535      // Found Val's bucket?  If so, return it.
536      if (LLVM_LIKELY(KeyInfoT::isEqual(Val, ThisBucket->getFirst()))) {
537        FoundBucket = ThisBucket;
538        return true;
539      }
540
541      // If we found an empty bucket, the key doesn't exist in the set.
542      // Insert it and return the default value.
543      if (LLVM_LIKELY(KeyInfoT::isEqual(ThisBucket->getFirst(), EmptyKey))) {
544        // If we've already seen a tombstone while probing, fill it in instead
545        // of the empty bucket we eventually probed to.
546        FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
547        return false;
548      }
549
550      // If this is a tombstone, remember it.  If Val ends up not in the map, we
551      // prefer to return it than something that would require more probing.
552      if (KeyInfoT::isEqual(ThisBucket->getFirst(), TombstoneKey) &&
553          !FoundTombstone)
554        FoundTombstone = ThisBucket;  // Remember the first tombstone found.
555
556      // Otherwise, it's a hash collision or a tombstone, continue quadratic
557      // probing.
558      BucketNo += ProbeAmt++;
559      BucketNo &= (NumBuckets-1);
560    }
561  }
562
563  template <typename LookupKeyT>
564  bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) {
565    const BucketT *ConstFoundBucket;
566    bool Result = const_cast<const DenseMapBase *>(this)
567      ->LookupBucketFor(Val, ConstFoundBucket);
568    FoundBucket = const_cast<BucketT *>(ConstFoundBucket);
569    return Result;
570  }
571
572public:
573  /// Return the approximate size (in bytes) of the actual map.
574  /// This is just the raw memory used by DenseMap.
575  /// If entries are pointers to objects, the size of the referenced objects
576  /// are not included.
577  size_t getMemorySize() const {
578    return getNumBuckets() * sizeof(BucketT);
579  }
580};
581
582template <typename KeyT, typename ValueT,
583          typename KeyInfoT = DenseMapInfo<KeyT>,
584          typename BucketT = detail::DenseMapPair<KeyT, ValueT>>
585class DenseMap : public DenseMapBase<DenseMap<KeyT, ValueT, KeyInfoT, BucketT>,
586                                     KeyT, ValueT, KeyInfoT, BucketT> {
587  // Lift some types from the dependent base class into this class for
588  // simplicity of referring to them.
589  typedef DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT> BaseT;
590  friend class DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
591
592  BucketT *Buckets;
593  unsigned NumEntries;
594  unsigned NumTombstones;
595  unsigned NumBuckets;
596
597public:
598  /// Create a DenseMap wth an optional \p InitialReserve that guarantee that
599  /// this number of elements can be inserted in the map without grow()
600  explicit DenseMap(unsigned InitialReserve = 0) { init(InitialReserve); }
601
602  DenseMap(const DenseMap &other) : BaseT() {
603    init(0);
604    copyFrom(other);
605  }
606
607  DenseMap(DenseMap &&other) : BaseT() {
608    init(0);
609    swap(other);
610  }
611
612  template<typename InputIt>
613  DenseMap(const InputIt &I, const InputIt &E) {
614    init(std::distance(I, E));
615    this->insert(I, E);
616  }
617
618  ~DenseMap() {
619    this->destroyAll();
620    operator delete(Buckets);
621  }
622
623  void swap(DenseMap& RHS) {
624    this->incrementEpoch();
625    RHS.incrementEpoch();
626    std::swap(Buckets, RHS.Buckets);
627    std::swap(NumEntries, RHS.NumEntries);
628    std::swap(NumTombstones, RHS.NumTombstones);
629    std::swap(NumBuckets, RHS.NumBuckets);
630  }
631
632  DenseMap& operator=(const DenseMap& other) {
633    if (&other != this)
634      copyFrom(other);
635    return *this;
636  }
637
638  DenseMap& operator=(DenseMap &&other) {
639    this->destroyAll();
640    operator delete(Buckets);
641    init(0);
642    swap(other);
643    return *this;
644  }
645
646  void copyFrom(const DenseMap& other) {
647    this->destroyAll();
648    operator delete(Buckets);
649    if (allocateBuckets(other.NumBuckets)) {
650      this->BaseT::copyFrom(other);
651    } else {
652      NumEntries = 0;
653      NumTombstones = 0;
654    }
655  }
656
657  void init(unsigned InitNumEntries) {
658    auto InitBuckets = BaseT::getMinBucketToReserveForEntries(InitNumEntries);
659    if (allocateBuckets(InitBuckets)) {
660      this->BaseT::initEmpty();
661    } else {
662      NumEntries = 0;
663      NumTombstones = 0;
664    }
665  }
666
667  void grow(unsigned AtLeast) {
668    unsigned OldNumBuckets = NumBuckets;
669    BucketT *OldBuckets = Buckets;
670
671    allocateBuckets(std::max<unsigned>(64, static_cast<unsigned>(NextPowerOf2(AtLeast-1))));
672    assert(Buckets);
673    if (!OldBuckets) {
674      this->BaseT::initEmpty();
675      return;
676    }
677
678    this->moveFromOldBuckets(OldBuckets, OldBuckets+OldNumBuckets);
679
680    // Free the old table.
