1 //===- llvm/ADT/SparseBitVector.h - Efficient Sparse BitVector -*- C++ -*- ===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the SparseBitVector class. See the doxygen comment for
11 // SparseBitVector for more details on the algorithm used.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ADT_SPARSEBITVECTOR_H
16 #define LLVM_ADT_SPARSEBITVECTOR_H
21 #include "llvm/Support/DataTypes.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/Support/MathExtras.h"
24 #include "llvm/ADT/ilist.h"
27 /// SparseBitVector is an implementation of a bitvector that is sparse by only
28 /// storing the elements that have non-zero bits set. In order to make this
29 /// fast for the most common cases, SparseBitVector is implemented as a linked
30 /// list of SparseBitVectorElements. We maintain a pointer to the last
31 /// SparseBitVectorElement accessed (in the form of a list iterator), in order
32 /// to make multiple in-order test/set constant time after the first one is
33 /// executed. Note that using vectors to store SparseBitVectorElement's does
34 /// not work out very well because it causes insertion in the middle to take
35 /// enormous amounts of time with a large amount of bits. Other structures that
36 /// have better worst cases for insertion in the middle (various balanced trees,
37 /// etc) do not perform as well in practice as a linked list with this iterator
38 /// kept up to date. They are also significantly more memory intensive.
41 template <unsigned ElementSize = 128>
42 struct SparseBitVectorElement {
44 typedef unsigned long BitWord;
46 BITWORD_SIZE = sizeof(BitWord) * 8,
47 BITWORDS_PER_ELEMENT = (ElementSize + BITWORD_SIZE - 1) / BITWORD_SIZE,
48 BITS_PER_ELEMENT = ElementSize
51 SparseBitVectorElement<ElementSize> *getNext() const {
54 SparseBitVectorElement<ElementSize> *getPrev() const {
58 void setNext(SparseBitVectorElement<ElementSize> *RHS) {
61 void setPrev(SparseBitVectorElement<ElementSize> *RHS) {
66 SparseBitVectorElement<ElementSize> *Next;
67 SparseBitVectorElement<ElementSize> *Prev;
68 // Index of Element in terms of where first bit starts.
69 unsigned ElementIndex;
70 BitWord Bits[BITWORDS_PER_ELEMENT];
71 // Needed for sentinels
72 SparseBitVectorElement() {
74 memset(&Bits[0], 0, sizeof (BitWord) * BITWORDS_PER_ELEMENT);
77 friend struct ilist_traits<SparseBitVectorElement<ElementSize> >;
79 explicit SparseBitVectorElement(unsigned Idx) {
81 memset(&Bits[0], 0, sizeof (BitWord) * BITWORDS_PER_ELEMENT);
84 ~SparseBitVectorElement() {
88 SparseBitVectorElement(const SparseBitVectorElement &RHS) {
89 ElementIndex = RHS.ElementIndex;
90 std::copy(&RHS.Bits[0], &RHS.Bits[BITWORDS_PER_ELEMENT], Bits);
94 SparseBitVectorElement& operator=(const SparseBitVectorElement& RHS) {
95 ElementIndex = RHS.ElementIndex;
96 std::copy(&RHS.Bits[0], &RHS.Bits[BITWORDS_PER_ELEMENT], Bits);
102 bool operator==(const SparseBitVectorElement &RHS) const {
103 if (ElementIndex != RHS.ElementIndex)
105 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
106 if (Bits[i] != RHS.Bits[i])
111 bool operator!=(const SparseBitVectorElement &RHS) const {
112 return !(*this == RHS);
115 // Return the bits that make up word Idx in our element.
