| /* |
| * 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.optimize.info; |
| |
| import proguard.classfile.*; |
| import proguard.classfile.attribute.*; |
| import proguard.classfile.attribute.visitor.AttributeVisitor; |
| import proguard.classfile.instruction.*; |
| import proguard.classfile.instruction.visitor.InstructionVisitor; |
| import proguard.classfile.util.SimplifiedVisitor; |
| |
| /** |
| * This AttributeVisitor marks the local variables that are used in the code |
| * attributes that it visits. |
| * |
| * @author Eric Lafortune |
| */ |
| public class VariableUsageMarker |
| extends SimplifiedVisitor |
| implements AttributeVisitor, |
| InstructionVisitor |
| { |
| private boolean[] variableUsed = new boolean[ClassConstants.TYPICAL_VARIABLES_SIZE]; |
| |
| |
| /** |
| * Returns whether the given variable has been marked as being used. |
| */ |
| public boolean isVariableUsed(int variableIndex) |
| { |
| return variableUsed[variableIndex]; |
| } |
| |
| |
| // Implementations for AttributeVisitor. |
| |
| public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} |
| |
| |
| public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) |
| { |
| int maxLocals = codeAttribute.u2maxLocals; |
| |
| // Try to reuse the previous array. |
| if (variableUsed.length < maxLocals) |
| { |
| variableUsed = new boolean[maxLocals]; |
| } |
| else |
| { |
| for (int index = 0; index < maxLocals; index++) |
| { |
| variableUsed[index] = false; |
| } |
| } |
| |
| codeAttribute.instructionsAccept(clazz, method, this); |
| } |
| |
| |
| // Implementations for InstructionVisitor. |
| |
| public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {} |
| |
| |
| public void visitVariableInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, VariableInstruction variableInstruction) |
| { |
| // Mark the variable. |
| variableUsed[variableInstruction.variableIndex] = true; |
| |
| // Account for Category 2 instructions, which take up two entries. |
| if (variableInstruction.isCategory2()) |
| { |
| variableUsed[variableInstruction.variableIndex + 1] = true; |
| } |
| } |
| } |