Mercurial > hg > graal-jvmci-8
view graal/com.oracle.truffle.api/src/com/oracle/truffle/api/CompilerDirectives.java @ 20804:7848fc12602b
Merge with jdk8u40-b25
author | Gilles Duboscq <gilles.m.duboscq@oracle.com> |
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date | Tue, 07 Apr 2015 14:58:49 +0200 |
parents | 9c4168877444 |
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/* * Copyright (c) 2013, 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 * questions. */ package com.oracle.truffle.api; import java.lang.annotation.*; import java.util.concurrent.*; /** * Directives that influence the optimizations of the Truffle compiler. All of the operations have * no effect when executed in the Truffle interpreter. */ public final class CompilerDirectives { public static final double LIKELY_PROBABILITY = 0.75; public static final double UNLIKELY_PROBABILITY = 1.0 - LIKELY_PROBABILITY; public static final double SLOWPATH_PROBABILITY = 0.0001; public static final double FASTPATH_PROBABILITY = 1.0 - SLOWPATH_PROBABILITY; /** * Directive for the compiler to discontinue compilation at this code position and instead * insert a transfer to the interpreter. */ public static void transferToInterpreter() { if (inInterpreter()) { Truffle.getRuntime().notifyTransferToInterpreter(); } } /** * Directive for the compiler to discontinue compilation at this code position and instead * insert a transfer to the interpreter, invalidating the currently executing machine code. */ public static void transferToInterpreterAndInvalidate() { if (inInterpreter()) { Truffle.getRuntime().notifyTransferToInterpreter(); } } /** * Returns a boolean value indicating whether the method is executed in the interpreter. * * @return {@code true} when executed in the interpreter, {@code false} in compiled code. */ public static boolean inInterpreter() { return true; } /** * Returns a boolean value indicating whether the method is executed in the compiled code. * * @return {@code false} when executed in the interpreter, {@code true} in compiled code. */ public static boolean inCompiledCode() { return false; } /** * Returns a boolean indicating whether or not a given value is seen as constant in optimized * code. If this method is called in the interpreter this method will always return * <code>true</code>. * * Note that optimizations that a compiler will apply to code that is conditional on * <code>isCompilationConstant</code> may be limited. For this reason * <code>isCompilationConstant</code> is not recommended for use to select between alternate * implementations of functionality depending on whether a value is constant. Instead, it is * intended for use as a diagnostic mechanism. * * @param value * @return {@code true} when given value is seen as compilation constant, {@code false} if not * compilation constant. */ public static boolean isCompilationConstant(Object value) { return CompilerDirectives.inInterpreter(); } /** * Directive for the compiler that the given runnable should only be executed in the interpreter * and ignored in the compiled code. * * @param runnable the closure that should only be executed in the interpreter */ public static void interpreterOnly(Runnable runnable) { runnable.run(); } /** * Directive for the compiler that the given callable should only be executed in the * interpreter. * * @param callable the closure that should only be executed in the interpreter * @return the result of executing the closure in the interpreter and null in the compiled code * @throws Exception If the closure throws an exception when executed in the interpreter. */ public static <T> T interpreterOnly(Callable<T> callable) throws Exception { return callable.call(); } /** * Injects a probability for the given condition into the probability information of the * immediately succeeding branch instruction for the condition. The probability must be a value * between 0.0 and 1.0 (inclusive). The condition should not be a combined condition. * * Example usage immediately before an if statement (it specifies that the likelihood for a to * be greater than b is 90%): * * <code> * if (injectBranchProbability(0.9, a > b)) { * // ... * } * </code> * * Example usage for a combined condition (it specifies that the likelihood for a to be greater * than b is 90% and under the assumption that this is true, the likelihood for a being 0 is * 10%): * * <code> * if (injectBranchProbability(0.9, a > b) && injectBranchProbability(0.1, a == 0)) { * // ... * } * </code> * * There are predefined constants for commonly used probabilities (see * {@link #LIKELY_PROBABILITY} , {@link #UNLIKELY_PROBABILITY}, {@link #SLOWPATH_PROBABILITY}, * {@link #FASTPATH_PROBABILITY} ). * * @param probability the probability value between 0.0 and 1.0 that should be injected */ public static boolean injectBranchProbability(double probability, boolean condition) { assert probability >= 0.0 && probability <= 1.0; return condition; } /** * Bails out of a compilation (e.g., for guest language features that should never be compiled). * * @param reason the reason for the bailout */ public static void bailout(String reason) { } /** * Marks fields that should be considered final for a Truffle compilation although they are not * final while executing in the interpreter. */ @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.FIELD}) public @interface CompilationFinal { } /** * Marks a method that it is considered as a boundary for Truffle partial evaluation. */ @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.METHOD, ElementType.CONSTRUCTOR}) public @interface TruffleBoundary { } /** * Marks classes as value types. Reference comparisons (==) between instances of those classes * have undefined semantics and can either return true or false. */ @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.TYPE}) public @interface ValueType { } /** * Ensures that the given object is not virtual, i.e., not removed by Escape Analysis at the * point of this call. * * @param obj the object to exclude from Escape Analysis */ public static void materialize(Object obj) { } }