[llvm] [VPlan] Handle WidenGEP in narrowToSingleScalars (PR #166740)

[Florian Hahn via llvm-commits]

fhahn wrote:

> > > if all operands are single scalar, we should be able to handle this in narrowToSingleScalar, and remove the special handling in the recipe altogether?
> > 
> > 
> > This is currently not possible, as narrowToSingleScalars' users check is too weak.
> 
> To prove this, I've rebased onto #166559.

Thanks, basing this on narrowToSingleScalar seems like a promising way forward,  nicely simplifying ::execute

https://github.com/llvm/llvm-project/pull/166740