1 /*
   2  * Copyright (c) 2012, 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.extended;
  24 
  25 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;
  26 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;
  27 
  28 import org.graalvm.compiler.core.common.LocationIdentity;
  29 import org.graalvm.compiler.core.common.type.Stamp;
  30 import org.graalvm.compiler.graph.Node;
  31 import org.graalvm.compiler.graph.NodeClass;
  32 import org.graalvm.compiler.graph.spi.Canonicalizable;
  33 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
  34 import org.graalvm.compiler.nodeinfo.NodeInfo;
  35 import org.graalvm.compiler.nodes.FixedWithNextNode;
  36 import org.graalvm.compiler.nodes.NamedLocationIdentity;
  37 import org.graalvm.compiler.nodes.ValueNode;
  38 import org.graalvm.compiler.nodes.type.StampTool;
  39 
  40 import jdk.vm.ci.meta.Assumptions;
  41 import jdk.vm.ci.meta.JavaKind;
  42 import jdk.vm.ci.meta.ResolvedJavaField;
  43 import jdk.vm.ci.meta.ResolvedJavaType;
  44 
  45 @NodeInfo(cycles = CYCLES_2, size = SIZE_1)
  46 public abstract class UnsafeAccessNode extends FixedWithNextNode implements Canonicalizable {
  47 
  48     public static final NodeClass<UnsafeAccessNode> TYPE = NodeClass.create(UnsafeAccessNode.class);
  49     @Input ValueNode object;
  50     @Input ValueNode offset;
  51     protected final JavaKind accessKind;
  52     protected final LocationIdentity locationIdentity;
  53 
  54     protected UnsafeAccessNode(NodeClass<? extends UnsafeAccessNode> c, Stamp stamp, ValueNode object, ValueNode offset, JavaKind accessKind, LocationIdentity locationIdentity) {
  55         super(c, stamp);
  56         assert accessKind != null;
  57         assert locationIdentity != null;
  58         this.object = object;
  59         this.offset = offset;
  60         this.accessKind = accessKind;
  61         this.locationIdentity = locationIdentity;
  62     }
  63 
  64     public LocationIdentity getLocationIdentity() {
  65         return locationIdentity;
  66     }
  67 
  68     public ValueNode object() {
  69         return object;
  70     }
  71 
  72     public ValueNode offset() {
  73         return offset;
  74     }
  75 
  76     public JavaKind accessKind() {
  77         return accessKind;
  78     }
  79 
  80     @Override
  81     public Node canonical(CanonicalizerTool tool) {
  82         if (this.getLocationIdentity().isAny() && offset().isConstant()) {
  83             long constantOffset = offset().asJavaConstant().asLong();
  84 
  85             // Try to canonicalize to a field access.
  86             ResolvedJavaType receiverType = StampTool.typeOrNull(object());
  87             if (receiverType != null) {
  88                 ResolvedJavaField field = receiverType.findInstanceFieldWithOffset(constantOffset, accessKind());
  89                 // No need for checking that the receiver is non-null. The field access includes
  90                 // the null check and if a field is found, the offset is so small that this is
  91                 // never a valid access of an arbitrary address.
  92                 if (field != null && field.getJavaKind() == this.accessKind()) {
  93                     assert !graph().isAfterFloatingReadPhase() : "cannot add more precise memory location after floating read phase";
  94                     return cloneAsFieldAccess(graph().getAssumptions(), field);
  95                 }
  96             }
  97         }
  98         if (this.getLocationIdentity().isAny()) {
  99             ResolvedJavaType receiverType = StampTool.typeOrNull(object());
 100             // Try to build a better location identity.
 101             if (receiverType != null && receiverType.isArray()) {
 102                 LocationIdentity identity = NamedLocationIdentity.getArrayLocation(receiverType.getComponentType().getJavaKind());
 103                 assert !graph().isAfterFloatingReadPhase() : "cannot add more precise memory location after floating read phase";
 104                 return cloneAsArrayAccess(offset(), identity);
 105             }
 106         }
 107 
 108         return this;
 109     }
 110 
 111     protected abstract ValueNode cloneAsFieldAccess(Assumptions assumptions, ResolvedJavaField field);
 112 
 113     protected abstract ValueNode cloneAsArrayAccess(ValueNode location, LocationIdentity identity);
 114 }