1  /* { dg-do compile } */
       2  /* { dg-options "-O2" } */
       3  
       4  static const unsigned long long magic = 0x03f08c5392f756cdULL;
       5  
       6  static const char table[64] = {
       7       0,  1, 12,  2, 13, 22, 17,  3,
       8      14, 33, 23, 36, 18, 58, 28,  4,
       9      62, 15, 34, 26, 24, 48, 50, 37,
      10      19, 55, 59, 52, 29, 44, 39,  5,
      11      63, 11, 21, 16, 32, 35, 57, 27,
      12      61, 25, 47, 49, 54, 51, 43, 38,
      13      10, 20, 31, 56, 60, 46, 53, 42,
      14       9, 30, 45, 41,  8, 40,  7,  6,
      15  };
      16  
      17  static inline int ctz1 (unsigned long long  b)
      18  {
      19    unsigned long long lsb = b & -b;
      20    return table[(lsb * magic) >> 58];
      21  }
      22  
      23  void f (unsigned long long x, int *p)
      24  {
      25    if (x != 0)
      26      {
      27        int a = ctz1 (x);
      28        *p = a | p[a];
      29      }
      30  }
      31  
      32  /* { dg-final { scan-assembler-times "rbit\t" 1 } } */
      33  /* { dg-final { scan-assembler-times "clz\t" 1 } } */
      34