src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/java/UnsafeCompareAndExchangeNode.java

/*
 * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package org.graalvm.compiler.nodes.java;

import jdk.vm.ci.meta.JavaKind;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.memory.AbstractMemoryCheckpoint;
import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
import org.graalvm.compiler.nodes.spi.Lowerable;
import org.graalvm.compiler.nodes.spi.LoweringTool;
import jdk.internal.vm.compiler.word.LocationIdentity;

import static org.graalvm.compiler.nodeinfo.InputType.Memory;
import static org.graalvm.compiler.nodeinfo.InputType.Value;
import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_8;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_8;

/**
 * Represents an atomic compare-and-swap operation. The result is the current value of the memory
 * location that was compared.
 */
@NodeInfo(allowedUsageTypes = {Value, Memory}, cycles = CYCLES_8, size = SIZE_8)
public final class UnsafeCompareAndExchangeNode extends AbstractMemoryCheckpoint implements Lowerable, MemoryCheckpoint.Single {

    public static final NodeClass<UnsafeCompareAndExchangeNode> TYPE = NodeClass.create(UnsafeCompareAndExchangeNode.class);
    @Input ValueNode object;
    @Input ValueNode offset;
    @Input ValueNode expected;
    @Input ValueNode newValue;

    private final JavaKind valueKind;
    private final LocationIdentity locationIdentity;

    public UnsafeCompareAndExchangeNode(ValueNode object, ValueNode offset, ValueNode expected, ValueNode newValue, JavaKind valueKind, LocationIdentity locationIdentity) {
        super(TYPE, meetInputs(expected.stamp(NodeView.DEFAULT), newValue.stamp(NodeView.DEFAULT)));
        this.object = object;
        this.offset = offset;
        this.expected = expected;
        this.newValue = newValue;
        this.valueKind = valueKind;
        this.locationIdentity = locationIdentity;
    }

    private static Stamp meetInputs(Stamp expected, Stamp newValue) {
        assert expected.isCompatible(newValue);
        return expected.unrestricted().meet(newValue.unrestricted());
    }

    public ValueNode object() {
        return object;
    }

    public ValueNode offset() {
        return offset;
    }

    public ValueNode expected() {
        return expected;
    }

    public ValueNode newValue() {
        return newValue;
    }

    public JavaKind getValueKind() {
        return valueKind;
    }

    @Override
    public LocationIdentity getLocationIdentity() {
        return locationIdentity;
    }

    @Override
    public void lower(LoweringTool tool) {
        tool.getLowerer().lower(this, tool);
    }
}