681    operator delete(OldBuckets);
682  }
683
684  void shrink_and_clear() {
685    unsigned OldNumEntries = NumEntries;
686    this->destroyAll();
687
688    // Reduce the number of buckets.
689    unsigned NewNumBuckets = 0;
690    if (OldNumEntries)
691      NewNumBuckets = std::max(64, 1 << (Log2_32_Ceil(OldNumEntries) + 1));
692    if (NewNumBuckets == NumBuckets) {
693      this->BaseT::initEmpty();
694      return;
695    }
696
697    operator delete(Buckets);
698    init(NewNumBuckets);
699  }
700
701private:
702  unsigned getNumEntries() const {
703    return NumEntries;
704  }
705  void setNumEntries(unsigned Num) {
706    NumEntries = Num;
707  }
708
709  unsigned getNumTombstones() const {
710    return NumTombstones;
711  }
712  void setNumTombstones(unsigned Num) {
713    NumTombstones = Num;
714  }
715
716  BucketT *getBuckets() const {
717    return Buckets;
718  }
719
720  unsigned getNumBuckets() const {
721    return NumBuckets;
722  }
723
724  bool allocateBuckets(unsigned Num) {
725    NumBuckets = Num;
726    if (NumBuckets == 0) {
727      Buckets = nullptr;
728      return false;
729    }
730
731    Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets));
732    return true;
733  }
734};
735
736template <typename KeyT, typename ValueT, unsigned InlineBuckets = 4,
737          typename KeyInfoT = DenseMapInfo<KeyT>,
738          typename BucketT = detail::DenseMapPair<KeyT, ValueT>>
739class SmallDenseMap
740    : public DenseMapBase<
741          SmallDenseMap<KeyT, ValueT, InlineBuckets, KeyInfoT, BucketT>, KeyT,
742          ValueT, KeyInfoT, BucketT> {
743  // Lift some types from the dependent base class into this class for
744  // simplicity of referring to them.
745  typedef DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT> BaseT;
746  friend class DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
747
748  unsigned Small : 1;
749  unsigned NumEntries : 31;
750  unsigned NumTombstones;
751
752  struct LargeRep {
753    BucketT *Buckets;
754    unsigned NumBuckets;
755  };
756
757  /// A "union" of an inline bucket array and the struct representing
758  /// a large bucket. This union will be discriminated by the 'Small' bit.
759  AlignedCharArrayUnion<BucketT[InlineBuckets], LargeRep> storage;
760
761public:
762  explicit SmallDenseMap(unsigned NumInitBuckets = 0) {
763    init(NumInitBuckets);
764  }
765
766  SmallDenseMap(const SmallDenseMap &other) : BaseT() {
767    init(0);
768    copyFrom(other);
769  }
770
771  SmallDenseMap(SmallDenseMap &&other) : BaseT() {
772    init(0);
773    swap(other);
774  }
775
776  template<typename InputIt>
777  SmallDenseMap(const InputIt &I, const InputIt &E) {
778    init(NextPowerOf2(std::distance(I, E)));
779    this->insert(I, E);
780  }
781
782  ~SmallDenseMap() {
783    this->destroyAll();
784    deallocateBuckets();
785  }
786
787  void swap(SmallDenseMap& RHS) {
788    unsigned TmpNumEntries = RHS.NumEntries;
789    RHS.NumEntries = NumEntries;
790    NumEntries = TmpNumEntries;
791    std::swap(NumTombstones, RHS.NumTombstones);
792
793    const KeyT EmptyKey = this->getEmptyKey();
794    const KeyT TombstoneKey = this->getTombstoneKey();
795    if (Small && RHS.Small) {
796      // If we're swapping inline bucket arrays, we have to cope with some of
797      // the tricky bits of DenseMap's storage system: the buckets are not
798      // fully initialized. Thus we swap every key, but we may have
799      // a one-directional move of the value.
