Home | History | Annotate | Download | only in optimize 
      1 /*
      2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
      3  *             of Java bytecode.
      4  *
      5  * Copyright (c) 2002-2014 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.*;
     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 int    descriptorLengthDelta;
     53 
     54 
     55     /**
     56      * Creates a new DuplicateInitializerInvocationFixer.
     57      */
     58     public DuplicateInitializerInvocationFixer()
     59     {
     60         this(null);
     61     }
     62 
     63 
     64     /**
     65      * Creates a new DuplicateInitializerInvocationFixer.
     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             descriptorLengthDelta = 0;
    106             clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this);
    107 
    108             if (descriptorLengthDelta > 0)
    109             {
    110                 Instruction extraInstruction =
    111                     new SimpleInstruction(descriptorLengthDelta == 1 ?
    112                                               InstructionConstants.OP_ICONST_0 :
    113                                               InstructionConstants.OP_ACONST_NULL);
    114 
    115                 codeAttributeEditor.insertBeforeInstruction(offset,
    116                                                             extraInstruction);
    117 
    118                 if (DEBUG)
    119                 {
    120                     System.out.println("  ["+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz)+"] Inserting "+extraInstruction.toString()+" before "+constantInstruction.toString(offset));
    121                 }
    122 
    123                 if (extraAddedInstructionVisitor != null)
    124                 {
    125                     extraInstruction.accept(null, null, null, offset, extraAddedInstructionVisitor);
    126                 }
    127             }
    128         }
    129     }
    130 
    131 
    132     // Implementations for ConstantVisitor.
    133 
    134     public void visitAnyMethodrefConstant(Clazz clazz, RefConstant refConstant)
    135     {
    136         // Check the referenced constructor descriptor.
    137         if (refConstant.getName(clazz).equals(ClassConstants.METHOD_NAME_INIT))
    138         {
    139             descriptor = refConstant.getType(clazz);
    140 
    141             refConstant.referencedMemberAccept(this);
    142         }
    143     }
    144 
    145 
    146     // Implementations for MemberVisitor.
    147 
    148     public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod) {}
    149 
    150 
    151     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
    152     {
    153         descriptorLengthDelta =
    154             programMethod.getDescriptor(programClass).length() - descriptor.length();
    155 
    156         if (DEBUG)
    157         {
    158             if (descriptorLengthDelta > 0)
    159             {
    160                 System.out.println("DuplicateInitializerInvocationFixer:");
    161                 System.out.println("  ["+programClass.getName()+"."+programMethod.getName(programClass)+programMethod.getDescriptor(programClass)+"] ("+ClassUtil.externalClassAccessFlags(programMethod.getAccessFlags())+") referenced by:");
    162             }
    163         }
    164     }
    165 }
    166