116 BitWord word(unsigned Idx) const {
117 assert (Idx < BITWORDS_PER_ELEMENT);
121 unsigned index() const {
126 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
132 void set(unsigned Idx) {
133 Bits[Idx / BITWORD_SIZE] |= 1L << (Idx % BITWORD_SIZE);
136 bool test_and_set (unsigned Idx) {
137 bool old = test(Idx);
145 void reset(unsigned Idx) {
146 Bits[Idx / BITWORD_SIZE] &= ~(1L << (Idx % BITWORD_SIZE));
149 bool test(unsigned Idx) const {
150 return Bits[Idx / BITWORD_SIZE] & (1L << (Idx % BITWORD_SIZE));
153 unsigned count() const {
154 unsigned NumBits = 0;
155 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
156 if (sizeof(BitWord) == 4)
157 NumBits += CountPopulation_32(Bits[i]);
158 else if (sizeof(BitWord) == 8)
159 NumBits += CountPopulation_64(Bits[i]);
161 assert(0 && "Unsupported!");
165 /// find_first - Returns the index of the first set bit.
166 int find_first() const {
167 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
169 if (sizeof(BitWord) == 4)
170 return i * BITWORD_SIZE + CountTrailingZeros_32(Bits[i]);
171 else if (sizeof(BitWord) == 8)
172 return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]);
174 assert(0 && "Unsupported!");
176 assert(0 && "Illegal empty element");
177 return 0; // Not reached
180 /// find_next - Returns the index of the next set bit starting from the
181 /// "Curr" bit. Returns -1 if the next set bit is not found.
182 int find_next(unsigned Curr) const {
183 if (Curr >= BITS_PER_ELEMENT)
186 unsigned WordPos = Curr / BITWORD_SIZE;
187 unsigned BitPos = Curr % BITWORD_SIZE;
188 BitWord Copy = Bits[WordPos];
189 assert (WordPos <= BITWORDS_PER_ELEMENT
190 && "Word Position outside of element");
192 // Mask off previous bits.
193 Copy &= ~0L << BitPos;
196 if (sizeof(BitWord) == 4)
197 return WordPos * BITWORD_SIZE + CountTrailingZeros_32(Copy);
198 else if (sizeof(BitWord) == 8)
199 return WordPos * BITWORD_SIZE + CountTrailingZeros_64(Copy);
201 assert(0 && "Unsupported!");
204 // Check subsequent words.
205 for (unsigned i = WordPos+1; i < BITWORDS_PER_ELEMENT; ++i)
207 if (sizeof(BitWord) == 4)
208 return i * BITWORD_SIZE + CountTrailingZeros_32(Bits[i]);
209 else if (sizeof(BitWord) == 8)
210 return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]);
212 assert(0 && "Unsupported!");
217 // Union this element with RHS and return true if this one changed.
218 bool unionWith(const SparseBitVectorElement &RHS) {
219 bool changed = false;
220 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
221 BitWord old = changed ? 0 : Bits[i];
223 Bits[i] |= RHS.Bits[i];
224 if (!changed && old != Bits[i])
230 // Return true if we have any bits in common with RHS
231 bool intersects(const SparseBitVectorElement &RHS) const {
232 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
233 if (RHS.Bits[i] & Bits[i])
239 // Intersect this Element with RHS and return true if this one changed.
240 // BecameZero is set to true if this element became all-zero bits.
241 bool intersectWith(const SparseBitVectorElement &RHS,
243 bool changed = false;
247 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
248 BitWord old = changed ? 0 : Bits[i];
250 Bits[i] &= RHS.Bits[i];
254 if (!changed && old != Bits[i])
257 BecameZero = allzero;
260 // Intersect this Element with the complement of RHS and return true if this
261 // one changed. BecameZero is set to true if this element became all-zero
263 bool intersectWithComplement(const SparseBitVectorElement &RHS,
265 bool changed = false;
269 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
270 BitWord old = changed ? 0 : Bits[i];
272 Bits[i] &= ~RHS.Bits[i];
276 if (!changed && old != Bits[i])
279 BecameZero = allzero;
282 // Three argument version of intersectWithComplement that intersects
283 // RHS1 & ~RHS2 into this element
284 void intersectWithComplement(const SparseBitVectorElement &RHS1,
285 const SparseBitVectorElement &RHS2,
290 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
291 Bits[i] = RHS1.Bits[i] & ~RHS2.Bits[i];
295 BecameZero = allzero;
298 // Get a hash value for this element;
299 uint64_t getHashValue() const {
300 uint64_t HashVal = 0;
301 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
308 template <unsigned ElementSize = 128>
309 class SparseBitVector {
310 typedef ilist<SparseBitVectorElement<ElementSize> > ElementList;
311 typedef typename ElementList::iterator ElementListIter;
312 typedef typename ElementList::const_iterator ElementListConstIter;
314 BITWORD_SIZE = SparseBitVectorElement<ElementSize>::BITWORD_SIZE
317 // Pointer to our current Element.
