[llvm] [VPlan] Run narrowInterleaveGroups during general VPlan optimizations. (PR #149706)

[Florian Hahn via llvm-commits]

fhahn wrote:

> Hi @fhahn, This PR is causing downstream failures for JAX. In particular, after pulling this commit I'm seeing egregious numerical errors when computing a Hessian with JAX on CPU. Any guesses as to why that might be?

Difficult to tell without a reproducer, could you share one?

https://github.com/llvm/llvm-project/pull/149706