1//===- llvm/ADT/BitVector.h - Bit vectors -----------------------*- 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 implements the BitVector class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_BITVECTOR_H
15#define LLVM_ADT_BITVECTOR_H
16
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/iterator_range.h"
19#include "llvm/Support/MathExtras.h"
20#include <algorithm>
21#include <cassert>
22#include <climits>
23#include <cstdint>
24#include <cstdlib>
25#include <cstring>
26#include <utility>
27
28namespace llvm {
29
30/// ForwardIterator for the bits that are set.
31/// Iterators get invalidated when resize / reserve is called.
32template <typename BitVectorT> class const_set_bits_iterator_impl {
33 const BitVectorT &Parent;
34 int Current = 0;
35
36 void advance() {
37 assert(Current != -1 && "Trying to advance past end.");
38 Current = Parent.find_next(Current);
39 }
40
41public:
42 const_set_bits_iterator_impl(const BitVectorT &Parent, int Current)
43 : Parent(Parent), Current(Current) {}
44 explicit const_set_bits_iterator_impl(const BitVectorT &Parent)
45 : const_set_bits_iterator_impl(Parent, Parent.find_first()) {}
46 const_set_bits_iterator_impl(const const_set_bits_iterator_impl &) = default;
47
48 const_set_bits_iterator_impl operator++(int) {
49 auto Prev = *this;
50 advance();
51 return Prev;
52 }
53
54 const_set_bits_iterator_impl &operator++() {
55 advance();
56 return *this;
57 }
58
59 unsigned operator*() const { return Current; }
60
61 bool operator==(const const_set_bits_iterator_impl &Other) const {
62 assert(&Parent == &Other.Parent &&
63 "Comparing iterators from different BitVectors");
64 return Current == Other.Current;
65 }
66
67 bool operator!=(const const_set_bits_iterator_impl &Other) const {
68 assert(&Parent == &Other.Parent &&
69 "Comparing iterators from different BitVectors");
70 return Current != Other.Current;
71 }
72};
73
74class BitVector {
75 typedef unsigned long BitWord;
76
77 enum { BITWORD_SIZE = (unsigned)sizeof(BitWord) * CHAR_BIT };
78
79 static_assert(BITWORD_SIZE == 64 || BITWORD_SIZE == 32,
80 "Unsupported word size");
81
82 MutableArrayRef<BitWord> Bits; // Actual bits.
83 unsigned Size; // Size of bitvector in bits.
84
85public:
86 typedef unsigned size_type;
87 // Encapsulation of a single bit.
88 class reference {
89 friend class BitVector;
90
91 BitWord *WordRef;
92 unsigned BitPos;
93
94 public:
95 reference(BitVector &b, unsigned Idx) {
96 WordRef = &b.Bits[Idx / BITWORD_SIZE];
97 BitPos = Idx % BITWORD_SIZE;
98 }
99
100 reference() = delete;
101 reference(const reference&) = default;
102
103 reference &operator=(reference t) {
104 *this = bool(t);
105 return *this;
106 }
107
108 reference& operator=(bool t) {
109 if (t)
110 *WordRef |= BitWord(1) << BitPos;
111 else
112 *WordRef &= ~(BitWord(1) << BitPos);
113 return *this;
114 }
115
116 operator bool() const {
117 return ((*WordRef) & (BitWord(1) << BitPos)) != 0;
118 }
119 };
120
121 typedef const_set_bits_iterator_impl<BitVector> const_set_bits_iterator;
122 typedef const_set_bits_iterator set_iterator;
123
124 const_set_bits_iterator set_bits_begin() const {
125 return const_set_bits_iterator(*this);
126 }
127 const_set_bits_iterator set_bits_end() const {
128 return const_set_bits_iterator(*this, -1);
129 }
130 iterator_range<const_set_bits_iterator> set_bits() const {
131 return make_range(set_bits_begin(), set_bits_end());
132 }
133
134 /// BitVector default ctor - Creates an empty bitvector.
135 BitVector() : Size(0) {}
136
137 /// BitVector ctor - Creates a bitvector of specified number of bits. All
138 /// bits are initialized to the specified value.
139 explicit BitVector(unsigned s, bool t = false) : Size(s) {
140 size_t Capacity = NumBitWords(s);
141 Bits = allocate(Capacity);
142 init_words(Bits, t);
143 if (t)
144 clear_unused_bits();
145 }
146
147 /// BitVector copy ctor.
