6964498: JSR 292 invokedynamic sites need local bootstrap methods
Summary: Add JVM_CONSTANT_InvokeDynamic records to constant pool to determine per-instruction BSMs; add MethodHandleProvider.
Reviewed-by: twisti
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package java.dyn;
import java.lang.annotation.*;
/**
* Annotation on InvokeDynamic method calls which requests the JVM to use a specific
* <a href="package-summary.html#bsm">bootstrap method</a>
* to link the call. This annotation is not retained as such in the class file,
* but is transformed into a constant-pool entry for the invokedynamic instruction which
* specifies the desired bootstrap method.
* <p>
* If only the <code>value</code> is given, it must name a subclass of {@link CallSite}
* with a constructor which accepts a class, string, and method type.
* If the <code>value</code> and <code>name</code> are both given, there must be
* a static method in the given class of the given name which accepts a class, string,
* and method type, and returns a reference coercible to {@link CallSite}.
* <p>
* This annotation can be placed either on the return type of a single {@link InvokeDynamic}
* call (see examples) or else it can be placed on an enclosing class or method, where it
* determines a default bootstrap method for any {@link InvokeDynamic} calls which are not
* specifically annotated with a bootstrap method.
* Every {@link InvokeDynamic} call must be given a bootstrap method.
* <p>
* Examples:
<blockquote><pre>
@BootstrapMethod(value=MyLanguageRuntime.class, name="bootstrapDynamic")
String x = (String) InvokeDynamic.greet();
//BSM => MyLanguageRuntime.bootstrapDynamic(Here.class, "greet", methodType(String.class))
@BootstrapMethod(MyCallSite.class)
void example() throws Throwable {
InvokeDynamic.greet();
//BSM => new MyCallSite(Here.class, "greet", methodType(void.class))
}
</pre></blockquote>
* <p>
*/
@Target({ElementType.TYPE_USE,
// For defaulting every indy site within a class or method; cf. @SuppressWarnings:
ElementType.TYPE, ElementType.METHOD, ElementType.CONSTRUCTOR
})
@Retention(RetentionPolicy.SOURCE)
public @interface BootstrapMethod {
/** The class containing the bootstrap method. */
Class<?> value();
/** The name of the bootstrap method.
* If this is the empty string, an instance of the bootstrap class is created,
* and a constructor is invoked.
* Otherwise, there must be a static method of the required name.
*/
String name() default ""; // empty string denotes a constructor with 'new'
/** The argument types of the bootstrap method, as passed out by the JVM.
* There is usually no reason to override the default.
*/
Class<?>[] arguments() default {Class.class, String.class, MethodType.class};
}