[Bug tree-optimization/20115] New: [4.0 Regression] Pure functions are missed handled

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

Take the following code, we should not abort:
int func_pure (void);
void func_other (int);
int global_int;
int func_pure (void) { return global_int; }
void func_other (int a)
{
  global_int = a + 1;
}
int f(void)
{
  int a;
  a = func_pure();
  func_other (a);
  a = func_pure (); // We are removing this function call
  return a;
}
void abort (void);

int main(void)
{
  global_int = 10;
  if (f() != 11)
    abort ();
}

-- 
           Summary: [4.0 Regression] Pure functions are missed handled
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20115