RFR: 8320500: [vectorapi] RISC-V: Optimize vector math operations with SLEEF [v6]

[Hamlin Li]

On Wed, 25 Sep 2024 14:04:35 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> src/hotspot/cpu/riscv/riscv.ad line 10079:
>> 
>>> 10077:   match(CallLeafVector);
>>> 10078: 
>>> 10079:   effect(USE meth, KILL cr);
>> 
>> I haven't checked the details of `CallLeafVector` yet. One more question here. Is it safe to assume that `FRM` will be saved and restored before and after the runtime call? Check this: https://bugs.openjdk.org/browse/JDK-8330094
>
> Good question!
> Let me do some further investigation and get back later.

I see sleef code only set frm to RNE, but I'm not quite sure.
Even if we can make sure current sleef only set frm to RNE, seems to me we can not depends on current implement, it could change. Although good news is we don't update sleef regularly.
Maybe we should take similar action as call-to-java and return-from-jni?

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PR Review Comment: https://git.openjdk.org/jdk/pull/21083#discussion_r1775935783