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.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.CodeAttributeEditor; 27b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.instruction.Instruction; 28b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.instruction.visitor.InstructionVisitor; 29b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.util.SimplifiedVisitor; 30b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 31b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/** 32b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This InstructionVisitor deletes blocks of code that can never be reached by 33b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * regular calls or branches. 34b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 35b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @author Eric Lafortune 36b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 37b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopublic class UnreachableCodeRemover 38b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoextends SimplifiedVisitor 39b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimplements AttributeVisitor, 40b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato InstructionVisitor 41b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato{ 42b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato //* 43b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private static final boolean DEBUG = false; 44b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /*/ 45b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private static boolean DEBUG = true; 46b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato //*/ 47b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 48b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private final InstructionVisitor extraInstructionVisitor; 49b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 50b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private final ReachableCodeMarker reachableCodeMarker = new ReachableCodeMarker(); 51b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private final CodeAttributeEditor codeAttributeEditor = new CodeAttributeEditor(); 52b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 53b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 54b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 55b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Creates a new UnreachableCodeRemover. 56b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 57b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public UnreachableCodeRemover() 58b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 59b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this(null); 60b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 61b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 62b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 63b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 64b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Creates a new UnreachableCodeRemover. 65b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @param extraInstructionVisitor an optional extra visitor for all 66b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * deleted instructions. 67b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 68b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public UnreachableCodeRemover(InstructionVisitor extraInstructionVisitor) 69b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 70b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this.extraInstructionVisitor = extraInstructionVisitor; 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// DEBUG = 82b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// clazz.getName().equals("abc/Def") && 83b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// method.getName(clazz).equals("abc"); 84b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 85b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // TODO: Remove this when the code has stabilized. 86b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Catch any unexpected exceptions from the actual visiting method. 87b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato try 88b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 89b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Process the code. 90b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato visitCodeAttribute0(clazz, method, codeAttribute); 91b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 92b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato catch (RuntimeException ex) 93b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 94b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.err.println("Unexpected error while removing unreachable code:"); 95b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.err.println(" Class = ["+clazz.getName()+"]"); 96b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.err.println(" Method = ["+method.getName(clazz)+method.getDescriptor(clazz)+"]"); 97b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.err.println(" Exception = ["+ex.getClass().getName()+"] ("+ex.getMessage()+")"); 98b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 99b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato throw ex; 100b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 101b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 102b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 103b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 104b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitCodeAttribute0(Clazz clazz, Method method, CodeAttribute codeAttribute) 105b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 106b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (DEBUG) 107b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 108b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.out.println("UnreachableCodeRemover: "+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz)); 109b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 110b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 111b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato reachableCodeMarker.visitCodeAttribute(clazz, method, codeAttribute); 112b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 113b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttributeEditor.reset(codeAttribute.u4codeLength); 114b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 115b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttribute.instructionsAccept(clazz, method, this); 116b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 117b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttributeEditor.visitCodeAttribute(clazz, method, codeAttribute); 118b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 119b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 120b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 121b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for InstructionVisitor. 122b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 123b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) 124b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 125b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (DEBUG) 126b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 127b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato System.out.println(" "+(reachableCodeMarker.isReachable(offset) ? "+" : "-")+" "+instruction.toString(offset)); 128b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 129b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 130b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Is this instruction unreachable? 131b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (!reachableCodeMarker.isReachable(offset)) 132b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 133b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Then delete it. 134b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato codeAttributeEditor.deleteInstruction(offset); 135b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 136b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Visit the instruction, if required. 137b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (extraInstructionVisitor != null) 138b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 139b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato instruction.accept(clazz, method, codeAttribute, offset, extraInstructionVisitor); 140b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 141b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 142b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 143b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato} 144