1//===- llvm/ADT/SparseBitVector.h - Efficient Sparse BitVector --*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the SparseBitVector class. See the doxygen comment for
10// SparseBitVector for more details on the algorithm used.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_SPARSEBITVECTOR_H
15#define LLVM_ADT_SPARSEBITVECTOR_H
16
17#include "llvm/Support/ErrorHandling.h"
18#include "llvm/Support/MathExtras.h"
19#include "llvm/Support/raw_ostream.h"
20#include <cassert>
21#include <climits>
22#include <cstring>
23#include <iterator>
24#include <list>
25
26namespace llvm {
27
28/// SparseBitVector is an implementation of a bitvector that is sparse by only
29/// storing the elements that have non-zero bits set. In order to make this
30/// fast for the most common cases, SparseBitVector is implemented as a linked
31/// list of SparseBitVectorElements. We maintain a pointer to the last
32/// SparseBitVectorElement accessed (in the form of a list iterator), in order
33/// to make multiple in-order test/set constant time after the first one is
34/// executed. Note that using vectors to store SparseBitVectorElement's does
35/// not work out very well because it causes insertion in the middle to take
36/// enormous amounts of time with a large amount of bits. Other structures that
37/// have better worst cases for insertion in the middle (various balanced trees,
38/// etc) do not perform as well in practice as a linked list with this iterator
39/// kept up to date. They are also significantly more memory intensive.
40
41template <unsigned ElementSize = 128> struct SparseBitVectorElement {
42public:
43 using BitWord = unsigned long;
44 using size_type = unsigned;
45 enum {
46 BITWORD_SIZE = sizeof(BitWord) * CHAR_BIT,
47 BITWORDS_PER_ELEMENT = (ElementSize + BITWORD_SIZE - 1) / BITWORD_SIZE,
48 BITS_PER_ELEMENT = ElementSize
49 };
50
51private:
52 // Index of Element in terms of where first bit starts.
53 unsigned ElementIndex;
54 BitWord Bits[BITWORDS_PER_ELEMENT];
55
56 SparseBitVectorElement() {
57 ElementIndex = ~0U;
58 memset(&Bits[0], 0, sizeof (BitWord) * BITWORDS_PER_ELEMENT);
59 }
60
61public:
62 explicit SparseBitVectorElement(unsigned Idx) {
63 ElementIndex = Idx;
64 memset(&Bits[0], 0, sizeof (BitWord) * BITWORDS_PER_ELEMENT);
65 }
66
67 // Comparison.
68 bool operator==(const SparseBitVectorElement &RHS) const {
69 if (ElementIndex != RHS.ElementIndex)
70 return false;
71 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
72 if (Bits[i] != RHS.Bits[i])
73 return false;
74 return true;
75 }
76
77 bool operator!=(const SparseBitVectorElement &RHS) const {
78 return !(*this == RHS);
79 }
80
81 // Return the bits that make up word Idx in our element.
82 BitWord word(unsigned Idx) const {
83 assert(Idx < BITWORDS_PER_ELEMENT);
84 return Bits[Idx];
85 }
86
87 unsigned index() const {
88 return ElementIndex;
89 }
90
91 bool empty() const {
92 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
93 if (Bits[i])
94 return false;
95 return true;
96 }
97
98 void set(unsigned Idx) {
99 Bits[Idx / BITWORD_SIZE] |= 1L << (Idx % BITWORD_SIZE);
100 }
101
102 bool test_and_set(unsigned Idx) {
103 bool old = test(Idx);
104 if (!old) {
105 set(Idx);
106 return true;
107 }
108 return false;
109 }
110
111 void reset(unsigned Idx) {
112 Bits[Idx / BITWORD_SIZE] &= ~(1L << (Idx % BITWORD_SIZE));
113 }
114
115 bool test(unsigned Idx) const {
116 return Bits[Idx / BITWORD_SIZE] & (1L << (Idx % BITWORD_SIZE));
117 }
118
119 size_type count() const {
120 unsigned NumBits = 0;
121 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
122 NumBits += countPopulation(Bits[i]);
123 return NumBits;
124 }
125
126 /// find_first - Returns the index of the first set bit.
127 int find_first() const {
128 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i)
129 if (Bits[i] != 0)
130 return i * BITWORD_SIZE + countTrailingZeros(Bits[i]);
131 llvm_unreachable("Illegal empty element");
132 }
133
134 /// find_last - Returns the index of the last set bit.
