[Bug tree-optimization/79744] [7 Regression] The polyhedron test rnflow.f90 is miscompiled with -O3 after r236361

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79744

--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
>  The pb11 version is fine though:

With pb11 I still see

         165 ,         197          9830        9748  0.829999983    
         165 ,         205          1529        1461   4.44999981    
         173 ,         181        194373      194038  0.170000002    
         173 ,         189         78369       78584  0.270000011    
         173 ,         197         19089       19180  0.469999999    
         181 ,         189         81645       81303  0.419999987    
         181 ,         197         29924       30302   1.25000000    
         189 ,         205         12258       12546   2.29999995    
         197 ,         213          2790        2698   3.29999995    
  0: 0:36.854 -> Completed program execution