RFR: 8365192: post_meth_exit should be in vm state when calling get_jvmti_thread_state [v2]

[Leonid Mesnik]

On Wed, 13 Aug 2025 06:03:38 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   simplified after feedback
>
> src/hotspot/share/prims/jvmtiExport.cpp line 1839:
> 
>> 1837:   JRT_BLOCK
>> 1838:   state = get_jvmti_thread_state(thread);
>> 1839:   JRT_BLOCK_END
> 
> The `JRT_BLOCK` is defined as:
> 
> #define JRT_BLOCK                                                    \
>     {                                                                \
>     assert(current == JavaThread::current(), "Must be");             \
>     ThreadInVMfromJava __tiv(current);                               \
>     JavaThread* THREAD = current; /* For exception macros. */        \
>     DEBUG_ONLY(VMEntryWrapper __vew;)
> 
> 
> I'd suggest something like this instead of using `JRT_BLOCK`:
> 
> -  JvmtiThreadState *state = get_jvmti_thread_state(thread);
> +   JvmtiThreadState *state = nullptr;
> +  {
> +     ThreadInVMfromJava __tiv(thread);
> +     state = get_jvmti_thread_state(thread);
> +  }
> 
> 
> Alternatively, the `JRT_BLOCK` can be started at the line 1837 and ended with `JRT_BLOCK_END` at the line 1875. Not sure, what issue we can encounter with this though. At least, it is worth a try.

As I understand the post_method_entry was called via JRT_BLOCK_ENTRY and not JRT_BLOCK by the reason. We need to be in Java. See comments for the method invocation. 

// This is a JRT_BLOCK_ENTRY because we have to stash away the return oop
// before transitioning to VM, and restore it after transitioning back
// to Java. The return oop at the top-of-stack, is not walked by the GC.
JRT_BLOCK_ENTRY(void, InterpreterRuntime::post_method_exit(JavaThread* current))
  LastFrameAccessor last_frame(current);
  JvmtiExport::post_method_exit(current, last_frame.method(), last_frame.get_frame());
JRT_END

And thanks for simplification, it is a good idea. I've updated the PR.
I am running tier1-8 for Hotspot tests to ensure that nothing is broken.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/26713#discussion_r2272174407