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/*
 * Copyright (c) 2014, 2015, 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
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 */
package com.oracle.truffle.api.profiles;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;

/**
 * 

* ConditionProfiles are useful to profile the outcome of conditions. *

* *

* Usage example: * *

 * class AbsoluteNode extends Node {
 *
 *     final ConditionProfile greaterZeroProfile = ConditionProfile.create{Binary,Counting}Profile();
 *
 *     void execute(int value) {
 *         if (greaterZeroProfile.profile(value >= 0)) {
 *             return value;
 *         } else {
 *             return -value;
 *         }
 *     }
 * }
 * 
* * {@inheritDoc} * * @see #createBinaryProfile() * @see #createCountingProfile() * @see LoopConditionProfile * @since 0.10 */ public abstract class ConditionProfile extends Profile { ConditionProfile() { } /** @since 0.10 */ public abstract boolean profile(boolean value); /** * Returns a {@link ConditionProfile} that speculates on conditions to be never * true or to be never false. 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() * @since 0.10 */ public static ConditionProfile createCountingProfile() { if (Profile.isProfilingEnabled()) { return Counting.create(); } else { return Disabled.INSTANCE; } } /** * 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() * @since 0.10 */ public static ConditionProfile createBinaryProfile() { if (Profile.isProfilingEnabled()) { return Binary.create(); } else { return Disabled.INSTANCE; } } static final class Disabled extends ConditionProfile { static final ConditionProfile INSTANCE = new Disabled(); @Override protected Object clone() { return INSTANCE; } @Override public boolean profile(boolean value) { return value; } @Override public String toString() { return toStringDisabled(ConditionProfile.class); } } static final class Counting extends ConditionProfile { @CompilationFinal private int trueCount; @CompilationFinal private int falseCount; /** * A constant holding the maximum value an {@code int} can have, 230-1. The sum * of the true and false count must not overflow. This constant is used to check whether one * of the counts does not exceed the required maximum value. */ public static final int MAX_VALUE = 0x3fffffff; Counting() { } @Override public boolean profile(boolean value) { // locals required to guarantee no overflow in multi-threaded environments int t = trueCount; int f = falseCount; if (value) { if (t == 0) { CompilerDirectives.transferToInterpreterAndInvalidate(); } if (CompilerDirectives.inInterpreter()) { if (t < MAX_VALUE) { trueCount = t + 1; } } } else { if (f == 0) { CompilerDirectives.transferToInterpreterAndInvalidate(); } if (CompilerDirectives.inInterpreter()) { if (f < MAX_VALUE) { falseCount = f + 1; } } } if (CompilerDirectives.inInterpreter()) { // no branch probability calculation in the interpreter return value; } else { int sum = t + f; return CompilerDirectives.injectBranchProbability((double) t / (double) sum, value); } } int getTrueCount() { return trueCount; } int getFalseCount() { return falseCount; } @Override public String toString() { int t = trueCount; int f = falseCount; int sum = t + f; String details = String.format("trueProbability=%s (trueCount=%s, falseCount=%s)", (double) t / (double) sum, t, f); return toString(ConditionProfile.class, sum == 0, false, details); } /* Needed for lazy class loading. */ static ConditionProfile create() { return new Counting(); } } /** * Utility class to speculate 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#createBinaryProfile() */ static final class Binary extends ConditionProfile { @CompilationFinal private boolean wasTrue; @CompilationFinal private boolean wasFalse; Binary() { } @Override public boolean profile(boolean value) { if (value) { if (!wasTrue) { CompilerDirectives.transferToInterpreterAndInvalidate(); wasTrue = true; } return true; } else { if (!wasFalse) { CompilerDirectives.transferToInterpreterAndInvalidate(); wasFalse = true; } return false; } } boolean wasTrue() { return wasTrue; } boolean wasFalse() { return wasFalse; } @Override public String toString() { return String.format("%s(wasTrue=%s, wasFalse=%s)@%x", getClass().getSimpleName(), wasTrue, wasFalse, hashCode()); } /* Needed for lazy class loading. */ static ConditionProfile create() { return new Binary(); } } }




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