[Bug target/63596] Saving of GPR/FPRs for stdarg even though the variable argument is not used

[jiwang at gcc dot gnu.org]

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.