[llvm] [GISel] Fold bitreverse(shl/srl(bitreverse(x),y)) -> srl/shl(x,y) (PR #91355)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

@tschuett @arsenm I've managed to move all the legality checking into the TD patterns. 

https://github.com/llvm/llvm-project/pull/91355