135 int find_last() const {
136 for (unsigned I = 0; I < BITWORDS_PER_ELEMENT; ++I) {
137 unsigned Idx = BITWORDS_PER_ELEMENT - I - 1;
138 if (Bits[Idx] != 0)
139 return Idx * BITWORD_SIZE + BITWORD_SIZE -
140 countLeadingZeros(Bits[Idx]) - 1;
141 }
142 llvm_unreachable("Illegal empty element");
143 }
144
145 /// find_next - Returns the index of the next set bit starting from the
146 /// "Curr" bit. Returns -1 if the next set bit is not found.
147 int find_next(unsigned Curr) const {
148 if (Curr >= BITS_PER_ELEMENT)
149 return -1;
150
151 unsigned WordPos = Curr / BITWORD_SIZE;
152 unsigned BitPos = Curr % BITWORD_SIZE;
153 BitWord Copy = Bits[WordPos];
154 assert(WordPos <= BITWORDS_PER_ELEMENT
155 && "Word Position outside of element");
156
157 // Mask off previous bits.
158 Copy &= ~0UL << BitPos;
159
160 if (Copy != 0)
161 return WordPos * BITWORD_SIZE + countTrailingZeros(Copy);
162
163 // Check subsequent words.
164 for (unsigned i = WordPos+1; i < BITWORDS_PER_ELEMENT; ++i)
165 if (Bits[i] != 0)
166 return i * BITWORD_SIZE + countTrailingZeros(Bits[i]);
167 return -1;
168 }
169
170 // Union this element with RHS and return true if this one changed.
171 bool unionWith(const SparseBitVectorElement &RHS) {
172 bool changed = false;
173 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
174 BitWord old = changed ? 0 : Bits[i];
175
176 Bits[i] |= RHS.Bits[i];
177 if (!changed && old != Bits[i])
178 changed = true;
179 }
180 return changed;
181 }
182
183 // Return true if we have any bits in common with RHS
184 bool intersects(const SparseBitVectorElement &RHS) const {
185 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
186 if (RHS.Bits[i] & Bits[i])
187 return true;
188 }
189 return false;
190 }
191
192 // Intersect this Element with RHS and return true if this one changed.
193 // BecameZero is set to true if this element became all-zero bits.
194 bool intersectWith(const SparseBitVectorElement &RHS,
195 bool &BecameZero) {
196 bool changed = false;
197 bool allzero = true;
198
199 BecameZero = false;
200 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
201 BitWord old = changed ? 0 : Bits[i];
202
203 Bits[i] &= RHS.Bits[i];
204 if (Bits[i] != 0)
205 allzero = false;
206
207 if (!changed && old != Bits[i])
208 changed = true;
209 }
210 BecameZero = allzero;
211 return changed;
212 }
213
214 // Intersect this Element with the complement of RHS and return true if this
215 // one changed. BecameZero is set to true if this element became all-zero
216 // bits.
217 bool intersectWithComplement(const SparseBitVectorElement &RHS,
218 bool &BecameZero) {
219 bool changed = false;
220 bool allzero = true;
221
222 BecameZero = false;
223 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
224 BitWord old = changed ? 0 : Bits[i];
225
226 Bits[i] &= ~RHS.Bits[i];
227 if (Bits[i] != 0)
228 allzero = false;
229
230 if (!changed && old != Bits[i])
231 changed = true;
232 }
233 BecameZero = allzero;
234 return changed;
235 }
236
237 // Three argument version of intersectWithComplement that intersects
238 // RHS1 & ~RHS2 into this element
239 void intersectWithComplement(const SparseBitVectorElement &RHS1,
240 const SparseBitVectorElement &RHS2,
241 bool &BecameZero) {
242 bool allzero = true;
243
244 BecameZero = false;
245 for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
246 Bits[i] = RHS1.Bits[i] & ~RHS2.Bits[i];
247 if (Bits[i] != 0)
248 allzero = false;
249 }
250 BecameZero = allzero;
251 }
252};
253
254template <unsigned ElementSize = 128>
255class SparseBitVector {
256 using ElementList = std::list<SparseBitVectorElement<ElementSize>>;
257 using ElementListIter = typename ElementList::iterator;
258 using ElementListConstIter = typename ElementList::const_iterator;
259 enum {
260 BITWORD_SIZE = SparseBitVectorElement<ElementSize>::BITWORD_SIZE
261 };
262
263 ElementList Elements;
264 // Pointer to our current Element. This has no visible effect on the external
265 // state of a SparseBitVector, it's just used to improve performance in the
266 // common case of testing/modifying bits with similar indices.
