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 */
23package org.graalvm.compiler.hotspot.nodes;
24
25import static org.graalvm.compiler.nodeinfo.InputType.Association;
26import static org.graalvm.compiler.nodeinfo.InputType.Memory;
27import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_30;
28import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_8;
29
30import org.graalvm.compiler.core.common.LocationIdentity;
31import org.graalvm.compiler.graph.NodeClass;
32import org.graalvm.compiler.hotspot.HotSpotNodeLIRBuilder;
33import org.graalvm.compiler.nodeinfo.NodeInfo;
34import org.graalvm.compiler.nodes.FixedWithNextNode;
35import org.graalvm.compiler.nodes.StateSplit;
36import org.graalvm.compiler.nodes.ValueNode;
37import org.graalvm.compiler.nodes.java.CompareAndSwapNode;
38import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
39import org.graalvm.compiler.nodes.memory.address.AddressNode;
40import org.graalvm.compiler.nodes.memory.address.AddressNode.Address;
41import org.graalvm.compiler.nodes.spi.LIRLowerable;
42import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
43import 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)
51public 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}
104