148 BitVector(const BitVector &RHS) : Size(RHS.size()) {
149 if (Size == 0) {
150 Bits = MutableArrayRef<BitWord>();
151 return;
152 }
153
154 size_t Capacity = NumBitWords(RHS.size());
155 Bits = allocate(Capacity);
156 std::memcpy(Bits.data(), RHS.Bits.data(), Capacity * sizeof(BitWord));
157 }
158
159 BitVector(BitVector &&RHS) : Bits(RHS.Bits), Size(RHS.Size) {
160 RHS.Bits = MutableArrayRef<BitWord>();
161 RHS.Size = 0;
162 }
163
164 ~BitVector() { std::free(Bits.data()); }
165
166 /// empty - Tests whether there are no bits in this bitvector.
167 bool empty() const { return Size == 0; }
168
169 /// size - Returns the number of bits in this bitvector.
170 size_type size() const { return Size; }
171
172 /// count - Returns the number of bits which are set.
173 size_type count() const {
174 unsigned NumBits = 0;
175 for (unsigned i = 0; i < NumBitWords(size()); ++i)
176 NumBits += countPopulation(Bits[i]);
177 return NumBits;
178 }
179
180 /// any - Returns true if any bit is set.
181 bool any() const {
182 for (unsigned i = 0; i < NumBitWords(size()); ++i)
183 if (Bits[i] != 0)
184 return true;
185 return false;
186 }
187
188 /// all - Returns true if all bits are set.
189 bool all() const {
190 for (unsigned i = 0; i < Size / BITWORD_SIZE; ++i)
191 if (Bits[i] != ~0UL)
192 return false;
193
194 // If bits remain check that they are ones. The unused bits are always zero.
195 if (unsigned Remainder = Size % BITWORD_SIZE)
196 return Bits[Size / BITWORD_SIZE] == (1UL << Remainder) - 1;
197
198 return true;
199 }
200
201 /// none - Returns true if none of the bits are set.
202 bool none() const {
203 return !any();
204 }
205
206 /// find_first_in - Returns the index of the first set bit in the range
207 /// [Begin, End). Returns -1 if all bits in the range are unset.
208 int find_first_in(unsigned Begin, unsigned End) const {
209 assert(Begin <= End && End <= Size);
210 if (Begin == End)
211 return -1;
212
213 unsigned FirstWord = Begin / BITWORD_SIZE;
214 unsigned LastWord = (End - 1) / BITWORD_SIZE;
215
216 // Check subsequent words.
217 for (unsigned i = FirstWord; i <= LastWord; ++i) {
218 BitWord Copy = Bits[i];
219
220 if (i == FirstWord) {
221 unsigned FirstBit = Begin % BITWORD_SIZE;
222 Copy &= maskTrailingZeros<BitWord>(FirstBit);
223 }
224
225 if (i == LastWord) {
226 unsigned LastBit = (End - 1) % BITWORD_SIZE;
227 Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
228 }
229 if (Copy != 0)
230 return i * BITWORD_SIZE + countTrailingZeros(Copy);
231 }
232 return -1;
233 }
234
235 /// find_last_in - Returns the index of the last set bit in the range
236 /// [Begin, End). Returns -1 if all bits in the range are unset.
237 int find_last_in(unsigned Begin, unsigned End) const {
238 assert(Begin <= End && End <= Size);
239 if (Begin == End)
240 return -1;
241
242 unsigned LastWord = (End - 1) / BITWORD_SIZE;
243 unsigned FirstWord = Begin / BITWORD_SIZE;
244
245 for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
246 unsigned CurrentWord = i - 1;
247
248 BitWord Copy = Bits[CurrentWord];
249 if (CurrentWord == LastWord) {
250 unsigned LastBit = (End - 1) % BITWORD_SIZE;
251 Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
252 }
253
254 if (CurrentWord == FirstWord) {
255 unsigned FirstBit = Begin % BITWORD_SIZE;
256 Copy &= maskTrailingZeros<BitWord>(FirstBit);
257 }
258
259 if (Copy != 0)
260 return (CurrentWord + 1) * BITWORD_SIZE - countLeadingZeros(Copy) - 1;
261 }
262
263 return -1;
264 }
265
266 /// find_first_unset_in - Returns the index of the first unset bit in the
267 /// range [Begin, End). Returns -1 if all bits in the range are set.
