PR debug/43058

	PR debug/43058
	* var-tracking.c (non_suitable_const): New function.
	(add_uses): For DEBUG_INSNs with constants, don't record any
	value, instead just the constant value itself.
	(compute_bb_dataflow) <case MO_VAL_LOC>: If PAT_VAR_LOCATION_LOC
	is not VAR_LOC_UNKNOWN_P, set var to the constant.
	(emit_notes_in_bb): Likewise.
	(emit_note_insn_var_location): For onepart variables if
	cur_loc is a VOIDmode constant, use DECL_MODE.

	* gcc.dg/pr43058.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@157547 138bc75d-0d04-0410-961f-82ee72b054a4