[clang] [llvm] [RISCV] Assembler support for XRivosVizip (PR #127694)

[Pengcheng Wang via cfe-commits]

wangpc-pp wrote:

> > I am kind of confused now. So the situation here is that RVIOS has already implemented these vendor extensions in cores and RVIOS is also trying to make these extensions official RVI standards, right?
> 
> You're confusing two things. We (Rivos) have defined a set of custom vendor extensions - this patch is the first in that sub-series. We are _also and separately_ proposing a subset of instructions for consideration at RVI for eventual standardization. As an example of how these are different, see XRivosVisni in the linked repo. That's a vendor extension which relates to gaps identified in RVV, but for which we're not currently proposing an extension at RVI.

Thanks, I'd like to know if these vendor extensions have been implemented in some type-out-ed cores. I have this question because I saw that these vendor extensions are of version 0.1. If they are going to be changeable (and experimental), then why are we supporting XRivosVizip extension in a hurry since XRivosVizip and Zvzip are overlapped.

https://github.com/llvm/llvm-project/pull/127694