[Bug tree-optimization/115579] [15 regression] wrong code at -Os with "-fno-tree-sra" on x86_64-linux-gnu since r15-1391-g4b75ed33fa5fd6

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115579

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So looking into the code. The problem is the ordering.
That is if the store to b is first things will just work.

The loop to call execute_sm:
          execute_sm (loop, ref, aux_map, true, !first_p);

Except use_other_flag_var is wrong if the first one didn't have a store flag.

  if (multi_threaded_model_p && !use_other_flag_var)
    aux->store_flag
      = execute_sm_if_changed_flag_set (loop, ref, &aux->flag_bbs);
  else
    aux->store_flag = NULL_TREE;