800      for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
801        BucketT *LHSB = &getInlineBuckets()[i],
802                *RHSB = &RHS.getInlineBuckets()[i];
803        bool hasLHSValue = (!KeyInfoT::isEqual(LHSB->getFirst(), EmptyKey) &&
804                            !KeyInfoT::isEqual(LHSB->getFirst(), TombstoneKey));
805        bool hasRHSValue = (!KeyInfoT::isEqual(RHSB->getFirst(), EmptyKey) &&
806                            !KeyInfoT::isEqual(RHSB->getFirst(), TombstoneKey));
807        if (hasLHSValue && hasRHSValue) {
808          // Swap together if we can...
809          std::swap(*LHSB, *RHSB);
810          continue;
811        }
812        // Swap separately and handle any assymetry.
813        std::swap(LHSB->getFirst(), RHSB->getFirst());
814        if (hasLHSValue) {
815          ::new (&RHSB->getSecond()) ValueT(std::move(LHSB->getSecond()));
816          LHSB->getSecond().~ValueT();
817        } else if (hasRHSValue) {
818          ::new (&LHSB->getSecond()) ValueT(std::move(RHSB->getSecond()));
819          RHSB->getSecond().~ValueT();
820        }
821      }
822      return;
823    }
824    if (!Small && !RHS.Small) {
825      std::swap(getLargeRep()->Buckets, RHS.getLargeRep()->Buckets);
826      std::swap(getLargeRep()->NumBuckets, RHS.getLargeRep()->NumBuckets);
827      return;
828    }
829
830    SmallDenseMap &SmallSide = Small ? *this : RHS;
831    SmallDenseMap &LargeSide = Small ? RHS : *this;
832
833    // First stash the large side's rep and move the small side across.
834    LargeRep TmpRep = std::move(*LargeSide.getLargeRep());
835    LargeSide.getLargeRep()->~LargeRep();
836    LargeSide.Small = true;
837    // This is similar to the standard move-from-old-buckets, but the bucket
838    // count hasn't actually rotated in this case. So we have to carefully
839    // move construct the keys and values into their new locations, but there
840    // is no need to re-hash things.
841    for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
842      BucketT *NewB = &LargeSide.getInlineBuckets()[i],
843              *OldB = &SmallSide.getInlineBuckets()[i];
844      ::new (&NewB->getFirst()) KeyT(std::move(OldB->getFirst()));
845      OldB->getFirst().~KeyT();
846      if (!KeyInfoT::isEqual(NewB->getFirst(), EmptyKey) &&
847          !KeyInfoT::isEqual(NewB->getFirst(), TombstoneKey)) {
848        ::new (&NewB->getSecond()) ValueT(std::move(OldB->getSecond()));
849        OldB->getSecond().~ValueT();
850      }
851    }
852
853    // The hard part of moving the small buckets across is done, just move
854    // the TmpRep into its new home.
855    SmallSide.Small = false;
856    new (SmallSide.getLargeRep()) LargeRep(std::move(TmpRep));
857  }
858
859  SmallDenseMap& operator=(const SmallDenseMap& other) {
860    if (&other != this)
861      copyFrom(other);
862    return *this;
863  }
864
865  SmallDenseMap& operator=(SmallDenseMap &&other) {
866    this->destroyAll();
867    deallocateBuckets();
868    init(0);
869    swap(other);
870    return *this;
871  }
872
873  void copyFrom(const SmallDenseMap& other) {
874    this->destroyAll();
875    deallocateBuckets();
876    Small = true;
877    if (other.getNumBuckets() > InlineBuckets) {
878      Small = false;
879      new (getLargeRep()) LargeRep(allocateBuckets(other.getNumBuckets()));
880    }
881    this->BaseT::copyFrom(other);
882  }
883
884  void init(unsigned InitBuckets) {
885    Small = true;
886    if (InitBuckets > InlineBuckets) {
887      Small = false;
888      new (getLargeRep()) LargeRep(allocateBuckets(InitBuckets));
889    }
890    this->BaseT::initEmpty();
891  }
892
893  void grow(unsigned AtLeast) {
894    if (AtLeast >= InlineBuckets)
895      AtLeast = std::max<unsigned>(64, NextPowerOf2(AtLeast-1));
896
897    if (Small) {
898      if (AtLeast < InlineBuckets)
899        return; // Nothing to do.
