//===- llvm/ADT/SmallBitVector.h - 'Normally small' bit vectors -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements the SmallBitVector class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_SMALLBITVECTOR_H
#define LLVM_ADT_SMALLBITVECTOR_H
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <cassert>
#include <climits>
#include <cstddef>
#include <cstdint>
#include <limits>
#include <utility>
namespace llvm {
/// This is a 'bitvector' (really, a variable-sized bit array), optimized for
/// the case when the array is small. It contains one pointer-sized field, which
/// is directly used as a plain collection of bits when possible, or as a
/// pointer to a larger heap-allocated array when necessary. This allows normal
/// "small" cases to be fast without losing generality for large inputs.
class SmallBitVector {
// TODO: In "large" mode, a pointer to a BitVector is used, leading to an
// unnecessary level of indirection. It would be more efficient to use a
// pointer to memory containing size, allocation size, and the array of bits.
uintptr_t X = 1;
enum {
// The number of bits in this class.
NumBaseBits = sizeof(uintptr_t) * CHAR_BIT,
// One bit is used to discriminate between small and large mode. The
// remaining bits are used for the small-mode representation.
SmallNumRawBits = NumBaseBits - 1,
// A few more bits are used to store the size of the bit set in small mode.
// Theoretically this is a ceil-log2. These bits are encoded in the most
// significant bits of the raw bits.
SmallNumSizeBits = (NumBaseBits == 32 ? 5 :
NumBaseBits == 64 ? 6 :
SmallNumRawBits),
// The remaining bits are used to store the actual set in small mode.
SmallNumDataBits = SmallNumRawBits - SmallNumSizeBits
};
static_assert(NumBaseBits == 64 || NumBaseBits == 32,
"Unsupported word size");
public:
using size_type = uintptr_t;
// Encapsulation of a single bit.
class reference {
SmallBitVector &TheVector;
unsigned BitPos;
public:
reference(SmallBitVector &b, unsigned Idx) : TheVector(b), BitPos(Idx) {}
reference(const reference&) = default;
reference& operator=(reference t) {
*this = bool(t);
return *this;
}
reference& operator=(bool t) {
if (t)
TheVector.set(BitPos);
else
TheVector.reset(BitPos);
return *this;
}
operator bool() const {
return const_cast<const SmallBitVector &>(TheVector).operator[](BitPos);
}
};
private:
BitVector *getPointer() const {
assert(!isSmall());
return reinterpret_cast<BitVector *>(X);
}
void switchToSmall(uintptr_t NewSmallBits, size_type NewSize) {
X = 1;
setSmallSize(NewSize);
setSmallBits(NewSmallBits);
}
void switchToLarge(BitVector *BV) {
X = reinterpret_cast<uintptr_t>(BV);
assert(!isSmall() && "Tried to use an unaligned pointer");
}
// Return all the bits used for the "small" representation; this includes
// bits for the size as well as the element bits.
uintptr_t getSmallRawBits() const {
assert(isSmall());
return X >> 1;
}
void setSmallRawBits(uintptr_t NewRawBits) {
assert(isSmall());
X = (NewRawBits << 1) | uintptr_t(1);
}
// Return the size.
size_type getSmallSize() const {
return getSmallRawBits() >> SmallNumDataBits;
}
void setSmallSize(size_type Size) {
setSmallRawBits(getSmallBits() | (Size << SmallNumDataBits));
}
// Return the element bits.
uintptr_t getSmallBits() const {
return getSmallRawBits() & ~(~uintptr_t(0) << getSmallSize());
}
void setSmallBits(uintptr_t NewBits) {
setSmallRawBits((NewBits & ~(~uintptr_t(0) << getSmallSize())) |
(getSmallSize() << SmallNumDataBits));
}
public:
/// Creates an empty bitvector.
SmallBitVector() = default;
/// Creates a bitvector of specified number of bits. All bits are initialized
/// to the specified value.
explicit SmallBitVector(unsigned s, bool t = false) {
if (s <= SmallNumDataBits)
switchToSmall(t ? ~uintptr_t(0) : 0, s);
else
switchToLarge(new BitVector(s, t));
}
/// SmallBitVector copy ctor.
