RFR: 8344381: [s390x] Test failures with error: Register type is not known [v3]

[Lutz Schmidt]

On Mon, 18 Nov 2024 14:11:24 GMT, Lutz Schmidt <lucy at openjdk.org> wrote:

>>>I think that the instructions can encode the maximum frame size.
>> 
>> both of the instruction support displacement up to `12bit unsigned integer`, which should give us flexibility of around 4000byte So I guess we should be fine.
>
>> > I think that the instructions can encode the maximum frame size.
>> 
>> both of the instruction support displacement up to `12bit unsigned integer`, which should give us flexibility of around 4000byte So I guess we should be fine.
> 
> Instead of speculation:
> - GPRs: 16 registers, 8 bytes each -> 128 bytes
> - FPRs: 16 registers, 8 bytes each -> 128 bytes
> - VRs: 32 registers, 16 bytes each -> 512 bytes
> - In total: 768 bytes. 
> 
> This is an easy fit into uimm12.

> Looks correct to me. I would probably not exclude F1. But if the decision not to use it for allocation is fixed, ok. @RealLucy: Please take a 2nd look.

Wasn't F1 used as float function return value register? If so, exclusion is very helpful.

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

PR Comment: https://git.openjdk.org/jdk/pull/22197#issuecomment-2486247637