267 mutable ElementListIter CurrElementIter;
268
269 // This is like std::lower_bound, except we do linear searching from the
270 // current position.
271 ElementListIter FindLowerBoundImpl(unsigned ElementIndex) const {
272
273 // We cache a non-const iterator so we're forced to resort to const_cast to
274 // get the begin/end in the case where 'this' is const. To avoid duplication
275 // of code with the only difference being whether the const cast is present
276 // 'this' is always const in this particular function and we sort out the
277 // difference in FindLowerBound and FindLowerBoundConst.
278 ElementListIter Begin =
279 const_cast<SparseBitVector<ElementSize> *>(this)->Elements.begin();
280 ElementListIter End =
281 const_cast<SparseBitVector<ElementSize> *>(this)->Elements.end();
282
283 if (Elements.empty()) {
284 CurrElementIter = Begin;
285 return CurrElementIter;
286 }
287
288 // Make sure our current iterator is valid.
289 if (CurrElementIter == End)
290 --CurrElementIter;
291
292 // Search from our current iterator, either backwards or forwards,
293 // depending on what element we are looking for.
294 ElementListIter ElementIter = CurrElementIter;
295 if (CurrElementIter->index() == ElementIndex) {
296 return ElementIter;
297 } else if (CurrElementIter->index() > ElementIndex) {
298 while (ElementIter != Begin
299 && ElementIter->index() > ElementIndex)
300 --ElementIter;
301 } else {
302 while (ElementIter != End &&
303 ElementIter->index() < ElementIndex)
304 ++ElementIter;
305 }
306 CurrElementIter = ElementIter;
307 return ElementIter;
308 }
309 ElementListConstIter FindLowerBoundConst(unsigned ElementIndex) const {
310 return FindLowerBoundImpl(ElementIndex);
311 }
312 ElementListIter FindLowerBound(unsigned ElementIndex) {
313 return FindLowerBoundImpl(ElementIndex);
314 }
315
316 // Iterator to walk set bits in the bitmap. This iterator is a lot uglier
317 // than it would be, in order to be efficient.
318 class SparseBitVectorIterator {
319 private:
320 bool AtEnd;
321
322 const SparseBitVector<ElementSize> *BitVector = nullptr;
323
324 // Current element inside of bitmap.
325 ElementListConstIter Iter;
326
327 // Current bit number inside of our bitmap.
328 unsigned BitNumber;
329
330 // Current word number inside of our element.
331 unsigned WordNumber;
332
333 // Current bits from the element.
334 typename SparseBitVectorElement<ElementSize>::BitWord Bits;
335
336 // Move our iterator to the first non-zero bit in the bitmap.
337 void AdvanceToFirstNonZero() {
338 if (AtEnd)
339 return;
340 if (BitVector->Elements.empty()) {
341 AtEnd = true;
342 return;
343 }
344 Iter = BitVector->Elements.begin();
345 BitNumber = Iter->index() * ElementSize;
346 unsigned BitPos = Iter->find_first();
347 BitNumber += BitPos;
348 WordNumber = (BitNumber % ElementSize) / BITWORD_SIZE;
349 Bits = Iter->word(WordNumber);
350 Bits >>= BitPos % BITWORD_SIZE;
351 }
352
353 // Move our iterator to the next non-zero bit.
354 void AdvanceToNextNonZero() {
355 if (AtEnd)
356 return;
357
358 while (Bits && !(Bits & 1)) {
359 Bits >>= 1;
360 BitNumber += 1;
361 }
362
363 // See if we ran out of Bits in this word.
364 if (!Bits) {
365 int NextSetBitNumber = Iter->find_next(BitNumber % ElementSize) ;
366 // If we ran out of set bits in this element, move to next element.
367 if (NextSetBitNumber == -1 || (BitNumber % ElementSize == 0)) {
368 ++Iter;
369 WordNumber = 0;
370
371 // We may run out of elements in the bitmap.
372 if (Iter == BitVector->Elements.end()) {
373 AtEnd = true;
374 return;
375 }
376 // Set up for next non-zero word in bitmap.
