1//===-- sanitizer_bitvector.h -----------------------------------*- C++ -*-===//
2//
3// This file is distributed under the University of Illinois Open Source
4// License. See LICENSE.TXT for details.
5//
6//===----------------------------------------------------------------------===//
7//
8// Specializer BitVector implementation.
9//
10//===----------------------------------------------------------------------===//
11
12#ifndef SANITIZER_BITVECTOR_H
13#define SANITIZER_BITVECTOR_H
14
15#include "sanitizer_common.h"
16
17namespace __sanitizer {
18
19// Fixed size bit vector based on a single basic integer.
20template <class basic_int_t = uptr>
21class BasicBitVector {
22 public:
23  enum SizeEnum : uptr { kSize = sizeof(basic_int_t) * 8 };
24
25  uptr size() const { return kSize; }
26  // No CTOR.
27  void clear() { bits_ = 0; }
28  void setAll() { bits_ = ~(basic_int_t)0; }
29  bool empty() const { return bits_ == 0; }
30
31  // Returns true if the bit has changed from 0 to 1.
32  bool setBit(uptr idx) {
33    basic_int_t old = bits_;
34    bits_ |= mask(idx);
35    return bits_ != old;
36  }
37
38  // Returns true if the bit has changed from 1 to 0.
39  bool clearBit(uptr idx) {
40    basic_int_t old = bits_;
41    bits_ &= ~mask(idx);
42    return bits_ != old;
43  }
44
45  bool getBit(uptr idx) const { return (bits_ & mask(idx)) != 0; }
46
47  uptr getAndClearFirstOne() {
48    CHECK(!empty());
49    uptr idx = LeastSignificantSetBitIndex(bits_);
50    clearBit(idx);
51    return idx;
52  }
53
54  // Do "this |= v" and return whether new bits have been added.
55  bool setUnion(const BasicBitVector &v) {
56    basic_int_t old = bits_;
57    bits_ |= v.bits_;
58    return bits_ != old;
59  }
60
61  // Do "this &= v" and return whether any bits have been removed.
62  bool setIntersection(const BasicBitVector &v) {
63    basic_int_t old = bits_;
64    bits_ &= v.bits_;
65    return bits_ != old;
66  }
67
68  // Do "this &= ~v" and return whether any bits have been removed.
69  bool setDifference(const BasicBitVector &v) {
70    basic_int_t old = bits_;
71    bits_ &= ~v.bits_;
72    return bits_ != old;
73  }
74
75  void copyFrom(const BasicBitVector &v) { bits_ = v.bits_; }
76
77  // Returns true if 'this' intersects with 'v'.
78  bool intersectsWith(const BasicBitVector &v) const {
79    return (bits_ & v.bits_) != 0;
80  }
81
82  // for (BasicBitVector<>::Iterator it(bv); it.hasNext();) {
83  //   uptr idx = it.next();
84  //   use(idx);
85  // }
86  class Iterator {
87   public:
88    Iterator() { }
89    explicit Iterator(const BasicBitVector &bv) : bv_(bv) {}
90    bool hasNext() const { return !bv_.empty(); }
91    uptr next() { return bv_.getAndClearFirstOne(); }
92    void clear() { bv_.clear(); }
93   private:
94    BasicBitVector bv_;
95  };
96
97 private:
98  basic_int_t mask(uptr idx) const {
99    CHECK_LT(idx, size());
100    return (basic_int_t)1UL << idx;
101  }
102  basic_int_t bits_;
103};
104
105// Fixed size bit vector of (kLevel1Size*BV::kSize**2) bits.
106// The implementation is optimized for better performance on
107// sparse bit vectors, i.e. the those with few set bits.
108template <uptr kLevel1Size = 1, class BV = BasicBitVector<> >
109class TwoLevelBitVector {
110  // This is essentially a 2-level bit vector.
111  // Set bit in the first level BV indicates that there are set bits
112  // in the corresponding BV of the second level.
113  // This structure allows O(kLevel1Size) time for clear() and empty(),
114  // as well fast handling of sparse BVs.
115 public:
116  enum SizeEnum : uptr { kSize = BV::kSize * BV::kSize * kLevel1Size };
117  // No CTOR.
