re PR debug/43983 (var-tracking needlessly throws away location info for SRAed vars)

re PR debug/43983 (var-tracking needlessly throws away location info for SRAed vars)

	PR debug/43983
	* var-tracking.c (track_expr_p): Allow tracking of variables optimized
	by SRA.
	* Makefile.in (dwarf2out.o): Depend on $(TREE_FLOW_H).
	* tree-sra.c (create_access_replacement): Call unshare_expr before
	passing expr to SET_DECL_DEBUG_EXPR, and remove any SSA_NAMEs from
	it.
	* dwarf2out.c: Include tree-flow.h.
	(struct var_loc_node): Rename var_loc_note field to loc, add comment.
	(size_of_loc_descr, output_loc_operands, output_loc_operands_raw):
	Handle DW_OP_bit_piece.
	(decl_piece_bitsize, decl_piece_varloc_ptr, decl_piece_node,
	construct_piece_list, adjust_piece_list): New functions.
	(add_var_loc_to_decl): Handle SRA optimized variables.
	Adjust for var_loc_note to loc field renaming.
	(dw_loc_list_1): For WANT_ADDRESS == 2 prefer DECL_MODE of decl
	in VAR_LOCATION note.
	(new_loc_descr_op_bit_piece): New function.
	(dw_sra_loc_expr): New function.
	(dw_loc_list): Use it.  Don't handle the last range after the
	loop, handle it inside of the loop.  Adjust for var_loc_note
	to loc field renaming.
	(add_location_or_const_value_attribute): Only special case
	single entry loc lists if loc is NOTE_P.  Adjust for
	var_loc_note to loc field renaming.
	(dwarf2out_var_location): Don't set newloc->var_loc_note
	and newloc->next here.

	* gcc.dg/guality/sra-1.c: New test.

From-SVN: r159357