libartbase/base/arena_bit_vector.h

/*
 * 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_ARENA_BIT_VECTOR_H_
#define ART_LIBARTBASE_BASE_ARENA_BIT_VECTOR_H_

#include <algorithm>

#include "arena_object.h"
#include "base/arena_allocator.h"
#include "bit_vector-inl.h"

namespace art {

class ScopedArenaAllocator;

/*
 * A BitVector implementation that uses Arena allocation. All constructors of ArenaBitVector start
 * with an empty ArenaBitVector.
 */
class ArenaBitVector : public BitVector, public ArenaObject<kArenaAllocGrowableBitMap> {
 public:
  template <typename Allocator>
  static ArenaBitVector* Create(Allocator* allocator,
                                uint32_t start_bits,
                                bool expandable,
                                ArenaAllocKind kind = kArenaAllocGrowableBitMap) {
    void* storage = allocator->template Alloc<ArenaBitVector>(kind);
    return new (storage) ArenaBitVector(allocator, start_bits, expandable, kind);
  }

  ArenaBitVector(ArenaAllocator* allocator,
                 uint32_t start_bits,
                 bool expandable,
                 ArenaAllocKind kind = kArenaAllocGrowableBitMap);
  ArenaBitVector(ScopedArenaAllocator* allocator,
                 uint32_t start_bits,
                 bool expandable,
                 ArenaAllocKind kind = kArenaAllocGrowableBitMap);
  ~ArenaBitVector() {}

  ArenaBitVector(ArenaBitVector&&) = default;
  ArenaBitVector(const ArenaBitVector&) = delete;

  template <typename StorageType = size_t, typename Allocator>
  static BitVectorView<StorageType> CreateFixedSize(
      Allocator* allocator, size_t bits, ArenaAllocKind kind = kArenaAllocGrowableBitMap) {
    static_assert(std::is_same_v<Allocator, ArenaAllocator> ||
                  std::is_same_v<Allocator, ScopedArenaAllocator>);
    size_t num_elements = BitVectorView<StorageType>::BitsToWords(bits);
    StorageType* storage = allocator->template AllocArray<StorageType>(num_elements, kind);
    BitVectorView<StorageType> result(storage, bits);
    if (std::is_same_v<Allocator, ScopedArenaAllocator>) {
      result.ClearAllBits();
    } else {
      DCHECK(!result.IsAnyBitSet());
    }
    return result;
  }
};

}  // namespace art

#endif  // ART_LIBARTBASE_BASE_ARENA_BIT_VECTOR_H_