Start line:  
End line:  

Snippet Preview

Snippet HTML Code

Stack Overflow Questions
  /* Soot - a J*va Optimization Framework
   * Copyright (C) 2000 Patrick Lam
   *
   * 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;
 
 import soot.*;
 import java.util.*;

Provides naive side effect information. Relies on no context information; instead, does the least conservative thing possible even in the possible presence of badness. Possible weakness of SideEffectTester: consider a Box. We don't have a name for "what-is-inside-the-box" and so we can't ask questions about it. But perhaps we need only ask questions about the box itself; the sideeffect tester can deal with that internally.
 
 
 //  ArrayRef, 
 //  CaughtExceptionRef, 
 //  FieldRef, 
 //  IdentityRef, 
 //  InstanceFieldRef, 
 //  InstanceInvokeExpr, 
 //  Local,  
 //  StaticFieldRef
 
 public class NaiveSideEffectTester implements SideEffectTester
 {
     public void newMethodSootMethod m ) {
     }

    
Returns true if the unit can read from v. Does not deal with expressions; deals with Refs.
 
     public boolean unitCanReadFrom(Unit uValue v)
     {
         Stmt s = (Stmt)u;
 
         // This doesn't really make any sense, but we need to return something.
         if (v instanceof Constant)
             return false;
 
         if (v instanceof Expr)
             throw new RuntimeException("can't deal with expr");
 
         // If it's an invoke, then only locals are safe.
         if (s.containsInvokeExpr())
         {
 	    if (!(v instanceof Local))
 		return true;
         }
 
         // otherwise, use boxes tell all.
         Iterator useIt = u.getUseBoxes().iterator();
         while (useIt.hasNext())
         {
             Value use = (Value)useIt.next();
 
             if (use.equivTo(v))
                 return true;
 
             Iterator vUseIt = v.getUseBoxes().iterator();
             while (vUseIt.hasNext())
             {
                 if (use.equivTo(vUseIt.next()))
                     return true;
             }
         }
         return false;
     }
 
     public boolean unitCanWriteTo(Unit uValue v)
     {
         Stmt s = (Stmt)u;
 
         if (v instanceof Constant)
            return false;
        if (v instanceof Expr)
            throw new RuntimeException("can't deal with expr");
        // If it's an invoke, then only locals are safe.
        if (s.containsInvokeExpr())
        {
            if (!(v instanceof Local))
                return true;
        }
        // otherwise, def boxes tell all.
        Iterator defIt = u.getDefBoxes().iterator();
        while (defIt.hasNext())
        {
            Value def = ((ValueBox)(defIt.next())).getValue();
            Iterator useIt = v.getUseBoxes().iterator();
            while (useIt.hasNext())
            {
                Value use = ((ValueBox)useIt.next()).getValue();
                if (def.equivTo(use))
                  return true;
            }
            // also handle the container of all these useboxes!
            if (def.equivTo(v))
                return true;
            // deal with aliasing - handle case where they
            // are a read to the same field, regardless of
            // base object.
            if (v instanceof InstanceFieldRef && 
                def instanceof InstanceFieldRef)
            {
                if (((InstanceFieldRef)v).getField() ==
                    ((InstanceFieldRef)def).getField())
                    return true;
            }
        }
        return false;
    }
New to GrepCode? Check out our FAQ X