Inline caches that refer to otherwise dead objects should be cleared
[WebKit-https.git] / Source / JavaScriptCore / bytecode / Instruction.h
1 /*
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3  *
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28
29 #ifndef Instruction_h
30 #define Instruction_h
31
32 #include "MacroAssembler.h"
33 #include "Opcode.h"
34 #include "PropertySlot.h"
35 #include "Structure.h"
36 #include "StructureChain.h"
37 #include <wtf/VectorTraits.h>
38
39 #define POLYMORPHIC_LIST_CACHE_SIZE 8
40
41 namespace JSC {
42
43     // *Sigh*, If the JIT is enabled we need to track the stubRountine (of type CodeLocationLabel),
44     // If the JIT is not in use we don't actually need the variable (that said, if the JIT is not in use we don't
45     // curently actually use PolymorphicAccessStructureLists, which we should).  Anyway, this seems like the best
46     // solution for now - will need to something smarter if/when we actually want mixed-mode operation.
47
48     class JSCell;
49     class Structure;
50     class StructureChain;
51
52 #if ENABLE(JIT)
53     typedef MacroAssemblerCodeRef PolymorphicAccessStructureListStubRoutineType;
54
55     // Structure used by op_get_by_id_self_list and op_get_by_id_proto_list instruction to hold data off the main opcode stream.
56     struct PolymorphicAccessStructureList {
57         WTF_MAKE_FAST_ALLOCATED;
58     public:
59         struct PolymorphicStubInfo {
60             bool isChain;
61             bool isDirect;
62             PolymorphicAccessStructureListStubRoutineType stubRoutine;
63             WriteBarrier<Structure> base;
64             union {
65                 WriteBarrierBase<Structure> proto;
66                 WriteBarrierBase<StructureChain> chain;
67             } u;
68
69             PolymorphicStubInfo()
70             {
71                 u.proto.clear();
72             }
73
74             void set(JSGlobalData& globalData, JSCell* owner, PolymorphicAccessStructureListStubRoutineType _stubRoutine, Structure* _base, bool isDirect)
75             {
76                 stubRoutine = _stubRoutine;
77                 base.set(globalData, owner, _base);
78                 u.proto.clear();
79                 isChain = false;
80                 this->isDirect = isDirect;
81             }
82             
83             void set(JSGlobalData& globalData, JSCell* owner, PolymorphicAccessStructureListStubRoutineType _stubRoutine, Structure* _base, Structure* _proto, bool isDirect)
84             {
85                 stubRoutine = _stubRoutine;
86                 base.set(globalData, owner, _base);
87                 u.proto.set(globalData, owner, _proto);
88                 isChain = false;
89                 this->isDirect = isDirect;
90             }
91             
92             void set(JSGlobalData& globalData, JSCell* owner, PolymorphicAccessStructureListStubRoutineType _stubRoutine, Structure* _base, StructureChain* _chain, bool isDirect)
93             {
94                 stubRoutine = _stubRoutine;
95                 base.set(globalData, owner, _base);
96                 u.chain.set(globalData, owner, _chain);
97                 isChain = true;
98                 this->isDirect = isDirect;
99             }
100         } list[POLYMORPHIC_LIST_CACHE_SIZE];
101         
102         PolymorphicAccessStructureList(JSGlobalData& globalData, JSCell* owner, PolymorphicAccessStructureListStubRoutineType stubRoutine, Structure* firstBase, bool isDirect)
103         {
104             list[0].set(globalData, owner, stubRoutine, firstBase, isDirect);
105         }
106
107         PolymorphicAccessStructureList(JSGlobalData& globalData, JSCell* owner, PolymorphicAccessStructureListStubRoutineType stubRoutine, Structure* firstBase, Structure* firstProto, bool isDirect)
108         {
109             list[0].set(globalData, owner, stubRoutine, firstBase, firstProto, isDirect);
110         }
111
112         PolymorphicAccessStructureList(JSGlobalData& globalData, JSCell* owner, PolymorphicAccessStructureListStubRoutineType stubRoutine, Structure* firstBase, StructureChain* firstChain, bool isDirect)
113         {
114             list[0].set(globalData, owner, stubRoutine, firstBase, firstChain, isDirect);
115         }
116
117         bool visitWeak(int count)
118         {
119             for (int i = 0; i < count; ++i) {
120                 PolymorphicStubInfo& info = list[i];
121                 if (!info.base) {
122                     // We're being marked during initialisation of an entry
123                     ASSERT(!info.u.proto);
124                     continue;
125                 }
126                 
127                 if (!Heap::isMarked(info.base.get()))
128                     return false;
129                 if (info.u.proto && !info.isChain
130                     && !Heap::isMarked(info.u.proto.get()))
131                     return false;
132                 if (info.u.chain && info.isChain
133                     && !Heap::isMarked(info.u.chain.get()))
134                     return false;
135             }
136             
137             return true;
138         }
139     };
140
141 #endif
142
143     struct Instruction {
144         Instruction(Opcode opcode)
145         {
146 #if !ENABLE(COMPUTED_GOTO_INTERPRETER)
147             // We have to initialize one of the pointer members to ensure that
148             // the entire struct is initialized, when opcode is not a pointer.
149             u.jsCell.clear();
150 #endif
151             u.opcode = opcode;
152         }
153
154         Instruction(int operand)
155         {
156             // We have to initialize one of the pointer members to ensure that
157             // the entire struct is initialized in 64-bit.
158             u.jsCell.clear();
159             u.operand = operand;
160         }
161
162         Instruction(JSGlobalData& globalData, JSCell* owner, Structure* structure)
163         {
164             u.structure.clear();
165             u.structure.set(globalData, owner, structure);
166         }
167         Instruction(JSGlobalData& globalData, JSCell* owner, StructureChain* structureChain)
168         {
169             u.structureChain.clear();
170             u.structureChain.set(globalData, owner, structureChain);
171         }
172         Instruction(JSGlobalData& globalData, JSCell* owner, JSCell* jsCell)
173         {
174             u.jsCell.clear();
175             u.jsCell.set(globalData, owner, jsCell);
176         }
177
178         Instruction(PropertySlot::GetValueFunc getterFunc) { u.getterFunc = getterFunc; }
179
180         union {
181             Opcode opcode;
182             int operand;
183             WriteBarrierBase<Structure> structure;
184             WriteBarrierBase<StructureChain> structureChain;
185             WriteBarrierBase<JSCell> jsCell;
186             PropertySlot::GetValueFunc getterFunc;
187         } u;
188         
189     private:
190         Instruction(StructureChain*);
191         Instruction(Structure*);
192     };
193
194 } // namespace JSC
195
196 namespace WTF {
197
198     template<> struct VectorTraits<JSC::Instruction> : VectorTraitsBase<true, JSC::Instruction> { };
199
200 } // namespace WTF
201
202 #endif // Instruction_h