re PR tree-optimization/52406 (likely wrong code bug)

re PR tree-optimization/52406 (likely wrong code bug)

2012-03-02  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52406
	* tree-data-ref.h: Update documentation about DR_BASE_OBJECT.
	(struct indices): Add unconstrained_base member.
	(struct dr_alias): Remove unused vops member.
	(DR_UNCONSTRAINED_BASE): New define.
	* tree-data-ref.c (dr_analyze_indices): For COMPONENT_REFs
	add indices to allow their disambiguation.  Make DR_BASE_OBJECT
	be an artificial access that covers the whole indexed object,
	or mark it with DR_UNCONSTRAINED_BASE if we cannot do so.  Canonicalize
	plain decl base-objects to their MEM_REF variant.
	(dr_may_alias_p): When the base-object of either data reference
	has unknown size use only points-to information.
	(compute_affine_dependence): Make dumps easier to read and
	more verbose.
	* tree-vect-data-ref.c (vector_alignment_reachable_p): Use
	DR_REF when looking for packed references.
	(vect_supportable_dr_alignment): Likewise.

	* gcc.dg/torture/pr52406.c: New testcase.

From-SVN: r184789