1 //===-- sanitizer_bitvector.h -----------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Specializer BitVector implementation.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef SANITIZER_BITVECTOR_H
14 #define SANITIZER_BITVECTOR_H
15
16 #include "sanitizer_common.h"
17
18 namespace __sanitizer {
19
20 // Fixed size bit vector based on a single basic integer.
21 template <class basic_int_t = uptr>
22 class BasicBitVector {
23 public:
24 enum SizeEnum : uptr { kSize = sizeof(basic_int_t) * 8 };
25
26 uptr size() const { return kSize; }
27 // No CTOR.
28 void clear() { bits_ = 0; }
29 void setAll() { bits_ = ~(basic_int_t)0; }
30 bool empty() const { return bits_ == 0; }
31
32 // Returns true if the bit has changed from 0 to 1.
33 bool setBit(uptr idx) {
34 basic_int_t old = bits_;
35 bits_ |= mask(idx);
36 return bits_ != old;
37 }
38
39 // Returns true if the bit has changed from 1 to 0.
40 bool clearBit(uptr idx) {
41 basic_int_t old = bits_;
42 bits_ &= ~mask(idx);
43 return bits_ != old;
44 }
45
46 bool getBit(uptr idx) const { return (bits_ & mask(idx)) != 0; }
47
48 uptr getAndClearFirstOne() {
49 CHECK(!empty());
50 uptr idx = LeastSignificantSetBitIndex(bits_);
51 clearBit(idx);
52 return idx;
53 }
54
55 // Do "this |= v" and return whether new bits have been added.
56 bool setUnion(const BasicBitVector &v) {
57 basic_int_t old = bits_;
58 bits_ |= v.bits_;
59 return bits_ != old;
60 }
61
62 // Do "this &= v" and return whether any bits have been removed.
63 bool setIntersection(const BasicBitVector &v) {
64 basic_int_t old = bits_;
65 bits_ &= v.bits_;
66 return bits_ != old;
67 }
68
69 // Do "this &= ~v" and return whether any bits have been removed.
70 bool setDifference(const BasicBitVector &v) {
71 basic_int_t old = bits_;
72 bits_ &= ~v.bits_;
73 return bits_ != old;
74 }
75
76 void copyFrom(const BasicBitVector &v) { bits_ = v.bits_; }
77
78 // Returns true if 'this' intersects with 'v'.
79 bool intersectsWith(const BasicBitVector &v) const {
80 return (bits_ & v.bits_) != 0;
81 }
82
83 // for (BasicBitVector<>::Iterator it(bv); it.hasNext();) {
84 // uptr idx = it.next();
85 // use(idx);
86 // }
87 class Iterator {
88 public:
89 Iterator() { }
90 explicit Iterator(const BasicBitVector &bv) : bv_(bv) {}
91 bool hasNext() const { return !bv_.empty(); }
92 uptr next() { return bv_.getAndClearFirstOne(); }
93 void clear() { bv_.clear(); }
94 private:
95 BasicBitVector bv_;
96 };
97
98 private:
99 basic_int_t mask(uptr idx) const {
100 CHECK_LT(idx, size());
101 return (basic_int_t)1UL << idx;
102 }
103 basic_int_t bits_;
104 };
105
106 // Fixed size bit vector of (kLevel1Size*BV::kSize**2) bits.
107 // The implementation is optimized for better performance on
108 // sparse bit vectors, i.e. the those with few set bits.
109 template <uptr kLevel1Size = 1, class BV = BasicBitVector<> >
110 class TwoLevelBitVector {
111 // This is essentially a 2-level bit vector.
112 // Set bit in the first level BV indicates that there are set bits
113 // in the corresponding BV of the second level.
114 // This structure allows O(kLevel1Size) time for clear() and empty(),
115 // as well fast handling of sparse BVs.
116 public:
117 enum SizeEnum : uptr { kSize = BV::kSize * BV::kSize * kLevel1Size };
118 // No CTOR.
119
120 uptr size() const { return kSize; }
121
122 void clear() {
123 for (uptr i = 0; i < kLevel1Size; i++)
124 l1_[i].clear();
125 }
126
127 void setAll() {
128 for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
129 l1_[i0].setAll();
130 for (uptr i1 = 0; i1 < BV::kSize; i1++)
131 l2_[i0][i1].setAll();
132 }
133 }
134
135 bool empty() const {
136 for (uptr i = 0; i < kLevel1Size; i++)
137 if (!l1_[i].empty())
138 return false;
139 return true;
140 }
141
142 // Returns true if the bit has changed from 0 to 1.
143 bool setBit(uptr idx) {
144 check(idx);
145 uptr i0 = idx0(idx);
146 uptr i1 = idx1(idx);
147 uptr i2 = idx2(idx);
148 if (!l1_[i0].getBit(i1)) {
149 l1_[i0].setBit(i1);
150 l2_[i0][i1].clear();
151 }
152 bool res = l2_[i0][i1].setBit(i2);
153 // Printf("%s: %zd => %zd %zd %zd; %d\n", __func__,
154 // idx, i0, i1, i2, res);
155 return res;
156 }
157
158 bool clearBit(uptr idx) {
159 check(idx);
160 uptr i0 = idx0(idx);
161 uptr i1 = idx1(idx);
162 uptr i2 = idx2(idx);
163 bool res = false;
164 if (l1_[i0].getBit(i1)) {
165 res = l2_[i0][i1].clearBit(i2);
166 if (l2_[i0][i1].empty())
167 l1_[i0].clearBit(i1);
168 }
169 return res;
170 }
171
172 bool getBit(uptr idx) const {
173 check(idx);
174 uptr i0 = idx0(idx);
175 uptr i1 = idx1(idx);
176 uptr i2 = idx2(idx);
177 // Printf("%s: %zd => %zd %zd %zd\n", __func__, idx, i0, i1, i2);
178 return l1_[i0].getBit(i1) && l2_[i0][i1].getBit(i2);
179 }
180
181 uptr getAndClearFirstOne() {
182 for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
183 if (l1_[i0].empty()) continue;
184 uptr i1 = l1_[i0].getAndClearFirstOne();
185 uptr i2 = l2_[i0][i1].getAndClearFirstOne();
186 if (!l2_[i0][i1].empty())
187 l1_[i0].setBit(i1);
188 uptr res = i0 * BV::kSize * BV::kSize + i1 * BV::kSize + i2;
189 // Printf("getAndClearFirstOne: %zd %zd %zd => %zd\n", i0, i1, i2, res);
190 return res;
191 }
192 CHECK(0);
193 return 0;
194 }
195
196 // Do "this |= v" and return whether new bits have been added.
197 bool setUnion(const TwoLevelBitVector &v) {
198 bool res = false;
199 for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
200 BV t = v.l1_[i0];
201 while (!t.empty()) {
202 uptr i1 = t.getAndClearFirstOne();
203 if (l1_[i0].setBit(i1))
204 l2_[i0][i1].clear();
205 if (l2_[i0][i1].setUnion(v.l2_[i0][i1]))
206 res = true;
207 }
208 }
209 return res;
210 }
211
212 // Do "this &= v" and return whether any bits have been removed.
213 bool setIntersection(const TwoLevelBitVector &v) {
214 bool res = false;
215 for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
216 if (l1_[i0].setIntersection(v.l1_[i0]))
217 res = true;
218 if (!l1_[i0].empty()) {
219 BV t = l1_[i0];
220 while (!t.empty()) {
221 uptr i1 = t.getAndClearFirstOne();
222 if (l2_[i0][i1].setIntersection(v.l2_[i0][i1]))
223 res = true;
224 if (l2_[i0][i1].empty())
225 l1_[i0].clearBit(i1);
226 }
227 }
228 }
229 return res;
230 }
231
232 // Do "this &= ~v" and return whether any bits have been removed.
