1/*
2 * Copyright (c) 2013, 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.nodes.java;
24
25import static org.graalvm.compiler.nodeinfo.InputType.Memory;
26import static org.graalvm.compiler.nodeinfo.InputType.State;
27
28import org.graalvm.compiler.core.common.type.Stamp;
29import org.graalvm.compiler.graph.NodeClass;
30import org.graalvm.compiler.nodeinfo.InputType;
31import org.graalvm.compiler.nodeinfo.NodeInfo;
32import org.graalvm.compiler.nodes.FrameState;
33import org.graalvm.compiler.nodes.StateSplit;
34import org.graalvm.compiler.nodes.ValueNode;
35import org.graalvm.compiler.nodes.memory.FixedAccessNode;
36import org.graalvm.compiler.nodes.memory.LIRLowerableAccess;
37import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
38import org.graalvm.compiler.nodes.memory.address.AddressNode;
39import org.graalvm.word.LocationIdentity;
40
41/**
42 * Low-level atomic compare-and-swap operation.
43 */
44@NodeInfo(allowedUsageTypes = {InputType.Value, Memory})
45public abstract class AbstractCompareAndSwapNode extends FixedAccessNode implements StateSplit, LIRLowerableAccess, MemoryCheckpoint.Single {
46    public static final NodeClass<AbstractCompareAndSwapNode> TYPE = NodeClass.create(AbstractCompareAndSwapNode.class);
47    @Input ValueNode expectedValue;
48    @Input ValueNode newValue;
49    @OptionalInput(State) FrameState stateAfter;
50
51    @Override
52    public FrameState stateAfter() {
53        return stateAfter;
54    }
55
56    @Override
57    public void setStateAfter(FrameState x) {
58        assert x == null || x.isAlive() : "frame state must be in a graph";
59        updateUsages(stateAfter, x);
60        stateAfter = x;
61    }
62
63    @Override
64    public boolean hasSideEffect() {
65        return true;
66    }
67
68    public ValueNode getExpectedValue() {
69        return expectedValue;
70    }
71
72    public ValueNode getNewValue() {
73        return newValue;
74    }
75
76    public AbstractCompareAndSwapNode(NodeClass<? extends AbstractCompareAndSwapNode> c, AddressNode address, LocationIdentity location, ValueNode expectedValue, ValueNode newValue,
77                    BarrierType barrierType, Stamp stamp) {
78        super(c, address, location, stamp, barrierType);
79        assert expectedValue.getStackKind() == newValue.getStackKind();
80        this.expectedValue = expectedValue;
81        this.newValue = newValue;
82    }
83
84    @Override
85    public boolean canNullCheck() {
86        return false;
87    }
88
89    @Override
90    public Stamp getAccessStamp() {
91        return expectedValue.stamp().meet(newValue.stamp()).unrestricted();
92    }
93}
94