1b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/* 2b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ProGuard -- shrinking, optimization, obfuscation, and preverification 3b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * of Java bytecode. 4b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 5b9cc48a43ed984587c939d02fba5316bf5c0df6eYing Wang * Copyright (c) 2002-2013 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.optimize.peephole; 22b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 23b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.*; 24b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.attribute.*; 25b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.attribute.visitor.AttributeVisitor; 26b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.editor.VariableEditor; 27b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.util.*; 28b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.visitor.MemberVisitor; 29b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.optimize.*; 30b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.optimize.info.*; 31b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 32b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/** 33b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This MemberVisitor removes unused local variables from the code of the methods 34b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * that it visits. 35b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 36b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @see ParameterUsageMarker 37b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @see MethodStaticizer 38b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @see MethodDescriptorShrinker 39b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @author Eric Lafortune 40b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 41b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopublic class VariableShrinker 42b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoextends SimplifiedVisitor 43b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimplements AttributeVisitor 44b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato{ 45b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private static final boolean DEBUG = false; 46b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 47b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 48b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private final MemberVisitor extraVariableMemberVisitor; 49b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 50b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private final VariableUsageMarker variableUsageMarker = new VariableUsageMarker(); 51b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private final VariableEditor variableEditor = new VariableEditor(); 52b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 53b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 54b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 55b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Creates a new VariableShrinker. 56b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 57b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public VariableShrinker() 58b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 59b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this(null); 60b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 61b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 62b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 63b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 64b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Creates a new VariableShrinker with an extra visitor. 65b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @param extraVariableMemberVisitor an optional extra visitor for all 66b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * removed variables. 67b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 68b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public VariableShrinker(MemberVisitor extraVariableMemberVisitor) 69b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 70b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this.extraVariableMemberVisitor = extraVariableMemberVisitor; 71b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 72b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 73b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 74b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for AttributeVisitor. 75b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 76b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} 77b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 78b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 79b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) 80b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 81b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if ((method.getAccessFlags() & ClassConstants.INTERNAL_ACC_ABSTRACT) == 0) 82b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 83b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Compute the parameter size. 84b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato int parameterSize = 85b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato ClassUtil.internalMethodParameterSize(method.getDescriptor(clazz), 86b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato method.getAccessFlags()); 87b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 88b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Get the total size of the local variable frame. 89b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato int maxLocals = codeAttribute.u2maxLocals; 90b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 91b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (DEBUG) 92b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 93b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.out.println("VariableShrinker: "+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz)); 94b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.out.println(" Parameter size = " + parameterSize); 95b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.out.println(" Max locals = " + maxLocals); 96b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 97b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 98b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Figure out the local variables that are used by the code. 99b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato variableUsageMarker.visitCodeAttribute(clazz, method, codeAttribute); 100b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 101b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Delete unused local variables from the local variable frame. 102b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato variableEditor.reset(maxLocals); 103b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 104b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato for (int variableIndex = parameterSize; variableIndex < maxLocals; variableIndex++) 105b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 106b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Is the variable not required? 107b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (!variableUsageMarker.isVariableUsed(variableIndex)) 108b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 109b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (DEBUG) 110b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 111b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.out.println(" Deleting local variable #"+variableIndex); 112b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 113b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 114b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Delete the unused variable. 115b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato variableEditor.deleteVariable(variableIndex); 116b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 117b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Visit the method, if required. 118b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (extraVariableMemberVisitor != null) 119b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 120b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato method.accept(clazz, extraVariableMemberVisitor); 121b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 122b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 123b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 124b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 125b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Shift all remaining parameters and variables in the byte code. 126b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato variableEditor.visitCodeAttribute(clazz, method, codeAttribute); 127b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 128b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 129b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato} 130