BitVector.h revision 9e10d773e155fcd9fba9c3e1a7d2e49f31c42731
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/ErrorHandling.h" 18#include "llvm/Support/MathExtras.h" 19#include <algorithm> 20#include <cassert> 21#include <climits> 22#include <cstdlib> 23 24namespace llvm { 25 26class BitVector { 27 typedef unsigned long BitWord; 28 29 enum { BITWORD_SIZE = (unsigned)sizeof(BitWord) * CHAR_BIT }; 30 31 BitWord *Bits; // Actual bits. 32 unsigned Size; // Size of bitvector in bits. 33 unsigned Capacity; // Size of allocated memory in BitWord. 34 35public: 36 // Encapsulation of a single bit. 37 class reference { 38 friend class BitVector; 39 40 BitWord *WordRef; 41 unsigned BitPos; 42 43 reference(); // Undefined 44 45 public: 46 reference(BitVector &b, unsigned Idx) { 47 WordRef = &b.Bits[Idx / BITWORD_SIZE]; 48 BitPos = Idx % BITWORD_SIZE; 49 } 50 51 ~reference() {} 52 53 reference &operator=(reference t) { 54 *this = bool(t); 55 return *this; 56 } 57 58 reference& operator=(bool t) { 59 if (t) 60 *WordRef |= 1L << BitPos; 61 else 62 *WordRef &= ~(1L << BitPos); 63 return *this; 64 } 65 66 operator bool() const { 67 return ((*WordRef) & (1L << BitPos)) ? true : false; 68 } 69 }; 70 71 72 /// BitVector default ctor - Creates an empty bitvector. 73 BitVector() : Size(0), Capacity(0) { 74 Bits = 0; 75 } 76 77 /// BitVector ctor - Creates a bitvector of specified number of bits. All 78 /// bits are initialized to the specified value. 79 explicit BitVector(unsigned s, bool t = false) : Size(s) { 80 Capacity = NumBitWords(s); 81 Bits = (BitWord *)std::malloc(Capacity * sizeof(BitWord)); 82 init_words(Bits, Capacity, t); 83 if (t) 84 clear_unused_bits(); 85 } 86 87 /// BitVector copy ctor. 88 BitVector(const BitVector &RHS) : Size(RHS.size()) { 89 if (Size == 0) { 90 Bits = 0; 91 Capacity = 0; 92 return; 93 } 94 95 Capacity = NumBitWords(RHS.size()); 96 Bits = (BitWord *)std::malloc(Capacity * sizeof(BitWord)); 97 std::memcpy(Bits, RHS.Bits, Capacity * sizeof(BitWord)); 98 } 99 100 ~BitVector() { 101 std::free(Bits); 102 } 103 104 /// empty - Tests whether there are no bits in this bitvector. 105 bool empty() const { return Size == 0; } 106 107 /// size - Returns the number of bits in this bitvector. 108 unsigned size() const { return Size; } 109 110 /// count - Returns the number of bits which are set. 111 unsigned count() const { 112 unsigned NumBits = 0; 113 for (unsigned i = 0; i < NumBitWords(size()); ++i) 114 if (sizeof(BitWord) == 4) 115 NumBits += CountPopulation_32((uint32_t)Bits[i]); 116 else if (sizeof(BitWord) == 8) 117 NumBits += CountPopulation_64(Bits[i]); 118 else 119 llvm_unreachable("Unsupported!"); 120 return NumBits; 121 } 122 123 /// any - Returns true if any bit is set. 124 bool any() const { 125 for (unsigned i = 0; i < NumBitWords(size()); ++i) 126 if (Bits[i] != 0) 127 return true; 128 return false; 129 } 130 131 /// all - Returns true if all bits are set. 132 bool all() const { 133 // TODO: Optimize this. 134 return count() == size(); 135 } 136 137 /// none - Returns true if none of the bits are set. 138 bool none() const { 139 return !any(); 140 } 141 142 /// find_first - Returns the index of the first set bit, -1 if none 143 /// of the bits are set. 144 int find_first() const { 145 for (unsigned i = 0; i < NumBitWords(size()); ++i) 146 if (Bits[i] != 0) { 147 if (sizeof(BitWord) == 4) 148 return i * BITWORD_SIZE + CountTrailingZeros_32((uint32_t)Bits[i]); 149 if (sizeof(BitWord) == 8) 150 return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]); 151 llvm_unreachable("Unsupported!"); 152 } 153 return -1; 154 } 155 156 /// find_next - Returns the index of the next set bit following the 157 /// "Prev" bit. Returns -1 if the next set bit is not found. 