[PATCH] D115261: [LV] Disable runtime unrolling for vectorized loops.

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

Hello. Sorry I have been travelling, I had not seen this had returned.

This looks like it disabled full unrolling after vectorization too? I think it is fairly important for performance to be able to simplify loops away where the runtime trip count is small enough by unrolling them. Either where the loop count becomes constant propagated through LTO or the trip count is just low enough. As far as I understand straight line code will almost always be better that looping, and preventing full unrolling would lead to performance regressions.

There is an example in https://godbolt.org/z/8YnsWfGGo where.. something is going wrong.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115261/new/

https://reviews.llvm.org/D115261