[llvm] [VectorCombine] Combine extract/insert from vector (PR #115213)

[David Green via llvm-commits]

davemgreen wrote:

Hi - I think so long as it is cost-modelled it should be OK. Our shuffle generation is not going to be optimal at times (if it doesn't go though perfect shuffle tables), but the costs should be equally high as far as I understand.

https://github.com/llvm/llvm-project/pull/115213