158 int find_next(unsigned Prev) const { 159 ++Prev; 160 if (Prev >= Size) 161 return -1; 162 163 unsigned WordPos = Prev / BITWORD_SIZE; 164 unsigned BitPos = Prev % BITWORD_SIZE; 165 BitWord Copy = Bits[WordPos]; 166 // Mask off previous bits. 167 Copy &= ~0L << BitPos; 168 169 if (Copy != 0) { 170 if (sizeof(BitWord) == 4) 171 return WordPos * BITWORD_SIZE + CountTrailingZeros_32((uint32_t)Copy); 172 if (sizeof(BitWord) == 8) 173 return WordPos * BITWORD_SIZE + CountTrailingZeros_64(Copy); 174 llvm_unreachable("Unsupported!"); 175 } 176 177 // Check subsequent words. 178 for (unsigned i = WordPos+1; i < NumBitWords(size()); ++i) 179 if (Bits[i] != 0) { 180 if (sizeof(BitWord) == 4) 181 return i * BITWORD_SIZE + CountTrailingZeros_32((uint32_t)Bits[i]); 182 if (sizeof(BitWord) == 8) 183 return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]); 184 llvm_unreachable("Unsupported!"); 185 } 186 return -1; 187 } 188 189 /// clear - Clear all bits. 190 void clear() { 191 Size = 0; 192 } 193 194 /// resize - Grow or shrink the bitvector. 195 void resize(unsigned N, bool t = false) { 196 if (N > Capacity * BITWORD_SIZE) { 197 unsigned OldCapacity = Capacity; 198 grow(N); 199 init_words(&Bits[OldCapacity], (Capacity-OldCapacity), t); 200 } 201 202 // Set any old unused bits that are now included in the BitVector. This 203 // may set bits that are not included in the new vector, but we will clear 204 // them back out below. 205 if (N > Size) 206 set_unused_bits(t); 207 208 // Update the size, and clear out any bits that are now unused 209 unsigned OldSize = Size; 210 Size = N; 211 if (t || N < OldSize) 212 clear_unused_bits(); 213 } 214 215 void reserve(unsigned N) { 216 if (N > Capacity * BITWORD_SIZE) 217 grow(N); 218 } 219 220 // Set, reset, flip 221 BitVector &set() { 222 init_words(Bits, Capacity, true); 223 clear_unused_bits(); 224 return *this; 225 } 226 227 BitVector &set(unsigned Idx) { 228 Bits[Idx / BITWORD_SIZE] |= 1L << (Idx % BITWORD_SIZE); 229 return *this; 230 } 231 232 BitVector &reset() { 233 init_words(Bits, Capacity, false); 234 return *this; 235 } 236 237 BitVector &reset(unsigned Idx) { 238 Bits[Idx / BITWORD_SIZE] &= ~(1L << (Idx % BITWORD_SIZE)); 239 return *this; 240 } 241 242 BitVector &flip() { 243 for (unsigned i = 0; i < NumBitWords(size()); ++i) 244 Bits[i] = ~Bits[i]; 245 clear_unused_bits(); 246 return *this; 247 } 248 249 BitVector &flip(unsigned Idx) { 250 Bits[Idx / BITWORD_SIZE] ^= 1L << (Idx % BITWORD_SIZE); 251 return *this; 252 } 253 254 // No argument flip. 255 BitVector operator~() const { 256 return BitVector(*this).flip(); 257 } 258 259 // Indexing. 260 reference operator[](unsigned Idx) { 261 assert (Idx < Size && "Out-of-bounds Bit access."); 262 return reference(*this, Idx); 263 } 264 265 bool operator[](unsigned Idx) const { 266 assert (Idx < Size && "Out-of-bounds Bit access."); 267 BitWord Mask = 1L << (Idx % BITWORD_SIZE); 268 return (Bits[Idx / BITWORD_SIZE] & Mask) != 0; 269 } 270 271 bool test(unsigned Idx) const { 272 return (*this)[Idx]; 273 } 274 275 /// Test if any common bits are set. 276 bool anyCommon(const BitVector &RHS) const { 277 unsigned ThisWords = NumBitWords(size()); 278 unsigned RHSWords = NumBitWords(RHS.size()); 279 for (unsigned i = 0, e = std::min(ThisWords, RHSWords); i != e; ++i) 280 if (Bits[i] & RHS.Bits[i]) 281 return true; 282 return false; 283 } 284 285 // Comparison operators. 