RFR: 8331577: RISC-V: C2 CountLeadingZerosV [v2]

[Hamlin Li]

On Thu, 9 May 2024 12:14:28 GMT, Fei Yang <fyang at openjdk.org> wrote:

> > > > BTW, I will also re-visit all existing masked version instructions to make sure it works as expected. tracked by https://bugs.openjdk.org/browse/JDK-8331992
> 
> Sorry for not being accurate. In fact, I mean requirement at the Java level. Why should we keep the origin value of inactive elements from the input vector? I didn't notice such a requirement before.

I'm not sure about other places, but in vector APi, if you do operations with a mask, then the untouched (inactive in riscv vector insts) elements should be unmodified, i.e. same as original values.

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PR Comment: https://git.openjdk.org/jdk/pull/19153#issuecomment-2102590188