DFGVariableAccessData.h   [plain text]


/*
 * Copyright (C) 2011 Apple Inc. All rights reserved.
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 *
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#ifndef DFGVariableAccessData_h
#define DFGVariableAccessData_h

#include "PredictedType.h"
#include "VirtualRegister.h"
#include <wtf/Platform.h>
#include <wtf/UnionFind.h>

namespace JSC { namespace DFG {

class VariableAccessData : public UnionFind<VariableAccessData> {
public:
    VariableAccessData()
        : m_local(static_cast<VirtualRegister>(std::numeric_limits<int>::min()))
        , m_prediction(PredictNone)
    {
    }
    
    VariableAccessData(VirtualRegister local)
        : m_local(local)
        , m_prediction(PredictNone)
    {
    }
    
    VirtualRegister local()
    {
        ASSERT(m_local == find()->m_local);
        return m_local;
    }
    
    int operand()
    {
        return static_cast<int>(local());
    }
    
    bool predict(PredictedType prediction)
    {
        return mergePrediction(find()->m_prediction, prediction);
    }
    
    PredictedType prediction()
    {
        return find()->m_prediction;
    }
    
private:
    // This is slightly space-inefficient, since anything we're unified with
    // will have the same operand and should have the same prediction. But
    // putting them here simplifies the code, and we don't expect DFG space
    // usage for variable access nodes do be significant.

    VirtualRegister m_local;
    PredictedType m_prediction;
};

} } // namespace JSC::DFG

#endif // DFGVariableAccessData_h