1  /* { dg-do run } */
       2  /* { dg-options "-O2 -funroll-loops -march=z9-109" } */
       3  /* { dg-require-effective-target stdint_types } */
       4  
       5  /* Folding of the FLOGR caused a wrong value to be returned by
       6     __builtin_clz becuase of a problem in the RTX we emit for FLOGR.
       7     The problematic folding can only be triggered with constants inputs
       8     introduced on RTL level.  In this case it happens with loop
       9     unrolling.  */
      10  
      11  #include <stdint.h>
      12  #include <assert.h>
      13  
      14  static inline uint32_t pow2_ceil_u32(uint32_t x) {
      15    if (x <= 1) {
      16      return x;
      17    }
      18    int msb_on_index;
      19    msb_on_index = (31 ^ __builtin_clz(x - 1));
      20    assert(msb_on_index < 31);
      21    return 1U << (msb_on_index + 1);
      22  }
      23  
      24  void __attribute__((noinline,noclone))
      25  die (int a)
      26  {
      27    if (a)
      28      __builtin_abort ();
      29  }
      30  
      31  void test_pow2_ceil_u32(void) {
      32    unsigned i;
      33  
      34    for (i = 0; i < 18; i++) {
      35        uint32_t a_ = (pow2_ceil_u32(((uint32_t)1) << i));
      36        if (!(a_ == (((uint32_t)1) << i))) {
      37  	die(1);
      38        }
      39    }
      40  }
      41  
      42  int
      43  main(void) {
      44    test_pow2_ceil_u32();
      45  
      46    return 0;
      47  }