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8185993: MethodHandle.invokeWithArguments jumbo-arity

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Reviewed-by: psandoz, vlivanov
This commit is contained in:
John R Rose 2017-09-22 15:28:16 -07:00
parent 71e91d9c2e
commit f98aab0db9
6 changed files with 294 additions and 46 deletions
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31
src/java.base/share/classes/java/lang/invoke/package-info.java
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@ -81,12 +81,19 @@
* in which dynamic call site occurs </li>
* <li>a {@code String}, the method name mentioned in the call site </li>
* <li>a {@code MethodType}, the resolved type descriptor of the call </li>
* <li>optionally, between 1 and 251 additional static arguments taken from the constant pool </li>
* <li>optionally, any number of additional static arguments taken from the constant pool </li>
* </ul>
* Invocation is as if by
* {@link java.lang.invoke.MethodHandle#invoke MethodHandle.invoke}.
* The returned result must be a {@link java.lang.invoke.CallSite CallSite}
* (or a subclass), otherwise a
* <p>
* In all cases, bootstrap method invocation is as if by
* {@link java.lang.invoke.MethodHandle#invokeWithArguments MethodHandle.invokeWithArguments},
* (This is also equivalent to
* {@linkplain java.lang.invoke.MethodHandle#invoke generic invocation}
* if the number of arguments is small enough.)
* <p>
* For an {@code invokedynamic} instruction, the
* returned result must be convertible to a non-null reference to a
* {@link java.lang.invoke.CallSite CallSite}.
* If the returned result cannot be converted to the expected type,
* {@link java.lang.BootstrapMethodError BootstrapMethodError} is thrown.
* The type of the call site's target must be exactly equal to the type
* derived from the dynamic call site's type descriptor and passed to
@ -150,10 +157,12 @@
* If the {@code invokedynamic} instruction specifies one or more static arguments,
* those values will be passed as additional arguments to the method handle.
* (Note that because there is a limit of 255 arguments to any method,
* at most 251 extra arguments can be supplied, since the bootstrap method
* at most 251 extra arguments can be supplied to a non-varargs bootstrap method,
* since the bootstrap method
* handle itself and its first three arguments must also be stacked.)
* The bootstrap method will be invoked as if by either {@code MethodHandle.invoke}
* or {@code invokeWithArguments}. (There is no way to tell the difference.)
* The bootstrap method will be invoked as if by {@code MethodHandle.invokeWithArguments}.
* A variable-arity bootstrap method can accept thousands of static arguments,
* subject only by limits imposed by the class-file format.
* <p>
* The normal argument conversion rules for {@code MethodHandle.invoke} apply to all stacked arguments.
* For example, if a pushed value is a primitive type, it may be converted to a reference by boxing conversion.
@ -194,9 +203,9 @@
* </tbody>
* </table>
* The last example assumes that the extra arguments are of type
* {@code CONSTANT_String} and {@code CONSTANT_Integer}, respectively.
* {@code String} and {@code Integer} (or {@code int}), respectively.
* The second-to-last example assumes that all extra arguments are of type
* {@code CONSTANT_String}.
* {@code String}.
* The other examples work with all types of extra arguments.
* <p>
* As noted above, the actual method type of the bootstrap method can vary.
@ -220,7 +229,7 @@
* to safely and compactly encode metadata.
* In principle, the name and extra arguments are redundant,
* since each call site could be given its own unique bootstrap method.
* Such a practice is likely to produce large class files and constant pools.
* Such a practice would be likely to produce large class files and constant pools.
*
* @author John Rose, JSR 292 EG
* @since 1.7