message: Try multiple vector sizes
diff: @@ -244,8 +244,8 @@ static void ContractionWrap(KernelList& r, const Contraction* c, FlatContraction
  while (SimplifyFlat(&flat)) {
  }
  // Do memory based tile optimization
  - if (settings.vec_size > 1) {
  - flat = Vectorize(flat, settings.vec_size);
  + for (auto vec_size = settings.vec_size; flat.agg_vec == 1 && 1 < vec_size; vec_size /= 2) {
  + flat = Vectorize(flat, vec_size);
  }
  IVLOG(4, "Optimizing " << kname);
  auto by_score = TileOptimize(settings, flat, tile_trials == 1, vars);
  