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/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2019 Guardsquare NV
 *
 * 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.CodeAttribute;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.SimplifiedVisitor;

/**
 * This InstructionVisitor marks whether a final field is assigned
 * in the methods whose instructions it visits.
 *
 * @author Thomas Neidhart
 */
public class FinalFieldAssignmentMarker
extends      SimplifiedVisitor
implements   InstructionVisitor,
             ConstantVisitor
{
    private Method referencedMethod;


    // Implementations for InstructionVisitor.

    public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}


    @Override
    public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction)
    {
        if (constantInstruction.opcode == InstructionConstants.OP_PUTSTATIC ||
            constantInstruction.opcode == InstructionConstants.OP_PUTFIELD)
        {
            referencedMethod = method;
            clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this);
        }
    }


    // Implementations for ConstantVisitor.

    @Override
    public void visitAnyConstant(Clazz clazz, Constant constant) {}


    @Override
    public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant)
    {
        if (fieldrefConstant.referencedMember != null &&
            (fieldrefConstant.referencedMember.getAccessFlags() & ClassConstants.ACC_FINAL) != 0)
        {
            setAssignsFinalField(referencedMethod);
        }
    }


    // Small utility methods.

    private static void setAssignsFinalField(Method method)
    {
        ProgramMethodOptimizationInfo.getProgramMethodOptimizationInfo(method).setAssignsFinalField();
    }


    /**
     * Returns whether the given method assigns a final field.
     */
    public static boolean assignsFinalField(Method method)
    {
        return MethodOptimizationInfo.getMethodOptimizationInfo(method).assignsFinalField();
    }
}