1//===- llvm/ADT/SmallBitVector.h - 'Normally small' 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 SmallBitVector class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_SMALLBITVECTOR_H
15#define LLVM_ADT_SMALLBITVECTOR_H
16
17#include "llvm/ADT/BitVector.h"
18#include "llvm/Support/Compiler.h"
19#include "llvm/Support/MathExtras.h"
20#include <cassert>
21
22namespace llvm {
23
24/// SmallBitVector - This is a 'bitvector' (really, a variable-sized bit array),
25/// optimized for the case when the array is small.  It contains one
26/// pointer-sized field, which is directly used as a plain collection of bits
27/// when possible, or as a pointer to a larger heap-allocated array when
28/// necessary.  This allows normal "small" cases to be fast without losing
29/// generality for large inputs.
30///
31class SmallBitVector {
32  // TODO: In "large" mode, a pointer to a BitVector is used, leading to an
33  // unnecessary level of indirection. It would be more efficient to use a
34  // pointer to memory containing size, allocation size, and the array of bits.
35  uintptr_t X;
36
37  enum {
38    // The number of bits in this class.
39    NumBaseBits = sizeof(uintptr_t) * CHAR_BIT,
40
41    // One bit is used to discriminate between small and large mode. The
42    // remaining bits are used for the small-mode representation.
43    SmallNumRawBits = NumBaseBits - 1,
44
45    // A few more bits are used to store the size of the bit set in small mode.
46    // Theoretically this is a ceil-log2. These bits are encoded in the most
47    // significant bits of the raw bits.
48    SmallNumSizeBits = (NumBaseBits == 32 ? 5 :
49                        NumBaseBits == 64 ? 6 :
50                        SmallNumRawBits),
51
52    // The remaining bits are used to store the actual set in small mode.
53    SmallNumDataBits = SmallNumRawBits - SmallNumSizeBits
54  };
55
56public:
57  // Encapsulation of a single bit.
58  class reference {
59    SmallBitVector &TheVector;
60    unsigned BitPos;
61
62  public:
63    reference(SmallBitVector &b, unsigned Idx) : TheVector(b), BitPos(Idx) {}
64
65    reference& operator=(reference t) {
66      *this = bool(t);
67      return *this;
68    }
69
70    reference& operator=(bool t) {
71      if (t)
72        TheVector.set(BitPos);
73      else
74        TheVector.reset(BitPos);
75      return *this;
76    }
77
78    operator bool() const {
79      return const_cast<const SmallBitVector &>(TheVector).operator[](BitPos);
80    }
81  };
82
83private:
84  bool isSmall() const {
85    return X & uintptr_t(1);
86  }
87
88  BitVector *getPointer() const {
89    assert(!isSmall());
90    return reinterpret_cast<BitVector *>(X);
91  }
92
93  void switchToSmall(uintptr_t NewSmallBits, size_t NewSize) {
94    X = 1;
95    setSmallSize(NewSize);
96    setSmallBits(NewSmallBits);
97  }
98
99  void switchToLarge(BitVector *BV) {
100    X = reinterpret_cast<uintptr_t>(BV);
101    assert(!isSmall() && "Tried to use an unaligned pointer");
102  }
103
104  // Return all the bits used for the "small" representation; this includes
105  // bits for the size as well as the element bits.
106  uintptr_t getSmallRawBits() const {
107    assert(isSmall());
108    return X >> 1;
109  }
110
111  void setSmallRawBits(uintptr_t NewRawBits) {
112    assert(isSmall());
113    X = (NewRawBits << 1) | uintptr_t(1);
114  }
115
116  // Return the size.
117  size_t getSmallSize() const {
118    return getSmallRawBits() >> SmallNumDataBits;
119  }
120
121  void setSmallSize(size_t Size) {
122    setSmallRawBits(getSmallBits() | (Size << SmallNumDataBits));
123  }
124
125  // Return the element bits.
126  uintptr_t getSmallBits() const {
127    return getSmallRawBits() & ~(~uintptr_t(0) << getSmallSize());
128  }
129
130  void setSmallBits(uintptr_t NewBits) {
131    setSmallRawBits((NewBits & ~(~uintptr_t(0) << getSmallSize())) |
132                    (getSmallSize() << SmallNumDataBits));
133  }
134
135public:
136  /// SmallBitVector default ctor - Creates an empty bitvector.
137  SmallBitVector() : X(1) {}
138
139  /// SmallBitVector ctor - Creates a bitvector of specified number of bits. All
140  /// bits are initialized to the specified value.
