arena_bit_vector.h revision 93ba893c20532990a430741e0a97212900094e8c 
1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_COMPILER_DEX_ARENA_BIT_VECTOR_H_
18#define ART_COMPILER_DEX_ARENA_BIT_VECTOR_H_
19
20#include <stdint.h>
21#include <stddef.h>
22#include "compiler_enums.h"
23#include "arena_allocator.h"
24
25namespace art {
26
27/*
28 * Expanding bitmap, used for tracking resources.  Bits are numbered starting
29 * from zero.  All operations on a BitVector are unsynchronized.
30 */
31class ArenaBitVector {
32  public:
33
34    class Iterator {
35      public:
36        explicit Iterator(ArenaBitVector* bit_vector)
37          : p_bits_(bit_vector),
38            bit_storage_(bit_vector->GetRawStorage()),
39            bit_index_(0),
40            bit_size_(p_bits_->storage_size_ * sizeof(uint32_t) * 8) {};
41
42        // Return the position of the next set bit.  -1 means end-of-element reached.
43        int Next() {
44          // Did anything obviously change since we started?
45          DCHECK_EQ(bit_size_, p_bits_->GetStorageSize() * sizeof(uint32_t) * 8);
46          DCHECK_EQ(bit_storage_, p_bits_->GetRawStorage());
47
48          if (bit_index_ >= bit_size_) return -1;
49
50          uint32_t word_index = bit_index_ / 32;
51          uint32_t word = bit_storage_[word_index];
52          // Mask out any bits in the first word we've already considered.
53          word >>= bit_index_ & 0x1f;
54          if (word == 0) {
55            bit_index_ &= ~0x1f;
56            do {
57              word_index++;
58              if ((word_index * 32) >= bit_size_) {
59                bit_index_ = bit_size_;
60                return -1;
61              }
62              word = bit_storage_[word_index];
63              bit_index_ += 32;
64            } while (word == 0);
65          }
66          bit_index_ += CTZ(word) + 1;
67          return bit_index_ - 1;
68        }
69
70        static void* operator new(size_t size, ArenaAllocator* arena) {
71          return arena->NewMem(sizeof(ArenaBitVector::Iterator), true,
72                               ArenaAllocator::kAllocGrowableBitMap);
73        };
74        static void operator delete(void* p) {};  // Nop.
75
76      private:
77        ArenaBitVector* const p_bits_;
78        uint32_t* const bit_storage_;
79        uint32_t bit_index_;              // Current index (size in bits).
80        const uint32_t bit_size_;       // Size of vector in bits.
81    };
82
83    ArenaBitVector(ArenaAllocator* arena, unsigned int start_bits, bool expandable,
84                   OatBitMapKind kind = kBitMapMisc);
85    ~ArenaBitVector() {};
86
87    static void* operator new( size_t size, ArenaAllocator* arena) {
88      return arena->NewMem(sizeof(ArenaBitVector), true, ArenaAllocator::kAllocGrowableBitMap);
89    }
90    static void operator delete(void* p) {};  // Nop.
91
92    void SetBit(unsigned int num);
93    void ClearBit(unsigned int num);
94    void MarkAllBits(bool set);
95    void DebugBitVector(char* msg, int length);
96    bool IsBitSet(unsigned int num);
97    void ClearAllBits();
98    void SetInitialBits(unsigned int num_bits);
99    void Copy(ArenaBitVector* src);
100    void Intersect(const ArenaBitVector* src2);
101    void Union(const ArenaBitVector* src);
102    // Are we equal to another bit vector?  Note: expandability attributes must also match.
103    bool Equal(const ArenaBitVector* src) {
104      return (storage_size_ == src->GetStorageSize()) &&
105        (expandable_ == src->IsExpandable()) &&
106        (memcmp(storage_, src->GetRawStorage(), storage_size_ * 4) == 0);
107    }
108    int NumSetBits();
109
110    uint32_t GetStorageSize() const { return storage_size_; }
111    bool IsExpandable() const { return expandable_; }
112    uint32_t GetRawStorageWord(size_t idx) const { return storage_[idx]; }
113    uint32_t* GetRawStorage() { return storage_; }
114    const uint32_t* GetRawStorage() const { return storage_; }
115
116  private:
117    ArenaAllocator* const arena_;
118    const bool expandable_;         // expand bitmap if we run out?
119    const OatBitMapKind kind_;      // for memory use tuning.
120    uint32_t   storage_size_;       // current size, in 32-bit words.
121    uint32_t*  storage_;
122};
123
124
125}  // namespace art
126
127#endif  // ART_COMPILER_DEX_ARENA_BIT_VECTOR_H_
128