RFR: 8327652: S390x: Implements SLP support [v2]

[Sidraya Jayagond]

On Mon, 18 Mar 2024 09:13:35 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Since f0-f15 overlap with v0-v15, does register allocate takes care of not to allocate same float register to corresponding live vector register or vice-versa? e.g f1 and v1 registers.
>
> You use `ALLOC_IN_RC(z_v_reg)` in `vecX(),` so FP and VR are disjoint. That looks correct. Only the comments are missing.

Thanks @TheRealMDoerr , I will add comments.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18162#discussion_r1528212282