[llvm] [RISCV] Disable performCombineVMergeAndVOps for PseduoVIOTA_M. (PR #71483)

[Luke Lau via llvm-commits]

lukel97 wrote:


> I think we can still does this transformation for `viota.m`, since all ones mask does not influence the prefix sum calculation.

Sorry yes, I meant as in it's correct and we should do this transform for viota.m, but we should also do it for vredsum.vs since we don't do it currently

https://github.com/llvm/llvm-project/pull/71483