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 22 namespace 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 /// 31 class 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 56 public: 57 typedef unsigned size_type; 58 // Encapsulation of a single bit. 59 class reference { 60 SmallBitVector &TheVector; 61 unsigned BitPos; 62 63 public: 64 reference(SmallBitVector &b, unsigned Idx) : TheVector(b), BitPos(Idx) {} 65 66 reference& operator=(reference t) { 67 *this = bool(t); 68 return *this; 69 } 70 71 reference& operator=(bool t) { 72 if (t) 73 TheVector.set(BitPos); 74 else 75 TheVector.reset(BitPos); 76 return *this; 77 } 78 79 operator bool() const { 80 return const_cast<const SmallBitVector &>(TheVector).operator[](BitPos); 81 } 82 }; 83 84 private: 85 bool isSmall() const { 86 return X & uintptr_t(1); 87 } 88 89 BitVector *getPointer() const { 90 assert(!isSmall()); 91 return reinterpret_cast<BitVector *>(X); 92 } 93 94 void switchToSmall(uintptr_t NewSmallBits, size_t NewSize) { 95 X = 1; 96 setSmallSize(NewSize); 97 setSmallBits(NewSmallBits); 98 } 99 100 void switchToLarge(BitVector *BV) { 101 X = reinterpret_cast<uintptr_t>(BV); 102 assert(!isSmall() && "Tried to use an unaligned pointer"); 103 } 104 105 // Return all the bits used for the "small" representation; this includes 106 // bits for the size as well as the element bits. 107 uintptr_t getSmallRawBits() const { 108 assert(isSmall()); 109 return X >> 1; 110 } 111 112 void setSmallRawBits(uintptr_t NewRawBits) { 113 assert(isSmall()); 114 X = (NewRawBits << 1) | uintptr_t(1); 115 } 116 117 // Return the size. 118 size_t getSmallSize() const { 119 return getSmallRawBits() >> SmallNumDataBits; 120 } 121 122 void setSmallSize(size_t Size) { 123 setSmallRawBits(getSmallBits() | (Size << SmallNumDataBits)); 124 } 125 126 // Return the element bits. 127 uintptr_t getSmallBits() const { 128 return getSmallRawBits() & ~(~uintptr_t(0) << getSmallSize()); 129 } 130 131 void setSmallBits(uintptr_t NewBits) { 132 setSmallRawBits((NewBits & ~(~uintptr_t(0) << getSmallSize())) | 133 (getSmallSize() << SmallNumDataBits)); 134 } 135 136 public: 137 /// SmallBitVector default ctor - Creates an empty bitvector. 138 SmallBitVector() : X(1) {} 139 140 /// SmallBitVector ctor - Creates a bitvector of specified number of bits. All 141 /// bits are initialized to the specified value. 142 explicit SmallBitVector(unsigned s, bool t = false) { 143 if (s <= SmallNumDataBits) 144 switchToSmall(t ? ~uintptr_t(0) : 0, s); 145 else 146 switchToLarge(new BitVector(s, t)); 147 } 148 149 /// SmallBitVector copy ctor. 150 SmallBitVector(const SmallBitVector &RHS) { 151 if (RHS.isSmall()) 152 X = RHS.X; 153 else 154 switchToLarge(new BitVector(*RHS.getPointer())); 155 } 156 157 SmallBitVector(SmallBitVector &&RHS) : X(RHS.X) { 158 RHS.X = 1; 159 } 160 161 ~SmallBitVector() { 162 if (!isSmall()) 163 delete getPointer(); 164 } 165 166 /// empty - Tests whether there are no bits in this bitvector. 167 bool empty() const { 168 return isSmall() ? getSmallSize() == 0 : getPointer()->empty(); 169 } 170 171 /// size - Returns the number of bits in this bitvector. 172 size_t size() const { 173 return isSmall() ? getSmallSize() : getPointer()->size(); 174 } 175 176 /// count - Returns the number of bits which are set. 177 size_type count() const { 178 if (isSmall()) { 179 uintptr_t Bits = getSmallBits(); 180 if (NumBaseBits == 32) 181 return CountPopulation_32(Bits); 182 if (NumBaseBits == 64) 183 return CountPopulation_64(Bits); 184 llvm_unreachable("Unsupported!"); 185 } 186 return getPointer()->count(); 187 } 188 189 /// any - Returns true if any bit is set. 190 bool any() const { 191 if (isSmall()) 192 return getSmallBits() != 0; 193 return getPointer()->any(); 194 } 195 196 /// all - Returns