[llvm] [RISCV] Fold (add (srl x, n), (srl x, n)) into (srl x, n-1) (PR #144507)

[Craig Topper via llvm-commits]

topperc wrote:

> I may have an alternate proposal for this patch. Investigating.

My alternate proposal https://github.com/llvm/llvm-project/pull/144565

https://github.com/llvm/llvm-project/pull/144507