318 ElementListIter CurrElementIter;
319 ElementList Elements;
321 // This is like std::lower_bound, except we do linear searching from the
323 ElementListIter FindLowerBound(unsigned ElementIndex) {
325 if (Elements.empty()) {
326 CurrElementIter = Elements.begin();
327 return Elements.begin();
330 // Make sure our current iterator is valid.
331 if (CurrElementIter == Elements.end())
334 // Search from our current iterator, either backwards or forwards,
335 // depending on what element we are looking for.
336 ElementListIter ElementIter = CurrElementIter;
337 if (CurrElementIter->index() == ElementIndex) {
339 } else if (CurrElementIter->index() > ElementIndex) {
340 while (ElementIter != Elements.begin()
341 && ElementIter->index() > ElementIndex)
344 while (ElementIter != Elements.end() &&
345 ElementIter->index() < ElementIndex)
348 CurrElementIter = ElementIter;
352 // Iterator to walk set bits in the bitmap. This iterator is a lot uglier
353 // than it would be, in order to be efficient.
354 class SparseBitVectorIterator {
358 const SparseBitVector<ElementSize> *BitVector;
360 // Current element inside of bitmap.
361 ElementListConstIter Iter;
363 // Current bit number inside of our bitmap.
366 // Current word number inside of our element.
369 // Current bits from the element.
370 typename SparseBitVectorElement<ElementSize>::BitWord Bits;
372 // Move our iterator to the first non-zero bit in the bitmap.
373 void AdvanceToFirstNonZero() {
376 if (BitVector->Elements.empty()) {
380 Iter = BitVector->Elements.begin();
381 BitNumber = Iter->index() * ElementSize;
382 unsigned BitPos = Iter->find_first();
384 WordNumber = (BitNumber % ElementSize) / BITWORD_SIZE;
385 Bits = Iter->word(WordNumber);
386 Bits >>= BitPos % BITWORD_SIZE;
389 // Move our iterator to the next non-zero bit.
390 void AdvanceToNextNonZero() {
394 while (Bits && !(Bits & 1)) {
399 // See if we ran out of Bits in this word.
401 int NextSetBitNumber = Iter->find_next(BitNumber % ElementSize) ;
402 // If we ran out of set bits in this element, move to next element.
403 if (NextSetBitNumber == -1 || (BitNumber % ElementSize == 0)) {
407 // We may run out of elements in the bitmap.
408 if (Iter == BitVector->Elements.end()) {
412 // Set up for next non zero word in bitmap.
413 BitNumber = Iter->index() * ElementSize;
414 NextSetBitNumber = Iter->find_first();
415 BitNumber += NextSetBitNumber;
416 WordNumber = (BitNumber % ElementSize) / BITWORD_SIZE;
417 Bits = Iter->word(WordNumber);
418 Bits >>= NextSetBitNumber % BITWORD_SIZE;
420 WordNumber = (NextSetBitNumber % ElementSize) / BITWORD_SIZE;
421 Bits = Iter->word(WordNumber);
422 Bits >>= NextSetBitNumber % BITWORD_SIZE;
423 BitNumber = Iter->index() * ElementSize;
424 BitNumber += NextSetBitNumber;
430 inline SparseBitVectorIterator& operator++() {
433 AdvanceToNextNonZero();
438 inline SparseBitVectorIterator operator++(int) {
439 SparseBitVectorIterator tmp = *this;
444 // Return the current set bit number.
