Ticket #13352: a.c

// Compile with : g++ a.c -o a ; ./a

#include <stdio.h>
#include <stdlib.h>

int popcount();
int popcountl();

__attribute__ ((target ("default")))
inline int popcountl(unsigned long i){
  if (sizeof(int) == 4){
    // Returns the number of '1' bits in a 32-bits integer.
    i = i - ((i >> 1) & 0x55555555);
    i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
    return( ((i + (i >> 4) & 0x0F0F0F0F) * 0x01010101) >> 24 );
  }
  else{
    // Returns the number of '1' bits in a 64-bits integer.
    i = i - ((i >> 1) & 0x5555555555555555ULL);
    i = (i & 0x3333333333333333ULL) + ((i >> 2) & 0x3333333333333333ULL);
    return( ( ((i + (i >> 4)) & 0x0f0f0f0f0f0f0f0fULL) * 0x0101010101010101ULL ) >> 56 );
  }
}

__attribute__ ((target ("default")))
inline int popcount(unsigned int i){
  return popcount((unsigned long) i);
}

__attribute__ ((target ("popcnt")))
inline int popcount(unsigned int i){
  return __builtin_popcount(i);
}
__attribute__ ((target ("popcnt")))
inline int popcountl(unsigned long i){
  return __builtin_popcountl(i);
}

int main(int argc, char ** argv){
  long n=atoi(argv[1]);
  printf("%d\n",popcountl(n));
}