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

[Dinar Temirbulatov via llvm-commits]

dtemirbulatov 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?

SLP considers only scalars to vectorize, not already vectorized operations, nor scalable vectors.

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