de.tuberlin.uebb.jbop.optimizer.array.FieldArrayLengthInliner.java Source code

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Here is the source code for de.tuberlin.uebb.jbop.optimizer.array.FieldArrayLengthInliner.java

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/*
 * Copyright (C) 2013 uebb.tu-berlin.de.
 * 
 * This file is part of JBOP (Java Bytecode OPtimizer).
 * 
 * JBOP is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * JBOP 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with JBOP. If not, see <http://www.gnu.org/licenses/>.
 */
package de.tuberlin.uebb.jbop.optimizer.array;

import java.util.ListIterator;

import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.MethodNode;

import de.tuberlin.uebb.jbop.exception.JBOPClassException;
import de.tuberlin.uebb.jbop.optimizer.IClassNodeAware;
import de.tuberlin.uebb.jbop.optimizer.IInputObjectAware;
import de.tuberlin.uebb.jbop.optimizer.IOptimizer;
import de.tuberlin.uebb.jbop.optimizer.var.GetFieldChainInliner;

/**
 * Inlines the size of an array (class field), so that further optimizationsteps
 * could handle these calls as constant.
 * 
 * eg:
 * 
 * <pre>
 * private final double[] d = {1.0, 2.0, 3.0};
 * ...
 * for(int i = 0; i < d.length; ++i){
 * ...
 * }
 * </pre>
 * 
 * becomes
 * 
 * <pre>
 * private final double[] d = {1.0, 2.0, 3.0};
 * ...
 * for(int i = 0; i < 3; ++i){
 * ...
 * }
 * </pre>
 * 
 * In bytecode this means
 * 
 * <pre>
 * aload        0
 * getfield     d
 * arraylength
 * </pre>
 * 
 * becomes one of
 * 
 * <pre>
 * iconstx
 * ore
 * bipush       x
 * or
 * ldc          x
 * </pre>
 * 
 * depending on the real size of d
 * 
 * @author Christopher Ewest
 */
public class FieldArrayLengthInliner implements IOptimizer, IInputObjectAware, IClassNodeAware {

    private boolean optimized = false;

    private Object instance;

    private ClassNode classNode;

    @Override
    public boolean isOptimized() {
        return optimized;
    }

    @Override
    public InsnList optimize(final InsnList original, final MethodNode method) throws JBOPClassException {
        optimized = false;
        final ListIterator<AbstractInsnNode> iterator = original.iterator();
        final ArrayHelper arrayHelper = new ArrayHelper();
        while (iterator.hasNext()) {
            final AbstractInsnNode aload = iterator.next();
            if (!arrayHelper.isArrayInstruction(classNode, aload, null)) {
                continue;
            }
            if (!arrayHelper.isArrayLength()) {
                continue;
            }
            final GetFieldChainInliner fieldChainInliner = new GetFieldChainInliner();
            fieldChainInliner.setIterator(iterator);
            fieldChainInliner.setInputObject(instance);
            fieldChainInliner.optimize(original, null);
            if (fieldChainInliner.isOptimized()) {
                optimized = true;
                original.remove(aload);
            }
        }
        return original;
    }

    @Override
    public void setInputObject(final Object input) {
        instance = input;
    }

    @Override
    public void setClassNode(final ClassNode classNode) {
        this.classNode = classNode;
    }
}