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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef JITWriteBarrier_h
#define JITWriteBarrier_h
#if ENABLE(JIT)
#include "MacroAssembler.h"
#include "SlotVisitor.h"
#include "WriteBarrier.h"
namespace JSC {
class JSCell;
class JSGlobalData;
// Needs to be even to appease some of the backends.
#define JITWriteBarrierFlag ((void*)2)
class JITWriteBarrierBase {
public:
typedef void* (JITWriteBarrierBase::*UnspecifiedBoolType);
operator UnspecifiedBoolType*() const { return get() ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; }
bool operator!() const { return !get(); }
void setFlagOnBarrier()
{
ASSERT(!m_location);
m_location = CodeLocationDataLabelPtr(JITWriteBarrierFlag);
}
bool isFlagged() const
{
return !!m_location;
}
void setLocation(CodeLocationDataLabelPtr location)
{
ASSERT(!m_location);
m_location = location;
}
CodeLocationDataLabelPtr location() const
{
ASSERT((!!m_location) && m_location.executableAddress() != JITWriteBarrierFlag);
return m_location;
}
void clear() { clear(0); }
void clearToMaxUnsigned() { clear(reinterpret_cast<void*>(-1)); }
protected:
JITWriteBarrierBase()
{
}
void set(JSGlobalData&, CodeLocationDataLabelPtr location, JSCell* owner, JSCell* value)
{
Heap::writeBarrier(owner, value);
m_location = location;
ASSERT(((!!m_location) && m_location.executableAddress() != JITWriteBarrierFlag) || (location.executableAddress() == m_location.executableAddress()));
MacroAssembler::repatchPointer(m_location, value);
ASSERT(get() == value);
}
JSCell* get() const
{
if (!m_location || m_location.executableAddress() == JITWriteBarrierFlag)
return 0;
void* result = static_cast<JSCell*>(MacroAssembler::readPointer(m_location));
// We use -1 to indicate a "safe" empty value in the instruction stream
if (result == (void*)-1)
return 0;
return static_cast<JSCell*>(result);
}
private:
void clear(void* clearedValue)
{
if (!m_location)
return;
if (m_location.executableAddress() != JITWriteBarrierFlag)
MacroAssembler::repatchPointer(m_location, clearedValue);
}
CodeLocationDataLabelPtr m_location;
};
#undef JITWriteBarrierFlag
template <typename T> class JITWriteBarrier : public JITWriteBarrierBase {
public:
JITWriteBarrier()
{
}
void set(JSGlobalData& globalData, CodeLocationDataLabelPtr location, JSCell* owner, T* value)
{
validateCell(owner);
validateCell(value);
JITWriteBarrierBase::set(globalData, location, owner, value);
}
void set(JSGlobalData& globalData, JSCell* owner, T* value)
{
set(globalData, location(), owner, value);
}
T* get() const
{
T* result = static_cast<T*>(JITWriteBarrierBase::get());
if (result)
validateCell(result);
return result;
}
};
template<typename T> inline void SlotVisitor::append(JITWriteBarrier<T>* slot)
{
internalAppend(slot->get());
}
}
#endif // ENABLE(JIT)
#endif