[llvm] [DAGCombiner] Handle type-promoted constants in UDIV lowering (PR #169491)

[Valeriy Savchenko via llvm-commits]

SavchenkoValeriy wrote:

> Can you skip all of this by just attempting to emit a truncate

Probably, but it doesn't really sound like an easier solution TBH. Plus, as I pointed out in the description, `AllowTruncation` seems to be historically quite a pattern.

https://github.com/llvm/llvm-project/pull/169491