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package com.oracle.truffle.api.library;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
The cached library annotation allows to use Truffle
Libraries conveniently in specializations or
exported messages. It is designed as the primary way of using libraries. The CachedLibrary annotation may be used for any parameters of methods annotated with @Specialization or @ExportMessage. Using Specialized Libraries
A cached library can be specialized for a value that is referred to with the
value expression attribute. A specialized library implicitly prepends a guard for the acceptance of a library with the provided value expression. Adding the acceptance guard leads to multiple specialization instances as it binds to the cached library value. The specialization or
export limit attribute must therefore be specified. If this limit overflows then the operation will rewrite itself to an uncached version of the library. Multiple specialized libraries may be used per export or specialization. The acceptance guards for these libraries will be added in the order of their declaration.
Usage:
@NodeChild
@NodeChild
abstract static class ArrayReadNode extends ExpressionNode {
@Specialization(guards = "arrays.isArray(array)", limit = "2")
int doDefault(Object array, int index,
@CachedLibrary("array") ArrayLibrary arrays) {
return arrays.read(array, index);
}
}
It is recommended to use the plural of the specialized parameter name as naming convention for
the library parameter name, e.g. a library for an array value is called
arrays. If multiple libraries are specialized for the same specialized expression it
is recommended to prepend the library name e.g. interopArrays.
Using Dispatched Libraries
If no specialized value expression can be specified, i.e. if the value is computed as part of the operation, then a dispatched version of a library can be used by omitting the
value attribute and specifying the limit() attribute instead. A dispatched library builds the specialized value inline cache internally for each invocation of a message instead of once per outer specialization or export. An instance of a dispatched library therefore accepts any value as receiver. It is recommended to use the same generic library instance for few message invocations of similar values only, could lead to duplication of inline cache dispatches in the compiled code. The limit of a dispatched library may be set to 0 to directly switch to an uncached version of a library.
Usage:
The following example combines the use of specialized and dispatched libraries. In this example
the array is read twice. For the first outer read the specializing expression can be used.
For the second read the specializing expression cannot be used as it depends on the result of the
outer read. We therefore use a dispatched library for the inner array.
@NodeChild
@NodeChild
@NodeChild
abstract static class TwoDimReadNode extends ExpressionNode {
@Specialization(guards = "outerArrays.isArray(array)", limit = "2")
int doDefault(Object array, int outerIndex, int innerIndex,
@CachedLibrary("array") ArrayLibrary outerArrays,
@CachedLibrary(limit = "2") ArrayLibrary innerArrays) {
return innerArrays.read(outerArrays.read(outerIndex), innerIndex);
}
}
See Also: Since: 19.0
/**
* The cached library annotation allows to use {@link com.oracle.truffle.api.library Truffle
* Libraries} conveniently in {@link Specialization specializations} or {@link ExportMessage
* exported messages}. It is designed as the primary way of using libraries. The
* {@link CachedLibrary} annotation may be used for any parameters of methods annotated with
* {@linkplain Specialization @Specialization} or {@linkplain ExportMessage @ExportMessage}.
*
* <h3>Using Specialized Libraries</h3>
*
* A cached library can be specialized for a value that is referred to with the {@link #value()
* value expression} attribute. A specialized library implicitly prepends a guard for the
* {@link Library#accepts(Object) acceptance} of a library with the provided value expression.
* Adding the acceptance guard leads to multiple specialization instances as it binds to the cached
* library value. The {@link Specialization#limit() specialization} or {@link ExportMessage#limit()
* export} limit attribute must therefore be specified. If this limit overflows then the operation
* will rewrite itself to an {@link LibraryFactory#getUncached(Object) uncached} version of the
* library. Multiple specialized libraries may be used per export or specialization. The acceptance
* guards for these libraries will be added in the order of their declaration.
* <p>
* <h4>Usage:</h4>
*
* <pre>
* @NodeChild
* @NodeChild
* abstract static class ArrayReadNode extends ExpressionNode {
* @Specialization(guards = "arrays.isArray(array)", limit = "2")
* int doDefault(Object array, int index,
* @CachedLibrary("array") ArrayLibrary arrays) {
* return arrays.read(array, index);
* }
* }
* </pre>
*
* <p>
* It is recommended to use the plural of the specialized parameter name as naming convention for
* the library parameter name, e.g. a library for an <code>array</code> value is called
* <code>arrays</code>. If multiple libraries are specialized for the same specialized expression it
* is recommended to prepend the library name e.g. <code>interopArrays</code>.
*
* <h3>Using Dispatched Libraries</h3>
* <p>
* If no specialized value expression can be specified, i.e. if the value is computed as part of the
* operation, then a dispatched version of a library can be used by omitting the {@link #value()
* value} attribute and specifying the {@link #limit()} attribute instead. A dispatched library
* builds the specialized value inline cache internally for each invocation of a message instead of
* once per outer specialization or export. An instance of a dispatched library therefore
* {@link Library#accepts(Object) accepts} any value as receiver. It is recommended to use the same
* generic library instance for few message invocations of similar values only, could lead to
* duplication of inline cache dispatches in the compiled code. The limit of a dispatched library
* may be set to 0 to directly switch to an uncached version of a library.
* <p>
*
* <h4>Usage:</h4>
*
* The following example combines the use of specialized and dispatched libraries. In this example
* the array is read twice. For the first <i>outer</i> read the specializing expression can be used.
* For the second read the specializing expression cannot be used as it depends on the result of the
* outer read. We therefore use a dispatched library for the inner array.
*
* <pre>
* @NodeChild
* @NodeChild
* @NodeChild
* abstract static class TwoDimReadNode extends ExpressionNode {
* @Specialization(guards = "outerArrays.isArray(array)", limit = "2")
* int doDefault(Object array, int outerIndex, int innerIndex,
* @CachedLibrary("array") ArrayLibrary outerArrays,
* @CachedLibrary(limit = "2") ArrayLibrary innerArrays) {
* return innerArrays.read(outerArrays.read(outerIndex), innerIndex);
* }
* }
* </pre>
*
* @see LibraryFactory for manually instantiating libraries
* @see com.oracle.truffle.api.library Truffle Library reference documentation
* @since 19.0
*/
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.PARAMETER})
public @interface CachedLibrary {
Sets the specialized value expression when using specialized libraries. The same syntax applies as for Cached value expressions. See Also: Since: 19.0
/**
* Sets the specialized value expression when using specialized libraries. The same syntax
* applies as for {@link Cached} value expressions.
*
* @see CachedLibrary for usage examples.
* @since 19.0
*/
String value() default "";
Sets the limit expression when using dispatched libraries. The limit expression sets the number of internally dispatched specialized libraries until an uncached version of the library will be used. See Also: Since: 19.0
/**
* Sets the limit expression when using dispatched libraries. The limit expression sets the
* number of internally dispatched specialized libraries until an
* {@link LibraryFactory#getUncached() uncached} version of the library will be used.
*
* @see CachedLibrary for usage examples.
* @since 19.0
*/
String limit() default "";
}