268 int find_first_unset_in(unsigned Begin, unsigned End) const {
269 assert(Begin <= End && End <= Size);
270 if (Begin == End)
271 return -1;
272
273 unsigned FirstWord = Begin / BITWORD_SIZE;
274 unsigned LastWord = (End - 1) / BITWORD_SIZE;
275
276 // Check subsequent words.
277 for (unsigned i = FirstWord; i <= LastWord; ++i) {
278 BitWord Copy = Bits[i];
279
280 if (i == FirstWord) {
281 unsigned FirstBit = Begin % BITWORD_SIZE;
282 Copy |= maskTrailingOnes<BitWord>(FirstBit);
283 }
284
285 if (i == LastWord) {
286 unsigned LastBit = (End - 1) % BITWORD_SIZE;
287 Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
288 }
289 if (Copy != ~0UL) {
290 unsigned Result = i * BITWORD_SIZE + countTrailingOnes(Copy);
291 return Result < size() ? Result : -1;
292 }
293 }
294 return -1;
295 }
296
297 /// find_last_unset_in - Returns the index of the last unset bit in the
298 /// range [Begin, End). Returns -1 if all bits in the range are set.
299 int find_last_unset_in(unsigned Begin, unsigned End) const {
300 assert(Begin <= End && End <= Size);
301 if (Begin == End)
302 return -1;
303
304 unsigned LastWord = (End - 1) / BITWORD_SIZE;
305 unsigned FirstWord = Begin / BITWORD_SIZE;
306
307 for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
308 unsigned CurrentWord = i - 1;
309
310 BitWord Copy = Bits[CurrentWord];
311 if (CurrentWord == LastWord) {
312 unsigned LastBit = (End - 1) % BITWORD_SIZE;
313 Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
314 }
315
316 if (CurrentWord == FirstWord) {
317 unsigned FirstBit = Begin % BITWORD_SIZE;
318 Copy |= maskTrailingOnes<BitWord>(FirstBit);
319 }
320
321 if (Copy != ~0UL) {
322 unsigned Result =
323 (CurrentWord + 1) * BITWORD_SIZE - countLeadingOnes(Copy) - 1;
324 return Result < Size ? Result : -1;
325 }
326 }
327 return -1;
328 }
329
330 /// find_first - Returns the index of the first set bit, -1 if none
331 /// of the bits are set.
332 int find_first() const { return find_first_in(0, Size); }
333
334 /// find_last - Returns the index of the last set bit, -1 if none of the bits
335 /// are set.
336 int find_last() const { return find_last_in(0, Size); }
337
338 /// find_next - Returns the index of the next set bit following the
339 /// "Prev" bit. Returns -1 if the next set bit is not found.
340 int find_next(unsigned Prev) const { return find_first_in(Prev + 1, Size); }
341
342 /// find_prev - Returns the index of the first set bit that precedes the
343 /// the bit at \p PriorTo. Returns -1 if all previous bits are unset.
344 int find_prev(unsigned PriorTo) const { return find_last_in(0, PriorTo); }
345
346 /// find_first_unset - Returns the index of the first unset bit, -1 if all
347 /// of the bits are set.
348 int find_first_unset() const { return find_first_unset_in(0, Size); }
349
350 /// find_next_unset - Returns the index of the next unset bit following the
351 /// "Prev" bit. Returns -1 if all remaining bits are set.
352 int find_next_unset(unsigned Prev) const {
353 return find_first_unset_in(Prev + 1, Size);
354 }
355
356 /// find_last_unset - Returns the index of the last unset bit, -1 if all of
357 /// the bits are set.
358 int find_last_unset() const { return find_last_unset_in(0, Size); }
359
360 /// find_prev_unset - Returns the index of the first unset bit that precedes
361 /// the bit at \p PriorTo. Returns -1 if all previous bits are set.
362 int find_prev_unset(unsigned PriorTo) {
363 return find_last_unset_in(0, PriorTo);
364 }
365
366 /// clear - Removes all bits from the bitvector. Does not change capacity.
367 void clear() {
368 Size = 0;
369 }
370
371 /// resize - Grow or shrink the bitvector.
