Context(上下文)運行時環境

1.概述????

???????? 上下文(Context):即運行時環境Runtime(內建(自定義)的對象(函數))

???????? 每個v8::Context含有一個global(全局)ObjectTemplate對象

Context::Scope:表示進入Context

?????????????????? 創建(1)保存頂層i::Context到i::HandleScopeImplementer

??????????????????????????? (2)設置頂層為當前Context

???????? ??? 銷毀:退出Context:恢復頂層i::Context

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2.運行時環境的建立(v8.cc)

(1)Logger::Setup()

(2)CpuProfiler::Setup()

(3)HeapProfiler::Setup()

(4)OS::Setup()

(5)Heap::Setup()

???????? MemoryAllocator內存分配器

???????? static NewSpace new_space_;

???????? static OldSpace* old_pointer_space_;???

???????? static OldSpace* old_data_space_;????????

???????? static OldSpace* code_space_;???????????????

???????? static MapSpace* map_space_;??????????????

???????? static CellSpace* cell_space_;???????????????????????????

???????? static LargeObjectSpace* lo_space_;????

???????? static HeapState gc_state;

???????? static Object* roots_[kRootListLength];//內建對象(指針)數組---全部內建對象

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(6)Bootstrapper::Initialize()

(7)Builtins::Setup() :內建函數 (跳轉到內建Code對象的機器指令)

(8)Top::Initialize()

(9)StubCache::Initialize()

(10)CPU::Setup()

(11)OProfileAgent::Initialize()

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3.CodeStub對象(用于訪問內建的Code對象)

(1)固定(Fixed)CodeStub

???????? CEntryStub

???????? |?????? CEntry Code:同時存放在roots_[kCEntryCodeRootIndex]和

???????? |????????????????????????????????????????????????????? roots_[kCodeStubsRootIndex]的NumberDictionary對象

???????? JSEntryStub

???????? |?????? JSEntry Code:同時存放在roots_[kJsEntryCodeRootIndex]和

???????? |????????????????????????????????????????????????????? ? roots_[kCodeStubsRootIndex]的NumberDictionary對象

???????? JSConstructEntryStub

?????????????????? JSConstructEntry Code:同時存放在roots_[kJsConstructEntryCodeRootIndex]和?????????????????????????????????? ???????????????????????????????????? ???????? roots_[kCodeStubsRootIndex]的NumberDictionary對象

(2)其他Stub

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4.Builtins類

???????? static Object* builtins_[];//內建函數的Code對象數組

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3類內建函數:(1)C++實現

??????????????????????????? (2)匯編實現

??????????????????????????? (3)匯編實現,用于debug

總結

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