RFR: 8331577: RISC-V: C2 CountLeadingZerosV [v3]

[Hamlin Li]

On Fri, 10 May 2024 07:10:36 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix masked ReverseBytesV & PopCountV by sharing dst&src regs
>
> src/hotspot/cpu/riscv/riscv_v.ad line 3766:
> 
>> 3764: instruct vreverse_bytes_masked(vReg dst_src, vRegMask_V0 v0) %{
>> 3765:   match(Set dst_src (ReverseBytesV dst_src v0));
>> 3766:   format %{ "vreverse_bytes_masked $dst_src, $dst_src, v0" %}
> 
> Nit: I think we can use something more accurate like `vrev8.v` as the opcode name in format. That will be consistent with the RVV spec. Also I suggest `v0.t` instead of `v0` or `$v0` as the mask for predicated instructs (Might deserve a separate PR for cleaning up other existing predicated instructs). Similar for other newly added instructs.

Sure, let me do it later, tracked by https://bugs.openjdk.org/browse/JDK-8332030.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19153#discussion_r1596384248