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comparison graal/com.oracle.jvmci.meta/src/com/oracle/jvmci/meta/LocationIdentity.java @ 21556:48c1ebd24120

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renamed com.oracle.graal.api[meta|code] modules to com.oracle.jvmci.[meta|code] (JBS:GRAAL-53)
author Doug Simon <doug.simon@oracle.com>
date Wed, 27 May 2015 00:36:16 +0200
parents graal/com.oracle.graal.api.meta/src/com/oracle/graal/api/meta/LocationIdentity.java@f9024b74dd9e
children
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21555:d12eaef9af72 21556:48c1ebd24120
1 /*
2 * Copyright (c) 2011, 2012, 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 com.oracle.jvmci.meta;
24
25 import java.util.*;
26
27 // JaCoCo Exclude
28
29 /**
30 * Marker interface for location identities. Apart from the special values {@link #ANY_LOCATION} and
31 * {@link #FINAL_LOCATION}, a different location identity of two memory accesses guarantees that the
32 * two accesses do not interfere.
33 *
34 * Clients of {@link LocationIdentity} must use {@link #equals(Object)}, not {@code ==}, when
35 * comparing two {@link LocationIdentity} values for equality. Likewise, they must not use
36 * {@link IdentityHashMap}s with {@link LocationIdentity} values as keys.
37 */
38 public abstract class LocationIdentity {
39
40 /**
41 * Denotes any location. A write to such a location kills all values in a memory map during an
42 * analysis of memory accesses. A read from this location cannot be moved or coalesced with
43 * other reads because its interaction with other reads is not known.
44 */
45 private static final LocationIdentity ANY_LOCATION = NamedLocationIdentity.mutable("ANY_LOCATION");
46
47 /**
48 * Denotes the location of a value that is guaranteed to be unchanging.
49 */
50 public static final LocationIdentity FINAL_LOCATION = NamedLocationIdentity.immutable("FINAL_LOCATION");
51
52 /**
53 * Denotes the location of the length field of a Java array.
54 */
55 public static final LocationIdentity ARRAY_LENGTH_LOCATION = NamedLocationIdentity.immutable("[].length");
56
57 public static LocationIdentity any() {
58 return ANY_LOCATION;
59 }
60
61 /**
62 * Denotes a location is unchanging in all cases. Not that this is different than the Java
63 * notion of final which only requires definite assignment.
64 */
65 public abstract boolean isImmutable();
66
67 public final boolean isMutable() {
68 return !isImmutable();
69 }
70
71 public final boolean isAny() {
72 return this == ANY_LOCATION;
73 }
74
75 public final boolean isSingle() {
76 return this != ANY_LOCATION;
77 }
78
79 public final boolean overlaps(LocationIdentity other) {
80 return isAny() || other.isAny() || this.equals(other);
81 }
82 }