[PATCH] D118566: [LoopVectorizer] Don't perform interleaving of predicated scalar loops

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen added a comment.

> This prevents it from making a bit of a mess, that is worse than the original and better left for the unroller to unroll if beneficial

Can you expand a little bit on why this becomes a bit of a mess? The original scalar loop has control-flow for predication as well, so I guess interleaving would just duplicate such control flow for the second scalar iteration. Is the code generated by the LV less efficient or are we missing any folds/simplification? Or is there a fundamental reason this can never be an improvement? I could imagine a scenario where most of the loop body would benefit from interleaving, but one statement in the loop doesn't because of predication, it would still be beneficial to interleave.


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  https://reviews.llvm.org/D118566/new/

https://reviews.llvm.org/D118566