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  */
  23 package org.graalvm.compiler.nodes.memory;
  24 
  25 import org.graalvm.compiler.core.common.LocationIdentity;
  26 import org.graalvm.compiler.core.common.type.Stamp;
  27 import org.graalvm.compiler.graph.NodeClass;
  28 import org.graalvm.compiler.nodeinfo.NodeInfo;
  29 import org.graalvm.compiler.nodes.FrameState;
  30 import org.graalvm.compiler.nodes.extended.GuardingNode;
  31 import org.graalvm.compiler.nodes.memory.address.AddressNode;
  32 
  33 /**
  34  * An {@link FixedAccessNode} that can be converted to a {@link FloatingAccessNode}.
  35  */
  36 @NodeInfo
  37 public abstract class FloatableAccessNode extends FixedAccessNode {
  38     public static final NodeClass<FloatableAccessNode> TYPE = NodeClass.create(FloatableAccessNode.class);
  39 
  40     protected FloatableAccessNode(NodeClass<? extends FloatableAccessNode> c, AddressNode address, LocationIdentity location, Stamp stamp) {
  41         super(c, address, location, stamp);
  42     }
  43 
  44     protected FloatableAccessNode(NodeClass<? extends FloatableAccessNode> c, AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType) {
  45         super(c, address, location, stamp, guard, barrierType, false, null);
  46     }
  47 
  48     protected FloatableAccessNode(NodeClass<? extends FloatableAccessNode> c, AddressNode address, LocationIdentity location, Stamp stamp, GuardingNode guard, BarrierType barrierType,
  49                     boolean nullCheck, FrameState stateBefore) {
  50         super(c, address, location, stamp, guard, barrierType, nullCheck, stateBefore);
  51     }
  52 
  53     public abstract FloatingAccessNode asFloatingNode(MemoryNode lastLocationAccess);
  54 
  55     protected boolean forceFixed;
  56 
  57     public void setForceFixed(boolean flag) {
  58         this.forceFixed = flag;
  59     }
  60 
  61     /**
  62      * AccessNodes can float only if their location identities are not ANY_LOCATION. Furthermore, in
  63      * case G1 is enabled any access (read) to the java.lang.ref.Reference.referent field which has
  64      * an attached write barrier with pre-semantics can not also float.
  65      */
  66     public boolean canFloat() {
  67         return !forceFixed && getLocationIdentity().isSingle() && getBarrierType() == BarrierType.NONE;
  68     }
  69 }