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llvm-mirror/include/llvm/ADT/BitVector.h
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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//===- llvm/ADT/BitVector.h - 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the BitVector class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_BITVECTOR_H
#define LLVM_ADT_BITVECTOR_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <cassert>
#include <climits>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <utility>
namespace llvm {
/// ForwardIterator for the bits that are set.
/// Iterators get invalidated when resize / reserve is called.
template <typename BitVectorT> class const_set_bits_iterator_impl {
const BitVectorT &Parent;
int Current = 0;
void advance() {
assert(Current != -1 && "Trying to advance past end.");
Current = Parent.find_next(Current);
}
public:
const_set_bits_iterator_impl(const BitVectorT &Parent, int Current)
: Parent(Parent), Current(Current) {}
explicit const_set_bits_iterator_impl(const BitVectorT &Parent)
: const_set_bits_iterator_impl(Parent, Parent.find_first()) {}
const_set_bits_iterator_impl(const const_set_bits_iterator_impl &) = default;
const_set_bits_iterator_impl operator++(int) {
auto Prev = *this;
advance();
return Prev;
}
const_set_bits_iterator_impl &operator++() {
advance();
return *this;
}
unsigned operator*() const { return Current; }
bool operator==(const const_set_bits_iterator_impl &Other) const {
assert(&Parent == &Other.Parent &&
"Comparing iterators from different BitVectors");
return Current == Other.Current;
}
bool operator!=(const const_set_bits_iterator_impl &Other) const {
assert(&Parent == &Other.Parent &&
"Comparing iterators from different BitVectors");
return Current != Other.Current;
}
};
class BitVector {
typedef unsigned long BitWord;
enum { BITWORD_SIZE = (unsigned)sizeof(BitWord) * CHAR_BIT };
static_assert(BITWORD_SIZE == 64 || BITWORD_SIZE == 32,
"Unsupported word size");
MutableArrayRef<BitWord> Bits; // Actual bits.
unsigned Size; // Size of bitvector in bits.
public:
typedef unsigned size_type;
// Encapsulation of a single bit.
class reference {
friend class BitVector;
BitWord *WordRef;
unsigned BitPos;
public:
reference(BitVector &b, unsigned Idx) {
WordRef = &b.Bits[Idx / BITWORD_SIZE];
BitPos = Idx % BITWORD_SIZE;
}
reference() = delete;
reference(const reference&) = default;
reference &operator=(reference t) {
*this = bool(t);
return *this;
}
reference& operator=(bool t) {
if (t)
*WordRef |= BitWord(1) << BitPos;
else
*WordRef &= ~(BitWord(1) << BitPos);
return *this;
}
operator bool() const {
return ((*WordRef) & (BitWord(1) << BitPos)) != 0;
}
};
typedef const_set_bits_iterator_impl<BitVector> const_set_bits_iterator;
typedef const_set_bits_iterator set_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());
}
/// BitVector default ctor - Creates an empty bitvector.
BitVector() : Size(0) {}
/// BitVector ctor - Creates a bitvector of specified number of bits. All
/// bits are initialized to the specified value.
explicit BitVector(unsigned s, bool t = false) : Size(s) {
size_t Capacity = NumBitWords(s);
Bits = allocate(Capacity);
init_words(Bits, t);
if (t)
clear_unused_bits();
}
/// BitVector copy ctor.
BitVector(const BitVector &RHS) : Size(RHS.size()) {
if (Size == 0) {
Bits = MutableArrayRef<BitWord>();
return;
}
size_t Capacity = NumBitWords(RHS.size());
Bits = allocate(Capacity);
std::memcpy(Bits.data(), RHS.Bits.data(), Capacity * sizeof(BitWord));
}
BitVector(BitVector &&RHS) : Bits(RHS.Bits), Size(RHS.Size) {
RHS.Bits = MutableArrayRef<BitWord>();
RHS.Size = 0;
}
~BitVector() { std::free(Bits.data()); }
/// empty - Tests whether there are no bits in this bitvector.
bool empty() const { return Size == 0; }
/// size - Returns the number of bits in this bitvector.
size_type size() const { return Size; }
/// count - Returns the number of bits which are set.
size_type count() const {
unsigned NumBits = 0;
for (unsigned i = 0; i < NumBitWords(size()); ++i)
NumBits += countPopulation(Bits[i]);
return NumBits;
}
/// any - Returns true if any bit is set.
