RFR: 8347981: RISC-V: Add Zfa zli imm loads [v3]

[Robbin Ehn]

On Thu, 23 Jan 2025 05:58:26 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> 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:
>> 
>>  - Merge branch 'master' into zfa
>>  - Merge branch 'master' into zfa
>>  - EXPERIMENTAL
>>  - Merge branch 'master' into zfa
>>  - Merge branch 'master' into zfa
>>  - Flip bool static decl
>>  - Merge branch 'master' into zfa
>>  - Baseline
>
> src/hotspot/cpu/riscv/vm_version_riscv.hpp line 160:
> 
>> 158:   decl(ext_Zbs         , "Zbs"         , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbs))         \
>> 159:   decl(ext_Zcb         , "Zcb"         , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZcb))         \
>> 160:   decl(ext_Zfa         , "Zfa"         , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfa))         \
> 
> Are we auto-enabling an experimental feature?

No, as Zfa is not mapped in RiscvHwprobe::add_features_from_query_result() I don't see how it would auto enbled?

 UPDATE_DEFAULT only updates "Use flag" after the extension, if it is default, i.e. not set by user, no?

As we have a two step mechanism hwprobe -> extensions flag -> Use flag.

But if you want I can do it the other way around, add it to hwprobe but do not update the Use flag?

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PR Review Comment: https://git.openjdk.org/jdk/pull/23171#discussion_r1926471771