Mercurial > hg > graal-compiler
view graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/ConditionProfile.java @ 21586:6da76343d830
Merge.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Fri, 29 May 2015 12:09:07 +0200 |
parents | 7d998dd2d1b0 |
children |
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/* * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.oracle.truffle.api.utilities; import com.oracle.truffle.api.*; import com.oracle.truffle.api.nodes.*; /** * Abstract utility class to speculate on conditions. Condition profiles are intended to be used as * part of if conditions. * * Example usage: * * <pre> * private final ConditionProfile zero = ConditionProfile.createBinaryProfile(); * * int value = ...; * if (zero.profile(value == 0)) { * return 0; * } else { * return value; * } * * </pre> * * All instances of {@code ConditionProfile} (and subclasses) must be held in {@code final} fields * for compiler optimizations to take effect. * * @see #createCountingProfile() * @see #createBinaryProfile() */ public abstract class ConditionProfile extends NodeCloneable { ConditionProfile() { } public abstract boolean profile(boolean value); /** * Returns a {@link ConditionProfile} that speculates on conditions to be never * <code>true</code> or to be never <code>false</code>. Additionally to a binary profile this * method returns a condition profile that also counts the number of times the condition was * true and false. This information is reported to the underlying optimization system using * {@link CompilerDirectives#injectBranchProbability(double, boolean)}. Condition profiles are * intended to be used as part of if conditions. * * @see ConditionProfile * @see #createBinaryProfile() */ public static ConditionProfile createCountingProfile() { return new CountingConditionProfile(); } /** * Returns a {@link ConditionProfile} that speculates on conditions to be never true or to be * never false. Condition profiles are intended to be used as part of if conditions. * * @see ConditionProfile * @see ConditionProfile#createCountingProfile() */ public static ConditionProfile createBinaryProfile() { return new BinaryConditionProfile(); } }