cse.c: Use rtx_insn

cse.c: Use rtx_insn

gcc/
	* cse.c (struct qty_table_elem): Strengthen field "const_insn"
	from rtx to rtx_insn *.
	(struct change_cc_mode_args): Likewise for field "insn".
	(this_insn): Strengthen from rtx to rtx_insn *.
	(make_new_qty): Replace use of NULL_RTX with NULL when dealing
	with insn.
	(validate_canon_reg): Strengthen param "insn" from rtx to
	rtx_insn *.
	(canon_reg): Likewise.
	(fold_rtx): Likewise.  Replace use of NULL_RTX with NULL when
	dealing with insn.
	(record_jump_equiv): Strengthen param "insn" from rtx to
	rtx_insn *.
	(try_back_substitute_reg): Likewise, also for locals "prev",
	"bb_head".
	(find_sets_in_insn): Likewise for param "insn".
	(canonicalize_insn): Likewise.
	(cse_insn): Likewise.  Add a checked cast.
	(invalidate_from_clobbers): Likewise for param "insn".
	(invalidate_from_sets_and_clobbers): Likewise.
	(cse_process_notes_1): Replace use of NULL_RTX with NULL when
	dealing with insn.
	(cse_prescan_path): Strengthen local "insn" from rtx to
	rtx_insn *.
	(cse_extended_basic_block): Likewise for locals "insn" and
	"prev_insn".
	(cse_main): Likewise for param "f".
	(check_for_label_ref): Likewise for local "insn".
	(set_live_p): Likewise for second param ("insn").
	(insn_live_p): Likewise for first param ("insn") and for local
	"next".
	(cse_change_cc_mode_insn): Likewise for first param "insn".
	(cse_change_cc_mode_insns): Likewise for first and second params
	"start" and "end".
	(cse_cc_succs): Likewise for locals "insns", "last_insns", "insn"
	and "end".
	(cse_condition_code_reg): Likewise for locals "last_insn", "insn",
	"cc_src_insn".

From-SVN: r214315