| /* |
| * ProGuard -- shrinking, optimization, obfuscation, and preverification |
| * of Java bytecode. |
| * |
| * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu) |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License as published by the Free |
| * Software Foundation; either version 2 of the License, or (at your option) |
| * any later version. |
| * |
| * This program 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 General Public License for |
| * more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| package proguard.classfile.editor; |
| |
| import proguard.classfile.*; |
| import proguard.classfile.attribute.*; |
| import proguard.classfile.attribute.visitor.*; |
| import proguard.classfile.instruction.*; |
| import proguard.classfile.instruction.visitor.InstructionVisitor; |
| import proguard.classfile.util.SimplifiedVisitor; |
| import proguard.optimize.info.VariableUsageMarker; |
| |
| /** |
| * This AttributeVisitor cleans up unused variables in all attributes that it |
| * visits. |
| * |
| * @author Eric Lafortune |
| */ |
| public class VariableCleaner |
| extends SimplifiedVisitor |
| implements AttributeVisitor |
| { |
| private final VariableUsageMarker variableUsageMarker = new VariableUsageMarker(); |
| |
| |
| // Implementations for AttributeVisitor. |
| |
| public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} |
| |
| |
| public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) |
| { |
| // Figure out the local variables that are used by the code. |
| variableUsageMarker.visitCodeAttribute(clazz, method, codeAttribute); |
| |
| // Clean up the variables of the attributes. |
| codeAttribute.attributesAccept(clazz, method, this); |
| } |
| |
| |
| public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute) |
| { |
| // Clean up local variables that aren't used. |
| localVariableTableAttribute.u2localVariableTableLength = |
| removeEmptyLocalVariables(localVariableTableAttribute.localVariableTable, |
| localVariableTableAttribute.u2localVariableTableLength, |
| codeAttribute.u2maxLocals); |
| } |
| |
| |
| public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute) |
| { |
| // Clean up local variables that aren't used. |
| localVariableTypeTableAttribute.u2localVariableTypeTableLength = |
| removeEmptyLocalVariableTypes(localVariableTypeTableAttribute.localVariableTypeTable, |
| localVariableTypeTableAttribute.u2localVariableTypeTableLength, |
| codeAttribute.u2maxLocals); |
| } |
| |
| |
| // Small utility methods. |
| |
| /** |
| * Returns the given list of local variables, without the ones that aren't |
| * used |
| */ |
| private int removeEmptyLocalVariables(LocalVariableInfo[] localVariableInfos, |
| int localVariableInfoCount, |
| int maxLocals) |
| { |
| // Overwrite all empty local variable entries. |
| int newIndex = 0; |
| for (int index = 0; index < localVariableInfoCount && index < maxLocals; index++) |
| { |
| if (variableUsageMarker.isVariableUsed(index)) |
| { |
| localVariableInfos[newIndex++] = localVariableInfos[index]; |
| } |
| } |
| |
| // Clean up any remaining array elements. |
| for (int index = newIndex; index < localVariableInfoCount; index++) |
| { |
| localVariableInfos[index] = null; |
| } |
| |
| return newIndex; |
| } |
| |
| |
| /** |
| * Returns the given list of local variable types, without the ones that |
| * aren't used |
| */ |
| private int removeEmptyLocalVariableTypes(LocalVariableTypeInfo[] localVariableTypeInfos, |
| int localVariableTypeInfoCount, |
| int maxLocals) |
| { |
| // Overwrite all empty local variable type entries. |
| int newIndex = 0; |
| for (int index = 0; index < localVariableTypeInfoCount && index < maxLocals; index++) |
| { |
| if (variableUsageMarker.isVariableUsed(index)) |
| { |
| localVariableTypeInfos[newIndex++] = localVariableTypeInfos[index]; |
| } |
| } |
| |
| // Clean up any remaining array elements. |
| for (int index = newIndex; index < localVariableTypeInfoCount; index++) |
| { |
| localVariableTypeInfos[index] = null; |
| } |
| |
| return newIndex; |
| } |
| } |