1 /*
   2  * Copyright (c) 2012, 2016, 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.hotspot.nodes;
  24 
  25 import static org.graalvm.compiler.nodeinfo.InputType.Association;
  26 import static org.graalvm.compiler.nodeinfo.InputType.Memory;
  27 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_30;
  28 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_8;
  29 
  30 import org.graalvm.compiler.core.common.LocationIdentity;
  31 import org.graalvm.compiler.graph.NodeClass;
  32 import org.graalvm.compiler.hotspot.HotSpotNodeLIRBuilder;
  33 import org.graalvm.compiler.nodeinfo.NodeInfo;
  34 import org.graalvm.compiler.nodes.FixedWithNextNode;
  35 import org.graalvm.compiler.nodes.StateSplit;
  36 import org.graalvm.compiler.nodes.ValueNode;
  37 import org.graalvm.compiler.nodes.java.CompareAndSwapNode;
  38 import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
  39 import org.graalvm.compiler.nodes.memory.address.AddressNode;
  40 import org.graalvm.compiler.nodes.memory.address.AddressNode.Address;
  41 import org.graalvm.compiler.nodes.spi.LIRLowerable;
  42 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
  43 import org.graalvm.compiler.word.Word;
  44 
  45 /**
  46  * A special purpose store node that differs from {@link CompareAndSwapNode} in that it is not a
  47  * {@link StateSplit} and it {@linkplain #compareAndSwap(Address, Word, Word, LocationIdentity)}
  48  * returns either the expected value or the compared against value instead of a boolean.
  49  */
  50 @NodeInfo(allowedUsageTypes = Memory, cycles = CYCLES_30, size = SIZE_8)
  51 public final class DirectCompareAndSwapNode extends FixedWithNextNode implements LIRLowerable, MemoryCheckpoint.Single {
  52 
  53     public static final NodeClass<DirectCompareAndSwapNode> TYPE = NodeClass.create(DirectCompareAndSwapNode.class);
  54     @Input(Association) AddressNode address;
  55     @Input ValueNode expectedValue;
  56     @Input ValueNode newValue;
  57 
  58     protected final LocationIdentity locationIdentity;
  59 
  60     public DirectCompareAndSwapNode(ValueNode address, ValueNode expected, ValueNode newValue, LocationIdentity locationIdentity) {
  61         super(TYPE, expected.stamp());
  62         this.address = (AddressNode) address;
  63         this.expectedValue = expected;
  64         this.newValue = newValue;
  65         this.locationIdentity = locationIdentity;
  66     }
  67 
  68     public AddressNode getAddress() {
  69         return address;
  70     }
  71 
  72     public ValueNode expectedValue() {
  73         return expectedValue;
  74     }
  75 
  76     public ValueNode newValue() {
  77         return newValue;
  78     }
  79 
  80     @Override
  81     public LocationIdentity getLocationIdentity() {
  82         return locationIdentity;
  83     }
  84 
  85     @Override
  86     public void generate(NodeLIRBuilderTool gen) {
  87         ((HotSpotNodeLIRBuilder) gen).visitDirectCompareAndSwap(this);
  88     }
  89 
  90     /**
  91      * Compares an expected value with the actual value in a location denoted by an address. Iff
  92      * they are same, {@code newValue} is placed into the location and the {@code expectedValue} is
  93      * returned. Otherwise, the actual value is returned. All of the above is performed in one
  94      * atomic hardware transaction.
  95      *
  96      * @param address the address to be atomically tested and updated
  97      * @param expectedValue if this value is currently in the field, perform the swap
  98      * @param newValue the new value to put into the field
  99      * @return either {@code expectedValue} or the actual value
 100      */
 101     @NodeIntrinsic
 102     public static native Word compareAndSwap(Address address, Word expectedValue, Word newValue, @ConstantNodeParameter LocationIdentity locationIdentity);
 103 }