[llvm-branch-commits] [RISCV] Combine vwaddu_wv+vabd(u) to vwabda(u) (PR #184603)

[Pengcheng Wang via llvm-branch-commits]

wangpc-pp wrote:

> @wangpc-pp I assume this will eventually lead to generating vwaddu instruction in x264? Can you please give your high-level overview of your plan?

Yes, we can generate Zvabd instructions now. I think most of `Zvabd` works have been upstreamed so I don't have a plan here.

> Have you considered doing this at IR level with intrinsics?

Actually I don't understand why we want to do it in the LLVM IR level. We don't have representations of absolute difference in the LLVM IR level (we don't have something like `llvm.abds/llvm.abdu` intrinsics).

https://github.com/llvm/llvm-project/pull/184603