RFR: 8349686: [s390x] C1: Improve Class.isInstance intrinsic [v8]

[Amit Kumar]

On Thu, 20 Feb 2025 11:30:34 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> But we are still using Z_R0, to resize the frame, at line 3708 and 3718.
>
> I missed that because you were using different names for the same register in this function. I searched for `Z_R0_scratch`. It would be better if you decided what to call `Z_R0`, and used the same name consistently for all usages, including `assert_different_registers()`.

I have moved the result in volatile-float registers, instead of using stack for the shuffling. With that we can get rid of `Z_R0_scratch` from `assert_different_registers` as per your suggestion.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23535#discussion_r1963417361