286 bool operator==(const BitVector &RHS) const { 287 unsigned ThisWords = NumBitWords(size()); 288 unsigned RHSWords = NumBitWords(RHS.size()); 289 unsigned i; 290 for (i = 0; i != std::min(ThisWords, RHSWords); ++i) 291 if (Bits[i] != RHS.Bits[i]) 292 return false; 293 294 // Verify that any extra words are all zeros. 295 if (i != ThisWords) { 296 for (; i != ThisWords; ++i) 297 if (Bits[i]) 298 return false; 299 } else if (i != RHSWords) { 300 for (; i != RHSWords; ++i) 301 if (RHS.Bits[i]) 302 return false; 303 } 304 return true; 305 } 306 307 bool operator!=(const BitVector &RHS) const { 308 return !(*this == RHS); 309 } 310 311 // Intersection, union, disjoint union. 312 BitVector &operator&=(const BitVector &RHS) { 313 unsigned ThisWords = NumBitWords(size()); 314 unsigned RHSWords = NumBitWords(RHS.size()); 315 unsigned i; 316 for (i = 0; i != std::min(ThisWords, RHSWords); ++i) 317 Bits[i] &= RHS.Bits[i]; 318 319 // Any bits that are just in this bitvector become zero, because they aren't 320 // in the RHS bit vector. Any words only in RHS are ignored because they 321 // are already zero in the LHS. 322 for (; i != ThisWords; ++i) 323 Bits[i] = 0; 324 325 return *this; 326 } 327 328 // reset - Reset bits that are set in RHS. Same as *this &= ~RHS. 329 BitVector &reset(const BitVector &RHS) { 330 unsigned ThisWords = NumBitWords(size()); 331 unsigned RHSWords = NumBitWords(RHS.size()); 332 unsigned i; 333 for (i = 0; i != std::min(ThisWords, RHSWords); ++i) 334 Bits[i] &= ~RHS.Bits[i]; 335 return *this; 336 } 337 338 BitVector &operator|=(const BitVector &RHS) { 339 if (size() < RHS.size()) 340 resize(RHS.size()); 341 for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i) 342 Bits[i] |= RHS.Bits[i]; 343 return *this; 344 } 345 346 BitVector &operator^=(const BitVector &RHS) { 347 if (size() < RHS.size()) 348 resize(RHS.size()); 349 for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i) 350 Bits[i] ^= RHS.Bits[i]; 351 return *this; 352 } 353 354 // Assignment operator. 355 const BitVector &operator=(const BitVector &RHS) { 356 if (this == &RHS) return *this; 357 358 Size = RHS.size(); 359 unsigned RHSWords = NumBitWords(Size); 360 if (Size <= Capacity * BITWORD_SIZE) { 361 if (Size) 362 std::memcpy(Bits, RHS.Bits, RHSWords * sizeof(BitWord)); 363 clear_unused_bits(); 364 return *this; 365 } 366 367 // Grow the bitvector to have enough elements. 368 Capacity = RHSWords; 369 BitWord *NewBits = (BitWord *)std::malloc(Capacity * sizeof(BitWord)); 370 std::memcpy(NewBits, RHS.Bits, Capacity * sizeof(BitWord)); 371 372 // Destroy the old bits. 373 std::free(Bits); 374 Bits = NewBits; 375 376 return *this; 377 } 378 379 void swap(BitVector &RHS) { 380 std::swap(Bits, RHS.Bits); 381 std::swap(Size, RHS.Size); 382 std::swap(Capacity, RHS.Capacity); 383 } 384 385 //===--------------------------------------------------------------------===// 386 // Portable bit mask operations. 