Defer stack slot address assignment for all parms that can't live in
pseudos, and accept pseudos assignments in assign_param_setup_block.

for  gcc/ChangeLog

	PR rtl-optimization/64164
	* cfgexpand.c (parm_maybe_byref_p): Renamed to...
	(parm_in_stack_slot_p): ... this.  Disregard mode, what
	matters is whether the parm will live in a pseudo or a stack
	slot.
	(expand_one_ssa_partition): Deal with params without a default
	def.  Disregard mode.
	* cfgexpand.h: Renamed function declaration.
	* tree-ssa-coalesce.c: Adjust.
	* function.c (split_complex_args): Allocate stack slot for
	unassigned parms before splitting.
	(parm_in_unassigned_mem_p): New.  Use it instead of
	parm_maybe_byref_p throughout this file.
	(assign_parm_setup_block): Use it.  Accept pseudos in the
	expand-assigned rtl.
	(assign_parm_setup_reg): Drop BLKmode requirement.
	(assign_parm_setup_stack): Allocate and fill in the address of
	unassigned MEM parms.

From-SVN: r227015