* config/s390/s390.c (struct machine_function): Use save_return_addr_p

	* config/s390/s390.c (struct machine_function): Use save_return_addr_p
	as a general flag that the return address register needs to be saved,
	not necessarily because of __builtin_return_addr (0).
	(s390_split_branches): Remove TEMP_REG and TEMP_USED arguments,
	remove special handling of zSeries machines.
	(s390_optimize_prolog): Remove TEMP_USED argument, treat the return
	register as a regular register on zSeries machines.
	(s390_reorg): Adjust calls to s390_split_branches and
	s390_optimize_prolog.
	(s390_frame_info): On zSeries machines, do not assume the return
	register is always used.  Update regs_ever_live with current data
	for the special registers.
	(s390_emit_epilogue): Use save_return_addr_p to determine whether
	the return register was saved.
	* config/s390/s390.h (CONDITIONAL_REGISTER_USAGE): Do not mark
	RETURN_REGNUM fixed on zSeries machines.
	(REG_ALLOC_ORDER): Use RETURN_REGNUM last.
	* config/s390/s390.md ("*doloop_si"): Handle branch overflow
	via ahi-jgne pair on zSeries machines.
	("*doloop_di"): Likewise.
	("*doloop_di_long"): Remove.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@73084 138bc75d-0d04-0410-961f-82ee72b054a4