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/***************************************************************************
* Copyright (C) 2005 by David Saxton *
* david@bluehaze.org *
* *
* 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 of the License, or *
* (at your option) any later version. *
***************************************************************************/
#ifndef OPTIMIZER_H
#define OPTIMIZER_H
#include "instruction.h"
/// Used for debugging; returns the uchar as a binary string (e.g. 01101010).
QString binary( uchar val );
/**
@author David Saxton
*/
class Optimizer
{
public:
Optimizer();
~Optimizer();
void optimize( Code * code );
protected:
/**
* Repeatedly generates links and states for the instructions and
* refining their input states, until equilibrium in the input states
* is reached.
*/
void propagateLinksAndStates();
/**
* Tell the instructions about their input states.
* @return whether any input states changed from the previous value
* stored in the instruction (if checkChanged is true - else returns
* true).
*/
bool giveInputStates();
/**
* Remove instructions without any input links (and the ones that are
* only linked to from a removed instruction).
* @return whether any instructions were removed
*/
bool pruneInstructions();
/**
* Perform optimizations (code cropping, modification, assembly, etc)
* based on instruction linkage and processor states.
* @return whether anything was changed
*/
bool optimizeInstructions();
/**
* Redirects any GOTOs that point at the given instruction to the given
* label.
* @return whether any GOTOs were redirected
*/
bool redirectGotos( Instruction * current, const QString & label );
/**
* Find out if the given instruction or any of its outputs overwrite
* any of the bits of the given register before they are used.
*/
uchar generateRegisterDepends( Instruction * current, const Register & reg );
/**
* This function should only be used from generateRegisterDepends.
* Recursively looks at the output links of the given instruction, and
* returns which bits are eventually used before being overwritten.
*/
uchar registerDepends( Instruction * current, const Register & reg );
/**
* We often need to know whether removing an instruction will affect the
* future processor state. This function looks are all possible future
* dependencies of the given register, and returns true if the removal
* of the instruction will have no critical effect.
* @param bitMask only look at the given bits of the register
*/
bool canRemove( Instruction * ins, const Register & reg, uchar bitMask = 0xff );
Code * m_pCode;
};
#endif
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