shuffle_fail.c

#include <stdio.h>
#include <xmmintrin.h> //SSE

inline __m64 shuf(int perm){
  __m64 a = _mm_setr_pi16(1,2,3,4);
  return _mm_shuffle_pi16 (a, perm);
}

int main()
{
  __m64 e = shuf(4);
  printf("v_out = %vhd\n", e);
  return 0;
}

// gcc -Wall -msse shuffle_fail.c 

/*
clang has a more descriptive error message than gcc:
argument to '__builtin_ia32_pshufw' must be a constant integer
*/