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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110474] Vect: the epilog vect loop should
 have small VF if the loop is unrolled during vectorization
Date: Thu, 29 Jun 2023 07:33:24 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110474

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu.org,
                   |                            |rsandifo at gcc dot gnu.org

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think it's reasonable to not apply unrolling to the vectorized epilogue, =
but
note we have to be careful to adjust the maximum number of iterations for i=
t we
compute.  Note this will also necessarily make the vectorized epilogue iter=
ate.

We could also leave the decision to the target, providing a
suggested_epilog_"unroll" factor.  That could also be used to for example
get a 128bit vector epilogue for a 512bit main loop to address similar
concerns there.=