1 //===- llvm/ADT/SmallBitVector.h - 'Normally small' bit vectors -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the SmallBitVector class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_SMALLBITVECTOR_H
15 #define LLVM_ADT_SMALLBITVECTOR_H
17 #include "llvm/ADT/BitVector.h"
18 #include "llvm/Support/Compiler.h"
19 #include "llvm/Support/MathExtras.h"
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.
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.
38 // The number of bits in this class.
39 NumBaseBits = sizeof(uintptr_t) * CHAR_BIT,
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,
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 :
52 // The remaining bits are used to store the actual set in small mode.
53 SmallNumDataBits = SmallNumRawBits - SmallNumSizeBits
56 static_assert(NumBaseBits == 64 || NumBaseBits == 32,
57 "Unsupported word size");
60 typedef unsigned size_type;
61 // Encapsulation of a single bit.
63 SmallBitVector &TheVector;
67 reference(SmallBitVector &b, unsigned Idx) : TheVector(b), BitPos(Idx) {}
69 reference& operator=(reference t) {
74 reference& operator=(bool t) {
76 TheVector.set(BitPos);
78 TheVector.reset(BitPos);
82 operator bool() const {
83 return const_cast<const SmallBitVector &>(TheVector).operator[](BitPos);
88 bool isSmall() const {
89 return X & uintptr_t(1);
92 BitVector *getPointer() const {
94 return reinterpret_cast<BitVector *>(X);
97 void switchToSmall(uintptr_t NewSmallBits, size_t NewSize) {
99 setSmallSize(NewSize);
100 setSmallBits(NewSmallBits);
103 void switchToLarge(BitVector *BV) {
104 X = reinterpret_cast<uintptr_t>(BV);
105 assert(!isSmall() && "Tried to use an unaligned pointer");
108 // Return all the bits used for the "small" representation; this includes
109 // bits for the size as well as the element bits.
110 uintptr_t getSmallRawBits() const {
115 void setSmallRawBits(uintptr_t NewRawBits) {
117 X = (NewRawBits << 1) | uintptr_t(1);
121 size_t getSmallSize() const {
122 return getSmallRawBits() >> SmallNumDataBits;
125 void setSmallSize(size_t Size) {
126 setSmallRawBits(getSmallBits() | (Size << SmallNumDataBits));
129 // Return the element bits.
130 uintptr_t getSmallBits() const {
131 return getSmallRawBits() & ~(~uintptr_t(0) << getSmallSize());
134 void setSmallBits(uintptr_t NewBits) {
135 setSmallRawBits((NewBits & ~(~uintptr_t(0) << getSmallSize())) |
136 (getSmallSize() << SmallNumDataBits));
140 /// SmallBitVector default ctor - Creates an empty bitvector.
141 SmallBitVector() : X(1) {}
143 /// SmallBitVector ctor - Creates a bitvector of specified number of bits. All
144 /// bits are initialized to the specified value.
145 explicit SmallBitVector(unsigned s, bool t = false) {
146 if (s <= SmallNumDataBits)
147 switchToSmall(t ? ~uintptr_t(0) : 0, s);
149 switchToLarge(new BitVector(s, t));
152 /// SmallBitVector copy ctor.
153 SmallBitVector(const SmallBitVector &RHS) {
157 switchToLarge(new BitVector(*RHS.getPointer()));
160 SmallBitVector(SmallBitVector &&RHS) : X(RHS.X) {
169 /// empty - Tests whether there are no bits in this bitvector.
171 return isSmall() ? getSmallSize() == 0 : getPointer()->empty();
174 /// size - Returns the number of bits in this bitvector.
175 size_t size() const {
176 return isSmall() ? getSmallSize() : getPointer()->size();
179 /// count - Returns the number of bits which are set.
180 size_type count() const {
182 uintptr_t Bits = getSmallBits();
183 return countPopulation(Bits);
185 return getPointer()->count();
188 /// any - Returns true if any bit is set.
191 return getSmallBits() != 0;
192 return getPointer()->any();
195 /// all - Returns true if all bits are set.
198 return getSmallBits() == (uintptr_t(1) << getSmallSize()) - 1;
199 return getPointer()->all();
202 /// none - Returns true if none of the bits are set.
205 return getSmallBits() == 0;
206 return getPointer()->none();
209 /// find_first - Returns the index of the first set bit, -1 if none
210 /// of the bits are set.
211 int find_first() const {
213 uintptr_t Bits = getSmallBits();
216 return countTrailingZeros(Bits);
218 return getPointer()->find_first();
221 /// find_next - Returns the index of the next set bit following the
222 /// "Prev" bit. Returns -1 if the next set bit is not found.
223 int find_next(unsigned Prev) const {
225 uintptr_t Bits = getSmallBits();
226 // Mask off previous bits.
