[Bug middle-end/58143] New: wrong code at -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58143

            Bug ID: 58143
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The current gcc trunk and gcc 4.8 produce wrong code for the following testcase
on x86_64-linux when compiled at -O3 (in both 32-bit and 64-bit modes). This is
a regression from 4.7.x.


$ gcc-trunk -v
gcc version 4.9.0 20130812 (experimental) [trunk revision 201658] (GCC) 
$ gcc-trunk -O2 small.c
$ a.out
0
$ gcc-4.7 -O3 small.c
$ a.out
0
$ gcc-trunk -O3 small.c
$ a.out
-1
$ gcc-4.8 -O3 small.c
$ a.out
-1
$ 


------------------------------------------------------


int printf (const char *, ...);

int a, b, c, d, e, f, g, h = 1, i;

int foo (int p)
{
  return p < 0 && a < -2147483647 - 1 - p ? 0 : 1;
}

int *bar ()
{
  int j; 
  i = h ? 0 : 1 % h;
  for (j = 0; j < 1; j++)
    for (d = 0; d; d++)
      for (e = 1; e;)
    return 0;
  return 0;
}

int baz ()
{
  for (; b >= 0; b--)
    for (c = 1; c >= 0; c--)
      {
    int *k = &c;
    for (;;)
      {
        for (f = 0; f < 1; f++)
          {
        g = foo (*k);
        bar ();
          }
        if (*k)
          break;
        return 0;
      }
      }
  return 0;
}

int main ()
{
  baz ();
  printf ("%d\n", b);
  return 0;
}