RFR: 8344381: [s390x] Test failures with error: Register type is not known [v2]

[Martin Doerr]

On Mon, 18 Nov 2024 16:22:36 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

> > Thanks for the update. Now, I only wonder about the `>= Z_V2` condition. How does this fit to
> > https://github.com/openjdk/jdk/blob/dfddbcaab886b9baa731cd748bb7f547e1903b64/src/hotspot/cpu/s390/s390.ad#L745
> > 
> > ?
> 
> I didn't get the question actually. You mean that why didn't preserve `Z_VR0` and `Z_VR1` ? Or why we are preserving vector register `VR16` to `VR31` ?

What's the reason for choosing `Z_V2`? Why are `Z_VR0` and `Z_VR1` excluded? Do `Z_VR0` to `Z_VR15` match the FP registers? If so, why are you saving and restoring `Z_V2` to `Z_V15` twice?

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PR Comment: https://git.openjdk.org/jdk/pull/22197#issuecomment-2483538186