On Thu, May 19, 2016 at 9:39 PM, Ilya Enkovich
<enkovich.gnu@gmail.com> wrote:
Hi,
This patch introduces changes required to run vectorizer on loop
epilogue. This also enables epilogue vectorization using a vector
of smaller size.
While the idea of epilogue vectorization sounds straight-forward the
implementation is somewhat icky with all the ->aux stuff, "redundant"
if-conversion and loop iteration stuff.
So I was thinking of when epilogue vectorization is beneficial which
is obviously when the overall loop trip count is low. We are not
good in optimizing for that case generally (too much peeling for
alignment, using expensive avx256 vectorization, etc.), so I wonder
if versioning for that case would be a better idea
(performance-wise).
Thus - what cases were you looking at when deciding that vectorizing
the epilogue (with a smaller vector size) is profitable? Do other
compilers generally do this?