001/*
002 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.nodes.memory;
024
025import jdk.internal.jvmci.meta.*;
026
027import com.oracle.graal.compiler.common.type.*;
028import com.oracle.graal.graph.*;
029import com.oracle.graal.nodeinfo.*;
030import com.oracle.graal.nodes.*;
031import com.oracle.graal.nodes.extended.*;
032import com.oracle.graal.nodes.memory.address.*;
033
034/**
035 * An {@link FixedAccessNode} that can be converted to a {@link FloatingAccessNode}.
036 */
037@NodeInfo
038public abstract class FloatableAccessNode extends FixedAccessNode {
039    public static final NodeClass<FloatableAccessNode> TYPE = NodeClass.create(FloatableAccessNode.class);
040
041    protected FloatableAccessNode(NodeClass<? extends FloatableAccessNode> c, AddressNode address, LocationIdentity location, Stamp stamp) {
042        super(c, address, location, stamp);
043    }
044
045    protected FloatableAccessNode(NodeClass<? extends FloatableAccessNode> c, AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType) {
046        super(c, address, location, stamp, guard, barrierType, false, null);
047    }
048
049    protected FloatableAccessNode(NodeClass<? extends FloatableAccessNode> c, AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType,
050                    boolean nullCheck, FrameState stateBefore) {
051        super(c, address, location, stamp, guard, barrierType, nullCheck, stateBefore);
052    }
053
054    public abstract FloatingAccessNode asFloatingNode(MemoryNode lastLocationAccess);
055
056    protected boolean forceFixed;
057
058    public void setForceFixed(boolean flag) {
059        this.forceFixed = flag;
060    }
061
062    /**
063     * AccessNodes can float only if their location identities are not ANY_LOCATION. Furthermore, in
064     * case G1 is enabled any access (read) to the java.lang.ref.Reference.referent field which has
065     * an attached write barrier with pre-semantics can not also float.
066     */
067    public boolean canFloat() {
068        return !forceFixed && getLocationIdentity().isSingle() && getBarrierType() == BarrierType.NONE;
069    }
070}