1 /*
   2  * Copyright (c) 2011, 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.EnumMap;
  26 
  27 import org.graalvm.util.Equivalence;
  28 import org.graalvm.word.LocationIdentity;
  29 import org.graalvm.util.EconomicSet;
  30 
  31 import jdk.vm.ci.meta.JavaKind;
  32 import jdk.vm.ci.meta.JavaKind.FormatWithToString;
  33 
  34 /**
  35  * A {@link LocationIdentity} with a name.
  36  */
  37 public class NamedLocationIdentity extends LocationIdentity implements FormatWithToString {
  38 
  39     /**
  40      * Map for asserting all {@link NamedLocationIdentity} instances have a unique name.
  41      */
  42     static class DB {
  43         private static final EconomicSet<String> map = EconomicSet.create(Equivalence.DEFAULT);
  44 
  45         static boolean checkUnique(String name) {
  46             if (!map.add(name)) {
  47                 throw new AssertionError("identity " + name + " already exists");
  48             }
  49             return true;
  50         }
  51     }
  52 
  53     /**
  54      * Denotes the location of a value that is guaranteed to be unchanging.
  55      */
  56     public static final LocationIdentity FINAL_LOCATION = NamedLocationIdentity.immutable("FINAL_LOCATION");
  57 
  58     /**
  59      * Denotes the location of the length field of a Java array.
  60      */
  61     public static final LocationIdentity ARRAY_LENGTH_LOCATION = NamedLocationIdentity.immutable("[].length");
  62 
  63     private final String name;
  64     private final boolean immutable;
  65 
  66     protected NamedLocationIdentity(String name, boolean immutable) {
  67         this.name = name;
  68         this.immutable = immutable;
  69         assert DB.checkUnique(name);
  70     }
  71 
  72     /**
  73      * Creates a named unique location identity for read and write operations against mutable
  74      * memory.
  75      *
  76      * @param name the name of the new location identity
  77      */
  78     public static NamedLocationIdentity mutable(String name) {
  79         return create(name, false);
  80     }
  81 
  82     /**
  83      * Creates a named unique location identity for read operations against immutable memory.
  84      * Immutable memory will never have a visible write in the graph, which is more restictive than
  85      * Java final.
  86      *
  87      * @param name the name of the new location identity
  88      */
  89     public static NamedLocationIdentity immutable(String name) {
  90         return create(name, true);
  91     }
  92 
  93     /**
  94      * Creates a named unique location identity for read and write operations.
  95      *
  96      * @param name the name of the new location identity
  97      * @param immutable true if the location is immutable
  98      */
  99     private static NamedLocationIdentity create(String name, boolean immutable) {
 100         return new NamedLocationIdentity(name, immutable);
 101     }
 102 
 103     @Override
 104     public boolean isImmutable() {
 105         return immutable;
 106     }
 107 
 108     @Override
 109     public String toString() {
 110         return name + (isImmutable() ? ":final" : "");
 111     }
 112 
 113     /**
 114      * Returns the named location identity for an array of the given element kind. Array accesses of
 115      * the same kind must have the same location identity unless an alias analysis guarantees that
 116      * two distinct arrays are accessed.
 117      */
 118     public static LocationIdentity getArrayLocation(JavaKind elementKind) {
 119         return ARRAY_LOCATIONS.get(elementKind);
 120     }
 121 
 122     private static final EnumMap<JavaKind, LocationIdentity> ARRAY_LOCATIONS = initArrayLocations();
 123 
 124     private static EnumMap<JavaKind, LocationIdentity> initArrayLocations() {
 125         EnumMap<JavaKind, LocationIdentity> result = new EnumMap<>(JavaKind.class);
 126         for (JavaKind kind : JavaKind.values()) {
 127             result.put(kind, NamedLocationIdentity.mutable("Array: " + kind.getJavaName()));
 128         }
 129         return result;
 130     }
 131 }