[Bug tree-optimization/21173] [4.0 regression] miscompiled pointer subtraction broke Linux kernel

[belyshev at depni dot sinp dot msu dot ru]

------- Additional Comments From belyshev at depni dot sinp dot msu dot ru  
2005-04-23 12:30 -------
// Confirmed on amd64 too, smaller testcase (compile with -O2):

void abort (void);

char q;
void *a[2];

void foo (char *p)
{
  int i;
  for (i = 0; i < 2; i++)
    a[i] += p - &q;
}

int main (void)
{
  int i;
  foo (&q);
  for (i = 0; i < 2; i ++)
    if (a[i])
      abort ();
  return 0;
}


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|c                           |tree-optimization
     Ever Confirmed|                            |1
  GCC build triplet|i686-pc-linux-gnu           |
   GCC host triplet|i686-pc-linux-gnu           |
 GCC target triplet|i686-pc-linux-gnu           |
           Keywords|                            |wrong-code
      Known to fail|                            |4.0.0
      Known to work|                            |3.4.4
           Priority|P2                          |P1
   Last reconfirmed|0000-00-00 00:00:00         |2005-04-23 12:30:26
               date|                            |
            Summary|miscompiled pointer         |[4.0 regression] miscompiled
                   |subtraction broke Linux     |pointer subtraction broke
                   |kernel                      |Linux kernel
   Target Milestone|---                         |4.0.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21173