372 void resize(unsigned N, bool t = false) {
373 if (N > getBitCapacity()) {
374 unsigned OldCapacity = Bits.size();
375 grow(N);
376 init_words(Bits.drop_front(OldCapacity), t);
377 }
378
379 // Set any old unused bits that are now included in the BitVector. This
380 // may set bits that are not included in the new vector, but we will clear
381 // them back out below.
382 if (N > Size)
383 set_unused_bits(t);
384
385 // Update the size, and clear out any bits that are now unused
386 unsigned OldSize = Size;
387 Size = N;
388 if (t || N < OldSize)
389 clear_unused_bits();
390 }
391
392 void reserve(unsigned N) {
393 if (N > getBitCapacity())
394 grow(N);
395 }
396
397 // Set, reset, flip
398 BitVector &set() {
399 init_words(Bits, true);
400 clear_unused_bits();
401 return *this;
402 }
403
404 BitVector &set(unsigned Idx) {
405 assert(Bits.data() && "Bits never allocated");
406 Bits[Idx / BITWORD_SIZE] |= BitWord(1) << (Idx % BITWORD_SIZE);
407 return *this;
408 }
409
410 /// set - Efficiently set a range of bits in [I, E)
411 BitVector &set(unsigned I, unsigned E) {
412 assert(I <= E && "Attempted to set backwards range!");
413 assert(E <= size() && "Attempted to set out-of-bounds range!");
414
415 if (I == E) return *this;
416
417 if (I / BITWORD_SIZE == E / BITWORD_SIZE) {
418 BitWord EMask = 1UL << (E % BITWORD_SIZE);
419 BitWord IMask = 1UL << (I % BITWORD_SIZE);
420 BitWord Mask = EMask - IMask;
421 Bits[I / BITWORD_SIZE] |= Mask;
422 return *this;
423 }
424
425 BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
426 Bits[I / BITWORD_SIZE] |= PrefixMask;
427 I = alignTo(I, BITWORD_SIZE);
428
429 for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
430 Bits[I / BITWORD_SIZE] = ~0UL;
431
432 BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
433 if (I < E)
434 Bits[I / BITWORD_SIZE] |= PostfixMask;
435
436 return *this;
437 }
438
439 BitVector &reset() {
440 init_words(Bits, false);
441 return *this;
442 }
443
444 BitVector &reset(unsigned Idx) {
445 Bits[Idx / BITWORD_SIZE] &= ~(BitWord(1) << (Idx % BITWORD_SIZE));
446 return *this;
447 }
448
449 /// reset - Efficiently reset a range of bits in [I, E)
450 BitVector &reset(unsigned I, unsigned E) {
451 assert(I <= E && "Attempted to reset backwards range!");
452 assert(E <= size() && "Attempted to reset out-of-bounds range!");
453
454 if (I == E) return *this;
455
456 if (I / BITWORD_SIZE == E / BITWORD_SIZE) {
457 BitWord EMask = 1UL << (E % BITWORD_SIZE);
458 BitWord IMask = 1UL << (I % BITWORD_SIZE);
459 BitWord Mask = EMask - IMask;
460 Bits[I / BITWORD_SIZE] &= ~Mask;
461 return *this;
462 }
463
464 BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
465 Bits[I / BITWORD_SIZE] &= ~PrefixMask;
466 I = alignTo(I, BITWORD_SIZE);
467
468 for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
469 Bits[I / BITWORD_SIZE] = 0UL;
470
471 BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
472 if (I < E)
473 Bits[I / BITWORD_SIZE] &= ~PostfixMask;
474
475 return *this;
476 }
477
478 BitVector &flip() {
479 for (unsigned i = 0; i < NumBitWords(size()); ++i)
480 Bits[i] = ~Bits[i];
481 clear_unused_bits();
482 return *this;
483 }
484
485 BitVector &flip(unsigned Idx) {
486 Bits[Idx / BITWORD_SIZE] ^= BitWord(1) << (Idx % BITWORD_SIZE);
487 return *this;
488 }
489
490 // Indexing.
491 reference operator[](unsigned Idx) {
492 assert (Idx < Size && "Out-of-bounds Bit access.");
493 return reference(*this, Idx);
494 }
495
496 bool operator[](unsigned Idx) const {
497 assert (Idx < Size && "Out-of-bounds Bit access.");
498 BitWord Mask = BitWord(1) << (Idx % BITWORD_SIZE);
499 return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
500 }
501
502 bool test(unsigned Idx) const {
503 return (*this)[Idx];
504 }
505
506 // Push single bit to end of vector.
