There are no instructions that do traditional AltiVec addresses (i.e.
with the low four bits of the address masked off) for OOmode and XOmode
objects. The solution is to modify the constraints used in the movoo and
movxo pattern to disallow these types of addresses, which assists LRA in
resolving this issue. Furthermore, the mode size 16 check has been
removed in vsx_quad_dform_memory_operand to allow OOmode and XOmode, and
quad_address_p already handles less than size 16.