1 /*
   2  * Copyright (c) 2009, 2015, 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 jdk.vm.ci.meta;
  24 
  25 /**
  26  * Abstract base class for values.
  27  */
  28 public abstract class Value {
  29 
  30     public static final Value[] NO_VALUES = new Value[0];
  31 
  32     public static final AllocatableValue ILLEGAL = new IllegalValue();
  33 
  34     private static final class IllegalValue extends AllocatableValue {
  35         private IllegalValue() {
  36             super(LIRKind.Illegal);
  37         }
  38 
  39         @Override
  40         public String toString() {
  41             return "-";
  42         }
  43 
  44         @Override
  45         public boolean equals(Object other) {
  46             // Due to de-serialization this object may exist multiple times. So we compare classes
  47             // instead of the individual objects. (This anonymous class has always the same meaning)
  48             return other instanceof IllegalValue;
  49         }
  50     }
  51 
  52     private final LIRKind lirKind;
  53 
  54     /**
  55      * Initializes a new value of the specified kind.
  56      *
  57      * @param lirKind the kind
  58      */
  59     protected Value(LIRKind lirKind) {
  60         this.lirKind = lirKind;
  61     }
  62 
  63     /**
  64      * Returns a String representation of the kind, which should be the end of all
  65      * {@link #toString()} implementation of subclasses.
  66      */
  67     protected final String getKindSuffix() {
  68         return "|" + getPlatformKind().getTypeChar();
  69     }
  70 
  71     public final LIRKind getLIRKind() {
  72         return lirKind;
  73     }
  74 
  75     /**
  76      * Returns the platform specific kind used to store this value.
  77      */
  78     public final PlatformKind getPlatformKind() {
  79         return lirKind.getPlatformKind();
  80     }
  81 
  82     @Override
  83     public int hashCode() {
  84         return 41 + lirKind.hashCode();
  85     }
  86 
  87     @Override
  88     public boolean equals(Object obj) {
  89         if (obj instanceof Value) {
  90             Value that = (Value) obj;
  91             return lirKind.equals(that.lirKind);
  92         }
  93         return false;
  94     }
  95 
  96     /**
  97      * Checks if this value is identical to {@code other}.
  98      *
  99      * Warning: Use with caution! Usually equivalence {@link #equals(Object)} is sufficient and
 100      * should be used.
 101      */
 102     public final boolean identityEquals(Value other) {
 103         return this == other;
 104     }
 105 }