true if all bits are set. 197 bool all() const { 198 if (isSmall()) 199 return getSmallBits() == (uintptr_t(1) << getSmallSize()) - 1; 200 return getPointer()->all(); 201 } 202 203 /// none - Returns true if none of the bits are set. 204 bool none() const { 205 if (isSmall()) 206 return getSmallBits() == 0; 207 return getPointer()->none(); 208 } 209 210 /// find_first - Returns the index of the first set bit, -1 if none 211 /// of the bits are set. 212 int find_first() const { 213 if (isSmall()) { 214 uintptr_t Bits = getSmallBits(); 215 if (Bits == 0) 216 return -1; 217 if (NumBaseBits == 32) 218 return countTrailingZeros(Bits); 219 if (NumBaseBits == 64) 220 return countTrailingZeros(Bits); 221 llvm_unreachable("Unsupported!"); 222 } 223 return getPointer()->find_first(); 224 } 225 226 /// find_next - Returns the index of the next set bit following the 227 /// "Prev" bit. Returns -1 if the next set bit is not found. 228 int find_next(unsigned Prev) const { 229 if (isSmall()) { 230 uintptr_t Bits = getSmallBits(); 231 // Mask off previous bits. 232 Bits &= ~uintptr_t(0) << (Prev + 1); 233 if (Bits == 0 || Prev + 1 >= getSmallSize()) 234 return -1; 235 if (NumBaseBits == 32) 236 return countTrailingZeros(Bits); 237 if (NumBaseBits == 64) 238 return countTrailingZeros(Bits); 239 llvm_unreachable("Unsupported!"); 240 } 241 return getPointer()->find_next(Prev); 242 } 243 244 /// clear - Clear all bits. 245 void clear() { 246 if (!isSmall()) 247 delete getPointer(); 248 switchToSmall(0, 0); 249 } 250 251 /// resize - Grow or shrink the bitvector. 252 void resize(unsigned N, bool t = false) { 253 if (!isSmall()) { 254 getPointer()->resize(N, t); 255 } else if (SmallNumDataBits >= N) { 256 uintptr_t NewBits = t ? ~uintptr_t(0) << getSmallSize() : 0; 257 setSmallSize(N); 258 setSmallBits(NewBits | getSmallBits()); 259 } else { 260 BitVector *BV = new BitVector(N, t); 261 uintptr_t OldBits = getSmallBits(); 262 for (size_t i = 0, e = getSmallSize(); i != e; ++i) 263 (*BV)[i] = (OldBits >> i) & 1; 264 switchToLarge(BV); 265 } 266 } 267 268 void reserve(unsigned N) { 269 if (isSmall()) { 270 if (N > SmallNumDataBits) { 271 uintptr_t OldBits = getSmallRawBits(); 272 size_t SmallSize = getSmallSize(); 273 BitVector *BV = new BitVector(SmallSize); 274 for (size_t i = 0; i < SmallSize; ++i) 275 if ((OldBits >> i) & 1) 276 BV->set(i); 277 BV->reserve(N); 278 switchToLarge(BV); 279 } 280 } else { 281 getPointer()->reserve(N); 282 } 283 } 284 285 // Set, reset, flip 286 SmallBitVector &set() { 287 if (isSmall()) 288 setSmallBits(~uintptr_t(0)); 289 else 290 getPointer()->set(); 291 return *this; 292 } 293 294 SmallBitVector &set(unsigned Idx) { 295 if (isSmall()) 296 setSmallBits(getSmallBits() | (uintptr_t(1) << Idx)); 297 else 298 getPointer()->set(Idx); 299 return *this; 300 } 301 302 /// set - Efficiently set a range of bits in [I, E) 303 SmallBitVector &set(unsigned I, unsigned E) { 304 assert(I <= E && "Attempted to set backwards range!"); 305 assert(E <= size() && "Attempted to set out-of-bounds range!"); 306 if (I == E) return *this; 307 if (isSmall()) { 308 uintptr_t EMask = ((uintptr_t)1) << E; 309 uintptr_t IMask = ((uintptr_t)1) << I; 310 uintptr_t Mask = EMask - IMask; 311 setSmallBits(getSmallBits() | Mask); 312 } else 313 getPointer()->set(I, E); 314 return *this; 315 } 316 317 SmallBitVector &reset() { 318 if (isSmall()) 319 setSmallBits(0); 320 else 321 getPointer()->reset(); 322 return *this; 323 } 324 325 SmallBitVector &reset(unsigned Idx) { 326 if (isSmall()) 327 setSmallBits(getSmallBits() & ~(uintptr_t(1) << Idx)); 328 else 329 getPointer()->reset(Idx); 330 return *this; 331 } 332 333 /// reset - Efficiently reset a range of bits in [I, E) 334 SmallBitVector &reset(unsigned I, unsigned E) { 335 assert(I <= E && "Attempted