[Bug tree-optimization/49279] [4.5/4.6/4.7 Regression] Optimization incorrectly presuming constant variable inside loop in g++ 4.5 and 4.6 with -O2 and -O3 for x86_64 targets

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49279

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-10-05 
08:09:24 UTC ---
BTW, the extra problematic casts aren't coming from the frontend, it is the
gimplifier that is inserting them:
  /* Insert pointer conversions required by the middle-end that are not
     required by the frontend.  This fixes middle-end type checking for
     for example gcc.dg/redecl-6.c.  */
  if (POINTER_TYPE_P (TREE_TYPE (*to_p)))
    {
      STRIP_USELESS_TYPE_CONVERSION (*from_p);
      if (!useless_type_conversion_p (TREE_TYPE (*to_p), TREE_TYPE (*from_p)))
        *from_p = fold_convert_loc (loc, TREE_TYPE (*to_p), *from_p);
    }