PR debug/44023

	PR debug/44023
	* df-problems.c (struct dead_debug): Add to_rescan field.
	(dead_debug_init): Clear to_rescan field.
	(dead_debug_finish): Rescan all debug insns in to_rescan
	bitmap and free the bitmap.
	(dead_debug_insert_before): Instead of rescanning debug insns
	immediately queue their rescanning until dead_debug_finish.
	(df_note_bb_compute): After dead_debug_add do continue instead
	of break.

	* gcc.dg/pr44023.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@159254 138bc75d-0d04-0410-961f-82ee72b054a4