[Bug target/49419] [4.6/4.7 regression] gcc -O2 miscompiles gp2c

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49419

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-06-15 12:19:00 UTC ---
So, i_47 which is the i value on entry of the second loop is determined to be
[0, +INF(OVF)] and something goes wrong afterwards.  The bug will be there, but
I should note that VRP should easily prove that i never overflows.
Simpler testcases for that:
void bar (void);

void foo (int x, int y)
{
  if (x < y)
    {
      if (x == __INT_MAX__)
        bar ();
    }
}

void baz (int x, int y, int z)
{
  if (x < y || x < z)
    {
      if (x == __INT_MAX__)
        bar ();
    }
}

Here IMNSHO vrp should optimize the call to bar away, as when x is smaller than
some variable of the same type, it can't be the maximum of that type, because
even if the other number is __INT_MAX__, x must be smaller than that.