NumericInstruction.hpp

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/* src/vm/jit/loop/NumericInstruction.hpp

   Copyright (C) 1996-2012
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/

#ifndef _NUMERIC_INSTRUCTION_HPP
#define _NUMERIC_INSTRUCTION_HPP

#include <limits>
#include <iostream>
#include <cassert>

#include "vm/types.hpp"


/**
 * Represents a constant numeric instruction.
 */
class NumericInstruction
{
public:

    enum Kind   // sorted
    {
        ZERO = 0,
        ARRAY_LENGTH,
        VARIABLE
    };

private:

    Kind    _kind;
    s4      _var;

    static s4 lowerBounds[3];
    static s4 upperBounds[3];

    NumericInstruction(Kind kind, s4 variable)
        : _kind(kind)
        , _var(variable)
    {}

public:
    
    NumericInstruction(const NumericInstruction& other)
        : _kind(other._kind)
        , _var(other._var)
    {}
    
    static NumericInstruction newZero();
    static NumericInstruction newArrayLength(s4 variable);
    static NumericInstruction newVariable(s4 variable);

    Kind kind() const { return _kind; }
    s4 variable() const { return _var; }

    /**
     * The smallest value this instruction can return.
     */
    s4 lower() const;

    /**
     * The largest value this instruction can return.
     */
    s4 upper() const;
};


inline NumericInstruction NumericInstruction::newZero()
{
    return NumericInstruction(ZERO, 0);
}

inline NumericInstruction NumericInstruction::newArrayLength(s4 variable)
{
    return NumericInstruction(ARRAY_LENGTH, variable);
}

inline NumericInstruction NumericInstruction::newVariable(s4 variable)
{
    return NumericInstruction(VARIABLE, variable);
}

inline bool operator==(const NumericInstruction& a, const NumericInstruction& b)
{
    return a.kind() == b.kind() && a.variable() == b.variable();
}

inline bool operator!=(const NumericInstruction& a, const NumericInstruction& b)
{
    return a.kind() != b.kind() || a.variable() != b.variable();
}

inline s4 NumericInstruction::lower() const
{
    return lowerBounds[_kind];
}

inline s4 NumericInstruction::upper() const
{
    return upperBounds[_kind];
}

inline std::ostream& operator<<(std::ostream& out, const NumericInstruction& instruction)
{
    switch (instruction.kind())
    {
        case NumericInstruction::ZERO:          return out << '0';
        case NumericInstruction::ARRAY_LENGTH:  return out << '(' << instruction.variable() << ").length";
        case NumericInstruction::VARIABLE:      return out << '(' << instruction.variable() << ')';
        default:                                assert(false);
    }
    return out;
}

#endif

/*
 * These are local overrides for various environment variables in Emacs.
 * Please do not remove this and leave it at the end of the file, where
 * Emacs will automagically detect them.
 * ---------------------------------------------------------------------
 * Local variables:
 * mode: c++
 * indent-tabs-mode: t
 * c-basic-offset: 4
 * tab-width: 4
 * End:
 * vim:noexpandtab:sw=4:ts=4:
 */