code: def autostack(self):
      
      num_slices = 0
      for v in self.graph.all_variables:
        num_slices += self.mesh_to_impl[v.mesh].size
      if num_slices >= 2 ** 16:
        # Startup times are slow with lots of variable slices.
        # Perform more aggressive stacking
        max_combined_slice_size = 2 ** 27
      else:
        # Stacking hurts memory utilization - only stack small variables.
        max_combined_slice_size = 2 ** 16
      self.graph.rewrite_stack_variables(
          mesh_to_impl=self.mesh_to_impl,
          max_combined_slice_size=max_combined_slice_size)
docs: Rewrite graph to combine similarly-shaped variables (faster startup).