SmallBitVector(const SmallBitVector &RHS) {
if (RHS.isSmall())
X = RHS.X;
else
switchToLarge(new BitVector(*RHS.getPointer()));
}
SmallBitVector(SmallBitVector &&RHS) : X(RHS.X) {
RHS.X = 1;
}
~SmallBitVector() {
if (!isSmall())
delete getPointer();
}
using const_set_bits_iterator = const_set_bits_iterator_impl<SmallBitVector>;
using set_iterator = const_set_bits_iterator;
const_set_bits_iterator set_bits_begin() const {
return const_set_bits_iterator(*this);
}
const_set_bits_iterator set_bits_end() const {
return const_set_bits_iterator(*this, -1);
}
iterator_range<const_set_bits_iterator> set_bits() const {
return make_range(set_bits_begin(), set_bits_end());
}
bool isSmall() const { return X & uintptr_t(1); }
/// Tests whether there are no bits in this bitvector.
bool empty() const {
return isSmall() ? getSmallSize() == 0 : getPointer()->empty();
}
/// Returns the number of bits in this bitvector.
size_type size() const {
return isSmall() ? getSmallSize() : getPointer()->size();
}
/// Returns the number of bits which are set.
size_type count() const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
return llvm::popcount(Bits);
}
return getPointer()->count();
}
/// Returns true if any bit is set.
bool any() const {
if (isSmall())
return getSmallBits() != 0;
return getPointer()->any();
}
/// Returns true if all bits are set.
bool all() const {
if (isSmall())
return getSmallBits() == (uintptr_t(1) << getSmallSize()) - 1;
return getPointer()->all();
}
/// Returns true if none of the bits are set.
bool none() const {
if (isSmall())
return getSmallBits() == 0;
return getPointer()->none();
}
/// Returns the index of the first set bit, -1 if none of the bits are set.
int find_first() const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
if (Bits == 0)
return -1;
return countTrailingZeros(Bits);
}
return getPointer()->find_first();
}
int find_last() const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
if (Bits == 0)
return -1;
return NumBaseBits - countLeadingZeros(Bits) - 1;
}
return getPointer()->find_last();
}
/// Returns the index of the first unset bit, -1 if all of the bits are set.
int find_first_unset() const {
if (isSmall()) {
if (count() == getSmallSize())
return -1;
uintptr_t Bits = getSmallBits();
return countTrailingOnes(Bits);
}
return getPointer()->find_first_unset();
}
int find_last_unset() const {
if (isSmall()) {
if (count() == getSmallSize())
return -1;
uintptr_t Bits = getSmallBits();
// Set unused bits.
Bits |= ~uintptr_t(0) << getSmallSize();
return NumBaseBits - countLeadingOnes(Bits) - 1;
}
return getPointer()->find_last_unset();
}
/// Returns the index of the next set bit following the "Prev" bit.
/// Returns -1 if the next set bit is not found.
int find_next(unsigned Prev) const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
// Mask off previous bits.
Bits &= ~uintptr_t(0) << (Prev + 1);
if (Bits == 0 || Prev + 1 >= getSmallSize())
return -1;
return countTrailingZeros(Bits);
}
return getPointer()->find_next(Prev);
}
/// Returns the index of the next unset bit following the "Prev" bit.
/// Returns -1 if the next unset bit is not found.
int find_next_unset(unsigned Prev) const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
// Mask in previous bits.
Bits |= (uintptr_t(1) << (Prev + 1)) - 1;
// Mask in unused bits.
Bits |= ~uintptr_t(0) << getSmallSize();
if (Bits == ~uintptr_t(0) || Prev + 1 >= getSmallSize())
return -1;
return countTrailingOnes(Bits);
}
return getPointer()->find_next_unset(Prev);
}
/// find_prev - Returns the index of the first set bit that precedes the
/// the bit at \p PriorTo. Returns -1 if all previous bits are unset.
int find_prev(unsigned PriorTo) const {
if (isSmall()) {
if (PriorTo == 0)
return -1;
--PriorTo;
uintptr_t Bits = getSmallBits();
Bits &= maskTrailingOnes<uintptr_t>(PriorTo + 1);
if (Bits == 0)
return -1;
return NumBaseBits - countLeadingZeros(Bits) - 1;
}
return getPointer()->find_prev(PriorTo);
}
/// Clear all bits.
