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26 #ifndef JITWriteBarrier_h
27 #define JITWriteBarrier_h
31 #include "MacroAssembler.h"
32 #include "MarkStack.h"
33 #include "WriteBarrier.h"
40 // Needs to be even to appease some of the backends.
41 #define JITWriteBarrierFlag ((void*)2)
42 class JITWriteBarrierBase {
44 typedef void* (JITWriteBarrierBase::*UnspecifiedBoolType);
45 operator UnspecifiedBoolType*() const { return get() ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; }
46 bool operator!() const { return !get(); }
48 void setFlagOnBarrier()
51 m_location = CodeLocationDataLabelPtr(JITWriteBarrierFlag);
54 bool isFlagged() const
59 void setLocation(CodeLocationDataLabelPtr location)
62 m_location = location;
65 CodeLocationDataLabelPtr location() const
67 ASSERT((!!m_location) && m_location.executableAddress() != JITWriteBarrierFlag);
71 void clear() { clear(0); }
78 void set(JSGlobalData&, CodeLocationDataLabelPtr location, JSCell* owner, JSCell* value)
80 Heap::writeBarrier(owner, value);
81 m_location = location;
82 ASSERT(((!!m_location) && m_location.executableAddress() != JITWriteBarrierFlag) || (location.executableAddress() == m_location.executableAddress()));
83 MacroAssembler::repatchPointer(m_location, value);
84 ASSERT(get() == value);
89 if (!m_location || m_location.executableAddress() == JITWriteBarrierFlag)
91 void* result = static_cast<JSCell*>(MacroAssembler::readPointer(m_location));
92 // We use -1 to indicate a "safe" empty value in the instruction stream
93 if (result == (void*)-1)
95 return static_cast<JSCell*>(result);
99 void clear(void* clearedValue)
103 if (m_location.executableAddress() != JITWriteBarrierFlag)
104 MacroAssembler::repatchPointer(m_location, clearedValue);
107 CodeLocationDataLabelPtr m_location;
110 #undef JITWriteBarrierFlag
112 template <typename T> class JITWriteBarrier : public JITWriteBarrierBase {
118 void set(JSGlobalData& globalData, CodeLocationDataLabelPtr location, JSCell* owner, T* value)
122 JITWriteBarrierBase::set(globalData, location, owner, value);
124 void set(JSGlobalData& globalData, JSCell* owner, T* value)
126 set(globalData, location(), owner, value);
130 T* result = static_cast<T*>(JITWriteBarrierBase::get());
132 validateCell(result);
137 template<typename T> inline void MarkStack::append(JITWriteBarrier<T>* slot)
139 internalAppend(slot->get());
144 #endif // ENABLE(JIT)