141  explicit SmallBitVector(unsigned s, bool t = false) {
142    if (s <= SmallNumDataBits)
143      switchToSmall(t ? ~uintptr_t(0) : 0, s);
144    else
145      switchToLarge(new BitVector(s, t));
146  }
147
148  /// SmallBitVector copy ctor.
149  SmallBitVector(const SmallBitVector &RHS) {
150    if (RHS.isSmall())
151      X = RHS.X;
152    else
153      switchToLarge(new BitVector(*RHS.getPointer()));
154  }
155
156#if LLVM_USE_RVALUE_REFERENCES
157  SmallBitVector(SmallBitVector &&RHS) : X(RHS.X) {
158    RHS.X = 1;
159  }
160#endif
161
162  ~SmallBitVector() {
163    if (!isSmall())
164      delete getPointer();
165  }
166
167  /// empty - Tests whether there are no bits in this bitvector.
168  bool empty() const {
169    return isSmall() ? getSmallSize() == 0 : getPointer()->empty();
170  }
171
172  /// size - Returns the number of bits in this bitvector.
173  size_t size() const {
174    return isSmall() ? getSmallSize() : getPointer()->size();
175  }
176
177  /// count - Returns the number of bits which are set.
178  unsigned count() const {
179    if (isSmall()) {
180      uintptr_t Bits = getSmallBits();
181      if (sizeof(uintptr_t) * CHAR_BIT == 32)
182        return CountPopulation_32(Bits);
183      if (sizeof(uintptr_t) * CHAR_BIT == 64)
184        return CountPopulation_64(Bits);
185      llvm_unreachable("Unsupported!");
186    }
187    return getPointer()->count();
188  }
189
190  /// any - Returns true if any bit is set.
191  bool any() const {
192    if (isSmall())
193      return getSmallBits() != 0;
194    return getPointer()->any();
195  }
196
197  /// all - Returns true if all bits are set.
198  bool all() const {
199    if (isSmall())
200      return getSmallBits() == (uintptr_t(1) << getSmallSize()) - 1;
201    return getPointer()->all();
202  }
203
204  /// none - Returns true if none of the bits are set.
205  bool none() const {
206    if (isSmall())
207      return getSmallBits() == 0;
208    return getPointer()->none();
209  }
210
211  /// find_first - Returns the index of the first set bit, -1 if none
212  /// of the bits are set.
213  int find_first() const {
214    if (isSmall()) {
215      uintptr_t Bits = getSmallBits();
216      if (Bits == 0)
217        return -1;
218      if (sizeof(uintptr_t) * CHAR_BIT == 32)
219        return CountTrailingZeros_32(Bits);
220      if (sizeof(uintptr_t) * CHAR_BIT == 64)
221        return CountTrailingZeros_64(Bits);
222      llvm_unreachable("Unsupported!");
223    }
224    return getPointer()->find_first();
225  }
226
227  /// find_next - Returns the index of the next set bit following the
228  /// "Prev" bit. Returns -1 if the next set bit is not found.
229  int find_next(unsigned Prev) const {
230    if (isSmall()) {
231      uintptr_t Bits = getSmallBits();
232      // Mask off previous bits.
233      Bits &= ~uintptr_t(0) << (Prev + 1);
234      if (Bits == 0 || Prev + 1 >= getSmallSize())
235        return -1;
236      if (sizeof(uintptr_t) * CHAR_BIT == 32)
237        return CountTrailingZeros_32(Bits);
238      if (sizeof(uintptr_t) * CHAR_BIT == 64)
239        return CountTrailingZeros_64(Bits);
240      llvm_unreachable("Unsupported!");
241    }
242    return getPointer()->find_next(Prev);
243  }
244
245  /// clear - Clear all bits.
246  void clear() {
247    if (!isSmall())
248      delete getPointer();
249    switchToSmall(0, 0);
250  }
251
252  /// resize - Grow or shrink the bitvector.