377 BitNumber = Iter->index() * ElementSize;
378 NextSetBitNumber = Iter->find_first();
379 BitNumber += NextSetBitNumber;
380 WordNumber = (BitNumber % ElementSize) / BITWORD_SIZE;
381 Bits = Iter->word(WordNumber);
382 Bits >>= NextSetBitNumber % BITWORD_SIZE;
383 } else {
384 WordNumber = (NextSetBitNumber % ElementSize) / BITWORD_SIZE;
385 Bits = Iter->word(WordNumber);
386 Bits >>= NextSetBitNumber % BITWORD_SIZE;
387 BitNumber = Iter->index() * ElementSize;
388 BitNumber += NextSetBitNumber;
389 }
390 }
391 }
392
393 public:
394 SparseBitVectorIterator() = default;
395
396 SparseBitVectorIterator(const SparseBitVector<ElementSize> *RHS,
397 bool end = false):BitVector(RHS) {
398 Iter = BitVector->Elements.begin();
399 BitNumber = 0;
400 Bits = 0;
401 WordNumber = ~0;
402 AtEnd = end;
403 AdvanceToFirstNonZero();
404 }
405
406 // Preincrement.
407 inline SparseBitVectorIterator& operator++() {
408 ++BitNumber;
409 Bits >>= 1;
410 AdvanceToNextNonZero();
411 return *this;
412 }
413
414 // Postincrement.
415 inline SparseBitVectorIterator operator++(int) {
416 SparseBitVectorIterator tmp = *this;
417 ++*this;
418 return tmp;
419 }
420
421 // Return the current set bit number.
422 unsigned operator*() const {
423 return BitNumber;
424 }
425
426 bool operator==(const SparseBitVectorIterator &RHS) const {
427 // If they are both at the end, ignore the rest of the fields.
428 if (AtEnd && RHS.AtEnd)
429 return true;
430 // Otherwise they are the same if they have the same bit number and
431 // bitmap.
432 return AtEnd == RHS.AtEnd && RHS.BitNumber == BitNumber;
433 }
434
435 bool operator!=(const SparseBitVectorIterator &RHS) const {
436 return !(*this == RHS);
437 }
438 };
439
440public:
441 using iterator = SparseBitVectorIterator;
442
443 SparseBitVector() : Elements(), CurrElementIter(Elements.begin()) {}
444
445 SparseBitVector(const SparseBitVector &RHS)
446 : Elements(RHS.Elements), CurrElementIter(Elements.begin()) {}
447 SparseBitVector(SparseBitVector &&RHS)
448 : Elements(std::move(RHS.Elements)), CurrElementIter(Elements.begin()) {}
449
450 // Clear.
451 void clear() {
452 Elements.clear();
453 }
454
455 // Assignment
456 SparseBitVector& operator=(const SparseBitVector& RHS) {
457 if (this == &RHS)
458 return *this;
459
460 Elements = RHS.Elements;
461 CurrElementIter = Elements.begin();
462 return *this;
463 }
464 SparseBitVector &operator=(SparseBitVector &&RHS) {
465 Elements = std::move(RHS.Elements);
466 CurrElementIter = Elements.begin();
467 return *this;
468 }
469
470 // Test, Reset, and Set a bit in the bitmap.
471 bool test(unsigned Idx) const {
472 if (Elements.empty())
473 return false;
474
475 unsigned ElementIndex = Idx / ElementSize;
476 ElementListConstIter ElementIter = FindLowerBoundConst(ElementIndex);
477
478 // If we can't find an element that is supposed to contain this bit, there
479 // is nothing more to do.
480 if (ElementIter == Elements.end() ||
481 ElementIter->index() != ElementIndex)
482 return false;
483 return ElementIter->test(Idx % ElementSize);
484 }
485
486 void reset(unsigned Idx) {
487 if (Elements.empty())
488 return;
489
490 unsigned ElementIndex = Idx / ElementSize;
491 ElementListIter ElementIter = FindLowerBound(ElementIndex);
492
493 // If we can't find an element that is supposed to contain this bit, there
494 // is nothing more to do.
495 if (ElementIter == Elements.end() ||
496 ElementIter->index() != ElementIndex)
497 return;
498 ElementIter->reset(Idx % ElementSize);
499
500 // When the element is zeroed out, delete it.
