Mercurial > hg > truffle
comparison truffle/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/AssumedValue.java @ 21951:9c8c0937da41
Moving all sources into truffle subdirectory
author | Jaroslav Tulach <jaroslav.tulach@oracle.com> |
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date | Wed, 17 Jun 2015 10:58:08 +0200 |
parents | graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/AssumedValue.java@935de03661c1 |
children | dc83cc1f94f2 |
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21950:2a5011c7e641 | 21951:9c8c0937da41 |
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1 /* | |
2 * Copyright (c) 2013, 2014, 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 value that the compiler can assume is constant, but can be changed by invalidation. | |
33 * <p> | |
34 * Compiled code that uses the value will be invalidated each time the value changes, so you should | |
35 * take care to only change values infrequently, or to monitor the number of times the value has | |
36 * changed and at some point to replace the value with something more generic so that it does not | |
37 * have to be changed and code does not have to keep being recompiled. | |
38 */ | |
39 public class AssumedValue<T> { | |
40 | |
41 private final String name; | |
42 | |
43 @CompilationFinal private T value; | |
44 @CompilationFinal private Assumption assumption; | |
45 | |
46 public AssumedValue(T initialValue) { | |
47 this(null, initialValue); | |
48 } | |
49 | |
50 public AssumedValue(String name, T initialValue) { | |
51 this.name = name; | |
52 value = initialValue; | |
53 assumption = Truffle.getRuntime().createAssumption(name); | |
54 } | |
55 | |
56 /** | |
57 * Get the current value, updating it if it has been {@link #set}. The compiler may be able to | |
58 * make this method return a constant value, but still accommodate mutation. | |
59 */ | |
60 public T get() { | |
61 try { | |
62 assumption.check(); | |
63 } catch (InvalidAssumptionException e) { | |
64 // No need to rewrite anything - just pick up the new values | |
65 } | |
66 | |
67 return value; | |
68 } | |
69 | |
70 /** | |
71 * Set a new value, which will be picked up the next time {@link #get} is called. | |
72 */ | |
73 public void set(T newValue) { | |
74 CompilerDirectives.transferToInterpreter(); | |
75 | |
76 value = newValue; | |
77 final Assumption oldAssumption = assumption; | |
78 assumption = Truffle.getRuntime().createAssumption(name); | |
79 oldAssumption.invalidate(); | |
80 } | |
81 | |
82 } |