253  void resize(unsigned N, bool t = false) {
254    if (!isSmall()) {
255      getPointer()->resize(N, t);
256    } else if (SmallNumDataBits >= N) {
257      uintptr_t NewBits = t ? ~uintptr_t(0) << getSmallSize() : 0;
258      setSmallSize(N);
259      setSmallBits(NewBits | getSmallBits());
260    } else {
261      BitVector *BV = new BitVector(N, t);
262      uintptr_t OldBits = getSmallBits();
263      for (size_t i = 0, e = getSmallSize(); i != e; ++i)
264        (*BV)[i] = (OldBits >> i) & 1;
265      switchToLarge(BV);
266    }
267  }
268
269  void reserve(unsigned N) {
270    if (isSmall()) {
271      if (N > SmallNumDataBits) {
272        uintptr_t OldBits = getSmallRawBits();
273        size_t SmallSize = getSmallSize();
274        BitVector *BV = new BitVector(SmallSize);
275        for (size_t i = 0; i < SmallSize; ++i)
276          if ((OldBits >> i) & 1)
277            BV->set(i);
278        BV->reserve(N);
279        switchToLarge(BV);
280      }
281    } else {
282      getPointer()->reserve(N);
283    }
284  }
285
286  // Set, reset, flip
287  SmallBitVector &set() {
288    if (isSmall())
289      setSmallBits(~uintptr_t(0));
290    else
291      getPointer()->set();
292    return *this;
293  }
294
295  SmallBitVector &set(unsigned Idx) {
296    if (isSmall())
297      setSmallBits(getSmallBits() | (uintptr_t(1) << Idx));
298    else
299      getPointer()->set(Idx);
300    return *this;
301  }
302
303  SmallBitVector &reset() {
304    if (isSmall())
305      setSmallBits(0);
306    else
307      getPointer()->reset();
308    return *this;
309  }
310
311  SmallBitVector &reset(unsigned Idx) {
312    if (isSmall())
313      setSmallBits(getSmallBits() & ~(uintptr_t(1) << Idx));
314    else
315      getPointer()->reset(Idx);
316    return *this;
317  }
318
319  SmallBitVector &flip() {
320    if (isSmall())
321      setSmallBits(~getSmallBits());
322    else
323      getPointer()->flip();
324    return *this;
325  }
326
327  SmallBitVector &flip(unsigned Idx) {
328    if (isSmall())
329      setSmallBits(getSmallBits() ^ (uintptr_t(1) << Idx));
330    else
331      getPointer()->flip(Idx);
332    return *this;
333  }
334
335  // No argument flip.
336  SmallBitVector operator~() const {
337    return SmallBitVector(*this).flip();
338  }
339
340  // Indexing.
341  reference operator[](unsigned Idx) {
342    assert(Idx < size() && "Out-of-bounds Bit access.");
343    return reference(*this, Idx);
344  }
345
346  bool operator[](unsigned Idx) const {
347    assert(Idx < size() && "Out-of-bounds Bit access.");
348    if (isSmall())
349      return ((getSmallBits() >> Idx) & 1) != 0;
350    return getPointer()->operator[](Idx);
351  }
352
353  bool test(unsigned Idx) const {
354    return (*this)[Idx];
355  }
356
357  /// Test if any common bits are set.
358  bool anyCommon(const SmallBitVector &RHS) const {
359    if (isSmall() && RHS.isSmall())
360      return (getSmallBits() & RHS.getSmallBits()) != 0;
361    if (!isSmall() && !RHS.isSmall())
362      return getPointer()->anyCommon(*RHS.getPointer());
363
364    for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
365      if (test(i) && RHS.test(i))
366        return true;
367    return false;
368  }
369
370  // Comparison operators.
371  bool operator==(const SmallBitVector &RHS) const {
372    if (size() != RHS.size())
373      return false;
374    if (isSmall())
375      return getSmallBits() == RHS.getSmallBits();
376    else
377      return *getPointer() == *RHS.getPointer();
378  }
379
380  bool operator!=(const SmallBitVector &RHS) const {
381    return !(*this == RHS);
382  }
383
384  // Intersection, union, disjoint union.
385  SmallBitVector &operator&=(const SmallBitVector &RHS) {
386    resize(std::max(size(), RHS.size()));
387    if (isSmall())
388      setSmallBits(getSmallBits() & RHS.getSmallBits());
389    else if (!RHS.isSmall())
390      getPointer()->operator&=(*RHS.getPointer());
391    else {
392      SmallBitVector Copy = RHS;
393      Copy.resize(size());
394      getPointer()->operator&=(*Copy.getPointer());
395    }
396    return *this;
397  }
398
399  SmallBitVector &operator|=(const SmallBitVector &RHS) {
400    resize(std::max(size(), RHS.size()));
401    if (isSmall())
402      setSmallBits(getSmallBits() | RHS.getSmallBits());
403    else if (!RHS.isSmall())
404      getPointer()->operator|=(*RHS.getPointer());
405    else {
406      SmallBitVector Copy = RHS;
407      Copy.resize(size());
408      getPointer()->operator|=(*Copy.getPointer());
409    }
410    return *this;
411  }
412
413  SmallBitVector &operator^=(const SmallBitVector &RHS) {
414    resize(std::max(size(), RHS.size()));
415    if (isSmall())
416      setSmallBits(getSmallBits() ^ RHS.getSmallBits());
417    else if (!RHS.isSmall())
418      getPointer()->operator^=(*RHS.getPointer());
419    else {
420      SmallBitVector Copy = RHS;
421      Copy.resize(size());
422      getPointer()->operator^=(*Copy.getPointer());
423    }
424    return *this;
425  }
426
427  // Assignment operator.
