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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_LIBARTBASE_BASE_BIT_VECTOR_H_
#define ART_LIBARTBASE_BASE_BIT_VECTOR_H_
#include <stdint.h>
#include <iterator>
#include "bit_utils.h"
#include "globals.h"
namespace art {
class Allocator;
class ArenaBitVector;
/*
* Expanding bitmap, used for tracking resources. Bits are numbered starting
* from zero. All operations on a BitVector are unsynchronized.
*/
class BitVector {
public:
static constexpr uint32_t kWordBytes = sizeof(uint32_t);
static constexpr uint32_t kWordBits = kWordBytes * 8;
class IndexContainer;
/**
* @brief Convenient iterator across the indexes of the BitVector's set bits.
*
* @details IndexIterator is a Forward iterator (C++11: 24.2.5) from the lowest
* to the highest index of the BitVector's set bits. Instances can be retrieved
* only through BitVector::Indexes() which returns an IndexContainer wrapper
* object with begin() and end() suitable for range-based loops:
* for (uint32_t idx : bit_vector.Indexes()) {
* // Use idx.
* }
*/
class IndexIterator :
public std::iterator<std::forward_iterator_tag, uint32_t, ptrdiff_t, void, uint32_t> {
public:
bool operator==(const IndexIterator& other) const;
bool operator!=(const IndexIterator& other) const {
return !(*this == other);
}
uint32_t operator*() const;
IndexIterator& operator++();
IndexIterator operator++(int);
// Helper function to check for end without comparing with bit_vector.Indexes().end().
bool Done() const {
return bit_index_ == BitSize();
}
private:
struct begin_tag { };
struct end_tag { };
IndexIterator(const BitVector* bit_vector, begin_tag);
IndexIterator(const BitVector* bit_vector, end_tag);
uint32_t BitSize() const {
return storage_size_ * kWordBits;
}
uint32_t FindIndex(uint32_t start_index) const;
const uint32_t* const bit_storage_;
const uint32_t storage_size_; // Size of vector in words.
uint32_t bit_index_; // Current index (size in bits).
friend class BitVector::IndexContainer;
};
/**
* @brief BitVector wrapper class for iteration across indexes of set bits.
*/
class IndexContainer {
public:
explicit IndexContainer(const BitVector* bit_vector) : bit_vector_(bit_vector) { }
IndexIterator begin() const;
IndexIterator end() const;
private:
const BitVector* const bit_vector_;
};
// MoveConstructible but not MoveAssignable, CopyConstructible or CopyAssignable.
BitVector(const BitVector& other) = delete;
BitVector& operator=(const BitVector& other) = delete;
BitVector(BitVector&& other) noexcept
: storage_(other.storage_),
storage_size_(other.storage_size_),
allocator_(other.allocator_),
expandable_(other.expandable_) {
other.storage_ = nullptr;
other.storage_size_ = 0u;
}
BitVector(uint32_t start_bits,
bool expandable,
Allocator* allocator);
BitVector(bool expandable,
Allocator* allocator,
uint32_t storage_size,
uint32_t* storage);
BitVector(const BitVector& src,
bool expandable,
Allocator* allocator);
virtual ~BitVector();
// The number of words necessary to encode bits.
static constexpr uint32_t BitsToWords(uint32_t bits) {
return RoundUp(bits, kWordBits) / kWordBits;
}
// Mark the specified bit as "set".
void SetBit(uint32_t idx) {
/*
* TUNING: this could have pathologically bad growth/expand behavior. Make sure we're
* not using it badly or change resize mechanism.
*/
if (idx >= storage_size_ * kWordBits) {
EnsureSize(idx);
}
storage_[WordIndex(idx)] |= BitMask(idx);
}
// Mark the specified bit as "unset".
void ClearBit(uint32_t idx) {
// If the index is over the size, we don't have to do anything, it is cleared.
if (idx < storage_size_ * kWordBits) {
// Otherwise, go ahead and clear it.
storage_[WordIndex(idx)] &= ~BitMask(idx);
}
}
// Determine whether or not the specified bit is set.
bool IsBitSet(uint32_t idx) const {
// If the index is over the size, whether it is expandable or not, this bit does not exist:
// thus it is not set.
return (idx < (storage_size_ * kWordBits)) && IsBitSet(storage_, idx);
}
// Mark all bits bit as "clear".
void ClearAllBits();
// Mark specified number of bits as "set". Cannot set all bits like ClearAll since there might
// be unused bits - setting those to one will confuse the iterator.
void SetInitialBits(uint32_t num_bits);
void Copy(const BitVector* src);
// Intersect with another bit vector.
void Intersect(const BitVector* src2);
// Union with another bit vector.
bool Union(const BitVector* src);
// Set bits of union_with that are not in not_in.
bool UnionIfNotIn(const BitVector* union_with, const BitVector* not_in);
void Subtract(const BitVector* src);
// Are we equal to another bit vector? Note: expandability attributes must also match.
bool Equal(const BitVector* src) const;
/**
* @brief Are all the bits set the same?
