| /* |
| * ProGuard -- shrinking, optimization, obfuscation, and preverification |
| * of Java bytecode. |
| * |
| * Copyright (c) 2002-2014 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.optimize.peephole; |
| |
| import proguard.classfile.*; |
| import proguard.classfile.attribute.*; |
| import proguard.classfile.attribute.visitor.AttributeVisitor; |
| import proguard.classfile.editor.CodeAttributeEditor; |
| import proguard.classfile.instruction.Instruction; |
| import proguard.classfile.instruction.visitor.InstructionVisitor; |
| import proguard.classfile.util.SimplifiedVisitor; |
| |
| /** |
| * This InstructionVisitor deletes blocks of code that can never be reached by |
| * regular calls or branches. |
| * |
| * @author Eric Lafortune |
| */ |
| public class UnreachableCodeRemover |
| extends SimplifiedVisitor |
| implements AttributeVisitor, |
| InstructionVisitor |
| { |
| //* |
| private static final boolean DEBUG = false; |
| /*/ |
| private static boolean DEBUG = true; |
| //*/ |
| |
| private final InstructionVisitor extraInstructionVisitor; |
| |
| private final ReachableCodeMarker reachableCodeMarker = new ReachableCodeMarker(); |
| private final CodeAttributeEditor codeAttributeEditor = new CodeAttributeEditor(); |
| |
| |
| /** |
| * Creates a new UnreachableCodeRemover. |
| */ |
| public UnreachableCodeRemover() |
| { |
| this(null); |
| } |
| |
| |
| /** |
| * Creates a new UnreachableCodeRemover. |
| * @param extraInstructionVisitor an optional extra visitor for all |
| * deleted instructions. |
| */ |
| public UnreachableCodeRemover(InstructionVisitor extraInstructionVisitor) |
| { |
| this.extraInstructionVisitor = extraInstructionVisitor; |
| } |
| |
| |
| // Implementations for AttributeVisitor. |
| |
| public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} |
| |
| |
| public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) |
| { |
| // DEBUG = |
| // clazz.getName().equals("abc/Def") && |
| // method.getName(clazz).equals("abc"); |
| |
| // TODO: Remove this when the code has stabilized. |
| // Catch any unexpected exceptions from the actual visiting method. |
| try |
| { |
| // Process the code. |
| visitCodeAttribute0(clazz, method, codeAttribute); |
| } |
| catch (RuntimeException ex) |
| { |
| System.err.println("Unexpected error while removing unreachable code:"); |
| System.err.println(" Class = ["+clazz.getName()+"]"); |
| System.err.println(" Method = ["+method.getName(clazz)+method.getDescriptor(clazz)+"]"); |
| System.err.println(" Exception = ["+ex.getClass().getName()+"] ("+ex.getMessage()+")"); |
| |
| throw ex; |
| } |
| } |
| |
| |
| public void visitCodeAttribute0(Clazz clazz, Method method, CodeAttribute codeAttribute) |
| { |
| if (DEBUG) |
| { |
| System.out.println("UnreachableCodeRemover: "+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz)); |
| } |
| |
| reachableCodeMarker.visitCodeAttribute(clazz, method, codeAttribute); |
| |
| codeAttributeEditor.reset(codeAttribute.u4codeLength); |
| |
| codeAttribute.instructionsAccept(clazz, method, this); |
| |
| codeAttributeEditor.visitCodeAttribute(clazz, method, codeAttribute); |
| } |
| |
| |
| // Implementations for InstructionVisitor. |
| |
| public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) |
| { |
| if (DEBUG) |
| { |
| System.out.println(" "+(reachableCodeMarker.isReachable(offset) ? "+" : "-")+" "+instruction.toString(offset)); |
| } |
| |
| // Is this instruction unreachable? |
| if (!reachableCodeMarker.isReachable(offset)) |
| { |
| // Then delete it. |
| codeAttributeEditor.deleteInstruction(offset); |
| |
| // Visit the instruction, if required. |
| if (extraInstructionVisitor != null) |
| { |
| instruction.accept(clazz, method, codeAttribute, offset, extraInstructionVisitor); |
| } |
| } |
| } |
| } |