[llvm] [RISCV] Remove artificial restriction on ShAmt from (shl (and X, C2), C) -> (slli (srliw X, C3), C3+C) isel. (PR #143010)

[Craig Topper via llvm-commits]

topperc wrote:

> LGTM, modulo the commit message. I think you are relaxing the `(shl (and X, C2), C) -> (srli (slli X, C4), C4-C)` pattern.

You're right. I copied the wrong comment while I was writing the message

https://github.com/llvm/llvm-project/pull/143010