/* Soot - a J*va Optimization Framework
 * Copyright (C) 1997-1999 Raja Vallee-Rai
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * Modified by the Sable Research Group and others 1997-1999.  
 * See the 'credits' file distributed with Soot for the complete list of
 * contributors.  (Soot is distributed at http://www.sable.mcgill.ca/soot)
 */

package soot.toolkits.scalar;

import soot.options.*;

import soot.*;

import java.util.*;

/**
 * A BodyTransformer that removes all unused local variables from a given Body.
 * Implemented as a singleton.
 * 
 * @see BodyTransformer
 * @see Body
 */
public class UnusedLocalEliminator extends BodyTransformer {
	public UnusedLocalEliminator(Singletons.Global g) {
	}

	public static UnusedLocalEliminator v() {
		return G.v().soot_toolkits_scalar_UnusedLocalEliminator();
	}

	protected void internalTransform(Body body, String phaseName, Map<String,String> options) {
		if (Options.v().verbose())
			G.v().out.println("[" + body.getMethod().getName()
					+ "] Eliminating unused locals...");

		
		int i = 0;
		int n = body.getLocals().size();
		int[] oldNumbers = new int[n];
		Local[] locals = body.getLocals().toArray(new Local[n]);
		for ( Local local :locals ) {
			oldNumbers[i] = local.getNumber();
			local.setNumber(i);		
			i++;
		}
		
		BitSet usedLocals = new BitSet(n);

		// Traverse statements noting all the uses and defs
		for (Unit s : body.getUnits()) {
			for (ValueBox vb : s.getDefBoxes()) {
				Value v = vb.getValue();
				if (value instanceof Local) {
					Local l = (Local) v;
					usedLocals.set(l.getNumber());
				}
			}
			for (ValueBox vb : s.getUseBoxes()) {
				Value v = vb.getValue();
				if (value instanceof Local) {
					Local l = (Local) v;
					usedLocals.set(l.getNumber());
				}
			}
		}

		// Remove all locals that are unused.
		for ( Local local : locals ) {
			int lno = local.getNumber();
			local.setNumber(oldNumbers[lno]);
			if ( !usedLocals.get(lno) ) {
				body.getLocals().remove(local);
			}
		}
	}
}

@@ -2192,36 +2192,32 @@
 lue();%0A%09%09%09%09if (v
-alue
  instanceof Loca
@@ -2373,20 +2373,16 @@
 %09%09%09if (v
-alue
  instanc

Update UnusedLocalEliminator.java