RFR: 8352159: RISC-V: add more zfa support [v4]

[Fei Yang]

On Tue, 18 Mar 2025 11:25:19 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this patch?
>> 
>> Previously in https://github.com/openjdk/jdk/pull/23844, `loadConH` is implemented only with `flh`, but `fli_h` should be more efficient if Zfa is supported; min/max for HF could use fmin/maxm.h instead too.
>> 
>> Thanks!
>
> Hamlin Li has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:
> 
>  - merge master
>  - fix fli_h
>  - fix rFlagsReg
>  - refactor min/max
>  - min/max
>  - initial commit

Looks good to me. I have a suggestion about the value searching. We can consider that in the future.

src/hotspot/cpu/riscv/assembler_riscv.hpp line 446:

> 444:       case 0x7c00 : return 29;
> 445:       // case 0x7c00 : return 30; // redundant with 29
> 446:       case 0x7e00 : return 31;

This switch-case seems nontrivial (Same for for all S & D variants). One possible enhancement to speed up might be putting the values in a table and doing a binary search.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24081#pullrequestreview-2697267136
PR Review Comment: https://git.openjdk.org/jdk/pull/24081#discussion_r2002647512