507 void push_back(bool Val) {
508 unsigned OldSize = Size;
509 unsigned NewSize = Size + 1;
510
511 // Resize, which will insert zeros.
512 // If we already fit then the unused bits will be already zero.
513 if (NewSize > getBitCapacity())
514 resize(NewSize, false);
515 else
516 Size = NewSize;
517
518 // If true, set single bit.
519 if (Val)
520 set(OldSize);
521 }
522
523 /// Test if any common bits are set.
524 bool anyCommon(const BitVector &RHS) const {
525 unsigned ThisWords = NumBitWords(size());
526 unsigned RHSWords = NumBitWords(RHS.size());
527 for (unsigned i = 0, e = std::min(ThisWords, RHSWords); i != e; ++i)
528 if (Bits[i] & RHS.Bits[i])
529 return true;
530 return false;
531 }
532
533 // Comparison operators.
534 bool operator==(const BitVector &RHS) const {
535 unsigned ThisWords = NumBitWords(size());
536 unsigned RHSWords = NumBitWords(RHS.size());
537 unsigned i;
538 for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
539 if (Bits[i] != RHS.Bits[i])
540 return false;
541
542 // Verify that any extra words are all zeros.
543 if (i != ThisWords) {
544 for (; i != ThisWords; ++i)
545 if (Bits[i])
546 return false;
547 } else if (i != RHSWords) {
548 for (; i != RHSWords; ++i)
549 if (RHS.Bits[i])
550 return false;
551 }
552 return true;
553 }
554
555 bool operator!=(const BitVector &RHS) const {
556 return !(*this == RHS);
557 }
558
559 /// Intersection, union, disjoint union.
560 BitVector &operator&=(const BitVector &RHS) {
561 unsigned ThisWords = NumBitWords(size());
562 unsigned RHSWords = NumBitWords(RHS.size());
563 unsigned i;
564 for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
565 Bits[i] &= RHS.Bits[i];
566
567 // Any bits that are just in this bitvector become zero, because they aren't
568 // in the RHS bit vector. Any words only in RHS are ignored because they
569 // are already zero in the LHS.
570 for (; i != ThisWords; ++i)
571 Bits[i] = 0;
572
573 return *this;
574 }
575
576 /// reset - Reset bits that are set in RHS. Same as *this &= ~RHS.
577 BitVector &reset(const BitVector &RHS) {
578 unsigned ThisWords = NumBitWords(size());
579 unsigned RHSWords = NumBitWords(RHS.size());
580 unsigned i;
581 for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
582 Bits[i] &= ~RHS.Bits[i];
583 return *this;
584 }
585
586 /// test - Check if (This - RHS) is zero.
587 /// This is the same as reset(RHS) and any().
588 bool test(const BitVector &RHS) const {
589 unsigned ThisWords = NumBitWords(size());
590 unsigned RHSWords = NumBitWords(RHS.size());
591 unsigned i;
592 for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
593 if ((Bits[i] & ~RHS.Bits[i]) != 0)
594 return true;
595
596 for (; i != ThisWords ; ++i)
597 if (Bits[i] != 0)
598 return true;
599
600 return false;
601 }
602
603 BitVector &operator|=(const BitVector &RHS) {
604 if (size() < RHS.size())
605 resize(RHS.size());
606 for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
607 Bits[i] |= RHS.Bits[i];
608 return *this;
609 }
610
611 BitVector &operator^=(const BitVector &RHS) {
612 if (size() < RHS.size())
613 resize(RHS.size());
614 for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
615 Bits[i] ^= RHS.Bits[i];
616 return *this;
617 }
618
619 BitVector &operator>>=(unsigned N) {
620 assert(N <= Size);
621 if (LLVM_UNLIKELY(empty() || N == 0))
622 return *this;
623
624 unsigned NumWords = NumBitWords(Size);
625 assert(NumWords >= 1);
626
627 wordShr(N / BITWORD_SIZE);
628
629 unsigned BitDistance = N % BITWORD_SIZE;
630 if (BitDistance == 0)
631 return *this;
632
633 // When the shift size is not a multiple of the word size, then we have
634 // a tricky situation where each word in succession needs to extract some
635 // of the bits from the next word and or them into this word while
636 // shifting this word to make room for the new bits. This has to be done
637 // for every word in the array.