bool any() const {
for (unsigned i = 0; i < NumBitWords(size()); ++i)
if (Bits[i] != 0)
return true;
return false;
}
/// all - Returns true if all bits are set.
bool all() const {
for (unsigned i = 0; i < Size / BITWORD_SIZE; ++i)
if (Bits[i] != ~0UL)
return false;
// If bits remain check that they are ones. The unused bits are always zero.
if (unsigned Remainder = Size % BITWORD_SIZE)
return Bits[Size / BITWORD_SIZE] == (1UL << Remainder) - 1;
return true;
}
/// none - Returns true if none of the bits are set.
bool none() const {
return !any();
}
/// find_first_in - Returns the index of the first set bit in the range
/// [Begin, End). Returns -1 if all bits in the range are unset.
int find_first_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned FirstWord = Begin / BITWORD_SIZE;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
// Check subsequent words.
for (unsigned i = FirstWord; i <= LastWord; ++i) {
BitWord Copy = Bits[i];
if (i == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy &= maskTrailingZeros<BitWord>(FirstBit);
}
if (i == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
}
if (Copy != 0)
return i * BITWORD_SIZE + countTrailingZeros(Copy);
}
return -1;
}
/// find_last_in - Returns the index of the last set bit in the range
/// [Begin, End). Returns -1 if all bits in the range are unset.
int find_last_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
unsigned FirstWord = Begin / BITWORD_SIZE;
for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
unsigned CurrentWord = i - 1;
BitWord Copy = Bits[CurrentWord];
if (CurrentWord == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
}
if (CurrentWord == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy &= maskTrailingZeros<BitWord>(FirstBit);
}
if (Copy != 0)
return (CurrentWord + 1) * BITWORD_SIZE - countLeadingZeros(Copy) - 1;
}
return -1;
}
/// find_first_unset_in - Returns the index of the first unset bit in the
/// range [Begin, End). Returns -1 if all bits in the range are set.
int find_first_unset_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned FirstWord = Begin / BITWORD_SIZE;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
// Check subsequent words.
for (unsigned i = FirstWord; i <= LastWord; ++i) {
BitWord Copy = Bits[i];
if (i == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy |= maskTrailingOnes<BitWord>(FirstBit);
}
if (i == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
}
if (Copy != ~0UL) {
unsigned Result = i * BITWORD_SIZE + countTrailingOnes(Copy);
return Result < size() ? Result : -1;
}
}
return -1;
}
/// find_last_unset_in - Returns the index of the last unset bit in the
/// range [Begin, End). Returns -1 if all bits in the range are set.
int find_last_unset_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
unsigned FirstWord = Begin / BITWORD_SIZE;
for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
unsigned CurrentWord = i - 1;
BitWord Copy = Bits[CurrentWord];
if (CurrentWord == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
}
if (CurrentWord == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy |= maskTrailingOnes<BitWord>(FirstBit);
}
if (Copy != ~0UL) {
unsigned Result =
(CurrentWord + 1) * BITWORD_SIZE - countLeadingOnes(Copy) - 1;
return Result < Size ? Result : -1;
}
}
return -1;
}
/// find_first - Returns the index of the first set bit, -1 if none
/// of the bits are set.
int find_first() const { return find_first_in(0, Size); }
/// find_last - Returns the index of the last set bit, -1 if none of the bits
/// are set.
int find_last() const { return find_last_in(0, Size); }
/// find_next - 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 { return find_first_in(Prev + 1, Size); }
/// 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 { return find_last_in(0, PriorTo); }
/// find_first_unset - Returns the index of the first unset bit, -1 if all
/// of the bits are set.
int find_first_unset() const { return find_first_unset_in(0, Size); }
/// find_next_unset - Returns the index of the next unset bit following the
/// "Prev" bit. Returns -1 if all remaining bits are set.
int find_next_unset(unsigned Prev) const {
return find_first_unset_in(Prev + 1, Size);
}
/// find_last_unset - Returns the index of the last unset bit, -1 if all of
/// the bits are set.
int find_last_unset() const { return find_last_unset_in(0, Size); }
/// find_prev_unset - Returns the index of the first unset bit that precedes
/// the bit at \p PriorTo. Returns -1 if all previous bits are set.
int find_prev_unset(unsigned PriorTo) {
return find_last_unset_in(0, PriorTo);
}
/// clear - Removes all bits from the bitvector. Does not change capacity.
void clear() {
Size = 0;
}
/// resize - Grow or shrink the bitvector.
