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      1 /*
      2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
      3  *             of Java bytecode.
      4  *
      5  * Copyright (c) 2002-2009 Eric Lafortune (eric (at) graphics.cornell.edu)
      6  *
      7  * This program is free software; you can redistribute it and/or modify it
      8  * under the terms of the GNU General Public License as published by the Free
      9  * Software Foundation; either version 2 of the License, or (at your option)
     10  * any later version.
     11  *
     12  * This program is distributed in the hope that it will be useful, but WITHOUT
     13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     14  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
     15  * more details.
     16  *
     17  * You should have received a copy of the GNU General Public License along
     18  * with this program; if not, write to the Free Software Foundation, Inc.,
     19  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     20  */
     21 package proguard.optimize;
     22 
     23 import proguard.classfile.*;
     24 import proguard.classfile.attribute.*;
     25 import proguard.classfile.attribute.visitor.AttributeVisitor;
     26 import proguard.classfile.constant.*;
     27 import proguard.classfile.constant.visitor.ConstantVisitor;
     28 import proguard.classfile.editor.CodeAttributeEditor;
     29 import proguard.classfile.instruction.*;
     30 import proguard.classfile.instruction.visitor.InstructionVisitor;
     31 import proguard.classfile.util.SimplifiedVisitor;
     32 import proguard.classfile.visitor.MemberVisitor;
     33 
     34 /**
     35  * This AttributeVisitor adds an additional integer parameter to the tweaked
     36  * initialization method invocations that it visits.
     37  */
     38 public class DuplicateInitializerInvocationFixer
     39 extends      SimplifiedVisitor
     40 implements   AttributeVisitor,
     41              InstructionVisitor,
     42              ConstantVisitor,
     43              MemberVisitor
     44 {
     45     private static final boolean DEBUG = false;
     46 
     47     private final InstructionVisitor extraAddedInstructionVisitor;
     48 
     49     private final CodeAttributeEditor codeAttributeEditor = new CodeAttributeEditor();
     50 
     51     private String  descriptor;
     52     private boolean hasBeenFixed;
     53 
     54 
     55     /**
     56      * Creates a new EvaluationSimplifier.
     57      */
     58     public DuplicateInitializerInvocationFixer()
     59     {
     60         this(null);
     61     }
     62 
     63 
     64     /**
     65      * Creates a new EvaluationSimplifier.
     66      * @param extraAddedInstructionVisitor an optional extra visitor for all
     67      *                                     added instructions.
     68      */
     69     public DuplicateInitializerInvocationFixer(InstructionVisitor extraAddedInstructionVisitor)
     70     {
     71         this.extraAddedInstructionVisitor = extraAddedInstructionVisitor;
     72     }
     73 
     74 
     75    // Implementations for AttributeVisitor.
     76 
     77     public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
     78 
     79 
     80     public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
     81     {
     82 
     83         // Reset the code changes.
     84         codeAttributeEditor.reset(codeAttribute.u4codeLength);
     85 
     86         // Fix any duplicate constructor invocations.
     87         codeAttribute.instructionsAccept(clazz,
     88                                          method,
     89                                          this);
     90 
     91         // Apply all accumulated changes to the code.
     92         codeAttributeEditor.visitCodeAttribute(clazz, method, codeAttribute);
     93     }
     94 
     95 
     96     // Implementations for InstructionVisitor.
     97 
     98     public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}
     99 
    100 
    101     public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction)
    102     {
    103         if (constantInstruction.opcode == InstructionConstants.OP_INVOKESPECIAL)
    104         {
    105             hasBeenFixed = false;
    106             clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this);
    107 
    108             if (hasBeenFixed)
    109             {
    110                 Instruction extraInstruction =
    111                     new SimpleInstruction(InstructionConstants.OP_ICONST_0);
    112 
    113                 codeAttributeEditor.insertBeforeInstruction(offset,
    114                                                             extraInstruction);
    115 
    116                 if (DEBUG)
    117                 {
    118                     System.out.println("DuplicateInitializerInvocationFixer:");
    119                     System.out.println("  Inserting "+extraInstruction.toString()+" before "+constantInstruction.toString(offset));
    120                 }
    121 
    122                 if (extraAddedInstructionVisitor != null)
    123                 {
    124                     extraInstruction.accept(null, null, null, offset, extraAddedInstructionVisitor);
    125                 }
    126             }
    127         }
    128     }
    129 
    130 
    131     // Implementations for ConstantVisitor.
    132 
    133     public void visitMethodrefConstant(Clazz clazz, MethodrefConstant methodrefConstant)
    134     {
    135         // Check the referenced constructor descriptor.
    136         descriptor = methodrefConstant.getType(clazz);
    137         methodrefConstant.referencedMemberAccept(this);
    138     }
    139 
    140 
    141     // Implementations for MemberVisitor.
    142 
    143     public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod) {}
    144 
    145 
    146     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
    147     {
    148         hasBeenFixed = !descriptor.equals(programMethod.getDescriptor(programClass));
    149     }
    150 }