638
639 // Since we're shifting each word right, some bits will fall off the end
640 // of each word to the right, and empty space will be created on the left.
641 // The final word in the array will lose bits permanently, so starting at
642 // the beginning, work forwards shifting each word to the right, and
643 // OR'ing in the bits from the end of the next word to the beginning of
644 // the current word.
645
646 // Example:
647 // Starting with {0xAABBCCDD, 0xEEFF0011, 0x22334455} and shifting right
648 // by 4 bits.
649 // Step 1: Word[0] >>= 4 ; 0x0ABBCCDD
650 // Step 2: Word[0] |= 0x10000000 ; 0x1ABBCCDD
651 // Step 3: Word[1] >>= 4 ; 0x0EEFF001
652 // Step 4: Word[1] |= 0x50000000 ; 0x5EEFF001
653 // Step 5: Word[2] >>= 4 ; 0x02334455
654 // Result: { 0x1ABBCCDD, 0x5EEFF001, 0x02334455 }
655 const BitWord Mask = maskTrailingOnes<BitWord>(BitDistance);
656 const unsigned LSH = BITWORD_SIZE - BitDistance;
657
658 for (unsigned I = 0; I < NumWords - 1; ++I) {
659 Bits[I] >>= BitDistance;
660 Bits[I] |= (Bits[I + 1] & Mask) << LSH;
661 }
662
663 Bits[NumWords - 1] >>= BitDistance;
664
665 return *this;
666 }
667
668 BitVector &operator<<=(unsigned N) {
669 assert(N <= Size);
670 if (LLVM_UNLIKELY(empty() || N == 0))
671 return *this;
672
673 unsigned NumWords = NumBitWords(Size);
674 assert(NumWords >= 1);
675
676 wordShl(N / BITWORD_SIZE);
677
678 unsigned BitDistance = N % BITWORD_SIZE;
679 if (BitDistance == 0)
680 return *this;
681
682 // When the shift size is not a multiple of the word size, then we have
683 // a tricky situation where each word in succession needs to extract some
684 // of the bits from the previous word and or them into this word while
685 // shifting this word to make room for the new bits. This has to be done
686 // for every word in the array. This is similar to the algorithm outlined
687 // in operator>>=, but backwards.
688
689 // Since we're shifting each word left, some bits will fall off the end
690 // of each word to the left, and empty space will be created on the right.
691 // The first word in the array will lose bits permanently, so starting at
692 // the end, work backwards shifting each word to the left, and OR'ing
693 // in the bits from the end of the next word to the beginning of the
694 // current word.
695
696 // Example:
697 // Starting with {0xAABBCCDD, 0xEEFF0011, 0x22334455} and shifting left
698 // by 4 bits.
699 // Step 1: Word[2] <<= 4 ; 0x23344550
700 // Step 2: Word[2] |= 0x0000000E ; 0x2334455E
701 // Step 3: Word[1] <<= 4 ; 0xEFF00110
702 // Step 4: Word[1] |= 0x0000000A ; 0xEFF0011A
703 // Step 5: Word[0] <<= 4 ; 0xABBCCDD0
704 // Result: { 0xABBCCDD0, 0xEFF0011A, 0x2334455E }
705 const BitWord Mask = maskLeadingOnes<BitWord>(BitDistance);
706 const unsigned RSH = BITWORD_SIZE - BitDistance;
707
708 for (int I = NumWords - 1; I > 0; --I) {
709 Bits[I] <<= BitDistance;
710 Bits[I] |= (Bits[I - 1] & Mask) >> RSH;
711 }
712 Bits[0] <<= BitDistance;
713 clear_unused_bits();
714
715 return *this;
716 }
717
718 // Assignment operator.
719 const BitVector &operator=(const BitVector &RHS) {
720 if (this == &RHS) return *this;
721
722 Size = RHS.size();
723 unsigned RHSWords = NumBitWords(Size);
724 if (Size <= getBitCapacity()) {
725 if (Size)
726 std::memcpy(Bits.data(), RHS.Bits.data(), RHSWords * sizeof(BitWord));
727 clear_unused_bits();
728 return *this;
729 }
730
731 // Grow the bitvector to have enough elements.
