RFR: 8313438: [s390x] build broken after JDK-8301996 [v2]

[Amit Kumar]

On Fri, 6 Oct 2023 12:25:15 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> If you want that this case to be handled in separate PR, then I'll file a JBS issue.
>
> I need an explanation why this code was changed this way. If it is required for this PR, please explain in comments. If it's a separate issue, please handle separately.

Oh, Issue was with the `flag` register value. We need to check the volatility at the end of `putfield_or_static` method. And previous implementation was not preserving the value till the end, why it was working then ? That I don't know. 

Current Implementation uses `z_tmp_1` for saving `flag` value till end. `obj` now points to `Z_ARG5` which is also pointed by `oopStore_tmp2`, and if we don't use `agr` then in case of `object/atos` , will run into `Multiple usecase for Z_R6` error from `do_oop_store()` method .

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

PR Review Comment: https://git.openjdk.org/jdk/pull/15885#discussion_r1348689521