[Bug tree-optimization/28794] missed optimization with non-COND_EXPR and vrp and comparisions

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=28794

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2020-01-17 00:00:00         |2021-6-8

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note really the loops at -O3 should really be optimized to:
void f3(int x, int y)
{
  int t;
  g(0);
  for (t = 1; t < 50; t++)
  {
   g(1);
  }
}

That is peel off the first iteration.  I don't know why -O3 -fno-ssa-phiopt
-fno-tree-vrp does not do that either. I will file that as a different bug
because this is about converting the comparison only in COND_EXPR gimple.