387 //===--------------------------------------------------------------------===// 388 // 389 // These methods all operate on arrays of uint32_t, each holding 32 bits. The 390 // fixed word size makes it easier to work with literal bit vector constants 391 // in portable code. 392 // 393 // The LSB in each word is the lowest numbered bit. The size of a portable 394 // bit mask is always a whole multiple of 32 bits. If no bit mask size is 395 // given, the bit mask is assumed to cover the entire BitVector. 396 397 /// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize. 398 /// This computes "*this |= Mask". 399 void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 400 applyMask<true, false>(Mask, MaskWords); 401 } 402 403 /// clearBitsInMask - Clear any bits in this vector that are set in Mask. 404 /// Don't resize. This computes "*this &= ~Mask". 405 void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 406 applyMask<false, false>(Mask, MaskWords); 407 } 408 409 /// setBitsNotInMask - Add a bit to this vector for every '0' bit in Mask. 410 /// Don't resize. This computes "*this |= ~Mask". 411 void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 412 applyMask<true, true>(Mask, MaskWords); 413 } 414 415 /// clearBitsNotInMask - Clear a bit in this vector for every '0' bit in Mask. 416 /// Don't resize. This computes "*this &= Mask". 417 void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 418 applyMask<false, true>(Mask, MaskWords); 419 } 420 421private: 422 unsigned NumBitWords(unsigned S) const { 423 return (S + BITWORD_SIZE-1) / BITWORD_SIZE; 424 } 425 426 // Set the unused bits in the high words. 427 void set_unused_bits(bool t = true) { 428 // Set high words first. 429 unsigned UsedWords = NumBitWords(Size); 430 if (Capacity > UsedWords) 431 init_words(&Bits[UsedWords], (Capacity-UsedWords), t); 432 433 // Then set any stray high bits of the last used word. 434 unsigned ExtraBits = Size % BITWORD_SIZE; 435 if (ExtraBits) { 436 Bits[UsedWords-1] &= ~(~0L << ExtraBits); 437 Bits[UsedWords-1] |= (0 - (BitWord)t) << ExtraBits; 438 } 439 } 440 441 // Clear the unused bits in the high words. 442 void clear_unused_bits() { 443 set_unused_bits(false); 444 } 445 446 void grow(unsigned NewSize) { 447 Capacity = std::max(NumBitWords(NewSize), Capacity * 2); 448 Bits = (BitWord *)std::realloc(Bits, Capacity * sizeof(BitWord)); 449 450 clear_unused_bits(); 451 } 452 453 void init_words(BitWord *B, unsigned NumWords, bool t) { 454 memset(B, 0 - (int)t, NumWords*sizeof(BitWord)); 455 } 456 457 template<bool AddBits, bool InvertMask> 458 void applyMask(const uint32_t *Mask, unsigned MaskWords) { 459 assert(BITWORD_SIZE % 32 == 0 && "Unsupported BitWord size."); 460 MaskWords = std::min(MaskWords, (size() + 31) / 32); 461 const unsigned Scale = BITWORD_SIZE / 32; 462 unsigned i; 463 for (i = 0; MaskWords >= Scale; ++i, MaskWords -= Scale) { 464 BitWord BW = Bits[i]; 465 // This inner loop should unroll completely when BITWORD_SIZE > 32. 466 for (unsigned b = 0; b != BITWORD_SIZE; b += 32) { 467 uint32_t M = *Mask++; 468 if (InvertMask) M = ~M; 469 if (AddBits) BW |= BitWord(M) << b; 470 else BW &= ~(BitWord(M) << b); 471 } 472 Bits[i] = BW; 473 } 474 for (unsigned b = 0; MaskWords; b += 32, --MaskWords) { 475 uint32_t M = *Mask++; 476 if (InvertMask) M = ~M; 477 if (AddBits) Bits[i] |= BitWord(M) << b; 478 else Bits[i] &= ~(BitWord(M) << b); 479 } 480 if (AddBits) 481 clear_unused_bits(); 482 } 483}; 484 485} // End llvm namespace 486 487namespace std { 488 /// Implement std::swap in terms of BitVector swap. 489 inline void 490 swap(llvm::BitVector &LHS, llvm::BitVector &RHS) { 491 LHS.swap(RHS); 492 } 493} 494 495#endif 496