[Bug tree-optimization/105216] [12 regression] 8% regression for m-queens compared to gcc11 O2

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105216

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Target Milestone|---                         |12.0
   Last reconfirmed|                            |2022-04-11
           Keywords|                            |missed-optimization,
                   |                            |needs-bisection
             Target|                            |x86_64-*-*
                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I suppose it's good again with -fno-tree-vectorize?  With vectorization enabled
we tame down PRE to avoid creating loop carried dependences the vectorizer
cannot handle.  For the "important" opportunities we try to recover after
vectorization with predictive commoning.

Hmm, confirmed with -fno-tree-vectorize even.

Possibly caused by r12-7389-ge25dce50133405