445 unsigned operator*() const {
449 bool operator==(const SparseBitVectorIterator &RHS) const {
450 // If they are both at the end, ignore the rest of the fields.
451 if (AtEnd && RHS.AtEnd)
453 // Otherwise they are the same if they have the same bit number and
455 return AtEnd == RHS.AtEnd && RHS.BitNumber == BitNumber;
457 bool operator!=(const SparseBitVectorIterator &RHS) const {
458 return !(*this == RHS);
460 SparseBitVectorIterator(): BitVector(NULL) {
464 SparseBitVectorIterator(const SparseBitVector<ElementSize> *RHS,
465 bool end = false):BitVector(RHS) {
466 Iter = BitVector->Elements.begin();
471 AdvanceToFirstNonZero();
475 typedef SparseBitVectorIterator iterator;
478 CurrElementIter = Elements.begin ();
484 // SparseBitVector copy ctor.
485 SparseBitVector(const SparseBitVector &RHS) {
486 ElementListConstIter ElementIter = RHS.Elements.begin();
487 while (ElementIter != RHS.Elements.end()) {
488 Elements.push_back(SparseBitVectorElement<ElementSize>(*ElementIter));
492 CurrElementIter = Elements.begin ();
496 SparseBitVector& operator=(const SparseBitVector& RHS) {
499 ElementListConstIter ElementIter = RHS.Elements.begin();
500 while (ElementIter != RHS.Elements.end()) {
501 Elements.push_back(SparseBitVectorElement<ElementSize>(*ElementIter));
505 CurrElementIter = Elements.begin ();
510 // Test, Reset, and Set a bit in the bitmap.
511 bool test(unsigned Idx) {
512 if (Elements.empty())
515 unsigned ElementIndex = Idx / ElementSize;
516 ElementListIter ElementIter = FindLowerBound(ElementIndex);
518 // If we can't find an element that is supposed to contain this bit, there
519 // is nothing more to do.
520 if (ElementIter == Elements.end() ||
521 ElementIter->index() != ElementIndex)
523 return ElementIter->test(Idx % ElementSize);
526 void reset(unsigned Idx) {
527 if (Elements.empty())
530 unsigned ElementIndex = Idx / ElementSize;
531 ElementListIter ElementIter = FindLowerBound(ElementIndex);
533 // If we can't find an element that is supposed to contain this bit, there
534 // is nothing more to do.
535 if (ElementIter == Elements.end() ||
536 ElementIter->index() != ElementIndex)
538 ElementIter->reset(Idx % ElementSize);
540 // When the element is zeroed out, delete it.
541 if (ElementIter->empty()) {
543 Elements.erase(ElementIter);
547 void set(unsigned Idx) {
548 unsigned ElementIndex = Idx / ElementSize;
549 SparseBitVectorElement<ElementSize> *Element;
550 ElementListIter ElementIter;
551 if (Elements.empty()) {
552 Element = new SparseBitVectorElement<ElementSize>(ElementIndex);
553 ElementIter = Elements.insert(Elements.end(), Element);
556 ElementIter = FindLowerBound(ElementIndex);
558 if (ElementIter == Elements.end() ||
559 ElementIter->index() != ElementIndex) {
560 Element = new SparseBitVectorElement<ElementSize>(ElementIndex);
561 // We may have hit the beginning of our SparseBitVector, in which case,
562 // we may need to insert right after this element, which requires moving
563 // the current iterator forward one, because insert does insert before.
564 if (ElementIter != Elements.end() &&
565 ElementIter->index() < ElementIndex)
566 ElementIter = Elements.insert(++ElementIter, Element);
568 ElementIter = Elements.insert(ElementIter, Element);
571 CurrElementIter = ElementIter;
573 ElementIter->set(Idx % ElementSize);
576 bool test_and_set (unsigned Idx) {
577 bool old = test(Idx);
585 bool operator!=(const SparseBitVector &RHS) const {
586 return !(*this == RHS);
589 bool operator==(const SparseBitVector &RHS) const {
590 ElementListConstIter Iter1 = Elements.begin();
591 ElementListConstIter Iter2 = RHS.Elements.begin();
593 for (; Iter1 != Elements.end() && Iter2 != RHS.Elements.end();
595 if (*Iter1 != *Iter2)
598 return Iter1 == Elements.end() && Iter2 == RHS.Elements.end();
601 // Union our bitmap with the RHS and return true if we changed.
