[JSC] Shrink size of VM by lazily allocating IsoSubspaces for non-common types
[WebKit-https.git] / Source / JavaScriptCore / heap / Subspace.cpp
1 /*
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24  */
25
26 #include "config.h"
27 #include "Subspace.h"
28
29 #include "AlignedMemoryAllocator.h"
30 #include "BlockDirectoryInlines.h"
31 #include "HeapCellType.h"
32 #include "JSCInlines.h"
33 #include "MarkedBlockInlines.h"
34 #include "ParallelSourceAdapter.h"
35 #include "PreventCollectionScope.h"
36 #include "SubspaceInlines.h"
37
38 namespace JSC {
39
40 Subspace::Subspace(CString name, Heap& heap)
41     : m_space(heap.objectSpace())
42     , m_name(name)
43 {
44 }
45
46 void Subspace::initialize(HeapCellType* heapCellType, AlignedMemoryAllocator* alignedMemoryAllocator)
47 {
48     m_heapCellType = heapCellType;
49     m_alignedMemoryAllocator = alignedMemoryAllocator;
50     m_directoryForEmptyAllocation = m_alignedMemoryAllocator->firstDirectory();
51
52     Heap& heap = *m_space.heap();
53     heap.objectSpace().m_subspaces.append(this);
54     m_alignedMemoryAllocator->registerSubspace(this);
55 }
56
57 Subspace::~Subspace()
58 {
59 }
60
61 void Subspace::finishSweep(MarkedBlock::Handle& block, FreeList* freeList)
62 {
63     m_heapCellType->finishSweep(block, freeList);
64 }
65
66 void Subspace::destroy(VM& vm, JSCell* cell)
67 {
68     m_heapCellType->destroy(vm, cell);
69 }
70
71 void Subspace::prepareForAllocation()
72 {
73     forEachDirectory(
74         [&] (BlockDirectory& directory) {
75             directory.prepareForAllocation();
76         });
77
78     m_directoryForEmptyAllocation = m_alignedMemoryAllocator->firstDirectory();
79 }
80
81 MarkedBlock::Handle* Subspace::findEmptyBlockToSteal()
82 {
83     for (; m_directoryForEmptyAllocation; m_directoryForEmptyAllocation = m_directoryForEmptyAllocation->nextDirectoryInAlignedMemoryAllocator()) {
84         if (MarkedBlock::Handle* block = m_directoryForEmptyAllocation->findEmptyBlockToSteal())
85             return block;
86     }
87     return nullptr;
88 }
89
90 Ref<SharedTask<BlockDirectory*()>> Subspace::parallelDirectorySource()
91 {
92     class Task : public SharedTask<BlockDirectory*()> {
93     public:
94         Task(BlockDirectory* directory)
95             : m_directory(directory)
96         {
97         }
98         
99         BlockDirectory* run() override
100         {
101             auto locker = holdLock(m_lock);
102             BlockDirectory* result = m_directory;
103             if (result)
104                 m_directory = result->nextDirectoryInSubspace();
105             return result;
106         }
107         
108     private:
109         BlockDirectory* m_directory;
110         Lock m_lock;
111     };
112     
113     return adoptRef(*new Task(m_firstDirectory));
114 }
115
116 Ref<SharedTask<MarkedBlock::Handle*()>> Subspace::parallelNotEmptyMarkedBlockSource()
117 {
118     return createParallelSourceAdapter<BlockDirectory*, MarkedBlock::Handle*>(
119         parallelDirectorySource(),
120         [] (BlockDirectory* directory) -> RefPtr<SharedTask<MarkedBlock::Handle*()>> {
121             if (!directory)
122                 return nullptr;
123             return directory->parallelNotEmptyBlockSource();
124         });
125 }
126
127 void Subspace::sweep()
128 {
129     forEachDirectory(
130         [&] (BlockDirectory& directory) {
131             directory.sweep();
132         });
133 }
134
135 void Subspace::didResizeBits(size_t)
136 {
137 }
138
139 void Subspace::didRemoveBlock(size_t)
140 {
141 }
142
143 void Subspace::didBeginSweepingToFreeList(MarkedBlock::Handle*)
144 {
145 }
146
147 } // namespace JSC
148