118
119  uptr size() const { return kSize; }
120
121  void clear() {
122    for (uptr i = 0; i < kLevel1Size; i++)
123      l1_[i].clear();
124  }
125
126  void setAll() {
127    for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
128      l1_[i0].setAll();
129      for (uptr i1 = 0; i1 < BV::kSize; i1++)
130        l2_[i0][i1].setAll();
131    }
132  }
133
134  bool empty() const {
135    for (uptr i = 0; i < kLevel1Size; i++)
136      if (!l1_[i].empty())
137        return false;
138    return true;
139  }
140
141  // Returns true if the bit has changed from 0 to 1.
142  bool setBit(uptr idx) {
143    check(idx);
144    uptr i0 = idx0(idx);
145    uptr i1 = idx1(idx);
146    uptr i2 = idx2(idx);
147    if (!l1_[i0].getBit(i1)) {
148      l1_[i0].setBit(i1);
149      l2_[i0][i1].clear();
150    }
151    bool res = l2_[i0][i1].setBit(i2);
152    // Printf("%s: %zd => %zd %zd %zd; %d\n", __func__,
153    // idx, i0, i1, i2, res);
154    return res;
155  }
156
157  bool clearBit(uptr idx) {
158    check(idx);
159    uptr i0 = idx0(idx);
160    uptr i1 = idx1(idx);
161    uptr i2 = idx2(idx);
162    bool res = false;
163    if (l1_[i0].getBit(i1)) {
164      res = l2_[i0][i1].clearBit(i2);
165      if (l2_[i0][i1].empty())
166        l1_[i0].clearBit(i1);
167    }
168    return res;
169  }
170
171  bool getBit(uptr idx) const {
172    check(idx);
173    uptr i0 = idx0(idx);
174    uptr i1 = idx1(idx);
175    uptr i2 = idx2(idx);
176    // Printf("%s: %zd => %zd %zd %zd\n", __func__, idx, i0, i1, i2);
177    return l1_[i0].getBit(i1) && l2_[i0][i1].getBit(i2);
178  }
179
180  uptr getAndClearFirstOne() {
181    for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
182      if (l1_[i0].empty()) continue;
183      uptr i1 = l1_[i0].getAndClearFirstOne();
184      uptr i2 = l2_[i0][i1].getAndClearFirstOne();
185      if (!l2_[i0][i1].empty())
186        l1_[i0].setBit(i1);
187      uptr res = i0 * BV::kSize * BV::kSize + i1 * BV::kSize + i2;
188      // Printf("getAndClearFirstOne: %zd %zd %zd => %zd\n", i0, i1, i2, res);
189      return res;
190    }
191    CHECK(0);
192    return 0;
193  }
194
195  // Do "this |= v" and return whether new bits have been added.
196  bool setUnion(const TwoLevelBitVector &v) {
197    bool res = false;
198    for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
199      BV t = v.l1_[i0];
200      while (!t.empty()) {
201        uptr i1 = t.getAndClearFirstOne();
202        if (l1_[i0].setBit(i1))
203          l2_[i0][i1].clear();
204        if (l2_[i0][i1].setUnion(v.l2_[i0][i1]))
205          res = true;
206      }
207    }
208    return res;
209  }
210
211  // Do "this &= v" and return whether any bits have been removed.
212  bool setIntersection(const TwoLevelBitVector &v) {
213    bool res = false;
214    for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
215      if (l1_[i0].setIntersection(v.l1_[i0]))
216        res = true;
217      if (!l1_[i0].empty()) {
218        BV t = l1_[i0];
219        while (!t.empty()) {
220          uptr i1 = t.getAndClearFirstOne();
221          if (l2_[i0][i1].setIntersection(v.l2_[i0][i1]))
222            res = true;
223          if (l2_[i0][i1].empty())
224            l1_[i0].clearBit(i1);
225        }
226      }
227    }
228    return res;
229  }
230
231  // Do "this &= ~v" and return whether any bits have been removed.