void resize(unsigned N, bool t = false) {
if (N > getBitCapacity()) {
unsigned OldCapacity = Bits.size();
grow(N);
init_words(Bits.drop_front(OldCapacity), t);
}
// Set any old unused bits that are now included in the BitVector. This
// may set bits that are not included in the new vector, but we will clear
// them back out below.
if (N > Size)
set_unused_bits(t);
// Update the size, and clear out any bits that are now unused
unsigned OldSize = Size;
Size = N;
if (t || N < OldSize)
clear_unused_bits();
}
void reserve(unsigned N) {
if (N > getBitCapacity())
grow(N);
}
// Set, reset, flip
BitVector &set() {
init_words(Bits, true);
clear_unused_bits();
return *this;
}
BitVector &set(unsigned Idx) {
assert(Bits.data() && "Bits never allocated");
Bits[Idx / BITWORD_SIZE] |= BitWord(1) << (Idx % BITWORD_SIZE);
return *this;
}
/// set - Efficiently set a range of bits in [I, E)
BitVector &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 (I / BITWORD_SIZE == E / BITWORD_SIZE) {
BitWord EMask = 1UL << (E % BITWORD_SIZE);
BitWord IMask = 1UL << (I % BITWORD_SIZE);
BitWord Mask = EMask - IMask;
Bits[I / BITWORD_SIZE] |= Mask;
return *this;
}
BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
Bits[I / BITWORD_SIZE] |= PrefixMask;
I = alignTo(I, BITWORD_SIZE);
for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
Bits[I / BITWORD_SIZE] = ~0UL;
BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
if (I < E)
Bits[I / BITWORD_SIZE] |= PostfixMask;
return *this;
}
BitVector &reset() {
init_words(Bits, false);
return *this;
}
BitVector &reset(unsigned Idx) {
Bits[Idx / BITWORD_SIZE] &= ~(BitWord(1) << (Idx % BITWORD_SIZE));
return *this;
}
/// reset - Efficiently reset a range of bits in [I, E)
BitVector &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 (I / BITWORD_SIZE == E / BITWORD_SIZE) {
BitWord EMask = 1UL << (E % BITWORD_SIZE);
BitWord IMask = 1UL << (I % BITWORD_SIZE);
BitWord Mask = EMask - IMask;
Bits[I / BITWORD_SIZE] &= ~Mask;
return *this;
}
BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
Bits[I / BITWORD_SIZE] &= ~PrefixMask;
I = alignTo(I, BITWORD_SIZE);
for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
Bits[I / BITWORD_SIZE] = 0UL;
BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
if (I < E)
Bits[I / BITWORD_SIZE] &= ~PostfixMask;
return *this;
}
BitVector &flip() {
for (unsigned i = 0; i < NumBitWords(size()); ++i)
Bits[i] = ~Bits[i];
clear_unused_bits();
return *this;
}
BitVector &flip(unsigned Idx) {
Bits[Idx / BITWORD_SIZE] ^= BitWord(1) << (Idx % BITWORD_SIZE);
return *this;
}
// 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.");
BitWord Mask = BitWord(1) << (Idx % BITWORD_SIZE);
return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
}
bool test(unsigned Idx) const {
return (*this)[Idx];
}
// Push single bit to end of vector.
void push_back(bool Val) {
unsigned OldSize = Size;
unsigned NewSize = Size + 1;
// Resize, which will insert zeros.
// If we already fit then the unused bits will be already zero.
if (NewSize > getBitCapacity())
resize(NewSize, false);
else
Size = NewSize;
// If true, set single bit.
if (Val)
set(OldSize);
}
/// Test if any common bits are set.
bool anyCommon(const BitVector &RHS) const {
unsigned ThisWords = NumBitWords(size());
unsigned RHSWords = NumBitWords(RHS.size());
for (unsigned i = 0, e = std::min(ThisWords, RHSWords); i != e; ++i)
if (Bits[i] & RHS.Bits[i])
return true;
return false;
}
// Comparison operators.
bool operator==(const BitVector &RHS) const {
unsigned ThisWords = NumBitWords(size());
unsigned RHSWords = NumBitWords(RHS.size());
unsigned i;
for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
if (Bits[i] != RHS.Bits[i])
return false;
// Verify that any extra words are all zeros.
if (i != ThisWords) {
for (; i != ThisWords; ++i)
if (Bits[i])
return false;
} else if (i != RHSWords) {
for (; i != RHSWords; ++i)
if (RHS.Bits[i])
return false;
}
return true;
}
bool operator!=(const BitVector &RHS) const {
return !(*this == RHS);
}
/// Intersection, union, disjoint union.
