[llvm-branch-commits] [llvm] [LV][REVEC][AArch64] Proof of concept for re-vectorisation (PR #208213)

[Gaëtan Bossu via llvm-branch-commits]

https://github.com/gbossu commented:

Thanks for looking into this PR :)

> I think it would be good to clarify somewhere what the new expectations are for places that previously dealt with scalar element types only and what they should hold in the REVEC path and why

Ultimately, the set of features supported for REVEC will be very close to the set of features for scalar->vector vectorisation. This means the "scalar type" that recipes/transforms refer to might actually be a vector type. Most of them transparently support "vector lane types", but some need adjustments like `Select`. Induction variables are an exception where we still only expect scalar types. I can try to summarise that somewhere, maybe at the top of `LoopVectorize.cpp`?

Note: I think "scalar type" should now the called "initial type" instead.

https://github.com/llvm/llvm-project/pull/208213