re PR debug/45055 (another -fcompare-debug failure with uninitialised read in walk_gimple_stmt)

	PR debug/45055
	PR rtl-optimization/45137
	* rtl.h (prev_nonnote_nondebug_insn, next_nonnote_nondebug_insn): New
	prototypes.
	* emit-rtl.c (prev_nonnote_nondebug_insn, next_nonnote_nondebug_insn):
	New functions.
	* combine.c (next_nonnote_nondebug_insn): Removed.
	* ifcvt.c (noce_process_if_block): Use prev_nonnote_nondebug_insn.
	* haifa-sched.c (queue_to_ready): Use next_nonnote_nondebug_insn.
	* sched-deps.c (sched_analyze_insn): Likewise.
	(fixup_sched_groups, deps_start_bb): Use prev_nonnote_nondebug_insn.
	* rtlanal.c (canonicalize_condition): Likewise.
	* postreload.c (reload_combine_recognize_pattern): Likewise.
	(reload_cse_move2add): Use next_nonnote_nondebug_insn.

	* gcc.dg/pr45055.c: New test.

From-SVN: r162714