227 Bits &= ~uintptr_t(0) << (Prev + 1);
228 if (Bits == 0 || Prev + 1 >= getSmallSize())
230 return countTrailingZeros(Bits);
232 return getPointer()->find_next(Prev);
235 /// clear - Clear all bits.
242 /// resize - Grow or shrink the bitvector.
243 void resize(unsigned N, bool t = false) {
245 getPointer()->resize(N, t);
246 } else if (SmallNumDataBits >= N) {
247 uintptr_t NewBits = t ? ~uintptr_t(0) << getSmallSize() : 0;
249 setSmallBits(NewBits | getSmallBits());
251 BitVector *BV = new BitVector(N, t);
252 uintptr_t OldBits = getSmallBits();
253 for (size_t i = 0, e = getSmallSize(); i != e; ++i)
254 (*BV)[i] = (OldBits >> i) & 1;
259 void reserve(unsigned N) {
261 if (N > SmallNumDataBits) {
262 uintptr_t OldBits = getSmallRawBits();
263 size_t SmallSize = getSmallSize();
264 BitVector *BV = new BitVector(SmallSize);
265 for (size_t i = 0; i < SmallSize; ++i)
266 if ((OldBits >> i) & 1)
272 getPointer()->reserve(N);
277 SmallBitVector &set() {
279 setSmallBits(~uintptr_t(0));
285 SmallBitVector &set(unsigned Idx) {
287 assert(Idx <= static_cast<unsigned>(
288 std::numeric_limits<uintptr_t>::digits) &&
289 "undefined behavior");
290 setSmallBits(getSmallBits() | (uintptr_t(1) << Idx));
293 getPointer()->set(Idx);
297 /// set - Efficiently set a range of bits in [I, E)
298 SmallBitVector &set(unsigned I, unsigned E) {
299 assert(I <= E && "Attempted to set backwards range!");
300 assert(E <= size() && "Attempted to set out-of-bounds range!");
301 if (I == E) return *this;
303 uintptr_t EMask = ((uintptr_t)1) << E;
304 uintptr_t IMask = ((uintptr_t)1) << I;
305 uintptr_t Mask = EMask - IMask;
306 setSmallBits(getSmallBits() | Mask);
308 getPointer()->set(I, E);
312 SmallBitVector &reset() {
316 getPointer()->reset();
320 SmallBitVector &reset(unsigned Idx) {
322 setSmallBits(getSmallBits() & ~(uintptr_t(1) << Idx));
324 getPointer()->reset(Idx);
328 /// reset - Efficiently reset a range of bits in [I, E)
329 SmallBitVector &reset(unsigned I, unsigned E) {
330 assert(I <= E && "Attempted to reset backwards range!");
331 assert(E <= size() && "Attempted to reset out-of-bounds range!");
332 if (I == E) return *this;
334 uintptr_t EMask = ((uintptr_t)1) << E;
335 uintptr_t IMask = ((uintptr_t)1) << I;
336 uintptr_t Mask = EMask - IMask;
337 setSmallBits(getSmallBits() & ~Mask);
339 getPointer()->reset(I, E);
343 SmallBitVector &flip() {
345 setSmallBits(~getSmallBits());
347 getPointer()->flip();
351 SmallBitVector &flip(unsigned Idx) {
353 setSmallBits(getSmallBits() ^ (uintptr_t(1) << Idx));
355 getPointer()->flip(Idx);
360 SmallBitVector operator~() const {
361 return SmallBitVector(*this).flip();
365 reference operator[](unsigned Idx) {
366 assert(Idx < size() && "Out-of-bounds Bit access.");
367 return reference(*this, Idx);
370 bool operator[](unsigned Idx) const {
371 assert(Idx < size() && "Out-of-bounds Bit access.");
373 return ((getSmallBits() >> Idx) & 1) != 0;
374 return getPointer()->operator[](Idx);
377 bool test(unsigned Idx) const {
381 /// Test if any common bits are set.
382 bool anyCommon(const SmallBitVector &RHS) const {
383 if (isSmall() && RHS.isSmall())
384 return (getSmallBits() & RHS.getSmallBits()) != 0;
385 if (!isSmall() && !RHS.isSmall())
386 return getPointer()->anyCommon(*RHS.getPointer());
388 for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
389 if (test(i) && RHS.test(i))
394 // Comparison operators.
395 bool operator==(const SmallBitVector &RHS) const {
396 if (size() != RHS.size())
399 return getSmallBits() == RHS.getSmallBits();
401 return *getPointer() == *RHS.getPointer();
404 bool operator!=(const SmallBitVector &RHS) const {
405 return !(*this == RHS);
408 // Intersection, union, disjoint union.
