1 /*
   2  * Copyright (c) 2013, 2013, 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.ListIterator;
  26 
  27 import org.graalvm.compiler.graph.Node;
  28 import org.graalvm.compiler.nodes.FixedNode;
  29 import org.graalvm.compiler.nodes.FixedWithNextNode;
  30 import org.graalvm.compiler.nodes.StructuredGraph.ScheduleResult;
  31 import org.graalvm.compiler.nodes.cfg.Block;
  32 
  33 /**
  34  * Iterates over a list of nodes, which usually comes from
  35  * {@link ScheduleResult#getBlockToNodesMap()}.
  36  *
  37  * While iterating, it is possible to {@link #insert(FixedNode, FixedWithNextNode) insert} and
  38  * {@link #replaceCurrent(FixedWithNextNode) replace} nodes.
  39  */
  40 public abstract class ScheduledNodeIterator {
  41 
  42     private FixedWithNextNode lastFixed;
  43     private FixedWithNextNode reconnect;
  44     private ListIterator<Node> iterator;
  45 
  46     public void processNodes(Block block, ScheduleResult schedule) {
  47         lastFixed = block.getBeginNode();
  48         assert lastFixed != null;
  49         reconnect = null;
  50         iterator = schedule.nodesFor(block).listIterator();
  51 
  52         while (iterator.hasNext()) {
  53             Node node = iterator.next();
  54             if (!node.isAlive()) {
  55                 continue;
  56             }
  57             if (reconnect != null && node instanceof FixedNode) {
  58                 reconnect.setNext((FixedNode) node);
  59                 reconnect = null;
  60             }
  61             if (node instanceof FixedWithNextNode) {
  62                 lastFixed = (FixedWithNextNode) node;
  63             }
  64             processNode(node);
  65         }
  66         if (reconnect != null) {
  67             assert block.getSuccessorCount() == 1;
  68             reconnect.setNext(block.getFirstSuccessor().getBeginNode());
  69         }
  70     }
  71 
  72     protected void insert(FixedNode start, FixedWithNextNode end) {
  73         this.lastFixed.setNext(start);
  74         this.lastFixed = end;
  75         this.reconnect = end;
  76     }
  77 
  78     protected void replaceCurrent(FixedWithNextNode newNode) {
  79         Node current = iterator.previous();
  80         iterator.next(); // needed because of the previous() call
  81         current.replaceAndDelete(newNode);
  82         insert(newNode, newNode);
  83         iterator.set(newNode);
  84     }
  85 
  86     protected abstract void processNode(Node node);
  87 }