AbstractCompareAndSwapNode.java

/*
 * Copyright (c) 2013, 2016, 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.
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package org.graalvm.compiler.nodes.java;

import static org.graalvm.compiler.nodeinfo.InputType.Memory;
import static org.graalvm.compiler.nodeinfo.InputType.State;

import org.graalvm.api.word.LocationIdentity;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.nodeinfo.InputType;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.FrameState;
import org.graalvm.compiler.nodes.StateSplit;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.memory.FixedAccessNode;
import org.graalvm.compiler.nodes.memory.LIRLowerableAccess;
import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
import org.graalvm.compiler.nodes.memory.address.AddressNode;

/**
 * Low-level atomic compare-and-swap operation.
 */
@NodeInfo(allowedUsageTypes = {InputType.Value, Memory})
public abstract class AbstractCompareAndSwapNode extends FixedAccessNode implements StateSplit, LIRLowerableAccess, MemoryCheckpoint.Single {
    public static final NodeClass<AbstractCompareAndSwapNode> TYPE = NodeClass.create(AbstractCompareAndSwapNode.class);
    @Input ValueNode expectedValue;
    @Input ValueNode newValue;
    @OptionalInput(State) FrameState stateAfter;

    @Override
    public FrameState stateAfter() {
        return stateAfter;
    }

    @Override
    public void setStateAfter(FrameState x) {
        assert x == null || x.isAlive() : "frame state must be in a graph";
        updateUsages(stateAfter, x);
        stateAfter = x;
    }

    @Override
    public boolean hasSideEffect() {
        return true;
    }

    public ValueNode getExpectedValue() {
        return expectedValue;
    }

    public ValueNode getNewValue() {
        return newValue;
    }

    public AbstractCompareAndSwapNode(NodeClass<? extends AbstractCompareAndSwapNode> c, AddressNode address, LocationIdentity location, ValueNode expectedValue, ValueNode newValue,
                    BarrierType barrierType, Stamp stamp) {
        super(c, address, location, stamp, barrierType);
        assert expectedValue.getStackKind() == newValue.getStackKind();
        this.expectedValue = expectedValue;
        this.newValue = newValue;
    }

    @Override
    public boolean canNullCheck() {
        return false;
    }

    @Override
    public Stamp getAccessStamp() {
        return expectedValue.stamp().meet(newValue.stamp()).unrestricted();
    }
}