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Truffle is a multi-language framework for executing dynamic languages
that achieves high performance when combined with Graal.
/*
* Copyright (c) 2013, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* The Universal Permissive License (UPL), Version 1.0
*
* Subject to the condition set forth below, permission is hereby granted to any
* person obtaining a copy of this software, associated documentation and/or
* data (collectively the "Software"), free of charge and under any and all
* copyright rights in the Software, and any and all patent rights owned or
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* unmodified Software as contributed to or provided by such licensor, or (ii)
* the Larger Works (as defined below), to deal in both
*
* (a) the Software, and
*
* (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
* one is included with the Software each a "Larger Work" to which the Software
* is contributed by such licensors),
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* Software and the Larger Work(s), and to sublicense the foregoing rights on
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* The above copyright notice and either this complete permission notice or at a
* minimum a reference to the UPL must be included in all copies or substantial
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package com.oracle.truffle.api;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.Objects;
import java.util.concurrent.Callable;
/**
* Directives that influence the optimizations of the Truffle compiler. All of the operations have
* no effect when executed in the Truffle interpreter.
*
* @since 0.8 or earlier
*/
public final class CompilerDirectives {
private CompilerDirectives() {
}
/** @since 0.8 or earlier */
public static final double LIKELY_PROBABILITY = 0.75;
/** @since 0.8 or earlier */
public static final double UNLIKELY_PROBABILITY = 1.0 - LIKELY_PROBABILITY;
/** @since 0.8 or earlier */
public static final double SLOWPATH_PROBABILITY = 0.0001;
/** @since 0.8 or earlier */
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.
*
* @since 0.8 or earlier
*/
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.
*
* @since 0.8 or earlier
*/
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.
* @since 0.8 or earlier
*/
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.
* @since 0.8 or earlier
*/
public static boolean inCompiledCode() {
return false;
}
/**
* Returns a boolean value indicating whether the method is executed in the root of a Truffle
* compilation.
*
* @return {@code false} when executed in the interpreter or in an inlined {@link CallTarget},
* {@code true} when in non-inlined compiled code.
* @since 0.28 or earlier
*/
public static boolean inCompilationRoot() {
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
* true.
*
* Note that optimizations that a compiler will apply to code that is conditional on
* isCompilationConstant may be limited. For this reason
* isCompilationConstant 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.
* @since 0.8 or earlier
*/
public static boolean isCompilationConstant(Object value) {
return CompilerDirectives.inInterpreter();
}
/**
* Returns a boolean indicating whether or not a given value is seen as constant during the
* initial partial evaluation phase. If this method is called in the interpreter this method
* will always return true.
*
* @param value
* @return {@code true} when given value is seen as compilation constant, {@code false} if not
* compilation constant.
* @since 0.8 or earlier
*/
public static boolean isPartialEvaluationConstant(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
* @since 0.8 or earlier
*/
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.
* @since 0.8 or earlier
*/
public static T interpreterOnly(Callable 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%):
*
*
* if (injectBranchProbability(0.9, a > b)) {
* // ...
* }
*
*
* 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%):
*
*
* if (injectBranchProbability(0.9, a > b) && injectBranchProbability(0.1, a == 0)) {
* // ...
* }
*
*
* 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
* @since 0.8 or earlier
*/
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
* @since 0.8 or earlier
*/
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. If the field type is an array type, the compiler
* considers reads with a constant index as constants.
*
* @since 0.8 or earlier
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD})
public @interface CompilationFinal {
/**
* Specifies the number of array dimensions to be marked as compilation final.
*
* This value should be specified for all array-typed compilation-final fields and should be
* left unspecified for other field types for which it has no meaning.
*
* The allowed range is from 0 to the number of declared array dimensions (inclusive).
* Specifically, a {@code dimensions} value of 0 marks only the reference to the (outermost)
* array as final but not its elements, a value of 1 marks the outermost array and all its
* elements as final but not the elements of any nested arrays.
*
* For compatibility reasons, array-typed fields without an explicit {@code dimensions}
* parameter default to the number of array dimensions declared in the field type.
*
* @since 0.14
*/
int dimensions() default -1;
}
/**
* Marks a method that it is considered as a boundary for Truffle partial evaluation.
*
* @since 0.8 or earlier
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
public @interface TruffleBoundary {
/**
* Determines whether execution should be transferred to the interpreter if an exception is
* thrown across this boundary, in which case the caller's compiled code is invalidated and
* will not transfer to the interpreter on exceptions for this method again.
*
* @since 0.28
*/
boolean transferToInterpreterOnException() default true;
/**
* Considers this Truffle boundary invoke as an inlining candidate.
*
* Partial evaluation cannot inline a boundary, but a later inlining pass can.
