[llvm] [VPlan] Impl VPlan-based pattern match for ExtendedRed and MulAccRed (PR #113903)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Thanks for all the updates. Basically looks good, but I think it would be good to split up the patch into adding the new recipes + transform + lowering but without the cost changes. And then land the cost changes separately, if possible?

https://github.com/llvm/llvm-project/pull/113903