1  /* { dg-do compile } */
       2  /* { dg-options "-O -ffast-math -fdump-tree-original" } */
       3  
       4  double foo (double x)
       5  {
       6    return (x + 0.5 - x - 0.5);
       7  }
       8  
       9  /* { dg-final { scan-tree-dump "return 0.0;" "original" } } */