de.tuberlin.uebb.jbop.optimizer.loop.ForLoop.java Source code

Introduction

Here is the source code for de.tuberlin.uebb.jbop.optimizer.loop.ForLoop.java

Source

/*
 * 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.loop;

import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.MethodNode;

/**
 * The Class ForLoop.
 * 
 * This is a DTO that stores the whole loop.
 * Additionally there is some logic, to evaluate
 * the loop condition / invariant.
 * 
 * It provides the unrolled loop.
 * 
 * @author Christopher Ewest
 */
public class ForLoop {

    private final ForLoopBody body;
    private final ForLoopFooter footer;
    private final Number start;

    /**
     * Instantiates a new for loop.
     * 
     * @param body
     *          the body
     * @param footer
     *          the footer
     * @param start
     *          the start
     */
    public ForLoop(final ForLoopBody body, final ForLoopFooter footer, final Number start) {
        this.body = body;
        this.footer = footer;
        this.start = start;
    }

    /**
     * Gets the insn list.
     * 
     * @param method
     *          the method
     * @return the insn list with the unroled loop.
     */
    public InsnList getInsnList(final MethodNode method) {
        final int loopCount = footer.getLoopCount();
        final int ifNode = footer.getIfNode().getOpcode();
        final InsnList unfolded = new InsnList();
        for (int i = start.intValue(); eval(i, loopCount, ifNode); i += footer.getIinc().incr) {
            unfolded.add(body.getInsnList(i, footer, method));
        }
        return unfolded;
    }

    private boolean eval(final int i, final int loopCount, final int ifNode) {
        if (ifNode == Opcodes.IF_ICMPLE) {
            return i <= loopCount;
        }
        if (ifNode == Opcodes.IF_ICMPEQ) {
            return i == loopCount;
        }
        if (ifNode == Opcodes.IF_ICMPGE) {
            return i >= loopCount;
        }
        if (ifNode == Opcodes.IF_ICMPGT) {
            return i > loopCount;
        }
        if (ifNode == Opcodes.IF_ICMPLT) {
            return i < loopCount;
        }
        if (ifNode == Opcodes.IF_ICMPNE) {
            return i != loopCount;
        }
        if (ifNode == Opcodes.IFGE) {
            return i >= 0;
        }
        if (ifNode == Opcodes.IFEQ) {
            return i == 0;
        }
        if (ifNode == Opcodes.IFGT) {
            return i > 0;
        }
        if (ifNode == Opcodes.IFLE) {
            return i <= 0;
        }
        if (ifNode == Opcodes.IFLT) {
            return i < 0;
        }
        if (ifNode == Opcodes.IFNE) {
            return i != 0;
        }
        return false;
    }
}