RFR: 8373046: Method::get_c2i_unverified_entry() and get_c2i_no_clinit_check_entry() are missing check for abstract method

[Ashutosh Mehra]

On Wed, 3 Dec 2025 20:05:02 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> This PR fixes a bug introduced by [JDK-8365501](https://bugs.openjdk.org/browse/JDK-8365501). It restores the behavior of `Method::get_c2i_unverified_entry` or `Method::get_c2i_no_clinit_check_entry` for abstract methods as it was before JDK-8365501. It was never the intention of JDK-8365501 to change the behavior.
>> I am not sure if there is any possible code flow that can result in calling `Method::get_c2i_unverified_entry` or `Method::get_c2i_no_clinit_check_entry` for abstract methods, but I think it is safe to keep the behavior of these functions as before.
>
> src/hotspot/share/oops/method.cpp line 180:
> 
>> 178: address Method::get_c2i_no_clinit_check_entry() {
>> 179:   if (is_abstract()) {
>> 180:     return nullptr;
> 
> Why it is `nullptr` instead of `SharedRuntime::get_handle_wrong_method_abstract_stub()`. Add comment.

This is not a new behavior. It was `nullptr` before JDK-8365501:

  _abstract_method_handler->set_entry_points(SharedRuntime::throw_AbstractMethodError_entry(),
                                             wrong_method_abstract,
                                             wrong_method_abstract,
                                             nullptr);

I am not sure why it was null and not `wrong_method_abstract`.
Change that sets `_c2i_no_clinit_check_entry` to null was introduced in https://github.com/openjdk/jdk/commit/242bd67c6c3bb314302502aae19e092e0820290c

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PR Review Comment: https://git.openjdk.org/jdk/pull/28645#discussion_r2586760646