BitVector.h revision 3a54b3dc87a581c203b18050b4f787b4ca28a12c 
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/Support/MathExtras.h"
18#include <algorithm>
19#include <cassert>
20#include <cstring>
21
22namespace llvm {
23
24class BitVector {
25  typedef unsigned long BitWord;
26
27  enum { BITWORD_SIZE = (unsigned)sizeof(BitWord) * 8 };
28
29  BitWord  *Bits;        // Actual bits.
30  unsigned Size;         // Size of bitvector in bits.
31  unsigned Capacity;     // Size of allocated memory in BitWord.
32
33public:
34  // Encapsulation of a single bit.
35  class reference {
36    friend class BitVector;
37
38    BitWord *WordRef;
39    unsigned BitPos;
40
41    reference();  // Undefined
42
43  public:
44    reference(BitVector &b, unsigned Idx) {
45      WordRef = &b.Bits[Idx / BITWORD_SIZE];
46      BitPos = Idx % BITWORD_SIZE;
47    }
48
49    ~reference() {}
50
51    reference& operator=(bool t) {
52      if (t)
53        *WordRef |= 1L << BitPos;
54      else
55        *WordRef &= ~(1L << BitPos);
56      return *this;
57    }
58
59    operator bool() const {
60      return ((*WordRef) & (1L << BitPos)) ? true : false;
61    }
62  };
63
64
65  /// BitVector default ctor - Creates an empty bitvector.
66  BitVector() : Size(0), Capacity(0) {
67    Bits = 0;
68  }
69
70  /// BitVector ctor - Creates a bitvector of specified number of bits. All
71  /// bits are initialized to the specified value.
72  explicit BitVector(unsigned s, bool t = false) : Size(s) {
73    Capacity = NumBitWords(s);
74    Bits = new BitWord[Capacity];
75    init_words(Bits, Capacity, t);
76    if (t)
77      clear_unused_bits();
78  }
79
80  /// BitVector copy ctor.
81  BitVector(const BitVector &RHS) : Size(RHS.size()) {
82    if (Size == 0) {
83      Bits = 0;
84      Capacity = 0;
85      return;
86    }
87
88    Capacity = NumBitWords(RHS.size());
89    Bits = new BitWord[Capacity];
90    std::copy(RHS.Bits, &RHS.Bits[Capacity], Bits);
91  }
92
93  ~BitVector() {
94    delete[] Bits;
95  }
96
97  /// size - Returns the number of bits in this bitvector.
98  unsigned size() const { return Size; }
99
100  /// count - Returns the number of bits which are set.
101  unsigned count() const {
102    unsigned NumBits = 0;
103    for (unsigned i = 0; i < NumBitWords(size()); ++i)
104      if (sizeof(BitWord) == 4)
105        NumBits += CountPopulation_32((uint32_t)Bits[i]);
106      else if (sizeof(BitWord) == 8)
107        NumBits += CountPopulation_64(Bits[i]);
108      else
109        assert(0 && "Unsupported!");
110    return NumBits;
111  }
112
113  /// any - Returns true if any bit is set.
114  bool any() const {
115    for (unsigned i = 0; i < NumBitWords(size()); ++i)
116      if (Bits[i] != 0)
117        return true;
118    return false;
119  }
120
121  /// none - Returns true if none of the bits are set.
122  bool none() const {
123    return !any();
124  }
125
126  /// find_first - Returns the index of the first set bit, -1 if none
127  /// of the bits are set.
128  int find_first() const {
129    for (unsigned i = 0; i < NumBitWords(size()); ++i)
130      if (Bits[i] != 0) {
131        if (sizeof(BitWord) == 4)
132          return i * BITWORD_SIZE + CountTrailingZeros_32((uint32_t)Bits[i]);
133        else if (sizeof(BitWord) == 8)
134          return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]);
135        else
136          assert(0 && "Unsupported!");
137      }
138    return -1;
139  }
140
141  /// find_next - Returns the index of the next set bit following the
142  /// "Prev" bit. Returns -1 if the next set bit is not found.
143  int find_next(unsigned Prev) const {
144    ++Prev;
145    if (Prev >= Size)
146      return -1;
147
148    unsigned WordPos = Prev / BITWORD_SIZE;
149    unsigned BitPos = Prev % BITWORD_SIZE;
150    BitWord Copy = Bits[WordPos];
151    // Mask off previous bits.
