PR target/48220
	* doc/md.texi (Standard Names): Document window_save.
	* cfgexpand.c (expand_debug_parm_decl): New function extracted from
	expand_debug_expr and expand_debug_source_expr.  If the target has
	a window_save instruction, adjust the ENTRY_VALUE_EXP.
	(expand_debug_expr) <SSA_NAME>: Call expand_debug_parm_decl if the
	SSA_NAME_VAR is a parameter.
	(expand_debug_source_expr) <PARM_DECL>: Call expand_debug_parm_decl.
	* var-tracking.c (parm_reg_t): New type and associated vector type.
	(windowed_parm_regs): New variable.
	(adjust_insn): If the target has a window_save instruction and this
	is the instruction, make its effect on parameter registers explicit.
	(next_non_note_insn_var_location): New function.
	(emit_notes_in_bb): Use it instead of NEXT_INSN throughout.
	(vt_add_function_parameter): If the target has a window_save insn,
	adjust the incoming RTL and record that in windowed_parm_regs.
	(vt_finalize): Free windowed_parm_regs.

From-SVN: r176318