[PATCH] D36113: [Loop Vectorize] Vectorize Loops with Backward Dependence

[Hal Finkel via Phabricator via llvm-commits]

hfinkel added a comment.

Two high-level thoughts:

1. Is this transformation always profitable even if we don't later vectorize? I worry that you're taking a stream of accesses that generally appear in order and making them appear out of order. That could have odd effects. Maybe this should all be a utility that the vectorizer uses more directly?
2. I don't think a goal of this should be to provide backup handling of things that LICM misses but MemorySSA can prove are loop invariant. We should improve LICM by making it use MemorySSA (see work on this in https://reviews.llvm.org/D35741 - pushing this along might help?). We could run LICM right before we vectorize too.


https://reviews.llvm.org/D36113