1 /*
   2  * Copyright (c) 2012, 2018, 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 
  24 
  25 package org.graalvm.compiler.nodes;
  26 
  27 import static org.graalvm.compiler.nodeinfo.InputType.Association;
  28 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
  29 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;
  30 
  31 import org.graalvm.compiler.graph.IterableNodeType;
  32 import org.graalvm.compiler.graph.Node;
  33 import org.graalvm.compiler.graph.NodeClass;
  34 import org.graalvm.compiler.graph.iterators.NodeIterable;
  35 import org.graalvm.compiler.graph.spi.Simplifiable;
  36 import org.graalvm.compiler.graph.spi.SimplifierTool;
  37 import org.graalvm.compiler.nodeinfo.NodeInfo;
  38 import org.graalvm.compiler.nodes.util.GraphUtil;
  39 
  40 @NodeInfo(allowedUsageTypes = {Association}, cycles = CYCLES_0, size = SIZE_0)
  41 public final class LoopExitNode extends BeginStateSplitNode implements IterableNodeType, Simplifiable {
  42 
  43     public static final NodeClass<LoopExitNode> TYPE = NodeClass.create(LoopExitNode.class);
  44 
  45     /*
  46      * The declared type of the field cannot be LoopBeginNode, because loop explosion during partial
  47      * evaluation can temporarily assign a non-loop begin. This node will then be deleted shortly
  48      * after - but we still must not have type system violations for that short amount of time.
  49      */
  50     @Input(Association) AbstractBeginNode loopBegin;
  51 
  52     public LoopExitNode(LoopBeginNode loop) {
  53         super(TYPE);
  54         assert loop != null;
  55         loopBegin = loop;
  56     }
  57 
  58     public LoopBeginNode loopBegin() {
  59         return (LoopBeginNode) loopBegin;
  60     }
  61 
  62     @Override
  63     public NodeIterable<Node> anchored() {
  64         return super.anchored().filter(n -> {
  65             if (n instanceof ProxyNode) {
  66                 ProxyNode proxyNode = (ProxyNode) n;
  67                 return proxyNode.proxyPoint() != this;
  68             }
  69             return true;
  70         });
  71     }
  72 
  73     @Override
  74     public void prepareDelete(FixedNode evacuateFrom) {
  75         removeProxies();
  76         super.prepareDelete(evacuateFrom);
  77     }
  78 
  79     public void removeProxies() {
  80         if (this.hasUsages()) {
  81             outer: while (true) {
  82                 for (ProxyNode vpn : proxies().snapshot()) {
  83                     ValueNode value = vpn.value();
  84                     vpn.replaceAtUsagesAndDelete(value);
  85                     if (value == this) {
  86                         // Guard proxy could have this input as value.
  87                         continue outer;
  88                     }
  89                 }
  90                 break;
  91             }
  92         }
  93     }
  94 
  95     @SuppressWarnings({"unchecked", "rawtypes"})
  96     public NodeIterable<ProxyNode> proxies() {
  97         return (NodeIterable) usages().filter(n -> {
  98             if (n instanceof ProxyNode) {
  99                 ProxyNode proxyNode = (ProxyNode) n;
 100                 return proxyNode.proxyPoint() == this;
 101             }
 102             return false;
 103         });
 104     }
 105 
 106     public void removeExit() {
 107         this.removeProxies();
 108         FrameState loopStateAfter = this.stateAfter();
 109         graph().replaceFixedWithFixed(this, graph().add(new BeginNode()));
 110         if (loopStateAfter != null) {
 111             GraphUtil.tryKillUnused(loopStateAfter);
 112         }
 113     }
 114 
 115     @Override
 116     public void simplify(SimplifierTool tool) {
 117         Node prev = this.predecessor();
 118         while (tool.allUsagesAvailable() && prev instanceof BeginNode && prev.hasNoUsages()) {
 119             AbstractBeginNode begin = (AbstractBeginNode) prev;
 120             this.setNodeSourcePosition(begin.getNodeSourcePosition());
 121             prev = prev.predecessor();
 122             graph().removeFixed(begin);
 123         }
 124     }
 125 }