inline float euclidean_distance()

in src/annoylib.h [336:357]

• 20 lines of code
• 4 McCabe index (conditional complexity)

inline float euclidean_distance<float>(const float* x, const float* y, int f) {
  float result=0;
  if (f > 15) {
    __m512 d = _mm512_setzero_ps();
    for (; f > 15; f -= 16) {
      const __m512 diff = _mm512_sub_ps(_mm512_loadu_ps(x), _mm512_loadu_ps(y));
      d = _mm512_fmadd_ps(diff, diff, d);
      x += 16;
      y += 16;
    }
    // Sum all floats in dot register.
    result = _mm512_reduce_add_ps(d);
  }
  // Don't forget the remaining values.
  for (; f > 0; f--) {
    float tmp = *x - *y;
    result += tmp * tmp;
    x++;
    y++;
  }
  return result;
}