RFR: 8370871: [s390x] consistently update top_frame_sp [v2]

[Richard Reingruber]

On Thu, 30 Oct 2025 06:48:43 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

>> Stores top_frame_sp for interpreter frames consistently. Although this is making one to assert fail in loom port but still I think this should be considered independent bug.
>> 
>> Changes in `generate_throw_exception` also helped with another issue in loom which was resolved by this workaround: https://github.com/offamitkumar/jdk/blob/5cb1322f58a4c676aac59244dcb62d8b67f0ed93/src/hotspot/cpu/s390/continuationFreezeThaw_s390.inline.hpp#L302C1-L318C2, issue: 
>> 
>> In `BasicExt.java` testcase there are two subtests : 
>> ```java 
>>         new Continuation3Frames(TestCaseVariants.THROW_HANDLED_EXCEPTION).runTestCase(4, compPolicy);
>>         new Continuation3Frames(TestCaseVariants.THROW_UNHANDLED_EXCEPTION).runTestCase(4, compPolicy);
>> 
>> 
>> these two testcase were failing because we were overwriting the interpreter frame content as we have to make the native call which saves the register from r6 to r15. So at that time the workaround was necessary, but it turns out that using `top_frame_sp` to extend the frame will fix the overwriting issue.
>
> Amit Kumar has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adding assert and frame extension for exception

Looks good to me.
Cheers, Richard.

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

Marked as reviewed by rrich (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28042#pullrequestreview-3397810208