gcc/testsuite/gcc.dg/tree-ssa/foldstring-1.c

/* { dg-do compile } */
/* { dg-options "-O1 -fdump-tree-fre" } */

void
arf ()
{
  if (""[0] == 0)
    blah ();
}
/* { dg-final { scan-tree-dump-times "= 0;" 1 "fre"} } */ 
/* { dg-final { cleanup-tree-dump "fre" } } */