On Fri, 15 Nov 2024 22:17:10 GMT, Chen Liang <li...@openjdk.org> wrote:
> When core reflection was migrated to be implemented by Method Handles, > somehow, the method handles are not used for native methods, which are > generally linkable by method handles. This causes significant performance > regressions when reflecting native methods, even if their overrides may be > non-native methods. This is evident in `Object.clone` and `Object.hashCode` > as shown in the original report. > > I believe the blanket restriction previously placed on the native methods was > because of signature polymorphic methods ([JLS > 15.12.3](https://docs.oracle.com/javase/specs/jls/se23/html/jls-15.html#jls-15.12.3), > [JVMS > 2.9.3](https://docs.oracle.com/javase/specs/jvms/se23/html/jvms-2.html#jvms-2.9.3)) > for MethodHandle and VarHandle; method handles do not link to the backing > implementation that throws UOE while core reflection is required to do so. I > have narrowed the restrictions to be specifically against these methods. > > Additionally, I cleaned up another check for invalid varargs flag. Together, > I clarified the scenarios where native method accessors are used - all to > bypass restrictions of java.lang.invoke. > > Testing: tier 1-5 green src/java.base/share/classes/jdk/internal/reflect/MethodHandleAccessorFactory.java line 430: > 428: // Single parameter of declared type Object[] > 429: Class<?>[] parameters = > reflectionFactory.getExecutableSharedParameterTypes(method); > 430: return parameters.length == 1 && parameters[0] == Object[].class; Would it be possible to check for the `PolymorphicSignature` annotation instead? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/22169#discussion_r1848647321