732 unsigned NewCapacity = RHSWords;
733 assert(NewCapacity > 0 && "negative capacity?");
734 auto NewBits = allocate(NewCapacity);
735 std::memcpy(NewBits.data(), RHS.Bits.data(), NewCapacity * sizeof(BitWord));
736
737 // Destroy the old bits.
738 std::free(Bits.data());
739 Bits = NewBits;
740
741 return *this;
742 }
743
744 const BitVector &operator=(BitVector &&RHS) {
745 if (this == &RHS) return *this;
746
747 std::free(Bits.data());
748 Bits = RHS.Bits;
749 Size = RHS.Size;
750
751 RHS.Bits = MutableArrayRef<BitWord>();
752 RHS.Size = 0;
753
754 return *this;
755 }
756
757 void swap(BitVector &RHS) {
758 std::swap(Bits, RHS.Bits);
759 std::swap(Size, RHS.Size);
760 }
761
762 //===--------------------------------------------------------------------===//
763 // Portable bit mask operations.
764 //===--------------------------------------------------------------------===//
765 //
766 // These methods all operate on arrays of uint32_t, each holding 32 bits. The
767 // fixed word size makes it easier to work with literal bit vector constants
768 // in portable code.
769 //
770 // The LSB in each word is the lowest numbered bit. The size of a portable
771 // bit mask is always a whole multiple of 32 bits. If no bit mask size is
772 // given, the bit mask is assumed to cover the entire BitVector.
773
774 /// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize.
775 /// This computes "*this |= Mask".
776 void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
777 applyMask<true, false>(Mask, MaskWords);
778 }
779
780 /// clearBitsInMask - Clear any bits in this vector that are set in Mask.
781 /// Don't resize. This computes "*this &= ~Mask".
782 void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
783 applyMask<false, false>(Mask, MaskWords);
784 }
785
786 /// setBitsNotInMask - Add a bit to this vector for every '0' bit in Mask.
787 /// Don't resize. This computes "*this |= ~Mask".
788 void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
789 applyMask<true, true>(Mask, MaskWords);
790 }
791
792 /// clearBitsNotInMask - Clear a bit in this vector for every '0' bit in Mask.
793 /// Don't resize. This computes "*this &= Mask".
794 void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
795 applyMask<false, true>(Mask, MaskWords);
796 }
797
798private:
799 /// Perform a logical left shift of \p Count words by moving everything
800 /// \p Count words to the right in memory.
801 ///
802 /// While confusing, words are stored from least significant at Bits[0] to
803 /// most significant at Bits[NumWords-1]. A logical shift left, however,
804 /// moves the current least significant bit to a higher logical index, and
805 /// fills the previous least significant bits with 0. Thus, we actually
806 /// need to move the bytes of the memory to the right, not to the left.
807 /// Example:
808 /// Words = [0xBBBBAAAA, 0xDDDDFFFF, 0x00000000, 0xDDDD0000]
809 /// represents a BitVector where 0xBBBBAAAA contain the least significant
810 /// bits. So if we want to shift the BitVector left by 2 words, we need to
811 /// turn this into 0x00000000 0x00000000 0xBBBBAAAA 0xDDDDFFFF by using a
812 /// memmove which moves right, not left.
813 void wordShl(uint32_t Count) {
814 if (Count == 0)
815 return;
816
817 uint32_t NumWords = NumBitWords(Size);
818
819 auto Src = Bits.take_front(NumWords).drop_back(Count);
820 auto Dest = Bits.take_front(NumWords).drop_front(Count);
821
822 // Since we always move Word-sized chunks of data with src and dest both
823 // aligned to a word-boundary, we don't need to worry about endianness
824 // here.
825 std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
826 std::memset(Bits.data(), 0, Count * sizeof(BitWord));
827 clear_unused_bits();
828 }
829
830 /// Perform a logical right shift of \p Count words by moving those
831 /// words to the left in memory. See wordShl for more information.
