[Bug tree-optimization/112281] [12/13/14 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-2097-g9f34b780b0461e

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112281

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |13.2.1
           Priority|P3                          |P2
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot 
gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Possibly a mixup of dependence direction somewhere.  If c would not iterate
backwards the transform would be correct.

We compute

(build_classic_dist_vector
  dist_vector = (1 0
  )

and then possibly get partition order wrong.  With 11 we had fixes there,
possibly this broke it.

I will have a look.  At some point ...