* @details expandability and size can differ as long as the same bits are set.
*/
bool SameBitsSet(const BitVector *src) const;
bool IsSubsetOf(const BitVector *other) const;
// Count the number of bits that are set.
uint32_t NumSetBits() const;
// Count the number of bits that are set in range [0, end).
uint32_t NumSetBits(uint32_t end) const;
IndexContainer Indexes() const {
return IndexContainer(this);
}
uint32_t GetStorageSize() const {
return storage_size_;
}
bool IsExpandable() const {
return expandable_;
}
uint32_t GetRawStorageWord(size_t idx) const {
return storage_[idx];
}
uint32_t* GetRawStorage() {
return storage_;
}
const uint32_t* GetRawStorage() const {
return storage_;
}
size_t GetSizeOf() const {
return storage_size_ * kWordBytes;
}
size_t GetBitSizeOf() const {
return storage_size_ * kWordBits;
}
/**
* @return the highest bit set, -1 if none are set
*/
int GetHighestBitSet() const;
/**
* @return true if there are any bits set, false otherwise.
*/
bool IsAnyBitSet() const {
return GetHighestBitSet() != -1;
}
// Minimum number of bits required to store this vector, 0 if none are set.
size_t GetNumberOfBits() const {
return GetHighestBitSet() + 1;
}
// Is bit set in storage. (No range check.)
static bool IsBitSet(const uint32_t* storage, uint32_t idx) {
return (storage[WordIndex(idx)] & BitMask(idx)) != 0;
}
// Number of bits set in range [0, end) in storage. (No range check.)
static uint32_t NumSetBits(const uint32_t* storage, uint32_t end);
// Fill given memory region with the contents of the vector and zero padding.
void CopyTo(void* dst, size_t len) const {
DCHECK_LE(static_cast<size_t>(GetHighestBitSet() + 1), len * kBitsPerByte);
size_t vec_len = GetSizeOf();
if (vec_len < len) {
void* dst_padding = reinterpret_cast<uint8_t*>(dst) + vec_len;
memcpy(dst, storage_, vec_len);
memset(dst_padding, 0, len - vec_len);
} else {
memcpy(dst, storage_, len);
}
}
void Dump(std::ostream& os, const char* prefix) const;
Allocator* GetAllocator() const;
private:
/**
* @brief Dump the bitvector into buffer in a 00101..01 format.
* @param buffer the ostringstream used to dump the bitvector into.
*/
void DumpHelper(const char* prefix, std::ostringstream& buffer) const;
// Ensure there is space for a bit at idx.
void EnsureSize(uint32_t idx);
// The index of the word within storage.
static constexpr uint32_t WordIndex(uint32_t idx) {
return idx >> 5;
}
// A bit mask to extract the bit for the given index.
static constexpr uint32_t BitMask(uint32_t idx) {
return 1 << (idx & 0x1f);
}
uint32_t* storage_; // The storage for the bit vector.
uint32_t storage_size_; // Current size, in 32-bit words.
Allocator* const allocator_; // Allocator if expandable.
const bool expandable_; // Should the bitmap expand if too small?
};
// Helper for dealing with 2d bit-vector arrays packed into a single bit-vec
class BaseBitVectorArray {
public:
BaseBitVectorArray(const BaseBitVectorArray& bv) = default;
BaseBitVectorArray& operator=(const BaseBitVectorArray& other) = default;
BaseBitVectorArray() : num_columns_(0), num_rows_(0) {}
BaseBitVectorArray(size_t num_rows, size_t num_columns)
: num_columns_(RoundUp(num_columns, BitVector::kWordBits)), num_rows_(num_rows) {}
virtual ~BaseBitVectorArray() {}
bool IsExpandable() const {
return GetRawData().IsExpandable();
}
// Let subclasses provide storage for various types.
