1 /*
   2  * Copyright (c) 2012, 2015, 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.nodes;
  24 
  25 import static org.graalvm.compiler.nodeinfo.InputType.Association;
  26 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
  27 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;
  28 
  29 import org.graalvm.compiler.graph.IterableNodeType;
  30 import org.graalvm.compiler.graph.Node;
  31 import org.graalvm.compiler.graph.NodeClass;
  32 import org.graalvm.compiler.graph.iterators.NodeIterable;
  33 import org.graalvm.compiler.graph.spi.Simplifiable;
  34 import org.graalvm.compiler.graph.spi.SimplifierTool;
  35 import org.graalvm.compiler.nodeinfo.NodeInfo;
  36 
  37 @NodeInfo(allowedUsageTypes = {Association}, cycles = CYCLES_0, size = SIZE_0)
  38 public final class LoopExitNode extends BeginStateSplitNode implements IterableNodeType, Simplifiable {
  39 
  40     public static final NodeClass<LoopExitNode> TYPE = NodeClass.create(LoopExitNode.class);
  41 
  42     /*
  43      * The declared type of the field cannot be LoopBeginNode, because loop explosion during partial
  44      * evaluation can temporarily assign a non-loop begin. This node will then be deleted shortly
  45      * after - but we still must not have type system violations for that short amount of time.
  46      */
  47     @Input(Association) AbstractBeginNode loopBegin;
  48 
  49     public LoopExitNode(LoopBeginNode loop) {
  50         super(TYPE);
  51         assert loop != null;
  52         loopBegin = loop;
  53     }
  54 
  55     public LoopBeginNode loopBegin() {
  56         return (LoopBeginNode) loopBegin;
  57     }
  58 
  59     @Override
  60     public NodeIterable<Node> anchored() {
  61         return super.anchored().filter(n -> {
  62             if (n instanceof ProxyNode) {
  63                 ProxyNode proxyNode = (ProxyNode) n;
  64                 return proxyNode.proxyPoint() != this;
  65             }
  66             return true;
  67         });
  68     }
  69 
  70     @Override
  71     public void prepareDelete(FixedNode evacuateFrom) {
  72         removeProxies();
  73         super.prepareDelete(evacuateFrom);
  74     }
  75 
  76     public void removeProxies() {
  77         if (this.hasUsages()) {
  78             outer: while (true) {
  79                 for (ProxyNode vpn : proxies().snapshot()) {
  80                     ValueNode value = vpn.value();
  81                     vpn.replaceAtUsagesAndDelete(value);
  82                     if (value == this) {
  83                         // Guard proxy could have this input as value.
  84                         continue outer;
  85                     }
  86                 }
  87                 break;
  88             }
  89         }
  90     }
  91 
  92     @SuppressWarnings({"unchecked", "rawtypes"})
  93     public NodeIterable<ProxyNode> proxies() {
  94         return (NodeIterable) usages().filter(n -> {
  95             if (n instanceof ProxyNode) {
  96                 ProxyNode proxyNode = (ProxyNode) n;
  97                 return proxyNode.proxyPoint() == this;
  98             }
  99             return false;
 100         });
 101     }
 102 
 103     @Override
 104     public void simplify(SimplifierTool tool) {
 105         Node prev = this.predecessor();
 106         while (tool.allUsagesAvailable() && prev instanceof BeginNode && prev.hasNoUsages()) {
 107             AbstractBeginNode begin = (AbstractBeginNode) prev;
 108             prev = prev.predecessor();
 109             graph().removeFixed(begin);
 110         }
 111     }
 112 }