Function hsum_float_8

src/quant.cpp:46–52

horizontally add 8 floats

#if __AVX__ || __AVX2__ || __AVX512F__
// horizontally add 8 floats
static inline float hsum_float_8(const __m256 x) {
  __m128 res = _mm256_extractf128_ps(x, 1);
  res = _mm_add_ps(res, _mm256_castps256_ps128(x));
  res = _mm_add_ps(res, _mm_movehl_ps(res, res));
  res = _mm_add_ss(res, _mm_movehdup_ps(res));
  return _mm_cvtss_f32(res);
}

// shuffles to pick the required scales in dot products
static inline __m256i get_scale_shuffle_q3k(int i) {