arena_bit_vector.h revision 0cd7ec2dcd8d7ba30bf3ca420b40dac52849876c 
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    class Iterator {
34      public:
35        explicit Iterator(ArenaBitVector* bit_vector)
36          : p_bits_(bit_vector),
37            bit_storage_(bit_vector->GetRawStorage()),
38            bit_index_(0),
39            bit_size_(p_bits_->storage_size_ * sizeof(uint32_t) * 8) {};
40
41        // Return the position of the next set bit.  -1 means end-of-element reached.
42        int Next() {
43          // Did anything obviously change since we started?
44          DCHECK_EQ(bit_size_, p_bits_->GetStorageSize() * sizeof(uint32_t) * 8);
45          DCHECK_EQ(bit_storage_, p_bits_->GetRawStorage());
46
47          if (bit_index_ >= bit_size_) return -1;
48
49          uint32_t word_index = bit_index_ / 32;
50          uint32_t word = bit_storage_[word_index];
51          // Mask out any bits in the first word we've already considered.
52          word >>= bit_index_ & 0x1f;
53          if (word == 0) {
54            bit_index_ &= ~0x1f;
55            do {
56              word_index++;
57              if ((word_index * 32) >= bit_size_) {
58                bit_index_ = bit_size_;
59                return -1;
60              }
61              word = bit_storage_[word_index];
62              bit_index_ += 32;
63            } while (word == 0);
64          }
65          bit_index_ += CTZ(word) + 1;
66          return bit_index_ - 1;
67        }
68
69        static void* operator new(size_t size, ArenaAllocator* arena) {
70          return arena->NewMem(sizeof(ArenaBitVector::Iterator), true,
71                               ArenaAllocator::kAllocGrowableBitMap);
72        };
73        static void operator delete(void* p) {};  // Nop.
74
75      private:
76        ArenaBitVector* const p_bits_;
77        uint32_t* const bit_storage_;
78        uint32_t bit_index_;              // Current index (size in bits).
79        const uint32_t bit_size_;       // Size of vector in bits.
80    };
81
82    ArenaBitVector(ArenaAllocator* arena, unsigned int start_bits, bool expandable,
83                   OatBitMapKind kind = kBitMapMisc);
84    ~ArenaBitVector() {};
85
86    static void* operator new( size_t size, ArenaAllocator* arena) {
87      return arena->NewMem(sizeof(ArenaBitVector), true, ArenaAllocator::kAllocGrowableBitMap);
88    }
89    static void operator delete(void* p) {};  // Nop.
90
91    void SetBit(unsigned int num);
92    void ClearBit(unsigned int num);
93    void MarkAllBits(bool set);
94    void DebugBitVector(char* msg, int length);
95    bool IsBitSet(unsigned int num);
96    void ClearAllBits();
97    void SetInitialBits(unsigned int num_bits);
98    void Copy(ArenaBitVector* src);
99    void Intersect(const ArenaBitVector* src2);
100    void Union(const ArenaBitVector* src);
101    // Are we equal to another bit vector?  Note: expandability attributes must also match.
102    bool Equal(const ArenaBitVector* src) {
103      return (storage_size_ == src->GetStorageSize()) &&
104        (expandable_ == src->IsExpandable()) &&
105        (memcmp(storage_, src->GetRawStorage(), storage_size_ * 4) == 0);
106    }
107    int NumSetBits();
108
109    uint32_t GetStorageSize() const { return storage_size_; }
110    bool IsExpandable() const { return expandable_; }
111    uint32_t GetRawStorageWord(size_t idx) const { return storage_[idx]; }
112    uint32_t* GetRawStorage() { return storage_; }
113    const uint32_t* GetRawStorage() const { return storage_; }
114
115  private:
116    ArenaAllocator* const arena_;
117    const bool expandable_;         // expand bitmap if we run out?
118    const OatBitMapKind kind_;      // for memory use tuning.
119    uint32_t   storage_size_;       // current size, in 32-bit words.
120    uint32_t*  storage_;
121};
122
123
124}  // namespace art
125
126#endif  // ART_COMPILER_DEX_ARENA_BIT_VECTOR_H_
127