BitVector &operator&=(const BitVector &RHS) {
unsigned ThisWords = NumBitWords(size());
unsigned RHSWords = NumBitWords(RHS.size());
unsigned i;
for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
Bits[i] &= RHS.Bits[i];
// Any bits that are just in this bitvector become zero, because they aren't
// in the RHS bit vector. Any words only in RHS are ignored because they
// are already zero in the LHS.
for (; i != ThisWords; ++i)
Bits[i] = 0;
return *this;
}
/// reset - Reset bits that are set in RHS. Same as *this &= ~RHS.
BitVector &reset(const BitVector &RHS) {
unsigned ThisWords = NumBitWords(size());
unsigned RHSWords = NumBitWords(RHS.size());
unsigned i;
for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
Bits[i] &= ~RHS.Bits[i];
return *this;
}
/// test - Check if (This - RHS) is zero.
/// This is the same as reset(RHS) and any().
bool test(const BitVector &RHS) const {
unsigned ThisWords = NumBitWords(size());
unsigned RHSWords = NumBitWords(RHS.size());
unsigned i;
for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
if ((Bits[i] & ~RHS.Bits[i]) != 0)
return true;
for (; i != ThisWords ; ++i)
if (Bits[i] != 0)
return true;
return false;
}
BitVector &operator|=(const BitVector &RHS) {
if (size() < RHS.size())
resize(RHS.size());
for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
Bits[i] |= RHS.Bits[i];
return *this;
}
BitVector &operator^=(const BitVector &RHS) {
if (size() < RHS.size())
resize(RHS.size());
for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
Bits[i] ^= RHS.Bits[i];
return *this;
}
BitVector &operator>>=(unsigned N) {
assert(N <= Size);
if (LLVM_UNLIKELY(empty() || N == 0))
return *this;
unsigned NumWords = NumBitWords(Size);
assert(NumWords >= 1);
wordShr(N / BITWORD_SIZE);
unsigned BitDistance = N % BITWORD_SIZE;
if (BitDistance == 0)
return *this;
// When the shift size is not a multiple of the word size, then we have
// a tricky situation where each word in succession needs to extract some
// of the bits from the next word and or them into this word while
// shifting this word to make room for the new bits. This has to be done
// for every word in the array.
// Since we're shifting each word right, some bits will fall off the end
// of each word to the right, and empty space will be created on the left.
// The final word in the array will lose bits permanently, so starting at
// the beginning, work forwards shifting each word to the right, and
// OR'ing in the bits from the end of the next word to the beginning of
// the current word.
// Example:
// Starting with {0xAABBCCDD, 0xEEFF0011, 0x22334455} and shifting right
// by 4 bits.
// Step 1: Word[0] >>= 4 ; 0x0ABBCCDD
// Step 2: Word[0] |= 0x10000000 ; 0x1ABBCCDD
// Step 3: Word[1] >>= 4 ; 0x0EEFF001
// Step 4: Word[1] |= 0x50000000 ; 0x5EEFF001
// Step 5: Word[2] >>= 4 ; 0x02334455
// Result: { 0x1ABBCCDD, 0x5EEFF001, 0x02334455 }
const BitWord Mask = maskTrailingOnes<BitWord>(BitDistance);
const unsigned LSH = BITWORD_SIZE - BitDistance;
for (unsigned I = 0; I < NumWords - 1; ++I) {
Bits[I] >>= BitDistance;
Bits[I] |= (Bits[I + 1] & Mask) << LSH;
}
Bits[NumWords - 1] >>= BitDistance;
return *this;
}
BitVector &operator<<=(unsigned N) {
assert(N <= Size);
if (LLVM_UNLIKELY(empty() || N == 0))
return *this;
unsigned NumWords = NumBitWords(Size);
assert(NumWords >= 1);
wordShl(N / BITWORD_SIZE);
unsigned BitDistance = N % BITWORD_SIZE;
if (BitDistance == 0)
return *this;
// When the shift size is not a multiple of the word size, then we have
// a tricky situation where each word in succession needs to extract some
// of the bits from the previous word and or them into this word while
// shifting this word to make room for the new bits. This has to be done
// for every word in the array. This is similar to the algorithm outlined
// in operator>>=, but backwards.