900
901      // First move the inline buckets into a temporary storage.
902      AlignedCharArrayUnion<BucketT[InlineBuckets]> TmpStorage;
903      BucketT *TmpBegin = reinterpret_cast<BucketT *>(TmpStorage.buffer);
904      BucketT *TmpEnd = TmpBegin;
905
906      // Loop over the buckets, moving non-empty, non-tombstones into the
907      // temporary storage. Have the loop move the TmpEnd forward as it goes.
908      const KeyT EmptyKey = this->getEmptyKey();
909      const KeyT TombstoneKey = this->getTombstoneKey();
910      for (BucketT *P = getBuckets(), *E = P + InlineBuckets; P != E; ++P) {
911        if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
912            !KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
913          assert(size_t(TmpEnd - TmpBegin) < InlineBuckets &&
914                 "Too many inline buckets!");
915          ::new (&TmpEnd->getFirst()) KeyT(std::move(P->getFirst()));
916          ::new (&TmpEnd->getSecond()) ValueT(std::move(P->getSecond()));
917          ++TmpEnd;
918          P->getSecond().~ValueT();
919        }
920        P->getFirst().~KeyT();
921      }
922
923      // Now make this map use the large rep, and move all the entries back
924      // into it.
925      Small = false;
926      new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
927      this->moveFromOldBuckets(TmpBegin, TmpEnd);
928      return;
929    }
930
931    LargeRep OldRep = std::move(*getLargeRep());
932    getLargeRep()->~LargeRep();
933    if (AtLeast <= InlineBuckets) {
934      Small = true;
935    } else {
936      new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
937    }
938
939    this->moveFromOldBuckets(OldRep.Buckets, OldRep.Buckets+OldRep.NumBuckets);
940
941    // Free the old table.
942    operator delete(OldRep.Buckets);
943  }
944
945  void shrink_and_clear() {
946    unsigned OldSize = this->size();
947    this->destroyAll();
948
949    // Reduce the number of buckets.
950    unsigned NewNumBuckets = 0;
951    if (OldSize) {
952      NewNumBuckets = 1 << (Log2_32_Ceil(OldSize) + 1);
953      if (NewNumBuckets > InlineBuckets && NewNumBuckets < 64u)
954        NewNumBuckets = 64;
955    }
956    if ((Small && NewNumBuckets <= InlineBuckets) ||
957        (!Small && NewNumBuckets == getLargeRep()->NumBuckets)) {
958      this->BaseT::initEmpty();
959      return;
960    }
961
962    deallocateBuckets();
963    init(NewNumBuckets);
964  }
965
966private:
967  unsigned getNumEntries() const {
968    return NumEntries;
969  }
970  void setNumEntries(unsigned Num) {
971    assert(Num < INT_MAX && "Cannot support more than INT_MAX entries");
972    NumEntries = Num;
973  }
974
975  unsigned getNumTombstones() const {
976    return NumTombstones;
977  }
978  void setNumTombstones(unsigned Num) {
979    NumTombstones = Num;
980  }
981
982  const BucketT *getInlineBuckets() const {
983    assert(Small);
984    // Note that this cast does not violate aliasing rules as we assert that
985    // the memory's dynamic type is the small, inline bucket buffer, and the
986    // 'storage.buffer' static type is 'char *'.
987    return reinterpret_cast<const BucketT *>(storage.buffer);
988  }
989  BucketT *getInlineBuckets() {
990    return const_cast<BucketT *>(
991      const_cast<const SmallDenseMap *>(this)->getInlineBuckets());
992  }
993  const LargeRep *getLargeRep() const {
994    assert(!Small);
995    // Note, same rule about aliasing as with getInlineBuckets.
