1 /*
   2  * Copyright (c) 2009, 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.java;
  26 
  27 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_64;
  28 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_64;
  29 
  30 import org.graalvm.compiler.graph.IterableNodeType;
  31 import org.graalvm.compiler.graph.NodeClass;
  32 import org.graalvm.compiler.nodeinfo.NodeInfo;
  33 import org.graalvm.compiler.nodes.ValueNode;
  34 import org.graalvm.compiler.nodes.extended.MonitorExit;
  35 import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
  36 import org.graalvm.compiler.nodes.spi.Lowerable;
  37 import org.graalvm.compiler.nodes.spi.LoweringTool;
  38 import org.graalvm.compiler.nodes.spi.Virtualizable;
  39 import org.graalvm.compiler.nodes.spi.VirtualizerTool;
  40 import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;
  41 import jdk.internal.vm.compiler.word.LocationIdentity;
  42 
  43 /**
  44  * The {@code MonitorExitNode} represents a monitor release. If it is the release of the monitor of
  45  * a synchronized method, then the return value of the method will be referenced via the edge
  46  * {@link #escapedReturnValue}, so that it will be materialized before releasing the monitor.
  47  */
  48 @NodeInfo(cycles = CYCLES_64, size = SIZE_64)
  49 public final class MonitorExitNode extends AccessMonitorNode implements Virtualizable, Lowerable, IterableNodeType, MonitorExit, MemoryCheckpoint.Single {
  50 
  51     public static final NodeClass<MonitorExitNode> TYPE = NodeClass.create(MonitorExitNode.class);
  52 
  53     /**
  54      * Non-null for the monitor exit introduced due to a synchronized root method and null in all
  55      * other cases.
  56      */
  57     @OptionalInput ValueNode escapedReturnValue;
  58 
  59     public MonitorExitNode(ValueNode object, MonitorIdNode monitorId, ValueNode escapedValue) {
  60         super(TYPE, object, monitorId);
  61         this.escapedReturnValue = escapedValue;
  62     }
  63 
  64     /**
  65      * Return value is cleared when a synchronized method graph is inlined.
  66      */
  67     public void clearEscapedValue() {
  68         updateUsages(escapedReturnValue, null);
  69         this.escapedReturnValue = null;
  70     }
  71 
  72     @Override
  73     public LocationIdentity getLocationIdentity() {
  74         return LocationIdentity.any();
  75     }
  76 
  77     @Override
  78     public void lower(LoweringTool tool) {
  79         tool.getLowerer().lower(this, tool);
  80     }
  81 
  82     @Override
  83     public void virtualize(VirtualizerTool tool) {
  84         ValueNode alias = tool.getAlias(object());
  85         if (alias instanceof VirtualObjectNode) {
  86             VirtualObjectNode virtual = (VirtualObjectNode) alias;
  87             if (virtual.hasIdentity()) {
  88                 MonitorIdNode removedLock = tool.removeLock(virtual);
  89                 assert removedLock == getMonitorId() : "mismatch at " + this + ": " + removedLock + " vs. " + getMonitorId();
  90                 tool.delete();
  91             }
  92         }
  93     }
  94 }