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Java > Open Source Codes > soot > jimple > toolkits > scalar > NopEliminator


1 /* Soot - a J*va Optimization Framework
2  * Copyright (C) 1997-1999 Raja Vallee-Rai
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * This library is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with this library; if not, write to the
16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17  * Boston, MA 02111-1307, USA.
18  */
19
20 /*
21  * Modified by the Sable Research Group and others 1997-1999.
22  * See the 'credits' file distributed with Soot for the complete list of
23  * contributors. (Soot is distributed at http://www.sable.mcgill.ca/soot)
24  */
25
26
27 package soot.jimple.toolkits.scalar;
28 import soot.options.*;
29
30 import soot.*;
31 import soot.jimple.*;
32 import soot.toolkits.scalar.*;
33 import soot.util.*;
34 import soot.toolkits.graph.*;
35 import java.util.*;
36
37 public class NopEliminator extends BodyTransformer
38 {
39     public NopEliminator( Singletons.Global g ) {}
40     public static NopEliminator v() { return G.v().soot_jimple_toolkits_scalar_NopEliminator(); }
41
42     /** Removes {@link NopStmt}s from the passed body (which must be
43     a {@link JimpleBody}). Complexity is linear
44         with respect to the statements.
45     */
46     
47     protected void internalTransform(Body b, String JavaDoc phaseName, Map options)
48     {
49         JimpleBody body = (JimpleBody)b;
50         
51         if(Options.v().verbose())
52             G.v().out.println("[" + body.getMethod().getName() +
53                 "] Removing nops...");
54                 
55         Chain units = body.getUnits();
56         
57         // Just do one trivial pass.
58 {
59             Iterator stmtIt = units.snapshotIterator();
60             
61             while(stmtIt.hasNext())
62             {
63                 Stmt s = (Stmt) stmtIt.next();
64                 
65                 if(s instanceof NopStmt)
66                     units.remove(s);
67             }
68         }
69     }
70 }
71
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