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/*
* Copyright (C) 2012, 2013 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. ``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
* 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 VariableWatchpointSet_h
#define VariableWatchpointSet_h
#include "Watchpoint.h"
#include "WriteBarrier.h"
namespace JSC {
class VariableWatchpointSet : public WatchpointSet {
friend class LLIntOffsetsExtractor;
public:
VariableWatchpointSet()
: WatchpointSet(ClearWatchpoint)
{
}
~VariableWatchpointSet() { }
// For the purpose of deciding whether or not to watch this variable, you only need
// to inspect inferredValue(). If this returns something other than the empty
// value, then it means that at all future safepoints, this watchpoint set will be
// in one of these states:
//
// IsWatched: in this case, the variable's value must still be the
// inferredValue.
//
// IsInvalidated: in this case the variable's value may be anything but you'll
// either notice that it's invalidated and not install the watchpoint, or
// you will have been notified that the watchpoint was fired.
JSValue inferredValue() const { return m_inferredValue; }
void notifyWrite(JSValue value)
{
ASSERT(!!value);
switch (state()) {
case ClearWatchpoint:
m_inferredValue = value;
startWatching();
return;
case IsWatched:
ASSERT(!!m_inferredValue);
if (value == m_inferredValue)
return;
invalidate();
return;
case IsInvalidated:
ASSERT(!m_inferredValue);
return;
}
ASSERT_NOT_REACHED();
}
void invalidate()
{
m_inferredValue = JSValue();
WatchpointSet::invalidate();
}
void finalizeUnconditionally()
{
ASSERT(!!m_inferredValue == (state() == IsWatched));
if (!m_inferredValue)
return;
if (!m_inferredValue.isCell())
return;
JSCell* cell = m_inferredValue.asCell();
if (Heap::isMarked(cell))
return;
invalidate();
}
JSValue* addressOfInferredValue() { return &m_inferredValue; }
private:
JSValue m_inferredValue;
};
} // namespace JSC
#endif // VariableWatchpointSet_h
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