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
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17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
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20  * or visit www.oracle.com if you need additional information or have any
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22  */
23 
24 
25 package org.graalvm.compiler.nodes;
26 
27 import java.util.EnumMap;
28 
29 import jdk.internal.vm.compiler.collections.EconomicSet;
30 import jdk.internal.vm.compiler.collections.Equivalence;
31 import jdk.internal.vm.compiler.word.LocationIdentity;
32 
33 import jdk.vm.ci.meta.JavaKind;
34 import jdk.vm.ci.meta.JavaKind.FormatWithToString;
35 
36 /**
37  * A {@link LocationIdentity} with a name.
38  */
39 public class NamedLocationIdentity extends LocationIdentity implements FormatWithToString {
40 
41     /**
42      * Map for asserting all {@link NamedLocationIdentity} instances have a unique name.
43      */
44     static class DB {
45         private static final EconomicSet<String> map = EconomicSet.create(Equivalence.DEFAULT);
46 
checkUnique(String name)47         static boolean checkUnique(String name) {
48             if (!map.add(name)) {
49                 throw new AssertionError("identity " + name + " already exists");
50             }
51             return true;
52         }
53     }
54 
55     /**
56      * Denotes the location of a value that is guaranteed to be unchanging.
57      */
58     public static final LocationIdentity FINAL_LOCATION = NamedLocationIdentity.immutable("FINAL_LOCATION");
59 
60     /**
61      * Denotes the location of the length field of a Java array.
62      */
63     public static final LocationIdentity ARRAY_LENGTH_LOCATION = NamedLocationIdentity.immutable("[].length");
64 
65     /**
66      * Denotes an off-heap address.
67      */
68     public static final LocationIdentity OFF_HEAP_LOCATION = NamedLocationIdentity.mutable("OFF_HEAP_LOCATION");
69 
70     private final String name;
71     private final boolean immutable;
72 
NamedLocationIdentity(String name, boolean immutable)73     protected NamedLocationIdentity(String name, boolean immutable) {
74         this.name = name;
75         this.immutable = immutable;
76         assert DB.checkUnique(name);
77     }
78 
79     /**
80      * Creates a named unique location identity for read and write operations against mutable
81      * memory.
82      *
83      * @param name the name of the new location identity
84      */
mutable(String name)85     public static NamedLocationIdentity mutable(String name) {
86         return create(name, false);
87     }
88 
89     /**
90      * Creates a named unique location identity for read operations against immutable memory.
91      * Immutable memory will never have a visible write in the graph, which is more restrictive than
92      * Java final.
93      *
94      * @param name the name of the new location identity
95      */
immutable(String name)96     public static NamedLocationIdentity immutable(String name) {
97         return create(name, true);
98     }
99 
100     /**
101      * Creates a named unique location identity for read and write operations.
102      *
103      * @param name the name of the new location identity
104      * @param immutable true if the location is immutable
105      */
create(String name, boolean immutable)106     private static NamedLocationIdentity create(String name, boolean immutable) {
107         return new NamedLocationIdentity(name, immutable);
108     }
109 
110     @Override
isImmutable()111     public boolean isImmutable() {
112         return immutable;
113     }
114 
115     @Override
toString()116     public String toString() {
117         return name + (isImmutable() ? ":final" : "");
118     }
119 
120     /**
121      * Returns the named location identity for an array of the given element kind. Array accesses of
122      * the same kind must have the same location identity unless an alias analysis guarantees that
123      * two distinct arrays are accessed.
124      */
getArrayLocation(JavaKind elementKind)125     public static LocationIdentity getArrayLocation(JavaKind elementKind) {
126         return ARRAY_LOCATIONS.get(elementKind);
127     }
128 
129     private static final EnumMap<JavaKind, LocationIdentity> ARRAY_LOCATIONS = initArrayLocations();
130 
initArrayLocations()131     private static EnumMap<JavaKind, LocationIdentity> initArrayLocations() {
132         EnumMap<JavaKind, LocationIdentity> result = new EnumMap<>(JavaKind.class);
133         for (JavaKind kind : JavaKind.values()) {
134             result.put(kind, NamedLocationIdentity.mutable("Array: " + kind.getJavaName()));
135         }
136         return result;
137     }
138 }
139