[llvm] [DAG] optimize llvm.ucmp for 1-bit inputs to return subtraction of operands (PR #150058)

[Gaurav Dhingra via llvm-commits]

gxyd wrote:

> We usually handle these upon creation inside SelectionDAG::getNode

Shouldn't the linked issue be handled as a special case in `TargetLowering::expandCMP`? (from comment here: https://github.com/llvm/llvm-project/issues/129401#issuecomment-2693324749), similar to how we replace CMP with Select statements in `TargetLowering::expandCMP`.

https://github.com/llvm/llvm-project/pull/150058