void clear() {
if (!isSmall())
delete getPointer();
switchToSmall(0, 0);
}
/// Grow or shrink the bitvector.
void resize(unsigned N, bool t = false) {
if (!isSmall()) {
getPointer()->resize(N, t);
} else if (SmallNumDataBits >= N) {
uintptr_t NewBits = t ? ~uintptr_t(0) << getSmallSize() : 0;
setSmallSize(N);
setSmallBits(NewBits | getSmallBits());
} else {
BitVector *BV = new BitVector(N, t);
uintptr_t OldBits = getSmallBits();
for (size_type I = 0, E = getSmallSize(); I != E; ++I)
(*BV)[I] = (OldBits >> I) & 1;
switchToLarge(BV);
}
}
void reserve(unsigned N) {
if (isSmall()) {
if (N > SmallNumDataBits) {
uintptr_t OldBits = getSmallRawBits();
size_type SmallSize = getSmallSize();
BitVector *BV = new BitVector(SmallSize);
for (size_type I = 0; I < SmallSize; ++I)
if ((OldBits >> I) & 1)
BV->set(I);
BV->reserve(N);
switchToLarge(BV);
}
} else {
getPointer()->reserve(N);
}
}
// Set, reset, flip
SmallBitVector &set() {
if (isSmall())
setSmallBits(~uintptr_t(0));
else
getPointer()->set();
return *this;
}
SmallBitVector &set(unsigned Idx) {
if (isSmall()) {
assert(Idx <= static_cast<unsigned>(
std::numeric_limits<uintptr_t>::digits) &&
"undefined behavior");
setSmallBits(getSmallBits() | (uintptr_t(1) << Idx));
}
else
getPointer()->set(Idx);
return *this;
}
/// Efficiently set a range of bits in [I, E)
SmallBitVector &set(unsigned I, unsigned E) {
assert(I <= E && "Attempted to set backwards range!");
assert(E <= size() && "Attempted to set out-of-bounds range!");
if (I == E) return *this;
if (isSmall()) {
uintptr_t EMask = ((uintptr_t)1) << E;
uintptr_t IMask = ((uintptr_t)1) << I;
uintptr_t Mask = EMask - IMask;
setSmallBits(getSmallBits() | Mask);
} else
getPointer()->set(I, E);
return *this;
}
SmallBitVector &reset() {
if (isSmall())
setSmallBits(0);
else
getPointer()->reset();
return *this;
}
SmallBitVector &reset(unsigned Idx) {
if (isSmall())
setSmallBits(getSmallBits() & ~(uintptr_t(1) << Idx));
else
getPointer()->reset(Idx);
return *this;
}
/// Efficiently reset a range of bits in [I, E)
SmallBitVector &reset(unsigned I, unsigned E) {
assert(I <= E && "Attempted to reset backwards range!");
assert(E <= size() && "Attempted to reset out-of-bounds range!");
if (I == E) return *this;
if (isSmall()) {
uintptr_t EMask = ((uintptr_t)1) << E;
uintptr_t IMask = ((uintptr_t)1) << I;
uintptr_t Mask = EMask - IMask;
setSmallBits(getSmallBits() & ~Mask);
} else
getPointer()->reset(I, E);
return *this;
}
SmallBitVector &flip() {
if (isSmall())
setSmallBits(~getSmallBits());
else
getPointer()->flip();
return *this;
}
SmallBitVector &flip(unsigned Idx) {
if (isSmall())
setSmallBits(getSmallBits() ^ (uintptr_t(1) << Idx));
else
getPointer()->flip(Idx);
return *this;
}
// No argument flip.
SmallBitVector operator~() const {
return SmallBitVector(*this).flip();
}
// Indexing.
reference operator[](unsigned Idx) {
assert(Idx < size() && "Out-of-bounds Bit access.");
return reference(*this, Idx);
}
bool operator[](unsigned Idx) const {
assert(Idx < size() && "Out-of-bounds Bit access.");
if (isSmall())
return ((getSmallBits() >> Idx) & 1) != 0;
return getPointer()->operator[](Idx);
}
/// Return the last element in the vector.
bool back() const {
assert(!empty() && "Getting last element of empty vector.");
return (*this)[size() - 1];
}
bool test(unsigned Idx) const {
return (*this)[Idx];
}
// Push single bit to end of vector.
