[llvm] [LV] Stop using the legacy cost model for udiv + friends (PR #152707)

[David Sherwood via llvm-commits]

david-arm wrote:

> I'll run this PR on a set of different configs to check for potential regressions.

Hi @fhahn, did you get a chance to run this PR on some configs? I'd like to land the patch today or tomorrow as part of work to remove the legacy cost model from vplan and ultimately remove the legacy/vplan cost model assert. I figure the worst thing that can happen is it triggers the assert somewhere and the patch needs reverting or tweaking.

https://github.com/llvm/llvm-project/pull/152707