001/*
002 * Copyright (c) 2011, 2011, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.phases.graph;
024
025import java.util.*;
026
027import com.oracle.graal.nodes.*;
028
029public abstract class MergeableState<T> {
030
031    @Override
032    public abstract T clone();
033
034    /**
035     * This method is called on merge on the state of the first branch. The {@code withStates} list
036     * contains the states of the of the other branches in the order of the merge's end nodes.
037     *
038     * @param merge the merge node
039     * @param withStates the state at the the merge's end node except the first one.
040     */
041    public abstract boolean merge(AbstractMergeNode merge, List<T> withStates);
042
043    /**
044     * This method is called before a loop is entered (before the {@link LoopBeginNode} is visited).
045     *
046     * @param loopBegin the begin node of the loop
047     */
048    public void loopBegin(LoopBeginNode loopBegin) {
049        // empty default implementation
050    }
051
052    /**
053     * This method is called after all {@link LoopEndNode}s belonging to a loop have been visited.
054     *
055     * @param loopBegin the begin node of the loop
056     * @param loopEndStates the states at the loop ends, sorted according to
057     *            {@link LoopBeginNode#orderedLoopEnds()}
058     */
059    public void loopEnds(LoopBeginNode loopBegin, List<T> loopEndStates) {
060        // empty default implementation
061    }
062
063    /**
064     * This method is called before the successors of a {@link ControlSplitNode} are visited.
065     *
066     * @param node the successor of the control split that is about to be visited
067     */
068    public void afterSplit(AbstractBeginNode node) {
069        // empty default implementation
070    }
071}