src/mesa/shader/slang/MachineIndependent/QualifierAlive.cpp

//
//Copyright (C) 2002-2005  3Dlabs Inc. Ltd.
//All rights reserved.
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//modification, are permitted provided that the following conditions
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#include "../Include/intermediate.h"

class TAliveTraverser : public TIntermTraverser {
public:
    TAliveTraverser(TQualifier q) : TIntermTraverser(), found(false), qualifier(q)
    {
        visitSymbol    = AliveSymbol;
        visitSelection = AliveSelection;
        rightToLeft    = true;
    }
    bool wasFound() { return found; }
protected:
    bool found;
    TQualifier qualifier;

    friend void AliveSymbol(TIntermSymbol*, TIntermTraverser*);
    friend bool AliveSelection(bool, TIntermSelection*, TIntermTraverser*);
};

//
// Report whether or not a variable of the given qualifier type
// is guaranteed written.  Not always possible to determine if
// it is written conditionally.
//
// ?? It does not do this well yet, this is just a place holder
// that simply determines if it was reference at all, anywhere.
//
bool QualifierWritten(TIntermNode* node, TQualifier qualifier)
{
    TAliveTraverser it(qualifier);

    if (node)
        node->traverse(&it);

    return it.wasFound();
}

void AliveSymbol(TIntermSymbol* node, TIntermTraverser* it)
{
    TAliveTraverser* lit = static_cast<TAliveTraverser*>(it);

    //
    // If it's what we're looking for, record it.
    //
    if (node->getQualifier() == lit->qualifier)
        lit->found = true;
}

bool AliveSelection(bool preVisit, TIntermSelection* node, TIntermTraverser* it)
{
    TAliveTraverser* lit = static_cast<TAliveTraverser*>(it);

    if (lit->wasFound())
        return false;

    return true;
}