832 ///
833 void wordShr(uint32_t Count) {
834 if (Count == 0)
835 return;
836
837 uint32_t NumWords = NumBitWords(Size);
838
839 auto Src = Bits.take_front(NumWords).drop_front(Count);
840 auto Dest = Bits.take_front(NumWords).drop_back(Count);
841 assert(Dest.size() == Src.size());
842
843 std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
844 std::memset(Dest.end(), 0, Count * sizeof(BitWord));
845 }
846
847 MutableArrayRef<BitWord> allocate(size_t NumWords) {
848 BitWord *RawBits = static_cast<BitWord *>(
849 safe_malloc(NumWords * sizeof(BitWord)));
850 return MutableArrayRef<BitWord>(RawBits, NumWords);
851 }
852
853 int next_unset_in_word(int WordIndex, BitWord Word) const {
854 unsigned Result = WordIndex * BITWORD_SIZE + countTrailingOnes(Word);
855 return Result < size() ? Result : -1;
856 }
857
858 unsigned NumBitWords(unsigned S) const {
859 return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
860 }
861
862 // Set the unused bits in the high words.
863 void set_unused_bits(bool t = true) {
864 // Set high words first.
865 unsigned UsedWords = NumBitWords(Size);
866 if (Bits.size() > UsedWords)
867 init_words(Bits.drop_front(UsedWords), t);
868
869 // Then set any stray high bits of the last used word.
870 unsigned ExtraBits = Size % BITWORD_SIZE;
871 if (ExtraBits) {
872 BitWord ExtraBitMask = ~0UL << ExtraBits;
873 if (t)
874 Bits[UsedWords-1] |= ExtraBitMask;
875 else
876 Bits[UsedWords-1] &= ~ExtraBitMask;
877 }
878 }
879
880 // Clear the unused bits in the high words.
881 void clear_unused_bits() {
882 set_unused_bits(false);
883 }
884
885 void grow(unsigned NewSize) {
886 size_t NewCapacity = std::max<size_t>(NumBitWords(NewSize), Bits.size() * 2);
887 assert(NewCapacity > 0 && "realloc-ing zero space");
888 BitWord *NewBits = static_cast<BitWord *>(
889 safe_realloc(Bits.data(), NewCapacity * sizeof(BitWord)));
890 Bits = MutableArrayRef<BitWord>(NewBits, NewCapacity);
891 clear_unused_bits();
892 }
893
894 void init_words(MutableArrayRef<BitWord> B, bool t) {
895 if (B.size() > 0)
896 memset(B.data(), 0 - (int)t, B.size() * sizeof(BitWord));
897 }
898
899 template<bool AddBits, bool InvertMask>
900 void applyMask(const uint32_t *Mask, unsigned MaskWords) {
901 static_assert(BITWORD_SIZE % 32 == 0, "Unsupported BitWord size.");
902 MaskWords = std::min(MaskWords, (size() + 31) / 32);
903 const unsigned Scale = BITWORD_SIZE / 32;
904 unsigned i;
905 for (i = 0; MaskWords >= Scale; ++i, MaskWords -= Scale) {
906 BitWord BW = Bits[i];
907 // This inner loop should unroll completely when BITWORD_SIZE > 32.
908 for (unsigned b = 0; b != BITWORD_SIZE; b += 32) {
909 uint32_t M = *Mask++;
910 if (InvertMask) M = ~M;
911 if (AddBits) BW |= BitWord(M) << b;
912 else BW &= ~(BitWord(M) << b);
913 }
914 Bits[i] = BW;
915 }
916 for (unsigned b = 0; MaskWords; b += 32, --MaskWords) {
917 uint32_t M = *Mask++;
918 if (InvertMask) M = ~M;
919 if (AddBits) Bits[i] |= BitWord(M) << b;
920 else Bits[i] &= ~(BitWord(M) << b);
921 }
922 if (AddBits)
923 clear_unused_bits();
924 }
925
926public:
927 /// Return the size (in bytes) of the bit vector.
928 size_t getMemorySize() const { return Bits.size() * sizeof(BitWord); }
929 size_t getBitCapacity() const { return Bits.size() * BITWORD_SIZE; }
930};
931
932inline size_t capacity_in_bytes(const BitVector &X) {
933 return X.getMemorySize();
934}
935
936} // end namespace llvm
937
938namespace std {
939 /// Implement std::swap in terms of BitVector swap.
940 inline void
941 swap(llvm::BitVector &LHS, llvm::BitVector &RHS) {
942 LHS.swap(RHS);
943 }
944} // end namespace std
945
946#endif // LLVM_ADT_BITVECTOR_H
947