// Since we're shifting each word left, some bits will fall off the end
// of each word to the left, and empty space will be created on the right.
// The first word in the array will lose bits permanently, so starting at
// the end, work backwards shifting each word to the left, and OR'ing
// in the bits from the end of the next word to the beginning of the
// current word.
// Example:
// Starting with {0xAABBCCDD, 0xEEFF0011, 0x22334455} and shifting left
// by 4 bits.
// Step 1: Word[2] <<= 4 ; 0x23344550
// Step 2: Word[2] |= 0x0000000E ; 0x2334455E
// Step 3: Word[1] <<= 4 ; 0xEFF00110
// Step 4: Word[1] |= 0x0000000A ; 0xEFF0011A
// Step 5: Word[0] <<= 4 ; 0xABBCCDD0
// Result: { 0xABBCCDD0, 0xEFF0011A, 0x2334455E }
const BitWord Mask = maskLeadingOnes<BitWord>(BitDistance);
const unsigned RSH = BITWORD_SIZE - BitDistance;
for (int I = NumWords - 1; I > 0; --I) {
Bits[I] <<= BitDistance;
Bits[I] |= (Bits[I - 1] & Mask) >> RSH;
}
Bits[0] <<= BitDistance;
clear_unused_bits();
return *this;
}
// Assignment operator.
const BitVector &operator=(const BitVector &RHS) {
if (this == &RHS) return *this;
Size = RHS.size();
unsigned RHSWords = NumBitWords(Size);
if (Size <= getBitCapacity()) {
if (Size)
std::memcpy(Bits.data(), RHS.Bits.data(), RHSWords * sizeof(BitWord));
clear_unused_bits();
return *this;
}
// Grow the bitvector to have enough elements.
unsigned NewCapacity = RHSWords;
assert(NewCapacity > 0 && "negative capacity?");
auto NewBits = allocate(NewCapacity);
std::memcpy(NewBits.data(), RHS.Bits.data(), NewCapacity * sizeof(BitWord));
// Destroy the old bits.
std::free(Bits.data());
Bits = NewBits;
return *this;
}
const BitVector &operator=(BitVector &&RHS) {
if (this == &RHS) return *this;
std::free(Bits.data());
Bits = RHS.Bits;
Size = RHS.Size;
RHS.Bits = MutableArrayRef<BitWord>();
RHS.Size = 0;
return *this;
}
void swap(BitVector &RHS) {
std::swap(Bits, RHS.Bits);
std::swap(Size, RHS.Size);
}
//===--------------------------------------------------------------------===//
// Portable bit mask operations.
//===--------------------------------------------------------------------===//
//
// These methods all operate on arrays of uint32_t, each holding 32 bits. The
// fixed word size makes it easier to work with literal bit vector constants
// in portable code.
//
// The LSB in each word is the lowest numbered bit. The size of a portable
// bit mask is always a whole multiple of 32 bits. If no bit mask size is
// given, the bit mask is assumed to cover the entire BitVector.
/// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize.
/// This computes "*this |= Mask".
void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
applyMask<true, false>(Mask, MaskWords);
}
/// clearBitsInMask - 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) {
applyMask<false, false>(Mask, MaskWords);
}
/// setBitsNotInMask - 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) {
applyMask<true, true>(Mask, MaskWords);
}
/// clearBitsNotInMask - 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) {
applyMask<false, true>(Mask, MaskWords);
}
private:
/// Perform a logical left shift of \p Count words by moving everything
/// \p Count words to the right in memory.
///
/// While confusing, words are stored from least significant at Bits[0] to
/// most significant at Bits[NumWords-1]. A logical shift left, however,
/// moves the current least significant bit to a higher logical index, and
/// fills the previous least significant bits with 0. Thus, we actually
/// need to move the bytes of the memory to the right, not to the left.
/// Example:
/// Words = [0xBBBBAAAA, 0xDDDDFFFF, 0x00000000, 0xDDDD0000]
/// represents a BitVector where 0xBBBBAAAA contain the least significant
/// bits. So if we want to shift the BitVector left by 2 words, we need to
/// turn this into 0x00000000 0x00000000 0xBBBBAAAA 0xDDDDFFFF by using a
/// memmove which moves right, not left.
void wordShl(uint32_t Count) {
if (Count == 0)
return;
uint32_t NumWords = NumBitWords(Size);
auto Src = Bits.take_front(NumWords).drop_back(Count);
auto Dest = Bits.take_front(NumWords).drop_front(Count);
// Since we always move Word-sized chunks of data with src and dest both
// aligned to a word-boundary, we don't need to worry about endianness
// here.
std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
std::memset(Bits.data(), 0, Count * sizeof(BitWord));
clear_unused_bits();
}
/// Perform a logical right shift of \p Count words by moving those
/// words to the left in memory. See wordShl for more information.
