2005-04-06  Daniel Berlin  <dberlin@dberlin.org>

	* params.def (PARAM_SALIAS_MAX_IMPLICIT_FIELDS): New
	* params.h (SALIAS_MAX_IMPLICIT_FIELDS): New
	* doc/invoke.texi: Documnet salias-max-implicit-fields.
	* tree-ssa-alias.c (struct used_part): Add implicit_uses and
	explicit_uses members.
	(get_or_create_used_part_for): Initialize new fields.
	(fieldoff_compare): New function.
	(create_overlap_variables_for): Count number of fields, use
	heuristic to determine whether to create subvars for vars with
	only implicit uses.
	Sort the field list by offset and avoid creating duplicate SFT's.

From-SVN: r97746