501 if (ElementIter->empty()) {
502 ++CurrElementIter;
503 Elements.erase(ElementIter);
504 }
505 }
506
507 void set(unsigned Idx) {
508 unsigned ElementIndex = Idx / ElementSize;
509 ElementListIter ElementIter;
510 if (Elements.empty()) {
511 ElementIter = Elements.emplace(Elements.end(), ElementIndex);
512 } else {
513 ElementIter = FindLowerBound(ElementIndex);
514
515 if (ElementIter == Elements.end() ||
516 ElementIter->index() != ElementIndex) {
517 // We may have hit the beginning of our SparseBitVector, in which case,
518 // we may need to insert right after this element, which requires moving
519 // the current iterator forward one, because insert does insert before.
520 if (ElementIter != Elements.end() &&
521 ElementIter->index() < ElementIndex)
522 ++ElementIter;
523 ElementIter = Elements.emplace(ElementIter, ElementIndex);
524 }
525 }
526 CurrElementIter = ElementIter;
527
528 ElementIter->set(Idx % ElementSize);
529 }
530
531 bool test_and_set(unsigned Idx) {
532 bool old = test(Idx);
533 if (!old) {
534 set(Idx);
535 return true;
536 }
537 return false;
538 }
539
540 bool operator!=(const SparseBitVector &RHS) const {
541 return !(*this == RHS);
542 }
543
544 bool operator==(const SparseBitVector &RHS) const {
545 ElementListConstIter Iter1 = Elements.begin();
546 ElementListConstIter Iter2 = RHS.Elements.begin();
547
548 for (; Iter1 != Elements.end() && Iter2 != RHS.Elements.end();
549 ++Iter1, ++Iter2) {
550 if (*Iter1 != *Iter2)
551 return false;
552 }
553 return Iter1 == Elements.end() && Iter2 == RHS.Elements.end();
554 }
555
556 // Union our bitmap with the RHS and return true if we changed.
557 bool operator|=(const SparseBitVector &RHS) {
558 if (this == &RHS)
559 return false;
560
561 bool changed = false;
562 ElementListIter Iter1 = Elements.begin();
563 ElementListConstIter Iter2 = RHS.Elements.begin();
564
565 // If RHS is empty, we are done
566 if (RHS.Elements.empty())
567 return false;
568
569 while (Iter2 != RHS.Elements.end()) {
570 if (Iter1 == Elements.end() || Iter1->index() > Iter2->index()) {
571 Elements.insert(Iter1, *Iter2);
572 ++Iter2;
573 changed = true;
574 } else if (Iter1->index() == Iter2->index()) {
575 changed |= Iter1->unionWith(*Iter2);
576 ++Iter1;
577 ++Iter2;
578 } else {
579 ++Iter1;
580 }
581 }
582 CurrElementIter = Elements.begin();
583 return changed;
584 }
585
586 // Intersect our bitmap with the RHS and return true if ours changed.
587 bool operator&=(const SparseBitVector &RHS) {
588 if (this == &RHS)
589 return false;
590
591 bool changed = false;
592 ElementListIter Iter1 = Elements.begin();
593 ElementListConstIter Iter2 = RHS.Elements.begin();
594
595 // Check if both bitmaps are empty.
596 if (Elements.empty() && RHS.Elements.empty())
597 return false;
598
599 // Loop through, intersecting as we go, erasing elements when necessary.
600 while (Iter2 != RHS.Elements.end()) {
601 if (Iter1 == Elements.end()) {
602 CurrElementIter = Elements.begin();
603 return changed;
604 }
605
606 if (Iter1->index() > Iter2->index()) {
607 ++Iter2;
608 } else if (Iter1->index() == Iter2->index()) {
609 bool BecameZero;
610 changed |= Iter1->intersectWith(*Iter2, BecameZero);
611 if (BecameZero) {
612 ElementListIter IterTmp = Iter1;
613 ++Iter1;
614 Elements.erase(IterTmp);
615 } else {
616 ++Iter1;
617 }
618 ++Iter2;
619 } else {
620 ElementListIter IterTmp = Iter1;
621 ++Iter1;
622 Elements.erase(IterTmp);
623 changed = true;
624 }
625 }
626 if (Iter1 != Elements.end()) {
627 Elements.erase(Iter1, Elements.end());
628 changed = true;
629 }
630 CurrElementIter = Elements.begin();
631 return changed;
632 }
633
634 // Intersect our bitmap with the complement of the RHS and return true
635 // if ours changed.