409 SmallBitVector &operator&=(const SmallBitVector &RHS) {
410 resize(std::max(size(), RHS.size()));
412 setSmallBits(getSmallBits() & RHS.getSmallBits());
413 else if (!RHS.isSmall())
414 getPointer()->operator&=(*RHS.getPointer());
416 SmallBitVector Copy = RHS;
418 getPointer()->operator&=(*Copy.getPointer());
423 /// reset - Reset bits that are set in RHS. Same as *this &= ~RHS.
424 SmallBitVector &reset(const SmallBitVector &RHS) {
425 if (isSmall() && RHS.isSmall())
426 setSmallBits(getSmallBits() & ~RHS.getSmallBits());
427 else if (!isSmall() && !RHS.isSmall())
428 getPointer()->reset(*RHS.getPointer());
430 for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
437 /// test - Check if (This - RHS) is zero.
438 /// This is the same as reset(RHS) and any().
439 bool test(const SmallBitVector &RHS) const {
440 if (isSmall() && RHS.isSmall())
441 return (getSmallBits() & ~RHS.getSmallBits()) != 0;
442 if (!isSmall() && !RHS.isSmall())
443 return getPointer()->test(*RHS.getPointer());
446 for (i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
447 if (test(i) && !RHS.test(i))
450 for (e = size(); i != e; ++i)
457 SmallBitVector &operator|=(const SmallBitVector &RHS) {
458 resize(std::max(size(), RHS.size()));
460 setSmallBits(getSmallBits() | RHS.getSmallBits());
461 else if (!RHS.isSmall())
462 getPointer()->operator|=(*RHS.getPointer());
464 SmallBitVector Copy = RHS;
466 getPointer()->operator|=(*Copy.getPointer());
471 SmallBitVector &operator^=(const SmallBitVector &RHS) {
472 resize(std::max(size(), RHS.size()));
474 setSmallBits(getSmallBits() ^ RHS.getSmallBits());
475 else if (!RHS.isSmall())
476 getPointer()->operator^=(*RHS.getPointer());
478 SmallBitVector Copy = RHS;
480 getPointer()->operator^=(*Copy.getPointer());
485 // Assignment operator.
486 const SmallBitVector &operator=(const SmallBitVector &RHS) {
491 switchToLarge(new BitVector(*RHS.getPointer()));
494 *getPointer() = *RHS.getPointer();
503 const SmallBitVector &operator=(SmallBitVector &&RHS) {
511 void swap(SmallBitVector &RHS) {
515 /// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize.
516 /// This computes "*this |= Mask".
517 void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
519 applyMask<true, false>(Mask, MaskWords);
521 getPointer()->setBitsInMask(Mask, MaskWords);
524 /// clearBitsInMask - Clear any bits in this vector that are set in Mask.
525 /// Don't resize. This computes "*this &= ~Mask".
526 void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
528 applyMask<false, false>(Mask, MaskWords);
530 getPointer()->clearBitsInMask(Mask, MaskWords);
533 /// setBitsNotInMask - Add a bit to this vector for every '0' bit in Mask.
534 /// Don't resize. This computes "*this |= ~Mask".
535 void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
537 applyMask<true, true>(Mask, MaskWords);
539 getPointer()->setBitsNotInMask(Mask, MaskWords);
542 /// clearBitsNotInMask - Clear a bit in this vector for every '0' bit in Mask.
543 /// Don't resize. This computes "*this &= Mask".
544 void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
546 applyMask<false, true>(Mask, MaskWords);
548 getPointer()->clearBitsNotInMask(Mask, MaskWords);
552 template<bool AddBits, bool InvertMask>
553 void applyMask(const uint32_t *Mask, unsigned MaskWords) {
554 if (NumBaseBits == 64 && MaskWords >= 2) {
555 uint64_t M = Mask[0] | (uint64_t(Mask[1]) << 32);
556 if (InvertMask) M = ~M;
557 if (AddBits) setSmallBits(getSmallBits() | M);
558 else setSmallBits(getSmallBits() & ~M);
560 uint32_t M = Mask[0];
561 if (InvertMask) M = ~M;
562 if (AddBits) setSmallBits(getSmallBits() | M);
563 else setSmallBits(getSmallBits() & ~M);
568 inline SmallBitVector
569 operator&(const SmallBitVector &LHS, const SmallBitVector &RHS) {
570 SmallBitVector Result(LHS);
575 inline SmallBitVector
576 operator|(const SmallBitVector &LHS, const SmallBitVector &RHS) {
577 SmallBitVector Result(LHS);
582 inline SmallBitVector
583 operator^(const SmallBitVector &LHS, const SmallBitVector &RHS) {
584 SmallBitVector Result(LHS);
589 } // End llvm namespace
592 /// Implement std::swap in terms of BitVector swap.
594 swap(llvm::SmallBitVector &LHS, llvm::SmallBitVector &RHS) {