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 import java.util.HashSet;
  27 
  28 import org.graalvm.compiler.core.common.LocationIdentity;
  29 
  30 import jdk.vm.ci.meta.JavaKind;
  31 import jdk.vm.ci.meta.JavaKind.FormatWithToString;
  32 
  33 /**
  34  * A {@link LocationIdentity} with a name.
  35  */
  36 public class NamedLocationIdentity extends LocationIdentity implements FormatWithToString {
  37 
  38     /**
  39      * Map for asserting all {@link NamedLocationIdentity} instances have a unique name.
  40      */
  41     static class DB {
  42         private static final HashSet<String> map = new HashSet<>();
  43 
  44         static boolean checkUnique(String name) {
  45             if (!map.add(name)) {
  46                 throw new AssertionError("identity " + name + " already exists");
  47             }
  48             return true;
  49         }
  50     }
  51 
  52     /**
  53      * Denotes the location of a value that is guaranteed to be unchanging.
  54      */
  55     public static final LocationIdentity FINAL_LOCATION = NamedLocationIdentity.immutable("FINAL_LOCATION");
  56 
  57     /**
  58      * Denotes the location of the length field of a Java array.
  59      */
  60     public static final LocationIdentity ARRAY_LENGTH_LOCATION = NamedLocationIdentity.immutable("[].length");
  61 
  62     public static LocationIdentity any() {
  63         return ANY_LOCATION;
  64     }
  65 
  66     private final String name;
  67     private final boolean immutable;
  68 
  69     protected NamedLocationIdentity(String name, boolean immutable) {
  70         this.name = name;
  71         this.immutable = immutable;
  72         assert DB.checkUnique(name);
  73     }
  74 
  75     /**
  76      * Creates a named unique location identity for read and write operations against mutable
  77      * memory.
  78      *
  79      * @param name the name of the new location identity
  80      */
  81     public static NamedLocationIdentity mutable(String name) {
  82         return create(name, false);
  83     }
  84 
  85     /**
  86      * Creates a named unique location identity for read operations against immutable memory.
  87      * Immutable memory will never have a visible write in the graph, which is more restictive than
  88      * Java final.
  89      *
  90      * @param name the name of the new location identity
  91      */
  92     public static NamedLocationIdentity immutable(String name) {
  93         return create(name, true);
  94     }
  95 
  96     /**
  97      * Creates a named unique location identity for read and write operations.
  98      *
  99      * @param name the name of the new location identity
 100      * @param immutable true if the location is immutable
 101      */
 102     private static NamedLocationIdentity create(String name, boolean immutable) {
 103         return new NamedLocationIdentity(name, immutable);
 104     }
 105 
 106     @Override
 107     public boolean isImmutable() {
 108         return immutable;
 109     }
 110 
 111     @Override
 112     public String toString() {
 113         return name + (isImmutable() ? ":final" : "");
 114     }
 115 
 116     /**
 117      * Returns the named location identity for an array of the given element kind. Array accesses of
 118      * the same kind must have the same location identity unless an alias analysis guarantees that
 119      * two distinct arrays are accessed.
 120      */
 121     public static LocationIdentity getArrayLocation(JavaKind elementKind) {
 122         return ARRAY_LOCATIONS.get(elementKind);
 123     }
 124 
 125     private static final EnumMap<JavaKind, LocationIdentity> ARRAY_LOCATIONS = initArrayLocations();
 126 
 127     private static EnumMap<JavaKind, LocationIdentity> initArrayLocations() {
 128         EnumMap<JavaKind, LocationIdentity> result = new EnumMap<>(JavaKind.class);
 129         for (JavaKind kind : JavaKind.values()) {
 130             result.put(kind, NamedLocationIdentity.mutable("Array: " + kind.getJavaName()));
 131         }
 132         return result;
 133     }
 134 }