RFR: 8321010: RISC-V: C2 RoundVF [v2]

[Hamlin Li]

On Wed, 21 Feb 2024 16:23:19 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you have a review on this patch to add RoundVF/RoundDF intrinsics?
>> Thanks!
>> 
>> ## Tests
>> 
>> test/hotspot/jtreg/compiler/vectorization/TestRoundVectRiscv64.java test/hotspot/jtreg/compiler/c2/cr6340864/TestFloatVect.java test/hotspot/jtreg/compiler/c2/cr6340864/TestDoubleVect.java test/hotspot/jtreg/compiler/floatingpoint/TestRound.java
>> 
>> test/jdk/java/lang/Math/RoundTests.java
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix space

> Hello Hamlin, I recall you had licheepi board. I would be nice if you can try to measure rvv performance gain with this https://github.com/syntacore/syntaj21/tree/rvv0.7.1
> 
> This PR showed it's not always easy to win perf just by using rvv - #17413
> 
> I understand it might not be possible, but would be nice to give it a try (I can share hsdis with support for 0.7.1 if needed)

Had a internal discussion about your suggestion, seems 0.7.1 is not incompatible with 1.0/2.0, and for this simple intrinsic, we think a better path is to have it first, then re-visit it when we have real hardware to measure the performance later.

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PR Comment: https://git.openjdk.org/jdk/pull/17745#issuecomment-1957209676