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+/***************************************************************************
+ *   Copyright (C) 2005 by David Saxton                                    *
+ *   [email protected]                                                    *
+ *                                                                         *
+ *   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