232  bool setDifference(const TwoLevelBitVector &v) {
233    bool res = false;
234    for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
235      BV t = l1_[i0];
236      t.setIntersection(v.l1_[i0]);
237      while (!t.empty()) {
238        uptr i1 = t.getAndClearFirstOne();
239        if (l2_[i0][i1].setDifference(v.l2_[i0][i1]))
240          res = true;
241        if (l2_[i0][i1].empty())
242          l1_[i0].clearBit(i1);
243      }
244    }
245    return res;
246  }
247
248  void copyFrom(const TwoLevelBitVector &v) {
249    clear();
250    setUnion(v);
251  }
252
253  // Returns true if 'this' intersects with 'v'.
254  bool intersectsWith(const TwoLevelBitVector &v) const {
255    for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
256      BV t = l1_[i0];
257      t.setIntersection(v.l1_[i0]);
258      while (!t.empty()) {
259        uptr i1 = t.getAndClearFirstOne();
260        if (!v.l1_[i0].getBit(i1)) continue;
261        if (l2_[i0][i1].intersectsWith(v.l2_[i0][i1]))
262          return true;
263      }
264    }
265    return false;
266  }
267
268  // for (TwoLevelBitVector<>::Iterator it(bv); it.hasNext();) {
269  //   uptr idx = it.next();
270  //   use(idx);
271  // }
272  class Iterator {
273   public:
274    Iterator() { }
275    explicit Iterator(const TwoLevelBitVector &bv) : bv_(bv), i0_(0), i1_(0) {
276      it1_.clear();
277      it2_.clear();
278    }
279
280    bool hasNext() const {
281      if (it1_.hasNext()) return true;
282      for (uptr i = i0_; i < kLevel1Size; i++)
283        if (!bv_.l1_[i].empty()) return true;
284      return false;
285    }
286
287    uptr next() {
288      // Printf("++++: %zd %zd; %d %d; size %zd\n", i0_, i1_, it1_.hasNext(),
289      //       it2_.hasNext(), kSize);
290      if (!it1_.hasNext() && !it2_.hasNext()) {
291        for (; i0_ < kLevel1Size; i0_++) {
292          if (bv_.l1_[i0_].empty()) continue;
293          it1_ = typename BV::Iterator(bv_.l1_[i0_]);
294          // Printf("+i0: %zd %zd; %d %d; size %zd\n", i0_, i1_, it1_.hasNext(),
295          //   it2_.hasNext(), kSize);
296          break;
297        }
298      }
299      if (!it2_.hasNext()) {
300        CHECK(it1_.hasNext());
301        i1_ = it1_.next();
302        it2_ = typename BV::Iterator(bv_.l2_[i0_][i1_]);
303        // Printf("++i1: %zd %zd; %d %d; size %zd\n", i0_, i1_, it1_.hasNext(),
304        //       it2_.hasNext(), kSize);
305      }
306      CHECK(it2_.hasNext());
307      uptr i2 = it2_.next();
308      uptr res = i0_ * BV::kSize * BV::kSize + i1_ * BV::kSize + i2;
309      // Printf("+ret: %zd %zd; %d %d; size %zd; res: %zd\n", i0_, i1_,
310      //       it1_.hasNext(), it2_.hasNext(), kSize, res);
311      if (!it1_.hasNext() && !it2_.hasNext())
312        i0_++;
313      return res;
314    }
315
316   private:
317    const TwoLevelBitVector &bv_;
318    uptr i0_, i1_;
319    typename BV::Iterator it1_, it2_;
320  };
321
322 private:
323  void check(uptr idx) const { CHECK_LE(idx, size()); }
324
325  uptr idx0(uptr idx) const {
326    uptr res = idx / (BV::kSize * BV::kSize);
327    CHECK_LE(res, kLevel1Size);
328    return res;
329  }
330
331  uptr idx1(uptr idx) const {
332    uptr res = (idx / BV::kSize) % BV::kSize;
333    CHECK_LE(res, BV::kSize);
334    return res;
335  }
336
337  uptr idx2(uptr idx) const {
338    uptr res = idx % BV::kSize;
339    CHECK_LE(res, BV::kSize);
340    return res;
341  }
342
343  BV l1_[kLevel1Size];
344  BV l2_[kLevel1Size][BV::kSize];
345};
346
347} // namespace __sanitizer
348
349#endif // SANITIZER_BITVECTOR_H
350