void push_back(bool Val) {
resize(size() + 1, Val);
}
/// Pop one bit from the end of the vector.
void pop_back() {
assert(!empty() && "Empty vector has no element to pop.");
resize(size() - 1);
}
/// Test if any common bits are set.
bool anyCommon(const SmallBitVector &RHS) const {
if (isSmall() && RHS.isSmall())
return (getSmallBits() & RHS.getSmallBits()) != 0;
if (!isSmall() && !RHS.isSmall())
return getPointer()->anyCommon(*RHS.getPointer());
for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
if (test(i) && RHS.test(i))
return true;
return false;
}
// Comparison operators.
bool operator==(const SmallBitVector &RHS) const {
if (size() != RHS.size())
return false;
if (isSmall() && RHS.isSmall())
return getSmallBits() == RHS.getSmallBits();
else if (!isSmall() && !RHS.isSmall())
return *getPointer() == *RHS.getPointer();
else {
for (size_type I = 0, E = size(); I != E; ++I) {
if ((*this)[I] != RHS[I])
return false;
}
return true;
}
}
bool operator!=(const SmallBitVector &RHS) const {
return !(*this == RHS);
}
// Intersection, union, disjoint union.
// FIXME BitVector::operator&= does not resize the LHS but this does
SmallBitVector &operator&=(const SmallBitVector &RHS) {
resize(std::max(size(), RHS.size()));
if (isSmall() && RHS.isSmall())
setSmallBits(getSmallBits() & RHS.getSmallBits());
else if (!isSmall() && !RHS.isSmall())
getPointer()->operator&=(*RHS.getPointer());
else {
size_type I, E;
for (I = 0, E = std::min(size(), RHS.size()); I != E; ++I)
(*this)[I] = test(I) && RHS.test(I);
for (E = size(); I != E; ++I)
reset(I);
}
return *this;
}
/// Reset bits that are set in RHS. Same as *this &= ~RHS.
SmallBitVector &reset(const SmallBitVector &RHS) {
if (isSmall() && RHS.isSmall())
setSmallBits(getSmallBits() & ~RHS.getSmallBits());
else if (!isSmall() && !RHS.isSmall())
getPointer()->reset(*RHS.getPointer());
else
for (unsigned i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
if (RHS.test(i))
reset(i);
return *this;
}
/// Check if (This - RHS) is zero. This is the same as reset(RHS) and any().
bool test(const SmallBitVector &RHS) const {
if (isSmall() && RHS.isSmall())
return (getSmallBits() & ~RHS.getSmallBits()) != 0;
if (!isSmall() && !RHS.isSmall())
return getPointer()->test(*RHS.getPointer());
unsigned i, e;
for (i = 0, e = std::min(size(), RHS.size()); i != e; ++i)
if (test(i) && !RHS.test(i))
return true;
for (e = size(); i != e; ++i)
if (test(i))
return true;
return false;
}
SmallBitVector &operator|=(const SmallBitVector &RHS) {
resize(std::max(size(), RHS.size()));
if (isSmall() && RHS.isSmall())
setSmallBits(getSmallBits() | RHS.getSmallBits());
else if (!isSmall() && !RHS.isSmall())
getPointer()->operator|=(*RHS.getPointer());
else {
for (size_type I = 0, E = RHS.size(); I != E; ++I)
(*this)[I] = test(I) || RHS.test(I);
}
return *this;
}
SmallBitVector &operator^=(const SmallBitVector &RHS) {
resize(std::max(size(), RHS.size()));
if (isSmall() && RHS.isSmall())
setSmallBits(getSmallBits() ^ RHS.getSmallBits());
else if (!isSmall() && !RHS.isSmall())
getPointer()->operator^=(*RHS.getPointer());
else {
for (size_type I = 0, E = RHS.size(); I != E; ++I)
(*this)[I] = test(I) != RHS.test(I);
}
return *this;
}
SmallBitVector &operator<<=(unsigned N) {
if (isSmall())
setSmallBits(getSmallBits() << N);
else
getPointer()->operator<<=(N);
return *this;
}
SmallBitVector &operator>>=(unsigned N) {
if (isSmall())
setSmallBits(getSmallBits() >> N);
else
getPointer()->operator>>=(N);
return *this;
}
// Assignment operator.