636 bool intersectWithComplement(const SparseBitVector &RHS) {
637 if (this == &RHS) {
638 if (!empty()) {
639 clear();
640 return true;
641 }
642 return false;
643 }
644
645 bool changed = false;
646 ElementListIter Iter1 = Elements.begin();
647 ElementListConstIter Iter2 = RHS.Elements.begin();
648
649 // If either our bitmap or RHS is empty, we are done
650 if (Elements.empty() || RHS.Elements.empty())
651 return false;
652
653 // Loop through, intersecting as we go, erasing elements when necessary.
654 while (Iter2 != RHS.Elements.end()) {
655 if (Iter1 == Elements.end()) {
656 CurrElementIter = Elements.begin();
657 return changed;
658 }
659
660 if (Iter1->index() > Iter2->index()) {
661 ++Iter2;
662 } else if (Iter1->index() == Iter2->index()) {
663 bool BecameZero;
664 changed |= Iter1->intersectWithComplement(*Iter2, BecameZero);
665 if (BecameZero) {
666 ElementListIter IterTmp = Iter1;
667 ++Iter1;
668 Elements.erase(IterTmp);
669 } else {
670 ++Iter1;
671 }
672 ++Iter2;
673 } else {
674 ++Iter1;
675 }
676 }
677 CurrElementIter = Elements.begin();
678 return changed;
679 }
680
681 bool intersectWithComplement(const SparseBitVector<ElementSize> *RHS) const {
682 return intersectWithComplement(*RHS);
683 }
684
685 // Three argument version of intersectWithComplement.
686 // Result of RHS1 & ~RHS2 is stored into this bitmap.
687 void intersectWithComplement(const SparseBitVector<ElementSize> &RHS1,
688 const SparseBitVector<ElementSize> &RHS2)
689 {
690 if (this == &RHS1) {
691 intersectWithComplement(RHS2);
692 return;
693 } else if (this == &RHS2) {
694 SparseBitVector RHS2Copy(RHS2);
695 intersectWithComplement(RHS1, RHS2Copy);
696 return;
697 }
698
699 Elements.clear();
700 CurrElementIter = Elements.begin();
701 ElementListConstIter Iter1 = RHS1.Elements.begin();
702 ElementListConstIter Iter2 = RHS2.Elements.begin();
703
704 // If RHS1 is empty, we are done
705 // If RHS2 is empty, we still have to copy RHS1
706 if (RHS1.Elements.empty())
707 return;
708
709 // Loop through, intersecting as we go, erasing elements when necessary.
710 while (Iter2 != RHS2.Elements.end()) {
711 if (Iter1 == RHS1.Elements.end())
712 return;
713
714 if (Iter1->index() > Iter2->index()) {
715 ++Iter2;
716 } else if (Iter1->index() == Iter2->index()) {
717 bool BecameZero = false;
718 Elements.emplace_back(Iter1->index());
719 Elements.back().intersectWithComplement(*Iter1, *Iter2, BecameZero);
720 if (BecameZero)
721 Elements.pop_back();
722 ++Iter1;
723 ++Iter2;
724 } else {
725 Elements.push_back(*Iter1++);
726 }
727 }
728
729 // copy the remaining elements
730 std::copy(Iter1, RHS1.Elements.end(), std::back_inserter(Elements));
731 }
732
733 void intersectWithComplement(const SparseBitVector<ElementSize> *RHS1,
734 const SparseBitVector<ElementSize> *RHS2) {
735 intersectWithComplement(*RHS1, *RHS2);
736 }
737
738 bool intersects(const SparseBitVector<ElementSize> *RHS) const {
739 return intersects(*RHS);
740 }
741
742 // Return true if we share any bits in common with RHS
743 bool intersects(const SparseBitVector<ElementSize> &RHS) const {
744 ElementListConstIter Iter1 = Elements.begin();
745 ElementListConstIter Iter2 = RHS.Elements.begin();
746
747 // Check if both bitmaps are empty.
748 if (Elements.empty() && RHS.Elements.empty())
749 return false;
750
751 // Loop through, intersecting stopping when we hit bits in common.