233 bool setDifference(const TwoLevelBitVector &v) {
234 bool res = false;
235 for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
236 BV t = l1_[i0];
237 t.setIntersection(v.l1_[i0]);
238 while (!t.empty()) {
239 uptr i1 = t.getAndClearFirstOne();
240 if (l2_[i0][i1].setDifference(v.l2_[i0][i1]))
241 res = true;
242 if (l2_[i0][i1].empty())
243 l1_[i0].clearBit(i1);
244 }
245 }
246 return res;
247 }
248
249 void copyFrom(const TwoLevelBitVector &v) {
250 clear();
251 setUnion(v);
252 }
253
254 // Returns true if 'this' intersects with 'v'.
255 bool intersectsWith(const TwoLevelBitVector &v) const {
256 for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
257 BV t = l1_[i0];
258 t.setIntersection(v.l1_[i0]);
259 while (!t.empty()) {
260 uptr i1 = t.getAndClearFirstOne();
261 if (!v.l1_[i0].getBit(i1)) continue;
262 if (l2_[i0][i1].intersectsWith(v.l2_[i0][i1]))
263 return true;
264 }
265 }
266 return false;
267 }
268
269 // for (TwoLevelBitVector<>::Iterator it(bv); it.hasNext();) {
270 // uptr idx = it.next();
271 // use(idx);
272 // }
273 class Iterator {
274 public:
275 Iterator() { }
276 explicit Iterator(const TwoLevelBitVector &bv) : bv_(bv), i0_(0), i1_(0) {
277 it1_.clear();
278 it2_.clear();
279 }
280
281 bool hasNext() const {
282 if (it1_.hasNext()) return true;
283 for (uptr i = i0_; i < kLevel1Size; i++)
284 if (!bv_.l1_[i].empty()) return true;
285 return false;
286 }
287
288 uptr next() {
289 // Printf("++++: %zd %zd; %d %d; size %zd\n", i0_, i1_, it1_.hasNext(),
290 // it2_.hasNext(), kSize);
291 if (!it1_.hasNext() && !it2_.hasNext()) {
292 for (; i0_ < kLevel1Size; i0_++) {
293 if (bv_.l1_[i0_].empty()) continue;
294 it1_ = typename BV::Iterator(bv_.l1_[i0_]);
295 // Printf("+i0: %zd %zd; %d %d; size %zd\n", i0_, i1_, it1_.hasNext(),
296 // it2_.hasNext(), kSize);
297 break;
298 }
299 }
300 if (!it2_.hasNext()) {
301 CHECK(it1_.hasNext());
302 i1_ = it1_.next();
303 it2_ = typename BV::Iterator(bv_.l2_[i0_][i1_]);
304 // Printf("++i1: %zd %zd; %d %d; size %zd\n", i0_, i1_, it1_.hasNext(),
305 // it2_.hasNext(), kSize);
306 }
307 CHECK(it2_.hasNext());
308 uptr i2 = it2_.next();
309 uptr res = i0_ * BV::kSize * BV::kSize + i1_ * BV::kSize + i2;
310 // Printf("+ret: %zd %zd; %d %d; size %zd; res: %zd\n", i0_, i1_,
311 // it1_.hasNext(), it2_.hasNext(), kSize, res);
312 if (!it1_.hasNext() && !it2_.hasNext())
313 i0_++;
314 return res;
315 }
316
317 private:
318 const TwoLevelBitVector &bv_;
319 uptr i0_, i1_;
320 typename BV::Iterator it1_, it2_;
321 };
322
323 private:
324 void check(uptr idx) const { CHECK_LE(idx, size()); }
325
326 uptr idx0(uptr idx) const {
327 uptr res = idx / (BV::kSize * BV::kSize);
328 CHECK_LE(res, kLevel1Size);
329 return res;
330 }
331
332 uptr idx1(uptr idx) const {
333 uptr res = (idx / BV::kSize) % BV::kSize;
334 CHECK_LE(res, BV::kSize);
335 return res;
336 }
337
338 uptr idx2(uptr idx) const {
339 uptr res = idx % BV::kSize;
340 CHECK_LE(res, BV::kSize);
341 return res;
342 }
343
344 BV l1_[kLevel1Size];
345 BV l2_[kLevel1Size][BV::kSize];
346 };
347
348 } // namespace __sanitizer
349
350 #endif // SANITIZER_BITVECTOR_H