const SmallBitVector &operator=(const SmallBitVector &RHS) {
if (isSmall()) {
if (RHS.isSmall())
X = RHS.X;
else
switchToLarge(new BitVector(*RHS.getPointer()));
} else {
if (!RHS.isSmall())
*getPointer() = *RHS.getPointer();
else {
delete getPointer();
X = RHS.X;
}
}
return *this;
}
const SmallBitVector &operator=(SmallBitVector &&RHS) {
if (this != &RHS) {
clear();
swap(RHS);
}
return *this;
}
void swap(SmallBitVector &RHS) {
std::swap(X, RHS.X);
}
/// Add '1' bits from Mask to this vector. Don't resize.
/// This computes "*this |= Mask".
void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
if (isSmall())
applyMask<true, false>(Mask, MaskWords);
else
getPointer()->setBitsInMask(Mask, MaskWords);
}
/// Clear any bits in this vector that are set in Mask. Don't resize.
/// This computes "*this &= ~Mask".
void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
if (isSmall())
applyMask<false, false>(Mask, MaskWords);
else
getPointer()->clearBitsInMask(Mask, MaskWords);
}
/// Add a bit to this vector for every '0' bit in Mask. Don't resize.
/// This computes "*this |= ~Mask".
void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
if (isSmall())
applyMask<true, true>(Mask, MaskWords);
else
getPointer()->setBitsNotInMask(Mask, MaskWords);
}
/// Clear a bit in this vector for every '0' bit in Mask. Don't resize.
/// This computes "*this &= Mask".
void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
if (isSmall())
applyMask<false, true>(Mask, MaskWords);
else
getPointer()->clearBitsNotInMask(Mask, MaskWords);
}
void invalid() {
assert(empty());
X = (uintptr_t)-1;
}
bool isInvalid() const { return X == (uintptr_t)-1; }
ArrayRef<uintptr_t> getData(uintptr_t &Store) const {
if (!isSmall())
return getPointer()->getData();
Store = getSmallBits();
return Store;
}
private:
template <bool AddBits, bool InvertMask>
void applyMask(const uint32_t *Mask, unsigned MaskWords) {
assert(MaskWords <= sizeof(uintptr_t) && "Mask is larger than base!");
uintptr_t M = Mask[0];
if (NumBaseBits == 64)
M |= uint64_t(Mask[1]) << 32;
if (InvertMask)
M = ~M;
if (AddBits)
setSmallBits(getSmallBits() | M);
else
setSmallBits(getSmallBits() & ~M);
}
};
inline SmallBitVector
operator&(const SmallBitVector &LHS, const SmallBitVector &RHS) {
SmallBitVector Result(LHS);
Result &= RHS;
return Result;
}
inline SmallBitVector
operator|(const SmallBitVector &LHS, const SmallBitVector &RHS) {
SmallBitVector Result(LHS);
Result |= RHS;
return Result;
}
inline SmallBitVector
operator^(const SmallBitVector &LHS, const SmallBitVector &RHS) {
SmallBitVector Result(LHS);
Result ^= RHS;
return Result;
}
template <> struct DenseMapInfo<SmallBitVector> {
static inline SmallBitVector getEmptyKey() { return SmallBitVector(); }
static inline SmallBitVector getTombstoneKey() {
SmallBitVector V;
V.invalid();
return V;
}
static unsigned getHashValue(const SmallBitVector &V) {
uintptr_t Store;
return DenseMapInfo<
std::pair<SmallBitVector::size_type, ArrayRef<uintptr_t>>>::
getHashValue(std::make_pair(V.size(), V.getData(Store)));
}
static bool isEqual(const SmallBitVector &LHS, const SmallBitVector &RHS) {
if (LHS.isInvalid() || RHS.isInvalid())
return LHS.isInvalid() == RHS.isInvalid();
return LHS == RHS;
}
};
} // end namespace llvm
namespace std {
/// Implement std::swap in terms of BitVector swap.
inline void
swap(llvm::SmallBitVector &LHS, llvm::SmallBitVector &RHS) {
LHS.swap(RHS);
}
} // end namespace std
#endif // LLVM_ADT_SMALLBITVECTOR_H