Mercurial > hg > graal-compiler
comparison graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/AssumedValue.java @ 13325:f28ea693056f
New assumption utilities.
author | Chris Seaton <chris.seaton@oracle.com> |
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date | Fri, 13 Dec 2013 15:53:30 +0000 |
parents | |
children | 0e7894989f37 |
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13324:e585ac5a385d | 13325:f28ea693056f |
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1 /* | |
2 * Copyright (c) 2013, 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. Oracle designates this | |
8 * particular file as subject to the "Classpath" exception as provided | |
9 * by Oracle in the LICENSE file that accompanied this code. | |
10 * | |
11 * This code is distributed in the hope that it will be useful, but WITHOUT | |
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 * version 2 for more details (a copy is included in the LICENSE file that | |
15 * accompanied this code). | |
16 * | |
17 * You should have received a copy of the GNU General Public License version | |
18 * 2 along with this work; if not, write to the Free Software Foundation, | |
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
20 * | |
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
22 * or visit www.oracle.com if you need additional information or have any | |
23 * questions. | |
24 */ | |
25 package com.oracle.truffle.api.utilities; | |
26 | |
27 import com.oracle.truffle.api.*; | |
28 import com.oracle.truffle.api.CompilerDirectives.CompilationFinal; | |
29 import com.oracle.truffle.api.nodes.*; | |
30 | |
31 /** | |
32 * A {@link CompilationFinal} value combined with an {@link Assumption} to notify when it changes. | |
33 * Note that you should be careful that modifications to this value do not cause deoptimization | |
34 * loops. This could be by using a value that is monotonic. | |
35 */ | |
36 public class AssumedValue<T> { | |
37 | |
38 @CompilationFinal private T value; | |
39 private final CyclicAssumption assumption; | |
40 | |
41 public AssumedValue(String name, T initialValue) { | |
42 assumption = new CyclicAssumption(name); | |
43 value = initialValue; | |
44 } | |
45 | |
46 /** | |
47 * Get the current value, updating it if it has been {@link #set}. The compiler may be able to | |
48 * make this method return a constant value, but still accommodate mutation. | |
49 */ | |
50 public T get() { | |
51 try { | |
52 assumption.getAssumption().check(); | |
53 } catch (InvalidAssumptionException e) { | |
54 // No need to rewrite anything - just pick up the new value | |
55 } | |
56 | |
57 return value; | |
58 } | |
59 | |
60 /** | |
61 * Set a new value, which will be picked up the next time {@link #get} is called. | |
62 */ | |
63 public void set(T newValue) { | |
64 value = newValue; | |
65 assumption.invalidate(); | |
66 } | |
67 | |
68 } |