RFR: 8318227: RISC-V: C2 ConvHF2F [v2]

[Hamlin Li]

On Wed, 29 Nov 2023 09:21:37 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Some more information:
>> 1. `fcvt_w_s_safe` is quite similar to float16_to_float in cost, it's labeled in `fp_f2i`.
>> 2. `float_compare` is too, but labeled with `pipe_class_default`
>> 3.  while instruct's with multiple instructions in riscv_v.ad are labeled with `pipe_slow`.
>> 
>> I'm not sure what should be chosen here, seems `fcvt_w_s_safe` is more similar to our situation, how do you think about it?
>
> I think we should `pipe_slow` here and for `fcvt_w_s_safe` and `float_compare` the multiple instruction cases. `fp_f2i` and `pipe_class_default` are supposed to be used for the single instruction cases.

OK, seems we have some old code to clean for `fp_f2i` and `pipe_class_default`?
If it's needed, I can do that in a separate pr later.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16802#discussion_r1409129254