996    return reinterpret_cast<const LargeRep *>(storage.buffer);
997  }
998  LargeRep *getLargeRep() {
999    return const_cast<LargeRep *>(
1000      const_cast<const SmallDenseMap *>(this)->getLargeRep());
1001  }
1002
1003  const BucketT *getBuckets() const {
1004    return Small ? getInlineBuckets() : getLargeRep()->Buckets;
1005  }
1006  BucketT *getBuckets() {
1007    return const_cast<BucketT *>(
1008      const_cast<const SmallDenseMap *>(this)->getBuckets());
1009  }
1010  unsigned getNumBuckets() const {
1011    return Small ? InlineBuckets : getLargeRep()->NumBuckets;
1012  }
1013
1014  void deallocateBuckets() {
1015    if (Small)
1016      return;
1017
1018    operator delete(getLargeRep()->Buckets);
1019    getLargeRep()->~LargeRep();
1020  }
1021
1022  LargeRep allocateBuckets(unsigned Num) {
1023    assert(Num > InlineBuckets && "Must allocate more buckets than are inline");
1024    LargeRep Rep = {
1025      static_cast<BucketT*>(operator new(sizeof(BucketT) * Num)), Num
1026    };
1027    return Rep;
1028  }
1029};
1030
1031template <typename KeyT, typename ValueT, typename KeyInfoT, typename Bucket,
1032          bool IsConst>
1033class DenseMapIterator : DebugEpochBase::HandleBase {
1034  typedef DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true> ConstIterator;
1035  friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>;
1036  friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, false>;
1037
1038public:
1039  typedef ptrdiff_t difference_type;
1040  typedef typename std::conditional<IsConst, const Bucket, Bucket>::type
1041  value_type;
1042  typedef value_type *pointer;
1043  typedef value_type &reference;
1044  typedef std::forward_iterator_tag iterator_category;
1045private:
1046  pointer Ptr, End;
1047public:
1048  DenseMapIterator() : Ptr(nullptr), End(nullptr) {}
1049
1050  DenseMapIterator(pointer Pos, pointer E, const DebugEpochBase &Epoch,
1051                   bool NoAdvance = false)
1052      : DebugEpochBase::HandleBase(&Epoch), Ptr(Pos), End(E) {
1053    assert(isHandleInSync() && "invalid construction!");
1054    if (!NoAdvance) AdvancePastEmptyBuckets();
1055  }
1056
1057  // Converting ctor from non-const iterators to const iterators. SFINAE'd out
1058  // for const iterator destinations so it doesn't end up as a user defined copy
1059  // constructor.
1060  template <bool IsConstSrc,
1061            typename = typename std::enable_if<!IsConstSrc && IsConst>::type>
1062  DenseMapIterator(
1063      const DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, IsConstSrc> &I)
1064      : DebugEpochBase::HandleBase(I), Ptr(I.Ptr), End(I.End) {}
1065
1066  reference operator*() const {
1067    assert(isHandleInSync() && "invalid iterator access!");
1068    return *Ptr;
1069  }
1070  pointer operator->() const {
1071    assert(isHandleInSync() && "invalid iterator access!");
1072    return Ptr;
1073  }
1074
1075  bool operator==(const ConstIterator &RHS) const {
1076    assert((!Ptr || isHandleInSync()) && "handle not in sync!");
1077    assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
1078    assert(getEpochAddress() == RHS.getEpochAddress() &&
1079           "comparing incomparable iterators!");
1080    return Ptr == RHS.Ptr;
1081  }
1082  bool operator!=(const ConstIterator &RHS) const {
1083    assert((!Ptr || isHandleInSync()) && "handle not in sync!");
1084    assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
1085    assert(getEpochAddress() == RHS.getEpochAddress() &&
1086           "comparing incomparable iterators!");
1087    return Ptr != RHS.Ptr;
1088  }
1089
1090  inline DenseMapIterator& operator++() {  // Preincrement
1091    assert(isHandleInSync() && "invalid iterator access!");
1092    ++Ptr;
1093    AdvancePastEmptyBuckets();
1094    return *this;
1095  }
1096  DenseMapIterator operator++(int) {  // Postincrement
1097    assert(isHandleInSync() && "invalid iterator access!");
1098    DenseMapIterator tmp = *this; ++*this; return tmp;
1099  }
1100
1101private:
1102  void AdvancePastEmptyBuckets() {
1103    const KeyT Empty = KeyInfoT::getEmptyKey();
1104    const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1105
1106    while (Ptr != End && (KeyInfoT::isEqual(Ptr->getFirst(), Empty) ||
1107                          KeyInfoT::isEqual(Ptr->getFirst(), Tombstone)))
1108      ++Ptr;
1109  }
1110};
1111
1112template<typename KeyT, typename ValueT, typename KeyInfoT>
1113static inline size_t
1114capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) {
1115  return X.getMemorySize();
1116}
1117
1118} // end namespace llvm
1119
1120#endif
1121