602 bool operator|=(const SparseBitVector &RHS) {
603 bool changed = false;
604 ElementListIter Iter1 = Elements.begin();
605 ElementListConstIter Iter2 = RHS.Elements.begin();
607 // If RHS is empty, we are done
608 if (RHS.Elements.empty())
611 while (Iter2 != RHS.Elements.end()) {
612 if (Iter1 == Elements.end() || Iter1->index() > Iter2->index()) {
613 Elements.insert(Iter1,
614 new SparseBitVectorElement<ElementSize>(*Iter2));
617 } else if (Iter1->index() == Iter2->index()) {
618 changed |= Iter1->unionWith(*Iter2);
625 CurrElementIter = Elements.begin();
629 // Intersect our bitmap with the RHS and return true if ours changed.
630 bool operator&=(const SparseBitVector &RHS) {
631 bool changed = false;
632 ElementListIter Iter1 = Elements.begin();
633 ElementListConstIter Iter2 = RHS.Elements.begin();
635 // Check if both bitmaps are empty.
636 if (Elements.empty() && RHS.Elements.empty())
639 // Loop through, intersecting as we go, erasing elements when necessary.
640 while (Iter2 != RHS.Elements.end()) {
641 if (Iter1 == Elements.end()) {
642 CurrElementIter = Elements.begin();
646 if (Iter1->index() > Iter2->index()) {
648 } else if (Iter1->index() == Iter2->index()) {
650 changed |= Iter1->intersectWith(*Iter2, BecameZero);
652 ElementListIter IterTmp = Iter1;
654 Elements.erase(IterTmp);
660 ElementListIter IterTmp = Iter1;
662 Elements.erase(IterTmp);
665 Elements.erase(Iter1, Elements.end());
666 CurrElementIter = Elements.begin();
670 // Intersect our bitmap with the complement of the RHS and return true if ours
672 bool intersectWithComplement(const SparseBitVector &RHS) {
673 bool changed = false;
674 ElementListIter Iter1 = Elements.begin();
675 ElementListConstIter Iter2 = RHS.Elements.begin();
677 // If either our bitmap or RHS is empty, we are done
678 if (Elements.empty() || RHS.Elements.empty())
681 // Loop through, intersecting as we go, erasing elements when necessary.
682 while (Iter2 != RHS.Elements.end()) {
683 if (Iter1 == Elements.end()) {
684 CurrElementIter = Elements.begin();
688 if (Iter1->index() > Iter2->index()) {
690 } else if (Iter1->index() == Iter2->index()) {
692 changed |= Iter1->intersectWithComplement(*Iter2, BecameZero);
694 ElementListIter IterTmp = Iter1;
696 Elements.erase(IterTmp);
705 CurrElementIter = Elements.begin();
709 bool intersectWithComplement(const SparseBitVector<ElementSize> *RHS) const {
710 return intersectWithComplement(*RHS);
714 // Three argument version of intersectWithComplement. Result of RHS1 & ~RHS2
715 // is stored into this bitmap.
716 void intersectWithComplement(const SparseBitVector<ElementSize> &RHS1,
717 const SparseBitVector<ElementSize> &RHS2)
720 CurrElementIter = Elements.begin();
721 ElementListConstIter Iter1 = RHS1.Elements.begin();
722 ElementListConstIter Iter2 = RHS2.Elements.begin();
724 // If RHS1 is empty, we are done
725 // If RHS2 is empty, we still have to copy RHS1
726 if (RHS1.Elements.empty())
729 // Loop through, intersecting as we go, erasing elements when necessary.
