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comparison truffle/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/ConditionProfile.java @ 21951:9c8c0937da41

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Moving all sources into truffle subdirectory
author Jaroslav Tulach <jaroslav.tulach@oracle.com>
date Wed, 17 Jun 2015 10:58:08 +0200
parents graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/ConditionProfile.java@7d998dd2d1b0
children dc83cc1f94f2
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21950:2a5011c7e641 21951:9c8c0937da41
1 /*
2 * Copyright (c) 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.nodes.*;
29
30 /**
31 * Abstract utility class to speculate on conditions. Condition profiles are intended to be used as
32 * part of if conditions.
33 *
34 * Example usage:
35 *
36 * <pre>
37 * private final ConditionProfile zero = ConditionProfile.createBinaryProfile();
38 *
39 * int value = ...;
40 * if (zero.profile(value == 0)) {
41 * return 0;
42 * } else {
43 * return value;
44 * }
45 *
46 * </pre>
47 *
48 * All instances of {@code ConditionProfile} (and subclasses) must be held in {@code final} fields
49 * for compiler optimizations to take effect.
50 *
51 * @see #createCountingProfile()
52 * @see #createBinaryProfile()
53 */
54 public abstract class ConditionProfile extends NodeCloneable {
55 ConditionProfile() {
56 }
57
58 public abstract boolean profile(boolean value);
59
60 /**
61 * Returns a {@link ConditionProfile} that speculates on conditions to be never
62 * <code>true</code> or to be never <code>false</code>. Additionally to a binary profile this
63 * method returns a condition profile that also counts the number of times the condition was
64 * true and false. This information is reported to the underlying optimization system using
65 * {@link CompilerDirectives#injectBranchProbability(double, boolean)}. Condition profiles are
66 * intended to be used as part of if conditions.
67 *
68 * @see ConditionProfile
69 * @see #createBinaryProfile()
70 */
71 public static ConditionProfile createCountingProfile() {
72 return new CountingConditionProfile();
73 }
74
75 /**
76 * Returns a {@link ConditionProfile} that speculates on conditions to be never true or to be
77 * never false. Condition profiles are intended to be used as part of if conditions.
78 *
79 * @see ConditionProfile
80 * @see ConditionProfile#createCountingProfile()
81 */
82 public static ConditionProfile createBinaryProfile() {
83 return new BinaryConditionProfile();
84 }
85 }