[llvm-branch-commits] [llvm] [RISCV] Add initial support of memcmp expansion (PR #107548)

[Pengcheng Wang via llvm-branch-commits]

wangpc-pp wrote:

Ping.

And some updates on vector support: currently, `ExpandMemCmp` will only generate integer types (`i128`, `i256`) and so on. So, if we simply add `128`, `256`, `vlen` to `LoadSizes`, the LLVM IR will use i128/i256/... and then they are expanded to legal scalar types as we don't mark i128/i256/... legal when RVV exists.

There are two ways to fix this:
1. Make `ExpandMemCmp` geenrate vector types/operations.
2. Make i128/i256/... legal.

I think the first one is the right approach but I need some agreements on this.

https://github.com/llvm/llvm-project/pull/107548