428  const SmallBitVector &operator=(const SmallBitVector &RHS) {
429    if (isSmall()) {
430      if (RHS.isSmall())
431        X = RHS.X;
432      else
433        switchToLarge(new BitVector(*RHS.getPointer()));
434    } else {
435      if (!RHS.isSmall())
436        *getPointer() = *RHS.getPointer();
437      else {
438        delete getPointer();
439        X = RHS.X;
440      }
441    }
442    return *this;
443  }
444
445#if LLVM_USE_RVALUE_REFERENCES
446  const SmallBitVector &operator=(SmallBitVector &&RHS) {
447    if (this != &RHS) {
448      clear();
449      swap(RHS);
450    }
451    return *this;
452  }
453#endif
454
455  void swap(SmallBitVector &RHS) {
456    std::swap(X, RHS.X);
457  }
458
459  /// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize.
460  /// This computes "*this |= Mask".
461  void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
462    if (isSmall())
463      applyMask<true, false>(Mask, MaskWords);
464    else
465      getPointer()->setBitsInMask(Mask, MaskWords);
466  }
467
468  /// clearBitsInMask - Clear any bits in this vector that are set in Mask.
469  /// Don't resize. This computes "*this &= ~Mask".
470  void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
471    if (isSmall())
472      applyMask<false, false>(Mask, MaskWords);
473    else
474      getPointer()->clearBitsInMask(Mask, MaskWords);
475  }
476
477  /// setBitsNotInMask - Add a bit to this vector for every '0' bit in Mask.
478  /// Don't resize.  This computes "*this |= ~Mask".
479  void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
480    if (isSmall())
481      applyMask<true, true>(Mask, MaskWords);
482    else
483      getPointer()->setBitsNotInMask(Mask, MaskWords);
484  }
485
486  /// clearBitsNotInMask - Clear a bit in this vector for every '0' bit in Mask.
487  /// Don't resize.  This computes "*this &= Mask".
488  void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
489    if (isSmall())
490      applyMask<false, true>(Mask, MaskWords);
491    else
492      getPointer()->clearBitsNotInMask(Mask, MaskWords);
493  }
494
495private:
496  template<bool AddBits, bool InvertMask>
497  void applyMask(const uint32_t *Mask, unsigned MaskWords) {
498    assert((NumBaseBits == 64 || NumBaseBits == 32) && "Unsupported word size");
499    if (NumBaseBits == 64 && MaskWords >= 2) {
500      uint64_t M = Mask[0] | (uint64_t(Mask[1]) << 32);
501      if (InvertMask) M = ~M;
502      if (AddBits) setSmallBits(getSmallBits() | M);
503      else         setSmallBits(getSmallBits() & ~M);
504    } else {
505      uint32_t M = Mask[0];
506      if (InvertMask) M = ~M;
507      if (AddBits) setSmallBits(getSmallBits() | M);
508      else         setSmallBits(getSmallBits() & ~M);
509    }
510  }
511};
512
513inline SmallBitVector
514operator&(const SmallBitVector &LHS, const SmallBitVector &RHS) {
515  SmallBitVector Result(LHS);
516  Result &= RHS;
517  return Result;
518}
519
520inline SmallBitVector
521operator|(const SmallBitVector &LHS, const SmallBitVector &RHS) {
522  SmallBitVector Result(LHS);
523  Result |= RHS;
524  return Result;
525}
526
527inline SmallBitVector
528operator^(const SmallBitVector &LHS, const SmallBitVector &RHS) {
529  SmallBitVector Result(LHS);
530  Result ^= RHS;
531  return Result;
532}
533
534} // End llvm namespace
535
536namespace std {
537  /// Implement std::swap in terms of BitVector swap.
538  inline void
539  swap(llvm::SmallBitVector &LHS, llvm::SmallBitVector &RHS) {
540    LHS.swap(RHS);
541  }
542}
543
544#endif
545