virtual const BitVector& GetRawData() const = 0;
virtual BitVector& GetRawData() = 0;
size_t NumRows() const {
return num_rows_;
}
// NB This might be more than the requested size for alignment purposes.
size_t NumColumns() const {
return num_columns_;
}
void Clear() {
GetRawData().ClearAllBits();
}
// Ensure that we can set all bits in the given range. The actual number of
// columns might be larger than requested for alignment purposes.
void Resize(size_t rows, size_t cols, bool clear = true);
void SetBit(size_t row, size_t col) {
DCHECK_LT(col, num_columns_);
DCHECK_LT(row, num_rows_);
GetRawData().SetBit(row * num_columns_ + col);
}
void ClearBit(size_t row, size_t col) {
DCHECK_LT(col, num_columns_);
DCHECK_LT(row, num_rows_);
GetRawData().ClearBit(row * num_columns_ + col);
}
bool IsBitSet(size_t row, size_t col) const {
DCHECK_LT(col, num_columns_);
DCHECK_LT(row, num_rows_);
return GetRawData().IsBitSet(row * num_columns_ + col);
}
// Union the vector of 'other' into 'dest_row'.
void UnionRows(size_t dest_row, size_t other);
static size_t RequiredBitVectorSize(size_t rows, size_t cols) {
return rows * RoundUp(cols, BitVector::kWordBits);
}
static size_t MaxRowsFor(const BitVector& bv, size_t cols) {
return cols != 0 ? bv.GetBitSizeOf() / RoundUp(cols, BitVector::kWordBits) : 0;
}
private:
size_t num_columns_;
size_t num_rows_;
};
// A BitVectorArray with a standard owned BitVector providing the backing
// storage. This should be used when the BitVectorArray is the owner of the
// whole BitVector and should use standard allocators for cleanup/allocation.
// Contrast this with ArenaBitVectorArray which uses arena allocators.
class BitVectorArray final : public BaseBitVectorArray {
public:
BitVectorArray(const BitVectorArray& bv) = delete;
BitVectorArray& operator=(const BitVectorArray& other) = delete;
explicit BitVectorArray(BitVector&& bv) : BaseBitVectorArray(), data_(std::move(bv)) {}
explicit BitVectorArray(BitVector&& bv, size_t cols)
: BaseBitVectorArray(BaseBitVectorArray::MaxRowsFor(bv, cols), cols), data_(std::move(bv)) {}
explicit BitVectorArray(BitVector&& bv, size_t rows, size_t cols)
: BaseBitVectorArray(rows, cols), data_(std::move(bv)) {}
BitVectorArray(uint32_t start_rows, uint32_t start_cols, bool expandable, Allocator* allocator)
: BaseBitVectorArray(start_rows, start_cols),
data_(BaseBitVectorArray::RequiredBitVectorSize(start_rows, start_cols),
expandable,
allocator) {}
BitVectorArray(const BaseBitVectorArray& src, bool expandable, Allocator* allocator)
: BaseBitVectorArray(src.NumRows(), src.NumColumns()),
data_(src.GetRawData(), expandable, allocator) {}
~BitVectorArray() override {}
const BitVector& GetRawData() const override {
return data_;
}
BitVector& GetRawData() override {
return data_;
}
private:
BitVector data_;
};
// A bit vector array that uses an unowned BitVector reference as it's backing
// data.
class BitVectorArrayWrapper final : public BaseBitVectorArray {
public:
BitVectorArrayWrapper& operator=(BitVectorArrayWrapper& other) = default;
BitVectorArrayWrapper(BitVectorArrayWrapper&) = default;
explicit BitVectorArrayWrapper(BitVector* bv) : BaseBitVectorArray(), data_(bv) {}
explicit BitVectorArrayWrapper(BitVector* bv, size_t cols)
: BaseBitVectorArray(BaseBitVectorArray::MaxRowsFor(*bv, cols), cols), data_(bv) {}
explicit BitVectorArrayWrapper(BitVector* bv, size_t rows, size_t cols)
: BaseBitVectorArray(rows, cols), data_(bv) {}
~BitVectorArrayWrapper() override {}
const BitVector& GetRawData() const override {
return *data_;
}
BitVector& GetRawData() override {
return *data_;
}
private:
BitVector* data_;
};
} // namespace art
#endif // ART_LIBARTBASE_BASE_BIT_VECTOR_H_