RFR: 8318158: RISC-V: implement roundD/roundF intrinsics [v12]

[Olga Mikhaltsova]

On Fri, 22 Dec 2023 09:35:08 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Olga Mikhaltsova has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Moved the code up + comments
>
> For normal cases, I guess `RUP` of riscv will work; but for some corner cases, we need the trick of `+0.5`, am I right?
> But all this information is just mentioned with `some inputs produce incorrect results`, which is unclear for potential readers and maintainers in the future.
> So, in the comments, can you add some information about this corner case, a simple example will definitely help here.

@Hamlin-Li @RealFYang Could you take a look once again, please, whether these comments are sufficient or something else is needed?

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PR Comment: https://git.openjdk.org/jdk/pull/16382#issuecomment-1871639418