Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame^] | 1 | // Copyright (C) 2008 The Android Open Source Project |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | #ifndef ART_SRC_OBJECT_BITMAP_H_ |
| 16 | #define ART_SRC_OBJECT_BITMAP_H_ |
| 17 | |
| 18 | #include <limits.h> |
| 19 | #include <stdint.h> |
| 20 | |
| 21 | #include "src/globals.h" |
| 22 | #include "src/logging.h" |
| 23 | |
| 24 | namespace art { |
| 25 | |
| 26 | class Object; |
| 27 | |
| 28 | // <offset> is the difference from .base to a pointer address. |
| 29 | // <index> is the index of .bits that contains the bit representing |
| 30 | // <offset>. |
| 31 | #define HB_OFFSET_TO_INDEX(offset_) \ |
| 32 | ((offset_) / kAlignment / kBitsPerWord) |
| 33 | #define HB_INDEX_TO_OFFSET(index_) \ |
| 34 | ((index_) * kAlignment * kBitsPerWord) |
| 35 | |
| 36 | #define HB_OFFSET_TO_BYTE_INDEX(offset_) \ |
| 37 | (HB_OFFSET_TO_INDEX(offset_) * sizeof(*((HeapBitmap *)0)->words_)) |
| 38 | |
| 39 | // Pack the bits in backwards so they come out in address order |
| 40 | // when using CLZ. |
| 41 | #define HB_OFFSET_TO_MASK(offset_) \ |
| 42 | (1 << \ |
| 43 | (31-(((uintptr_t)(offset_) / kAlignment) % kBitsPerWord))) |
| 44 | |
| 45 | class HeapBitmap { |
| 46 | public: |
| 47 | static const size_t kAlignment = 8; |
| 48 | |
| 49 | typedef void Callback(Object *obj, void *arg); |
| 50 | |
| 51 | typedef void ScanCallback(Object *obj, void *finger, void *arg); |
| 52 | |
| 53 | typedef void SweepCallback(size_t numPtrs, void **ptrs, void *arg); |
| 54 | |
| 55 | static HeapBitmap* Create(byte* base, size_t length); |
| 56 | |
| 57 | ~HeapBitmap(); |
| 58 | |
| 59 | void Set(const Object* obj) { |
| 60 | Modify(obj, true); |
| 61 | } |
| 62 | |
| 63 | void Clear(const Object* obj) { |
| 64 | Modify(obj, false); |
| 65 | } |
| 66 | |
| 67 | void Clear(); |
| 68 | |
| 69 | bool Test(const Object* obj) { |
| 70 | CHECK(HasAddress(obj)); |
| 71 | CHECK(words_ != NULL); |
| 72 | CHECK_GE((uintptr_t)obj, base_); |
| 73 | if ((uintptr_t)obj <= max_) { |
| 74 | const uintptr_t offset = (uintptr_t)obj - base_; |
| 75 | unsigned long word = words_[HB_OFFSET_TO_INDEX(offset)]; |
| 76 | return (word & HB_OFFSET_TO_MASK(offset)) != 0; |
| 77 | } else { |
| 78 | return false; |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | bool HasAddress(const void* addr) const; |
| 83 | |
| 84 | void Walk(Callback* callback, void* arg); |
| 85 | |
| 86 | void ScanWalk(uintptr_t base, uintptr_t max, |
| 87 | ScanCallback* thunk, void* arg); |
| 88 | |
| 89 | static void SweepWalk(const HeapBitmap& live, |
| 90 | const HeapBitmap& mark, |
| 91 | uintptr_t base, uintptr_t max, |
| 92 | SweepCallback* thunk, void* arg); |
| 93 | |
| 94 | private: |
| 95 | HeapBitmap(const void* base, size_t length) |
| 96 | : words_(NULL), |
| 97 | num_bytes_(length), |
| 98 | base_(reinterpret_cast<uintptr_t>(base)) { |
| 99 | }; |
| 100 | |
| 101 | void Modify(const Object* obj, bool do_set) { |
| 102 | uintptr_t addr = reinterpret_cast<uintptr_t>(obj); |
| 103 | CHECK_GE(addr, base_); |
| 104 | const uintptr_t offset = addr - base_; |
| 105 | const size_t index = HB_OFFSET_TO_INDEX(offset); |
| 106 | const unsigned long mask = HB_OFFSET_TO_MASK(offset); |
| 107 | CHECK_LT(index, num_bytes_ / kWordSize); |
| 108 | if (do_set) { |
| 109 | if (addr > max_) { |
| 110 | max_ = addr; |
| 111 | } |
| 112 | words_[index] |= mask; |
| 113 | } else { |
| 114 | words_[index] &= ~mask; |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | bool Init(const byte* base, size_t length); |
| 119 | |
| 120 | unsigned long* words_; |
| 121 | |
| 122 | size_t num_bytes_; |
| 123 | |
| 124 | // The base address, which corresponds to the word containing the |
| 125 | // first bit in the bitmap. |
| 126 | uintptr_t base_; |
| 127 | |
| 128 | // The highest pointer value ever returned by an allocation from |
| 129 | // this heap. I.e., the highest address that may correspond to a |
| 130 | // set bit. If there are no bits set, (max < base). |
| 131 | uintptr_t max_; |
| 132 | |
| 133 | const char* name_; |
| 134 | }; |
| 135 | |
| 136 | } // namespace art |
| 137 | |
| 138 | #endif // ART_SRC_OBJECT_BITMAP_H_ |