*
* @since 0.27
*/
boolean allowInlining() default false;
}
/**
* Marks classes as value types. Reference comparisons (==) between instances of those classes
* have undefined semantics and can either return true or false.
*
* @since 0.8 or earlier
*/
@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
* @since 0.8 or earlier
*/
public static void materialize(Object obj) {
}
/**
* Ensures that the given object will be virtual (escape analyzed) at all points that are
* dominated by the current position.
*
* @since 0.8 or earlier
*/
public static void ensureVirtualized(@SuppressWarnings("unused") Object object) {
}
/**
* Ensures that the given object will be virtual at the current position.
*
* @since 0.8 or earlier
*/
public static void ensureVirtualizedHere(@SuppressWarnings("unused") Object object) {
}
/**
* Casts the given object to the exact class represented by {@code clazz}. The cast succeeds
* only if {@code object == null || object.getClass() == clazz} and thus fails for any subclass.
*
* @param object the object to be cast
* @param clazz the class to check against, must not be null
* @return the object after casting
* @throws ClassCastException if the object is non-null and not exactly of the given class
* @throws NullPointerException if the class argument is null
* @since 0.33
* @see Class#cast(Object)
*/
@SuppressWarnings("unchecked")
public static T castExact(Object object, Class clazz) {
Objects.requireNonNull(clazz);
if (object == null || object.getClass() == clazz) {
return (T) object;
} else {
throw new ClassCastException();
}
}
/**
* Indicates a code path that is not supposed to be reached during compilation or
* interpretation. Reaching this method is considered a fatal internal error and execution
* should not continue. Transfers to interpreter and
* {@link CompilerDirectives#transferToInterpreterAndInvalidate() invalidates} the compiled code
* and always throws an {@link AssertionError} when invoked.
*
* This method returns a runtime exception to be conveniently used in combination with Java
* throw statements, for example:
*
*
* if (expectedCondition) {
* return 42;
* } else {
* throw shouldNotReachHere();
* }
*
*
* @since 20.2
*/
public static RuntimeException shouldNotReachHere() {
transferToInterpreterAndInvalidate();
throw shouldNotReachHere(null, null);
}
/**
* Indicates a code path that is not supposed to be reached during compilation or
* interpretation. Reaching this method is considered a fatal internal error and execution
* should not continue. Transfers to interpreter and
* {@link CompilerDirectives#transferToInterpreterAndInvalidate() invalidates} the compiled code
* and always throws an {@link AssertionError} when invoked.
*
* This method returns a runtime exception to be conveniently used in combination with Java
* throw statements, for example:
*
*
* if (expectedCondition) {
* return 42;
* } else {
* throw shouldNotReachHere("Additional message");
* }
*
*
* @param message an additional message for the exception thrown.
* @since 20.2
*/
public static RuntimeException shouldNotReachHere(String message) {
transferToInterpreterAndInvalidate();
throw shouldNotReachHere(message, null);
}
/**
* Indicates a code path that is not supposed to be reached during compilation or
* interpretation. Reaching this method is considered a fatal internal error and execution
* should not continue. Transfers to interpreter and
* {@link CompilerDirectives#transferToInterpreterAndInvalidate() invalidates} the compiled code
* and always throws an {@link AssertionError} when invoked.
*
* This method returns a runtime exception to be conveniently used in combination with Java
* throw statements, for example:
*
*
* if (expectedCondition) {
* return 42;
* } else {
* throw shouldNotReachHere("Additional message");
* }
*
*
* @param cause the cause if an exception was responsible for the unexpected case.
* @since 20.2
*/
public static RuntimeException shouldNotReachHere(Throwable cause) {
transferToInterpreterAndInvalidate();
throw shouldNotReachHere(null, cause);
}
/**
* Indicates a code path that is not supposed to be reached during compilation or
* interpretation. Reaching this method is considered a fatal internal error and execution
* should not continue. Transfers to interpreter and
* {@link CompilerDirectives#transferToInterpreterAndInvalidate() invalidates} the compiled code
* and always throws an {@link AssertionError} when invoked.
*
* This method returns a runtime exception to be conveniently used in combination with Java
* throw statements, for example:
*
*
* if (expectedCondition) {
* return 42;
* } else {
* throw shouldNotReachHere("Additional message");
* }
*
*
* @param message an additional message for the exception thrown.
* @param cause the cause if an exception was responsible for the unexpected case.
*
* @since 20.2
*/
public static RuntimeException shouldNotReachHere(String message, Throwable cause) {
transferToInterpreterAndInvalidate();
throw new ShouldNotReachHere(message, cause);
}
@SuppressWarnings("serial")
static final class ShouldNotReachHere extends AssertionError {
ShouldNotReachHere(String message, Throwable cause) {
super(message, cause);
}
}
}