[llvm] [RISCV] Use `experimental-p` extension for zero-extended narrow unsigned types (PR #213260)

[Craig Topper via llvm-commits]

topperc wrote:

Doesn't this work for SUB and other operations too?

How much real code does this help? The example of a function with 1 add and nothing else doesn't seem very realistic. That would be better being inlined.

https://github.com/llvm/llvm-project/pull/213260