RFR: 8318218: RISC-V: C2 CompressBits

[Hamlin Li]

On Fri, 3 Nov 2023 01:33:43 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

>> I made a mistake, UseRVVForCompressBitsIntrinsics is only defined in riscv global.hpp.
>> I think I can resolve the issue by defining it in global global.hpp, but seems it's not a good idea either.
>> Any suggestions?
>
>> I made a mistake, UseRVVForCompressBitsIntrinsics is only defined in riscv global.hpp. I think I can resolve the issue by defining it in global global.hpp, but seems it's not a good idea either. Any suggestions?
> 
> Maybe `bool Matcher::match_rule_supported(int opcode) {` in `riscv.ad` is a good place, and just returning `UseRVV` would be enough for `Op_CompressBits`?:
> https://github.com/openjdk/jdk/blob/c788160f8acea7b58b54ad857b601bb7ffb53f8e/src/hotspot/cpu/riscv/riscv.ad#L1896-L1897

Thanks @feilongjiang for pointing at the postion.

@robehn @theRealAph I agree, thanks for discussion

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PR Comment: https://git.openjdk.org/jdk/pull/16481#issuecomment-1792336266