BitVector.h revision 0c81450a0c1f859738a2f209a89de10f889fcd84 
1//===- llvm/ADT/BitVector.h - Bit vectors -----------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by Evan Cheng and is distributed under
6// the University of Illinois Open Source 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 <cstdlib>
20#include <cassert>
21
22namespace llvm {
23
24class BitVector {
25  typedef unsigned long BitWord;
26
27  enum { BITWORD_SIZE = 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);
61    }
62  };
63
64
65  /// BitVector default ctor - Creates an empty bitvector.
66  BitVector() : Size(0), Capacity(0) {
67    Bits = NULL;
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 = NULL;
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(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(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(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(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    // If we previously had no size, initialize the low word
190    if (Size == 0)
191      Bits[0] = t;
192
193    Size = N;
194    clear_unused_bits();
195  }
196
197  void reserve(unsigned N) {
198    if (N > Capacity * BITWORD_SIZE)
199      grow(N);
200  }
201
202  // Set, reset, flip
203  BitVector &set() {
204    init_words(Bits, Capacity, true);
205    clear_unused_bits();
206    return *this;
207  }
208
209  BitVector &set(unsigned Idx) {
210    Bits[Idx / BITWORD_SIZE] |= 1L << (Idx % BITWORD_SIZE);
211    return *this;
212  }
213
214  BitVector &reset() {
215    init_words(Bits, Capacity, false);
216    return *this;
217  }
218
219  BitVector &reset(unsigned Idx) {
220    Bits[Idx / BITWORD_SIZE] &= ~(1L << (Idx % BITWORD_SIZE));
221    return *this;
222  }
223
224  BitVector &flip() {
225    for (unsigned i = 0; i < NumBitWords(size()); ++i)
226      Bits[i] = ~Bits[i];
227    clear_unused_bits();
228    return *this;
229  }
230
231  BitVector &flip(unsigned Idx) {
232    Bits[Idx / BITWORD_SIZE] ^= 1L << (Idx % BITWORD_SIZE);
233    return *this;
234  }
235
236  // No argument flip.
237  BitVector operator~() const {
238    return BitVector(*this).flip();
239  }
240
241  // Indexing.
242  reference operator[](unsigned Idx) {
243    return reference(*this, Idx);
244  }
245
246  bool operator[](unsigned Idx) const {
247    BitWord Mask = 1L << (Idx % BITWORD_SIZE);
248    return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
249  }
250
251  bool test(unsigned Idx) const {
252    return (*this)[Idx];
253  }
254
255  // Comparison operators.
256  bool operator==(const BitVector &RHS) const {
257    if (Size != RHS.Size)
258      return false;
259
260    for (unsigned i = 0; i < NumBitWords(size()); ++i)
261      if (Bits[i] != RHS.Bits[i])
262        return false;
263    return true;
264  }
265
266  bool operator!=(const BitVector &RHS) const {
267    return !(*this == RHS);
268  }
269
270  // Intersection, union, disjoint union.
271  BitVector operator&=(const BitVector &RHS) {
272    assert(Size == RHS.Size && "Illegal operation!");
273    for (unsigned i = 0; i < NumBitWords(size()); ++i)
274      Bits[i] &= RHS.Bits[i];
275    return *this;
276  }
277
278  BitVector operator|=(const BitVector &RHS) {
279    assert(Size == RHS.Size && "Illegal operation!");
280    for (unsigned i = 0; i < NumBitWords(size()); ++i)
281      Bits[i] |= RHS.Bits[i];
282    return *this;
283  }
284
285  BitVector operator^=(const BitVector &RHS) {
286    assert(Size == RHS.Size && "Illegal operation!");
287    for (unsigned i = 0; i < NumBitWords(size()); ++i)
288      Bits[i] ^= RHS.Bits[i];
289    return *this;
290  }
291
292  // Assignment operator.
293  const BitVector &operator=(const BitVector &RHS) {
294    if (this == &RHS) return *this;
295
296    Size = RHS.size();
297    unsigned RHSWords = NumBitWords(Size);
298    if (Size <= Capacity * BITWORD_SIZE) {
299      std::copy(RHS.Bits, &RHS.Bits[RHSWords], Bits);
300      clear_unused_bits();
301      return *this;
302    }
303
304    // Grow the bitvector to have enough elements.
305    Capacity = NumBitWords(Size);
306    BitWord *NewBits = new BitWord[Capacity];
307    std::copy(RHS.Bits, &RHS.Bits[RHSWords], NewBits);
308
309    // Destroy the old bits.
310    delete[] Bits;
311    Bits = NewBits;
312
313    return *this;
314  }
315
316private:
317  unsigned NumBitWords(unsigned S) const {
318    return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
319  }
320
321  // Clear the unused top bits in the high word.
322  void clear_unused_bits() {
323    unsigned ExtraBits = Size % BITWORD_SIZE;
324    if (ExtraBits) {
325      unsigned index = Size / BITWORD_SIZE;
326      Bits[index] &= ~(~0L << ExtraBits);
327    }
328  }
329
330  void grow(unsigned NewSize) {
331    unsigned OldCapacity = Capacity;
332    Capacity = NumBitWords(NewSize);
333    BitWord *NewBits = new BitWord[Capacity];
334
335    // Copy the old bits over.
336    if (OldCapacity != 0)
337      std::copy(Bits, &Bits[OldCapacity], NewBits);
338
339    // Destroy the old bits.
340    delete[] Bits;
341    Bits = NewBits;
342  }
343
344  void init_words(BitWord *B, unsigned NumWords, bool t) {
345    memset(B, 0 - (int)t, NumWords*sizeof(BitWord));
346  }
347};
348
349inline BitVector operator&(const BitVector &LHS, const BitVector &RHS) {
350  BitVector Result(LHS);
351  Result &= RHS;
352  return Result;
353}
354
355inline BitVector operator|(const BitVector &LHS, const BitVector &RHS) {
356  BitVector Result(LHS);
357  Result |= RHS;
358  return Result;
359}
360
361inline BitVector operator^(const BitVector &LHS, const BitVector &RHS) {
362  BitVector Result(LHS);
363  Result ^= RHS;
364  return Result;
365}
366
367} // End llvm namespace
368#endif
369