1  
       2  void a()
       3  {
       4  #if defined __s390__
       5    register int b asm("r5");
       6  #elif defined __x86_64__
       7    register int b asm("eax");
       8  #else
       9    volatile int b;
      10  #endif
      11    if (b)
      12      b = 1;
      13    for (; b;)
      14      ;
      15  }