1  #if defined (__aarch64__)
       2  # define REG1 "x0"
       3  # define REG2 "x1"
       4  #elif defined (__arm__)
       5  # define REG1 "r0"
       6  # define REG2 "r1"
       7  #elif defined (__i386__)
       8  # define REG1 "%eax"
       9  # define REG2 "%edx"
      10  #elif defined (__powerpc__) || defined (__POWERPC__)
      11  # define REG1 "r3"
      12  # define REG2 "r4"
      13  #elif defined (__s390__)
      14  # define REG1 "0"
      15  # define REG2 "1"
      16  #elif defined (__x86_64__)
      17  # define REG1 "rax"
      18  # define REG2 "rdx"
      19  #endif