inline float dot()

in src/annoylib.h [289:309]

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

inline float dot<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) {
      //AVX512F includes FMA
      d = _mm512_fmadd_ps(_mm512_loadu_ps(x), _mm512_loadu_ps(y), 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--) {
    result += *x * *y;
    x++;
    y++;
  }
  return result;
}