Stack layout change during lra

[Joey Ye]

Vlad,

When fixing PR60169, I found that reload fail to assert
verify_initial_elim_offsets ()
  if (insns_need_reload != 0 || something_needs_elimination
      || something_needs_operands_changed)
    {
      HOST_WIDE_INT old_frame_size = get_frame_size ();

      reload_as_needed (global);

      gcc_assert (old_frame_size == get_frame_size ());

      gcc_assert (verify_initial_elim_offsets ());
    }

The reason is that stack layout changes during reload_as_needed as a result
of a thumb1 backend heuristic.

I have a patch to make sure the heuristic doesn't change stack layout during
and after reload, and the assertion disappeared. However, I'm not sure if it
will also be a problem in lra. Here is the question more specific:

Is that any chance during lra_in_progress that: stack layout can no longer
be altered, but insns can still be added or changed?

Thanks,
Joey