/* Soot - a J*va Optimization Framework
 * Copyright (C) 1999 Phong Co
 *
 * 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.jimple.toolkits.scalar;
import soot.options.*;

import soot.util.*;
import soot.*;
import soot.jimple.*;
import java.util.*;


public class ConditionalBranchFolder  extends BodyTransformer
{
    public ConditionalBranchFolder ( Singletons.Global g ) {}
    public static ConditionalBranchFolder  v() { return G.v().soot_jimple_toolkits_scalar_ConditionalBranchFolder (); }

    protected void internalTransform(Body body, String phaseName, Map options)
    {
        StmtBody stmtBody = (StmtBody)body;

        int numTrue = 0, numFalse = 0;

        if (Options.v().verbose())
            G.v().out.println("[" + stmtBody.getMethod().getName() +
                               "] Folding conditional branches...");

        Chain units = stmtBody.getUnits();
        ArrayList<Unit> unitList = new ArrayList<Unit>(); unitList.addAll(units);

        Iterator<Unit> stmtIt = unitList.iterator();
        while (stmtIt.hasNext()) {
            Stmt stmt = (Stmt)stmtIt.next();
            if (stmt instanceof IfStmt) {
                // check for constant-valued conditions
                Value cond = ((IfStmt) stmt).getCondition();
                if (Evaluator.isValueConstantValued(cond)) {
                    cond = Evaluator.getConstantValueOf(cond);

                    if (((IntConstant) cond).value == 1) {
                        // if condition always true, convert if to goto
                        Stmt newStmt =
                            Jimple.v().newGotoStmt(((IfStmt)stmt).getTarget());
                        
                        units.insertAfter(newStmt, stmt);
                        
                        numTrue++;
                    }
                    else
                        numFalse++;
                        
                    // remove if
                    units.remove(stmt);
                }
            }
        }

       if (Options.v().verbose())
            G.v().out.println("[" + stmtBody.getMethod().getName() +
                "]     Folded " + numTrue + " true, " + numFalse +
                               " conditional branches");

    } // foldBranches

} // BranchFolder