152    Copy &= ~0L << BitPos;
153
154    if (Copy != 0) {
155      if (sizeof(BitWord) == 4)
156        return WordPos * BITWORD_SIZE + CountTrailingZeros_32((uint32_t)Copy);
157      else if (sizeof(BitWord) == 8)
158        return WordPos * BITWORD_SIZE + CountTrailingZeros_64(Copy);
159      else
160        assert(0 && "Unsupported!");
161    }
162
163    // Check subsequent words.
164    for (unsigned i = WordPos+1; i < NumBitWords(size()); ++i)
165      if (Bits[i] != 0) {
166        if (sizeof(BitWord) == 4)
167          return i * BITWORD_SIZE + CountTrailingZeros_32((uint32_t)Bits[i]);
168        else if (sizeof(BitWord) == 8)
169          return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]);
170        else
171          assert(0 && "Unsupported!");
172      }
173    return -1;
174  }
175
176  /// clear - Clear all bits.
177  void clear() {
178    Size = 0;
179  }
180
181  /// resize - Grow or shrink the bitvector.
182  void resize(unsigned N, bool t = false) {
183    if (N > Capacity * BITWORD_SIZE) {
184      unsigned OldCapacity = Capacity;
185      grow(N);
186      init_words(&Bits[OldCapacity], (Capacity-OldCapacity), t);
187    }
188
189    // Set any old unused bits that are now included in the BitVector. This
190    // may set bits that are not included in the new vector, but we will clear
191    // them back out below.
192    if (N > Size)
193      set_unused_bits(t);
194
195    // Update the size, and clear out any bits that are now unused
196    unsigned OldSize = Size;
197    Size = N;
198    if (t || N < OldSize)
199      clear_unused_bits();
200  }
201
202  void reserve(unsigned N) {
203    if (N > Capacity * BITWORD_SIZE)
204      grow(N);
205  }
206
207  // Set, reset, flip
208  BitVector &set() {
209    init_words(Bits, Capacity, true);
210    clear_unused_bits();
211    return *this;
212  }
213
214  BitVector &set(unsigned Idx) {
215    Bits[Idx / BITWORD_SIZE] |= 1L << (Idx % BITWORD_SIZE);
216    return *this;
217  }
218
219  BitVector &reset() {
220    init_words(Bits, Capacity, false);
221    return *this;
222  }
223
224  BitVector &reset(unsigned Idx) {
225    Bits[Idx / BITWORD_SIZE] &= ~(1L << (Idx % BITWORD_SIZE));
226    return *this;
227  }
228
229  BitVector &flip() {
230    for (unsigned i = 0; i < NumBitWords(size()); ++i)
231      Bits[i] = ~Bits[i];
232    clear_unused_bits();
233    return *this;
234  }
235
236  BitVector &flip(unsigned Idx) {
237    Bits[Idx / BITWORD_SIZE] ^= 1L << (Idx % BITWORD_SIZE);
238    return *this;
239  }
240
241  // No argument flip.
242  BitVector operator~() const {
243    return BitVector(*this).flip();
244  }
245
246  // Indexing.
247  reference operator[](unsigned Idx) {
248    assert (Idx < Size && "Out-of-bounds Bit access.");
249    return reference(*this, Idx);
250  }
251
252  bool operator[](unsigned Idx) const {
253    assert (Idx < Size && "Out-of-bounds Bit access.");
254    BitWord Mask = 1L << (Idx % BITWORD_SIZE);
255    return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
256  }
257
258  bool test(unsigned Idx) const {
259    return (*this)[Idx];
260  }
261
262  // Comparison operators.
263  bool operator==(const BitVector &RHS) const {
264    unsigned ThisWords = NumBitWords(size());
265    unsigned RHSWords  = NumBitWords(RHS.size());
266    unsigned i;
267    for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
268      if (Bits[i] != RHS.Bits[i])
269        return false;
270
271    // Verify that any extra words are all zeros.
272    if (i != ThisWords) {
273      for (; i != ThisWords; ++i)
274        if (Bits[i])
275          return false;
276    } else if (i != RHSWords) {
277      for (; i != RHSWords; ++i)
278        if (RHS.Bits[i])
279          return false;
280    }
281    return true;
282  }
283
284  bool operator!=(const BitVector &RHS) const {
285    return !(*this == RHS);
286  }
287
288  // Intersection, union, disjoint union.