///
void wordShr(uint32_t Count) {
if (Count == 0)
return;
uint32_t NumWords = NumBitWords(Size);
auto Src = Bits.take_front(NumWords).drop_front(Count);
auto Dest = Bits.take_front(NumWords).drop_back(Count);
assert(Dest.size() == Src.size());
std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
std::memset(Dest.end(), 0, Count * sizeof(BitWord));
}
MutableArrayRef<BitWord> allocate(size_t NumWords) {
BitWord *RawBits = static_cast<BitWord *>(
safe_malloc(NumWords * sizeof(BitWord)));
return MutableArrayRef<BitWord>(RawBits, NumWords);
}
int next_unset_in_word(int WordIndex, BitWord Word) const {
unsigned Result = WordIndex * BITWORD_SIZE + countTrailingOnes(Word);
return Result < size() ? Result : -1;
}
unsigned NumBitWords(unsigned S) const {
return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
}
// Set the unused bits in the high words.
void set_unused_bits(bool t = true) {
// Set high words first.
unsigned UsedWords = NumBitWords(Size);
if (Bits.size() > UsedWords)
init_words(Bits.drop_front(UsedWords), t);
// Then set any stray high bits of the last used word.
unsigned ExtraBits = Size % BITWORD_SIZE;
if (ExtraBits) {
BitWord ExtraBitMask = ~0UL << ExtraBits;
if (t)
Bits[UsedWords-1] |= ExtraBitMask;
else
Bits[UsedWords-1] &= ~ExtraBitMask;
}
}
// Clear the unused bits in the high words.
void clear_unused_bits() {
set_unused_bits(false);
}
void grow(unsigned NewSize) {
size_t NewCapacity = std::max<size_t>(NumBitWords(NewSize), Bits.size() * 2);
assert(NewCapacity > 0 && "realloc-ing zero space");
BitWord *NewBits = static_cast<BitWord *>(
safe_realloc(Bits.data(), NewCapacity * sizeof(BitWord)));
Bits = MutableArrayRef<BitWord>(NewBits, NewCapacity);
clear_unused_bits();
}
void init_words(MutableArrayRef<BitWord> B, bool t) {
if (B.size() > 0)
memset(B.data(), 0 - (int)t, B.size() * sizeof(BitWord));
}
template<bool AddBits, bool InvertMask>
void applyMask(const uint32_t *Mask, unsigned MaskWords) {
static_assert(BITWORD_SIZE % 32 == 0, "Unsupported BitWord size.");
MaskWords = std::min(MaskWords, (size() + 31) / 32);
const unsigned Scale = BITWORD_SIZE / 32;
unsigned i;
for (i = 0; MaskWords >= Scale; ++i, MaskWords -= Scale) {
BitWord BW = Bits[i];
// This inner loop should unroll completely when BITWORD_SIZE > 32.
for (unsigned b = 0; b != BITWORD_SIZE; b += 32) {
uint32_t M = *Mask++;
if (InvertMask) M = ~M;
if (AddBits) BW |= BitWord(M) << b;
else BW &= ~(BitWord(M) << b);
}
Bits[i] = BW;
}
for (unsigned b = 0; MaskWords; b += 32, --MaskWords) {
uint32_t M = *Mask++;
if (InvertMask) M = ~M;
if (AddBits) Bits[i] |= BitWord(M) << b;
else Bits[i] &= ~(BitWord(M) << b);
}
if (AddBits)
clear_unused_bits();
}
public:
/// Return the size (in bytes) of the bit vector.
size_t getMemorySize() const { return Bits.size() * sizeof(BitWord); }
size_t getBitCapacity() const { return Bits.size() * BITWORD_SIZE; }
};
inline size_t capacity_in_bytes(const BitVector &X) {
return X.getMemorySize();
}
} // end namespace llvm
namespace std {
/// Implement std::swap in terms of BitVector swap.
inline void
swap(llvm::BitVector &LHS, llvm::BitVector &RHS) {
LHS.swap(RHS);
}
} // end namespace std
#endif // LLVM_ADT_BITVECTOR_H
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