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 Done. Performance numbers: New: Benchmark Mode Cnt Score Error Units NativeMethodInvoke.objectHashCode avgt 15 41.200 ± 2.783 ns/op NativeMethodInvoke.threadCurrentThread avgt 15 2.963 ± 0.143 ns/op Old: Benchmark Mode Cnt Score Error Units NativeMethodInvoke.objectHashCode avgt 15 533.562 ± 27.083 ns/op NativeMethodInvoke.threadCurrentThread avgt 15 108.492 ± 4.101 ns/op ------------- PR Comment: https://git.openjdk.org/jdk/pull/22169#issuecomment-2502376813
