[llvm] VectorWiden pass to widen aleady vectorized instrctions (PR #67029)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> For the example in the description, isn't the issue that the SLP vectorizer doesn't support generating code for scalable vectors? Or has this recently been implemented?

Scalable vectors are meaningless for SLP, it always operates with constant number of scalars/fixed vectors size (equal it number of scalars).

https://github.com/llvm/llvm-project/pull/67029