PR debug/43161
	* regcprop.c (struct queued_debug_insn_change): New type.
	(struct value_data_entry): Add debug_insn_changes field.
	(struct value_data): Add n_debug_insn_changes field.
	(debug_insn_changes_pool): New variable.
	(free_debug_insn_changes, apply_debug_insn_changes,
	cprop_find_used_regs_1, cprop_find_used_regs): New functions.
	(kill_value_one_regno): Call free_debug_insn_changes if needed.
	(init_value_data): Clear debug_insn_changes and n_debug_insn_changes
	fields.
	(replace_oldest_value_reg): Don't change DEBUG_INSNs, instead queue
	changes for them.
	(copyprop_hardreg_forward_1): Don't call apply_change_group for
	DEBUG_INSNs.  For a real insn, if there are queued DEBUG_INSN
	changes, call cprop_find_used_regs via note_stores.
	(copyprop_hardreg_forward): When copying vd from predecessor
	which has any queued DEBUG_INSN changes, make sure the pointers are
	cleared.  At the end call df_analyze and then if there are any
	DEBUG_INSN changes queued at the end of some basic block for still
	live registers, apply them.
	(pass_cprop_hardreg): Set TODO_df_finish in todo_flags_finish.

From-SVN: r157083