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1 // Copyright 2011 the V8 project authors. All rights reserved. | 1 // Copyright 2011 the V8 project authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef V8_HEAP_SPACES_H_ | 5 #ifndef V8_HEAP_SPACES_H_ |
6 #define V8_HEAP_SPACES_H_ | 6 #define V8_HEAP_SPACES_H_ |
7 | 7 |
8 #include "src/allocation.h" | 8 #include "src/allocation.h" |
9 #include "src/base/atomicops.h" | 9 #include "src/base/atomicops.h" |
10 #include "src/base/bits.h" | 10 #include "src/base/bits.h" |
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27 // scavenger implements Cheney's copying algorithm. The old generation is | 27 // scavenger implements Cheney's copying algorithm. The old generation is |
28 // separated into a map space and an old object space. The map space contains | 28 // separated into a map space and an old object space. The map space contains |
29 // all (and only) map objects, the rest of old objects go into the old space. | 29 // all (and only) map objects, the rest of old objects go into the old space. |
30 // The old generation is collected by a mark-sweep-compact collector. | 30 // The old generation is collected by a mark-sweep-compact collector. |
31 // | 31 // |
32 // The semispaces of the young generation are contiguous. The old and map | 32 // The semispaces of the young generation are contiguous. The old and map |
33 // spaces consists of a list of pages. A page has a page header and an object | 33 // spaces consists of a list of pages. A page has a page header and an object |
34 // area. | 34 // area. |
35 // | 35 // |
36 // There is a separate large object space for objects larger than | 36 // There is a separate large object space for objects larger than |
37 // Page::kMaxHeapObjectSize, so that they do not have to move during | 37 // Page::kMaxRegularHeapObjectSize, so that they do not have to move during |
38 // collection. The large object space is paged. Pages in large object space | 38 // collection. The large object space is paged. Pages in large object space |
39 // may be larger than the page size. | 39 // may be larger than the page size. |
40 // | 40 // |
41 // A store-buffer based write barrier is used to keep track of intergenerational | 41 // A store-buffer based write barrier is used to keep track of intergenerational |
42 // references. See heap/store-buffer.h. | 42 // references. See heap/store-buffer.h. |
43 // | 43 // |
44 // During scavenges and mark-sweep collections we sometimes (after a store | 44 // During scavenges and mark-sweep collections we sometimes (after a store |
45 // buffer overflow) iterate intergenerational pointers without decoding heap | 45 // buffer overflow) iterate intergenerational pointers without decoding heap |
46 // object maps so if the page belongs to old pointer space or large object | 46 // object maps so if the page belongs to old pointer space or large object |
47 // space it is essential to guarantee that the page does not contain any | 47 // space it is essential to guarantee that the page does not contain any |
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2685 | 2685 |
2686 protected: | 2686 protected: |
2687 virtual void VerifyObject(HeapObject* obj); | 2687 virtual void VerifyObject(HeapObject* obj); |
2688 | 2688 |
2689 public: | 2689 public: |
2690 TRACK_MEMORY("CellSpace") | 2690 TRACK_MEMORY("CellSpace") |
2691 }; | 2691 }; |
2692 | 2692 |
2693 | 2693 |
2694 // ----------------------------------------------------------------------------- | 2694 // ----------------------------------------------------------------------------- |
2695 // Large objects ( > Page::kMaxHeapObjectSize ) are allocated and managed by | 2695 // Large objects ( > Page::kMaxRegularHeapObjectSize ) are allocated and |
2696 // the large object space. A large object is allocated from OS heap with | 2696 // managed by the large object space. A large object is allocated from OS |
2697 // extra padding bytes (Page::kPageSize + Page::kObjectStartOffset). | 2697 // heap with extra padding bytes (Page::kPageSize + Page::kObjectStartOffset). |
2698 // A large object always starts at Page::kObjectStartOffset to a page. | 2698 // A large object always starts at Page::kObjectStartOffset to a page. |
2699 // Large objects do not move during garbage collections. | 2699 // Large objects do not move during garbage collections. |
2700 | 2700 |
2701 class LargeObjectSpace : public Space { | 2701 class LargeObjectSpace : public Space { |
2702 public: | 2702 public: |
2703 LargeObjectSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id); | 2703 LargeObjectSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id); |
2704 virtual ~LargeObjectSpace() {} | 2704 virtual ~LargeObjectSpace() {} |
2705 | 2705 |
2706 // Initializes internal data structures. | 2706 // Initializes internal data structures. |
2707 bool SetUp(); | 2707 bool SetUp(); |
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2870 count = 0; | 2870 count = 0; |
2871 } | 2871 } |
2872 // Must be small, since an iteration is used for lookup. | 2872 // Must be small, since an iteration is used for lookup. |
2873 static const int kMaxComments = 64; | 2873 static const int kMaxComments = 64; |
2874 }; | 2874 }; |
2875 #endif | 2875 #endif |
2876 } | 2876 } |
2877 } // namespace v8::internal | 2877 } // namespace v8::internal |
2878 | 2878 |
2879 #endif // V8_HEAP_SPACES_H_ | 2879 #endif // V8_HEAP_SPACES_H_ |
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