to reset backwards range!"); 336 assert(E <= size() && "Attempted to reset out-of-bounds range!"); 337 if (I == E) return *this; 338 if (isSmall()) { 339 uintptr_t EMask = ((uintptr_t)1) << E; 340 uintptr_t IMask = ((uintptr_t)1) << I; 341 uintptr_t Mask = EMask - IMask; 342 setSmallBits(getSmallBits() & ~Mask); 343 } else 344 getPointer()->reset(I, E); 345 return *this; 346 } 347 348 SmallBitVector &flip() { 349 if (isSmall()) 350 setSmallBits(~getSmallBits()); 351 else 352 getPointer()->flip(); 353 return *this; 354 } 355 356 SmallBitVector &flip(unsigned Idx) { 357 if (isSmall()) 358 setSmallBits(getSmallBits() ^ (uintptr_t(1) << Idx)); 359 else 360 getPointer()->flip(Idx); 361 return *this; 362 } 363 364 // No argument flip. 365 SmallBitVector operator~() const { 366 return SmallBitVector(*this).flip(); 367 } 368 369 // Indexing. 370 reference operator[](unsigned Idx) { 371 assert(Idx < size() && "Out-of-bounds Bit access."); 372 return reference(*this, Idx); 373 } 374 375 bool operator[](unsigned Idx) const { 376 assert(Idx < size() && "Out-of-bounds Bit access."); 377 if (isSmall()) 378 return ((getSmallBits() >> Idx) & 1) != 0; 379 return getPointer()->operator[](Idx); 380 } 381 382 bool test(unsigned Idx) const { 383 return (*this)[Idx]; 384 } 385 386 /// Test if any common bits are set. 387 bool anyCommon(const SmallBitVector &RHS) const { 388 if (isSmall() && RHS.isSmall()) 389 return (getSmallBits() & RHS.getSmallBits()) != 0; 390 if (!isSmall() && !RHS.isSmall()) 391 return getPointer()->anyCommon(*RHS.getPointer()); 392 393 for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i) 394 if (test(i) && RHS.test(i)) 395 return true; 396 return false; 397 } 398 399 // Comparison operators. 400 bool operator==(const SmallBitVector &RHS) const { 401 if (size() != RHS.size()) 402 return false; 403 if (isSmall()) 404 return getSmallBits() == RHS.getSmallBits(); 405 else 406 return *getPointer() == *RHS.getPointer(); 407 } 408 409 bool operator!=(const SmallBitVector &RHS) const { 410 return !(*this == RHS); 411 } 412 413 // Intersection, union, disjoint union. 414 SmallBitVector &operator&=(const SmallBitVector &RHS) { 415 resize(std::max(size(), RHS.size())); 416 if (isSmall()) 417 setSmallBits(getSmallBits() & RHS.getSmallBits()); 418 else if (!RHS.isSmall()) 419 getPointer()->operator&=(*RHS.getPointer()); 420 else { 421 SmallBitVector Copy = RHS; 422 Copy.resize(size()); 423 getPointer()->operator&=(*Copy.getPointer()); 424 } 425 return *this; 426 } 427 428 /// reset - Reset bits that are set in RHS. Same as *this &= ~RHS. 429 SmallBitVector &reset(const SmallBitVector &RHS) { 430 if (isSmall() && RHS.isSmall()) 431 setSmallBits(getSmallBits() & ~RHS.getSmallBits()); 432 else if (!isSmall() && !RHS.isSmall()) 433 getPointer()->reset(*RHS.getPointer()); 434 else 435 for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i) 436 if (RHS.test(i)) 437 reset(i); 438 439 return *this; 440 } 441 442 /// test - Check if (This - RHS) is zero. 443 /// This is the same as reset(RHS) and any(). 444 bool test(const SmallBitVector &RHS) const { 445 if (isSmall() && RHS.isSmall()) 446 return (getSmallBits() & ~RHS.getSmallBits()) != 0; 447 if (!isSmall() && !RHS.isSmall()) 448 return getPointer()->test(*RHS.getPointer()); 449 450 unsigned i, e; 451 for (i = 0, e = std::min(size(), RHS.size()); i != e; ++i) 452 if (test(i) && !RHS.test(i)) 453 return true; 454 455 for (e = size(); i != e; ++i) 456 if (test(i)) 457 return true; 458 459 return false; 460 } 461 462 SmallBitVector &operator|=(const SmallBitVector &RHS) { 463 resize(std::max(size(), RHS.size())); 464 if (isSmall()) 465 setSmallBits(getSmallBits() | RHS.getSmallBits()); 466 else if (!RHS.isSmall()) 467 getPointer()->operator|=(*RHS.getPointer()); 468 else { 469 SmallBitVector Copy = RHS; 470 Copy.resize(size()); 471 getPointer()->operator|=(*Copy.getPointer()); 472 } 473 return *this; 474 } 475 476 SmallBitVector &operator^=(const SmallBitVector &RHS) { 477 resize(std::max(size(), RHS.size())); 478 if (isSmall()) 479 setSmallBits(getSmallBits() ^ RHS.getSmallBits()); 480 else if (!RHS.isSmall()) 481 getPointer()->operator^=(*RHS.getPointer()); 482 else { 483 SmallBitVector Copy = RHS; 484 Copy.resize(size()); 485 getPointer()->operator^=(*Copy.getPointer()); 486 } 487 return *this; 488 } 489 490 // Assignment operator. 