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1 // Copyright 2017 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef V8_HEAP_LOCAL_ALLOCATOR_H_
6 #define V8_HEAP_LOCAL_ALLOCATOR_H_
7 
8 #include "src/globals.h"
9 #include "src/heap/heap.h"
10 #include "src/heap/spaces.h"
11 
12 namespace v8 {
13 namespace internal {
14 
15 // Allocator encapsulating thread-local allocation. Assumes that all other
16 // allocations also go through LocalAllocator.
17 class LocalAllocator {
18  public:
19   static const int kLabSize = 32 * KB;
20   static const int kMaxLabObjectSize = 8 * KB;
21 
LocalAllocator(Heap * heap)22   explicit LocalAllocator(Heap* heap)
23       : heap_(heap),
24         new_space_(heap->new_space()),
25         compaction_spaces_(heap),
26         new_space_lab_(LocalAllocationBuffer::InvalidBuffer()),
27         lab_allocation_will_fail_(false) {}
28 
29   // Needs to be called from the main thread to finalize this LocalAllocator.
Finalize()30   void Finalize() {
31     heap_->old_space()->MergeCompactionSpace(compaction_spaces_.Get(OLD_SPACE));
32     heap_->code_space()->MergeCompactionSpace(
33         compaction_spaces_.Get(CODE_SPACE));
34     // Give back remaining LAB space if this LocalAllocator's new space LAB
35     // sits right next to new space allocation top.
36     const LinearAllocationArea info = new_space_lab_.Close();
37     const Address top = new_space_->top();
38     if (info.limit() != kNullAddress && info.limit() == top) {
39       DCHECK_NE(info.top(), kNullAddress);
40       *new_space_->allocation_top_address() = info.top();
41     }
42   }
43 
44   inline AllocationResult Allocate(AllocationSpace space, int object_size,
45                                    AllocationAlignment alignment);
46   inline void FreeLast(AllocationSpace space, HeapObject* object,
47                        int object_size);
48 
49  private:
50   inline AllocationResult AllocateInNewSpace(int object_size,
51                                              AllocationAlignment alignment);
52   inline bool NewLocalAllocationBuffer();
53   inline AllocationResult AllocateInLAB(int object_size,
54                                         AllocationAlignment alignment);
55   inline void FreeLastInNewSpace(HeapObject* object, int object_size);
56   inline void FreeLastInOldSpace(HeapObject* object, int object_size);
57 
58   Heap* const heap_;
59   NewSpace* const new_space_;
60   CompactionSpaceCollection compaction_spaces_;
61   LocalAllocationBuffer new_space_lab_;
62   bool lab_allocation_will_fail_;
63 };
64 
65 }  // namespace internal
66 }  // namespace v8
67 
68 #endif  // V8_HEAP_LOCAL_ALLOCATOR_H_
69