https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64265
--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Doing it in gimplify_function_tree is pretty straightforward, after all, we
already have there code to handle
if (flag_instrument_function_entry_exit
&& !DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (fndecl)
&& !flag_instrument_functions_exclude_p (fndecl))
which does very similar thing - on entry add a call to one function with
address of current function and __builtin_return_address (0), on exit
(including exit through exceptions) another call with the same arguments.
So, the question is just if you want to do it that way...
