1b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/* 2b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ProGuard -- shrinking, optimization, obfuscation, and preverification 3b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * of Java bytecode. 4b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 59f606f95f03a75961498803e24bee6799a7c0885Ying Wang * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu) 6b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 7b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This program is free software; you can redistribute it and/or modify it 8b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * under the terms of the GNU General Public License as published by the Free 9b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Software Foundation; either version 2 of the License, or (at your option) 10b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * any later version. 11b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 12b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This program is distributed in the hope that it will be useful, but WITHOUT 13b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * more details. 16b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 17b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * You should have received a copy of the GNU General Public License along 18b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * with this program; if not, write to the Free Software Foundation, Inc., 19b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 21b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopackage proguard.classfile.editor; 22b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 23b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.*; 24b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.attribute.*; 259f606f95f03a75961498803e24bee6799a7c0885Ying Wangimport proguard.classfile.attribute.visitor.*; 269f606f95f03a75961498803e24bee6799a7c0885Ying Wangimport proguard.classfile.instruction.*; 279f606f95f03a75961498803e24bee6799a7c0885Ying Wangimport proguard.classfile.instruction.visitor.InstructionVisitor; 28b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.util.SimplifiedVisitor; 299f606f95f03a75961498803e24bee6799a7c0885Ying Wangimport proguard.optimize.info.VariableUsageMarker; 30b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 31b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/** 329f606f95f03a75961498803e24bee6799a7c0885Ying Wang * This AttributeVisitor cleans up unused variables in all attributes that it 339f606f95f03a75961498803e24bee6799a7c0885Ying Wang * visits. 34b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 35b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @author Eric Lafortune 36b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 37b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopublic class VariableCleaner 38b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoextends SimplifiedVisitor 39b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimplements AttributeVisitor 40b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato{ 419f606f95f03a75961498803e24bee6799a7c0885Ying Wang private final VariableUsageMarker variableUsageMarker = new VariableUsageMarker(); 42b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 43b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 44b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for AttributeVisitor. 45b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 46b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} 47b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 48b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 49b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) 50b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 519f606f95f03a75961498803e24bee6799a7c0885Ying Wang // Figure out the local variables that are used by the code. 529f606f95f03a75961498803e24bee6799a7c0885Ying Wang variableUsageMarker.visitCodeAttribute(clazz, method, codeAttribute); 53b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 549f606f95f03a75961498803e24bee6799a7c0885Ying Wang // Clean up the variables of the attributes. 55b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttribute.attributesAccept(clazz, method, this); 56b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 57b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 58b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 59b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute) 60b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 61b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Clean up local variables that aren't used. 62b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato localVariableTableAttribute.u2localVariableTableLength = 639f606f95f03a75961498803e24bee6799a7c0885Ying Wang removeEmptyLocalVariables(localVariableTableAttribute.localVariableTable, 649f606f95f03a75961498803e24bee6799a7c0885Ying Wang localVariableTableAttribute.u2localVariableTableLength, 659f606f95f03a75961498803e24bee6799a7c0885Ying Wang codeAttribute.u2maxLocals); 66b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 67b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 68b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 69b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute) 70b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 71b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Clean up local variables that aren't used. 72b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato localVariableTypeTableAttribute.u2localVariableTypeTableLength = 739f606f95f03a75961498803e24bee6799a7c0885Ying Wang removeEmptyLocalVariableTypes(localVariableTypeTableAttribute.localVariableTypeTable, 749f606f95f03a75961498803e24bee6799a7c0885Ying Wang localVariableTypeTableAttribute.u2localVariableTypeTableLength, 759f606f95f03a75961498803e24bee6799a7c0885Ying Wang codeAttribute.u2maxLocals); 76b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 77b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 78b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 79b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Small utility methods. 80b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 81b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 82b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Returns the given list of local variables, without the ones that aren't 839f606f95f03a75961498803e24bee6799a7c0885Ying Wang * used 84b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 859f606f95f03a75961498803e24bee6799a7c0885Ying Wang private int removeEmptyLocalVariables(LocalVariableInfo[] localVariableInfos, 869f606f95f03a75961498803e24bee6799a7c0885Ying Wang int localVariableInfoCount, 879f606f95f03a75961498803e24bee6799a7c0885Ying Wang int maxLocals) 88b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 89b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Overwrite all empty local variable entries. 90b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato int newIndex = 0; 919f606f95f03a75961498803e24bee6799a7c0885Ying Wang for (int index = 0; index < localVariableInfoCount && index < maxLocals; index++) 92b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 939f606f95f03a75961498803e24bee6799a7c0885Ying Wang if (variableUsageMarker.isVariableUsed(index)) 94b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 95b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato localVariableInfos[newIndex++] = localVariableInfos[index]; 96b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 97b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 98b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 99b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Clean up any remaining array elements. 1009f606f95f03a75961498803e24bee6799a7c0885Ying Wang for (int index = newIndex; index < localVariableInfoCount; index++) 1019f606f95f03a75961498803e24bee6799a7c0885Ying Wang { 1029f606f95f03a75961498803e24bee6799a7c0885Ying Wang localVariableInfos[index] = null; 1039f606f95f03a75961498803e24bee6799a7c0885Ying Wang } 104b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 105b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return newIndex; 106b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 107b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 108b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 109b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 110b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Returns the given list of local variable types, without the ones that 1119f606f95f03a75961498803e24bee6799a7c0885Ying Wang * aren't used 112b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 1139f606f95f03a75961498803e24bee6799a7c0885Ying Wang private int removeEmptyLocalVariableTypes(LocalVariableTypeInfo[] localVariableTypeInfos, 1149f606f95f03a75961498803e24bee6799a7c0885Ying Wang int localVariableTypeInfoCount, 1159f606f95f03a75961498803e24bee6799a7c0885Ying Wang int maxLocals) 116b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 117b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Overwrite all empty local variable type entries. 118b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato int newIndex = 0; 1199f606f95f03a75961498803e24bee6799a7c0885Ying Wang for (int index = 0; index < localVariableTypeInfoCount && index < maxLocals; index++) 120b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 1219f606f95f03a75961498803e24bee6799a7c0885Ying Wang if (variableUsageMarker.isVariableUsed(index)) 122b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 123b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato localVariableTypeInfos[newIndex++] = localVariableTypeInfos[index]; 124b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 125b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 126b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 127b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Clean up any remaining array elements. 1289f606f95f03a75961498803e24bee6799a7c0885Ying Wang for (int index = newIndex; index < localVariableTypeInfoCount; index++) 129b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 1309f606f95f03a75961498803e24bee6799a7c0885Ying Wang localVariableTypeInfos[index] = null; 131b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 132cfead78069f3dc32998dc118ee08cab3867acea2Ying Wang 1339f606f95f03a75961498803e24bee6799a7c0885Ying Wang return newIndex; 134b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 135b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato}