Add check for prefixed addresses.

Add check for prefixed addresses.

2019-10-10  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (quad_address_p): Add check for prefixed
	addresses.
	(mem_operand_gpr): Add check for prefixed addresses.
	(mem_operand_ds_form): Add check for prefixed addresses.
	(rs6000_legitimate_offset_address_p): If we support prefixed
	addresses, check for a 34-bit offset instead of 16-bit.
	(rs6000_legitimate_address_p): Add check for prefixed addresses.
	Do not allow load/store with update if the address is prefixed.
	(rs6000_mode_dependent_address):  If we support prefixed
	addresses, check for a 34-bit offset instead of 16-bit.

From-SVN: r276846