730 while (Iter2 != RHS2.Elements.end()) {
731 if (Iter1 == RHS1.Elements.end())
734 if (Iter1->index() > Iter2->index()) {
736 } else if (Iter1->index() == Iter2->index()) {
737 bool BecameZero = false;
738 SparseBitVectorElement<ElementSize> *NewElement =
739 new SparseBitVectorElement<ElementSize>(Iter1->index());
740 NewElement->intersectWithComplement(*Iter1, *Iter2, BecameZero);
742 Elements.push_back(NewElement);
749 SparseBitVectorElement<ElementSize> *NewElement =
750 new SparseBitVectorElement<ElementSize>(*Iter1);
751 Elements.push_back(NewElement);
756 // copy the remaining elements
757 while (Iter1 != RHS1.Elements.end()) {
758 SparseBitVectorElement<ElementSize> *NewElement =
759 new SparseBitVectorElement<ElementSize>(*Iter1);
760 Elements.push_back(NewElement);
767 void intersectWithComplement(const SparseBitVector<ElementSize> *RHS1,
768 const SparseBitVector<ElementSize> *RHS2) {
769 intersectWithComplement(*RHS1, *RHS2);
772 bool intersects(const SparseBitVector<ElementSize> *RHS) const {
773 return intersects(*RHS);
776 // Return true if we share any bits in common with RHS
777 bool intersects(const SparseBitVector<ElementSize> &RHS) const {
778 ElementListConstIter Iter1 = Elements.begin();
779 ElementListConstIter Iter2 = RHS.Elements.begin();
781 // Check if both bitmaps are empty.
782 if (Elements.empty() && RHS.Elements.empty())
785 // Loop through, intersecting stopping when we hit bits in common.
786 while (Iter2 != RHS.Elements.end()) {
787 if (Iter1 == Elements.end())
790 if (Iter1->index() > Iter2->index()) {
792 } else if (Iter1->index() == Iter2->index()) {
793 if (Iter1->intersects(*Iter2))
804 // Return the first set bit in the bitmap. Return -1 if no bits are set.
805 int find_first() const {
806 if (Elements.empty())
808 const SparseBitVectorElement<ElementSize> &First = *(Elements.begin());
809 return (First.index() * ElementSize) + First.find_first();
812 // Return true if the SparseBitVector is empty
814 return Elements.empty();
817 unsigned count() const {
818 unsigned BitCount = 0;
819 for (ElementListConstIter Iter = Elements.begin();
820 Iter != Elements.end();
822 BitCount += Iter->count();
826 iterator begin() const {
827 return iterator(this);
830 iterator end() const {
831 return iterator(this, true);
834 // Get a hash value for this bitmap.
835 uint64_t getHashValue() const {
836 uint64_t HashVal = 0;
837 for (ElementListConstIter Iter = Elements.begin();
838 Iter != Elements.end();
840 HashVal ^= Iter->index();
841 HashVal ^= Iter->getHashValue();
847 // Convenience functions to allow Or and And without dereferencing in the user
850 template <unsigned ElementSize>
851 inline bool operator |=(SparseBitVector<ElementSize> &LHS,
852 const SparseBitVector<ElementSize> *RHS) {
856 template <unsigned ElementSize>
857 inline bool operator |=(SparseBitVector<ElementSize> *LHS,
858 const SparseBitVector<ElementSize> &RHS) {
859 return LHS->operator|=(RHS);
862 template <unsigned ElementSize>
863 inline bool operator &=(SparseBitVector<ElementSize> *LHS,
864 const SparseBitVector<ElementSize> &RHS) {
865 return LHS->operator&=(RHS);
868 template <unsigned ElementSize>
869 inline bool operator &=(SparseBitVector<ElementSize> &LHS,
870 const SparseBitVector<ElementSize> *RHS) {
871 return LHS &= (*RHS);
875 // Dump a SparseBitVector to a stream
876 template <unsigned ElementSize>
877 void dump(const SparseBitVector<ElementSize> &LHS, llvm::OStream &out) {
880 typename SparseBitVector<ElementSize>::iterator bi;
881 for (bi = LHS.begin(); bi != LHS.end(); ++bi) {