https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63596
--- Comment #2 from Jiong Wang <jiwang at gcc dot gnu.org> --- we are also lack of initialization for va_list_gpr_counter_field and va_list_vpr_counter_field, thus currently the whole tree-stdarg optimization doesn't work for AArch64, and lots of other targets, like arm, sparc, mips etc are lack of this vaarg opt tuning also.
