2006-01-16  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-alias.c (struct used_part): Add write_only field.
	(get_or_create_used_part_for): Initialize it to true.
	(create_overlap_variables_for): Don't create structure variables
	for structures that only are written to.
	(find_used_portions): Handle MODIFY_EXPR to track whether a
	structure is only written to.

	* gcc.dg/tree-ssa/20031015-1.c: Adjust testcase.

From-SVN: r109766