re PR rtl-optimization/84614 (wrong code with u16->u128 extension at aarch64 -fno...

re PR rtl-optimization/84614 (wrong code with u16->u128 extension at aarch64 -fno-split-wide-types -g3 --param=max-combine-insns=3)

	PR target/84614
	* rtl.h (prev_real_nondebug_insn, next_real_nondebug_insn): New
	prototypes.
	* emit-rtl.c (next_real_insn, prev_real_insn): Fix up function
	comments.
	(next_real_nondebug_insn, prev_real_nondebug_insn): New functions.
	* cfgcleanup.c (try_head_merge_bb): Use prev_real_nondebug_insn
	instead of a loop around prev_real_insn.
	* combine.c (move_deaths): Use prev_real_nondebug_insn instead of
	prev_real_insn.

	* gcc.dg/pr84614.c: New test.

From-SVN: r258129