RFR: 8320995: RISC-V: C2 PopCountVI [v2]

[Ludovic Henry]

On Fri, 3 May 2024 14:27:03 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this patch?
>> Both auto-vect and vector api depends on this intrinsic.
>> Thanks!
>> 
>> ## Performance
>> Not performance test was done, as this depends on vcpop.v instruction in zvbb extension and the code seqeunce is rather simple than non-intrinsic version.
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix minor flag

src/hotspot/cpu/riscv/globals_riscv.hpp line 118:

> 116:   product(bool, UseZihintpause, false, EXPERIMENTAL,                             \
> 117:           "Use Zihintpause instructions")                                        \
> 118:   product(bool, UseZvbb, false, "Use Zvbb instructions")                         \

Shouldn't this be marked `EXPERIMENTAL` as we have no hardware to test it on?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19065#discussion_r1589624536