[Bug tree-optimization/57396] [4.7/4.8/4.9 Regression] Wrong code with -fpredictive-commoning in Fortran double-loop

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57396

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-05-24
   Target Milestone|---                         |4.7.4
            Summary|Wrong code with             |[4.7/4.8/4.9 Regression]
                   |-fpredictive-commoning in   |Wrong code with
                   |Fortran double-loop         |-fpredictive-commoning in
                   |                            |Fortran double-loop
     Ever confirmed|0                           |1
      Known to fail|                            |4.3.4, 4.6.4, 4.7.2, 4.8.1,
                   |                            |4.9.0

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
We have

  {stride.3_18 * -2 - _30, +, stride.3_18 + 1}_4

vs.

  {-stride.3_18 - _30, +, stride.3_18 + 1}_4

for the two a-based accesses.  But that isn't stride.3_18 + 1 apart.

Regression since predictive commoning is enabled by default at -O3.