1 /*
   2  * Copyright (c) 2009, 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;
  24 
  25 import java.util.function.Predicate;
  26 
  27 import org.graalvm.compiler.core.common.type.Stamp;
  28 import org.graalvm.compiler.graph.Node;
  29 import org.graalvm.compiler.graph.NodeClass;
  30 import org.graalvm.compiler.graph.iterators.NodePredicate;
  31 import org.graalvm.compiler.nodeinfo.InputType;
  32 import org.graalvm.compiler.nodeinfo.NodeInfo;
  33 import org.graalvm.compiler.nodeinfo.Verbosity;
  34 import org.graalvm.compiler.nodes.spi.NodeValueMap;
  35 
  36 import jdk.vm.ci.meta.Constant;
  37 import jdk.vm.ci.meta.JavaConstant;
  38 import jdk.vm.ci.meta.JavaKind;
  39 
  40 /**
  41  * This class represents a value within the graph, including local variables, phis, and all other
  42  * instructions.
  43  */
  44 @NodeInfo
  45 public abstract class ValueNode extends org.graalvm.compiler.graph.Node implements ValueNodeInterface {
  46 
  47     public static final NodeClass<ValueNode> TYPE = NodeClass.create(ValueNode.class);
  48     /**
  49      * The kind of this value. This is {@link JavaKind#Void} for instructions that produce no value.
  50      * This kind is guaranteed to be a {@linkplain JavaKind#getStackKind() stack kind}.
  51      */
  52     protected Stamp stamp;
  53 
  54     public ValueNode(NodeClass<? extends ValueNode> c, Stamp stamp) {
  55         super(c);
  56         this.stamp = stamp;
  57     }
  58 
  59     public final Stamp stamp() {
  60         return stamp;
  61     }
  62 
  63     public final void setStamp(Stamp stamp) {
  64         this.stamp = stamp;
  65         assert !isAlive() || !inferStamp() : "setStamp called on a node that overrides inferStamp: " + this;
  66     }
  67 
  68     @Override
  69     public final StructuredGraph graph() {
  70         return (StructuredGraph) super.graph();
  71     }
  72 
  73     /**
  74      * Checks if the given stamp is different than the current one (
  75      * {@code newStamp.equals(oldStamp) == false}). If it is different then the new stamp will
  76      * become the current stamp for this node.
  77      *
  78      * @return true if the stamp has changed, false otherwise.
  79      */
  80     protected final boolean updateStamp(Stamp newStamp) {
  81         if (newStamp == null || newStamp.equals(stamp)) {
  82             return false;
  83         } else {
  84             stamp = newStamp;
  85             return true;
  86         }
  87     }
  88 
  89     /**
  90      * This method can be overridden by subclasses of {@link ValueNode} if they need to recompute
  91      * their stamp if their inputs change. A typical implementation will compute the stamp and pass
  92      * it to {@link #updateStamp(Stamp)}, whose return value can be used as the result of this
  93      * method.
  94      *
  95      * @return true if the stamp has changed, false otherwise.
  96      */
  97     public boolean inferStamp() {
  98         return false;
  99     }
 100 
 101     public final JavaKind getStackKind() {
 102         return stamp().getStackKind();
 103     }
 104 
 105     /**
 106      * Checks whether this value is a constant (i.e. it is of type {@link ConstantNode}.
 107      *
 108      * @return {@code true} if this value is a constant
 109      */
 110     public final boolean isConstant() {
 111         return this instanceof ConstantNode;
 112     }
 113 
 114     private static final NodePredicate IS_CONSTANT = new NodePredicate() {
 115         @Override
 116         public boolean apply(Node n) {
 117             return n instanceof ConstantNode;
 118         }
 119     };
 120 
 121     public static NodePredicate isConstantPredicate() {
 122         return IS_CONSTANT;
 123     }
 124 
 125     /**
 126      * Checks whether this value represents the null constant.
 127      *
 128      * @return {@code true} if this value represents the null constant
 129      */
 130     public final boolean isNullConstant() {
 131         JavaConstant value = asJavaConstant();
 132         return value != null && value.isNull();
 133     }
 134 
 135     /**
 136      * Convert this value to a constant if it is a constant, otherwise return null.
 137      *
 138      * @return the {@link JavaConstant} represented by this value if it is a constant; {@code null}
 139      *         otherwise
 140      */
 141     public final Constant asConstant() {
 142         if (this instanceof ConstantNode) {
 143             return ((ConstantNode) this).getValue();
 144         } else {
 145             return null;
 146         }
 147     }
 148 
 149     public final boolean isJavaConstant() {
 150         return isConstant() && asConstant() instanceof JavaConstant;
 151     }
 152 
 153     public final JavaConstant asJavaConstant() {
 154         Constant value = asConstant();
 155         if (value instanceof JavaConstant) {
 156             return (JavaConstant) value;
 157         } else {
 158             return null;
 159         }
 160     }
 161 
 162     @Override
 163     public ValueNode asNode() {
 164         return this;
 165     }
 166 
 167     @Override
 168     public boolean isAllowedUsageType(InputType type) {
 169         if (getStackKind() != JavaKind.Void && type == InputType.Value) {
 170             return true;
 171         } else {
 172             return super.isAllowedUsageType(type);
 173         }
 174     }
 175 
 176     /**
 177      * Checks if this node has usages other than the given node {@code node}.
 178      *
 179      * @param node node which is ignored when searching for usages
 180      * @param nodeValueMap
 181      * @return true if this node has other usages, false otherwise
 182      */
 183     public boolean hasUsagesOtherThan(ValueNode node, NodeValueMap nodeValueMap) {
 184         for (Node usage : usages()) {
 185             if (usage != node && usage instanceof ValueNode && nodeValueMap.hasOperand(usage)) {
 186                 return true;
 187             }
 188         }
 189         return false;
 190     }
 191 
 192     @Override
 193     protected void replaceAtUsages(Node other, Predicate<Node> filter, Node toBeDeleted) {
 194         super.replaceAtUsages(other, filter, toBeDeleted);
 195         assert checkReplaceAtUsagesInvariants(other);
 196     }
 197 
 198     private boolean checkReplaceAtUsagesInvariants(Node other) {
 199         assert other == null || other instanceof ValueNode;
 200         if (this.hasUsages() && !this.stamp().isEmpty() && !(other instanceof PhiNode) && other != null) {
 201             assert ((ValueNode) other).stamp().getClass() == stamp().getClass() : "stamp have to be of same class";
 202             boolean morePrecise = ((ValueNode) other).stamp().join(stamp()).equals(((ValueNode) other).stamp());
 203             assert morePrecise : "stamp can only get more precise " + toString(Verbosity.All) + " " +
 204                             other.toString(Verbosity.All);
 205         }
 206         return true;
 207     }
 208 }