491 const SmallBitVector &operator=(const SmallBitVector &RHS) { 492 if (isSmall()) { 493 if (RHS.isSmall()) 494 X = RHS.X; 495 else 496 switchToLarge(new BitVector(*RHS.getPointer())); 497 } else { 498 if (!RHS.isSmall()) 499 *getPointer() = *RHS.getPointer(); 500 else { 501 delete getPointer(); 502 X = RHS.X; 503 } 504 } 505 return *this; 506 } 507 508 const SmallBitVector &operator=(SmallBitVector &&RHS) { 509 if (this != &RHS) { 510 clear(); 511 swap(RHS); 512 } 513 return *this; 514 } 515 516 void swap(SmallBitVector &RHS) { 517 std::swap(X, RHS.X); 518 } 519 520 /// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize. 521 /// This computes "*this |= Mask". 522 void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 523 if (isSmall()) 524 applyMask<true, false>(Mask, MaskWords); 525 else 526 getPointer()->setBitsInMask(Mask, MaskWords); 527 } 528 529 /// clearBitsInMask - Clear any bits in this vector that are set in Mask. 530 /// Don't resize. This computes "*this &= ~Mask". 531 void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 532 if (isSmall()) 533 applyMask<false, false>(Mask, MaskWords); 534 else 535 getPointer()->clearBitsInMask(Mask, MaskWords); 536 } 537 538 /// setBitsNotInMask - Add a bit to this vector for every '0' bit in Mask. 539 /// Don't resize. This computes "*this |= ~Mask". 540 void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 541 if (isSmall()) 542 applyMask<true, true>(Mask, MaskWords); 543 else 544 getPointer()->setBitsNotInMask(Mask, MaskWords); 545 } 546 547 /// clearBitsNotInMask - Clear a bit in this vector for every '0' bit in Mask. 548 /// Don't resize. This computes "*this &= Mask". 549 void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) { 550 if (isSmall()) 551 applyMask<false, true>(Mask, MaskWords); 552 else 553 getPointer()->clearBitsNotInMask(Mask, MaskWords); 554 } 555 556 private: 557 template<bool AddBits, bool InvertMask> 558 void applyMask(const uint32_t *Mask, unsigned MaskWords) { 559 assert((NumBaseBits == 64 || NumBaseBits == 32) && "Unsupported word size"); 560 if (NumBaseBits == 64 && MaskWords >= 2) { 561 uint64_t M = Mask[0] | (uint64_t(Mask[1]) << 32); 562 if (InvertMask) M = ~M; 563 if (AddBits) setSmallBits(getSmallBits() | M); 564 else setSmallBits(getSmallBits() & ~M); 565 } else { 566 uint32_t M = Mask[0]; 567 if (InvertMask) M = ~M; 568 if (AddBits) setSmallBits(getSmallBits() | M); 569 else setSmallBits(getSmallBits() & ~M); 570 } 571 } 572 }; 573 574 inline SmallBitVector 575 operator&(const SmallBitVector &LHS, const SmallBitVector &RHS) { 576 SmallBitVector Result(LHS); 577 Result &= RHS; 578 return Result; 579 } 580 581 inline SmallBitVector 582 operator|(const SmallBitVector &LHS, const SmallBitVector &RHS) { 583 SmallBitVector Result(LHS); 584 Result |= RHS; 585 return Result; 586 } 587 588 inline SmallBitVector 589 operator^(const SmallBitVector &LHS, const SmallBitVector &RHS) { 590 SmallBitVector Result(LHS); 591 Result ^= RHS; 592 return Result; 593 } 594 595 } // End llvm namespace 596 597 namespace std { 598 /// Implement std::swap in terms of BitVector swap. 599 inline void 600 swap(llvm::SmallBitVector &LHS, llvm::SmallBitVector &RHS) { 601 LHS.swap(RHS); 602 } 603 } 604 605 #endif 606