289  BitVector operator&=(const BitVector &RHS) {
290    unsigned ThisWords = NumBitWords(size());
291    unsigned RHSWords  = NumBitWords(RHS.size());
292    unsigned i;
293    for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
294      Bits[i] &= RHS.Bits[i];
295
296    // Any bits that are just in this bitvector become zero, because they aren't
297    // in the RHS bit vector.  Any words only in RHS are ignored because they
298    // are already zero in the LHS.
299    for (; i != ThisWords; ++i)
300      Bits[i] = 0;
301
302    return *this;
303  }
304
305  BitVector operator|=(const BitVector &RHS) {
306    assert(Size == RHS.Size && "Illegal operation!");
307    for (unsigned i = 0; i < NumBitWords(size()); ++i)
308      Bits[i] |= RHS.Bits[i];
309    return *this;
310  }
311
312  BitVector operator^=(const BitVector &RHS) {
313    assert(Size == RHS.Size && "Illegal operation!");
314    for (unsigned i = 0; i < NumBitWords(size()); ++i)
315      Bits[i] ^= RHS.Bits[i];
316    return *this;
317  }
318
319  // Assignment operator.
320  const BitVector &operator=(const BitVector &RHS) {
321    if (this == &RHS) return *this;
322
323    Size = RHS.size();
324    unsigned RHSWords = NumBitWords(Size);
325    if (Size <= Capacity * BITWORD_SIZE) {
326      std::copy(RHS.Bits, &RHS.Bits[RHSWords], Bits);
327      clear_unused_bits();
328      return *this;
329    }
330
331    // Grow the bitvector to have enough elements.
332    Capacity = RHSWords;
333    BitWord *NewBits = new BitWord[Capacity];
334    std::copy(RHS.Bits, &RHS.Bits[RHSWords], NewBits);
335
336    // Destroy the old bits.
337    delete[] Bits;
338    Bits = NewBits;
339
340    return *this;
341  }
342
343private:
344  unsigned NumBitWords(unsigned S) const {
345    return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
346  }
347
348  // Set the unused bits in the high words.
349  void set_unused_bits(bool t = true) {
350    //  Set high words first.
351    unsigned UsedWords = NumBitWords(Size);
352    if (Capacity > UsedWords)
353      init_words(&Bits[UsedWords], (Capacity-UsedWords), t);
354
355    //  Then set any stray high bits of the last used word.
356    unsigned ExtraBits = Size % BITWORD_SIZE;
357    if (ExtraBits) {
358      Bits[UsedWords-1] &= ~(~0L << ExtraBits);
359      Bits[UsedWords-1] |= (0 - (BitWord)t) << ExtraBits;
360    }
361  }
362
363  // Clear the unused bits in the high words.
364  void clear_unused_bits() {
365    set_unused_bits(false);
366  }
367
368  void grow(unsigned NewSize) {
369    unsigned OldCapacity = Capacity;
370    Capacity = NumBitWords(NewSize);
371    BitWord *NewBits = new BitWord[Capacity];
372
373    // Copy the old bits over.
374    if (OldCapacity != 0)
375      std::copy(Bits, &Bits[OldCapacity], NewBits);
376
377    // Destroy the old bits.
378    delete[] Bits;
379    Bits = NewBits;
380
381    clear_unused_bits();
382  }
383
384  void init_words(BitWord *B, unsigned NumWords, bool t) {
385    memset(B, 0 - (int)t, NumWords*sizeof(BitWord));
386  }
387};
388
389inline BitVector operator&(const BitVector &LHS, const BitVector &RHS) {
390  BitVector Result(LHS);
391  Result &= RHS;
392  return Result;
393}
394
395inline BitVector operator|(const BitVector &LHS, const BitVector &RHS) {
396  BitVector Result(LHS);
397  Result |= RHS;
398  return Result;
399}
400
401inline BitVector operator^(const BitVector &LHS, const BitVector &RHS) {
402  BitVector Result(LHS);
403  Result ^= RHS;
404  return Result;
405}
406
407} // End llvm namespace
408#endif
409