https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89324
--- Comment #4 from Matthew Malcomson <matmal01 at gcc dot gnu.org> --- There were similar problems in handling the stack pointer with subs/adds instructions elsewhere in the aarch64 backend. Patch proposed & being worked on here: https://gcc.gnu.org/ml/gcc-patches/2019-02/msg01458.html
