re PR tree-optimization/53295 (Vectorizer support for non-constant strided loads depends on gather support overwriting the data-ref with bogus data)

2012-05-11  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/53295
	* tree-data-ref.h (stride_of_unit_type_p): Handle non-constant
	strides.
	* tree-data-ref.c (dr_analyze_innermost): Allow non-constant
	strides when analyzing data-references in a loop context.
	* tree-vect-data-refs.c (vect_mark_for_runtime_alias_test): Reject
	non-constant strides for now.
	(vect_enhance_data_refs_alignment): Ignore data references
	that are strided loads.
	(vect_analyze_data_ref_access): Handle non-constant strides.
	(vect_check_strided_load): Verify the data-reference is a load.
	(vect_analyze_data_refs): Restructure to make strided load
	support not dependent on gather support.
	* tree-vect-stmts.c (vectorizable_load): Avoid useless work
	when doing strided or gather loads.
	* tree-vect-loop-manip.c (vect_vfa_segment_size): Use
	integer_zerop to compare stride with zero.

From-SVN: r187402