[llvm] [LegalizeTypes] Handle non byte-sized elt types when splitting INSERT/EXTRACT_VECTOR_ELT (PR #93357)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Is the nearest byte really what we want here?  We can widen to any type we want, and on most targets, storing an `<N x i32>` is going to be a lot more efficient than storing an `<N x i24>`.

Instead of expanding immediately, should we just construct an EXTRACT_VECTOR_ELT with the promoted vector type, and legalize that?  That might allow custom legalization to kick in in certain cases.

https://github.com/llvm/llvm-project/pull/93357