1 /*
   2  * Copyright (c) 2011, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.graalvm.compiler.phases.graph;
  24 
  25 import java.util.List;
  26 
  27 import org.graalvm.compiler.nodes.AbstractBeginNode;
  28 import org.graalvm.compiler.nodes.AbstractMergeNode;
  29 import org.graalvm.compiler.nodes.ControlSplitNode;
  30 import org.graalvm.compiler.nodes.LoopBeginNode;
  31 import org.graalvm.compiler.nodes.LoopEndNode;
  32 
  33 public abstract class MergeableState<T> {
  34 
  35     @Override
  36     public abstract T clone();
  37 
  38     /**
  39      * This method is called on merge on the state of the first branch. The {@code withStates} list
  40      * contains the states of the of the other branches in the order of the merge's end nodes.
  41      *
  42      * @param merge the merge node
  43      * @param withStates the state at the the merge's end node except the first one.
  44      */
  45     public abstract boolean merge(AbstractMergeNode merge, List<T> withStates);
  46 
  47     /**
  48      * This method is called before a loop is entered (before the {@link LoopBeginNode} is visited).
  49      *
  50      * @param loopBegin the begin node of the loop
  51      */
  52     public void loopBegin(LoopBeginNode loopBegin) {
  53         // empty default implementation
  54     }
  55 
  56     /**
  57      * This method is called after all {@link LoopEndNode}s belonging to a loop have been visited.
  58      *
  59      * @param loopBegin the begin node of the loop
  60      * @param loopEndStates the states at the loop ends, sorted according to
  61      *            {@link LoopBeginNode#orderedLoopEnds()}
  62      */
  63     public void loopEnds(LoopBeginNode loopBegin, List<T> loopEndStates) {
  64         // empty default implementation
  65     }
  66 
  67     /**
  68      * This method is called before the successors of a {@link ControlSplitNode} are visited.
  69      *
  70      * @param node the successor of the control split that is about to be visited
  71      */
  72     public void afterSplit(AbstractBeginNode node) {
  73         // empty default implementation
  74     }
  75 }