RFR: 8352218: RISC-V: Zvfh requires RVV [v4]

[Fei Yang]

On Mon, 24 Mar 2025 08:36:57 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> Hi please consider.
>> 
>> Added case to turn off UseZvfh when no RVV. 
>> Which is the cause of the test issues, zvfh on but no rvv.
>> 
>> Also made all case identical and added no warning when default.
>> Move them to the common init, as the "UseExtension" is not C2 specific.
>> 
>> Manual tested and some random compiler tests.
>> 
>> Thanks, Robbin
>
> Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
> 
>  - dep check
>  - Merge branch 'master' into maxvector_0
>  - Merge branch 'master' into maxvector_0
>  - Merge branch 'master' into maxvector_0
>  - hwprobe deps
>  - Merge branch 'master' into maxvector_0
>  - Moved to common
>  - Disable UseZvfh when no RVV

src/hotspot/cpu/riscv/vm_version_riscv.hpp line 161:

> 159:   #define RV_NO_FLAG_BIT (BitsPerWord+1) // nth_bit will return 0 on values larger than BitsPerWord
> 160: 
> 161:   // Note: the order matters, depender should be after thier dependee. E.g. ext_V before ext_Zvbb.

Noticed a typo here: s/thier/their/

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

PR Review Comment: https://git.openjdk.org/jdk/pull/24094#discussion_r2011194786