752 while (Iter2 != RHS.Elements.end()) {
753 if (Iter1 == Elements.end())
754 return false;
755
756 if (Iter1->index() > Iter2->index()) {
757 ++Iter2;
758 } else if (Iter1->index() == Iter2->index()) {
759 if (Iter1->intersects(*Iter2))
760 return true;
761 ++Iter1;
762 ++Iter2;
763 } else {
764 ++Iter1;
765 }
766 }
767 return false;
768 }
769
770 // Return true iff all bits set in this SparseBitVector are
771 // also set in RHS.
772 bool contains(const SparseBitVector<ElementSize> &RHS) const {
773 SparseBitVector<ElementSize> Result(*this);
774 Result &= RHS;
775 return (Result == RHS);
776 }
777
778 // Return the first set bit in the bitmap. Return -1 if no bits are set.
779 int find_first() const {
780 if (Elements.empty())
781 return -1;
782 const SparseBitVectorElement<ElementSize> &First = *(Elements.begin());
783 return (First.index() * ElementSize) + First.find_first();
784 }
785
786 // Return the last set bit in the bitmap. Return -1 if no bits are set.
787 int find_last() const {
788 if (Elements.empty())
789 return -1;
790 const SparseBitVectorElement<ElementSize> &Last = *(Elements.rbegin());
791 return (Last.index() * ElementSize) + Last.find_last();
792 }
793
794 // Return true if the SparseBitVector is empty
795 bool empty() const {
796 return Elements.empty();
797 }
798
799 unsigned count() const {
800 unsigned BitCount = 0;
801 for (ElementListConstIter Iter = Elements.begin();
802 Iter != Elements.end();
803 ++Iter)
804 BitCount += Iter->count();
805
806 return BitCount;
807 }
808
809 iterator begin() const {
810 return iterator(this);
811 }
812
813 iterator end() const {
814 return iterator(this, true);
815 }
816};
817
818// Convenience functions to allow Or and And without dereferencing in the user
819// code.
820
821template <unsigned ElementSize>
822inline bool operator |=(SparseBitVector<ElementSize> &LHS,
823 const SparseBitVector<ElementSize> *RHS) {
824 return LHS |= *RHS;
825}
826
827template <unsigned ElementSize>
828inline bool operator |=(SparseBitVector<ElementSize> *LHS,
829 const SparseBitVector<ElementSize> &RHS) {
830 return LHS->operator|=(RHS);
831}
832
833template <unsigned ElementSize>
834inline bool operator &=(SparseBitVector<ElementSize> *LHS,
835 const SparseBitVector<ElementSize> &RHS) {
836 return LHS->operator&=(RHS);
837}
838
839template <unsigned ElementSize>
840inline bool operator &=(SparseBitVector<ElementSize> &LHS,
841 const SparseBitVector<ElementSize> *RHS) {
842 return LHS &= *RHS;
843}
844
845// Convenience functions for infix union, intersection, difference operators.
846
847template <unsigned ElementSize>
848inline SparseBitVector<ElementSize>
849operator|(const SparseBitVector<ElementSize> &LHS,
850 const SparseBitVector<ElementSize> &RHS) {
851 SparseBitVector<ElementSize> Result(LHS);
852 Result |= RHS;
853 return Result;
854}
855
856template <unsigned ElementSize>
857inline SparseBitVector<ElementSize>
858operator&(const SparseBitVector<ElementSize> &LHS,
859 const SparseBitVector<ElementSize> &RHS) {
860 SparseBitVector<ElementSize> Result(LHS);
861 Result &= RHS;
862 return Result;
863}
864
865template <unsigned ElementSize>
866inline SparseBitVector<ElementSize>
867operator-(const SparseBitVector<ElementSize> &LHS,
868 const SparseBitVector<ElementSize> &RHS) {
869 SparseBitVector<ElementSize> Result;
870 Result.intersectWithComplement(LHS, RHS);
871 return Result;
872}
873
874// Dump a SparseBitVector to a stream
875template <unsigned ElementSize>
876void dump(const SparseBitVector<ElementSize> &LHS, raw_ostream &out) {
877 out << "[";
878
879 typename SparseBitVector<ElementSize>::iterator bi = LHS.begin(),
880 be = LHS.end();
881 if (bi != be) {
882 out << *bi;
883 for (++bi; bi != be; ++bi) {
884 out << " " << *bi;
885 }
886 }
887 out << "]\n";
888}
889
890} // end namespace llvm
891
892#endif // LLVM_ADT_SPARSEBITVECTOR_H
893