[PATCH] D57837: [LV] Prevent interleaving if computeMaxVF returned None.

[Hideki Saito via Phabricator via llvm-commits]

hsaito added a comment.

I have a little mental barrier in accepting this change as is. I think this feeling of mine is mainly due to the name and the "stated" functionality of computeMaxVF and "indirect inference" towards using it for suppressing interleaving. Maybe I'm just being too picky here. If so, my apologies ahead of time.

Other than just the function name and the associated comment:

1. runtime ptr check && hasBranchDivergence                   interleave w/ VF=1 still okay?
2. For interleaving, the remaining checks other than TC==0/1 (for better diagnostics) and OptForSize appear useless. Even if TC is evenly divisible by VF or canFoldTailByMasking, we still can't interleave under OptForSize.

I think we should start thinking in terms of separate "is vectorization feasible" and "is interleaving feasible" (plus possibly "is unrolling feasible"), even if we evaluate those feasibility in one function.

Possibly going to tangent, but while we look at computeMaxVF, at the bottom, we say use pragma, but we bail out of plan() w/o checking whether UserVF exists or not.

Hopefully, this conveys enough about my feeling of uneasiness.


Repository:
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  https://reviews.llvm.org/D57837/new/

https://reviews.llvm.org/D57837