RFR: 8360775: Fix Shenandoah GC test failures when APX is enabled [v2]

[Jatin Bhateja]

On Mon, 30 Jun 2025 22:14:14 GMT, Srinivas Vamsi Parasa <sparasa at openjdk.org> wrote:

>> @jatin-bhateja Pusha is not expected to change any registers. The inadvertent change of registers is very hard to debug. So in my thoughts it is better to have a conservative implementation currently which doesn't change RAX register.
>
> Please see the updated code which fixes the issue by restoring the contents of RAX. The tests are passing with this update.

Thanks @vamsi-parasa , yes this looks fine to me now, I had a similar thought to fix it.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/26009#discussion_r2176475736