tree-data-ref.c (dr_step_indicator): Handle NULL DR_STEP.

tree-data-ref.c (dr_step_indicator): Handle NULL DR_STEP.

2018-06-21  Richard Biener  <rguenther@suse.de>

	* tree-data-ref.c (dr_step_indicator): Handle NULL DR_STEP.
	* tree-vect-data-refs.c (vect_analyze_possibly_independent_ddr):
	Avoid calling vect_mark_for_runtime_alias_test with gathers or scatters.
	(vect_analyze_data_ref_dependence): Re-order checks to deal with
	NULL DR_STEP.
	(vect_record_base_alignments): Do not record base alignment
	for gathers or scatters.
	(vect_compute_data_ref_alignment): Drop return value that is always
	true.  Bail out early for gathers or scatters.
	(vect_enhance_data_refs_alignment): Bail out early for gathers
	or scatters.
	(vect_find_same_alignment_drs): Likewise.
	(vect_analyze_data_refs_alignment): Remove dead code.
	(vect_slp_analyze_and_verify_node_alignment): Likewise.
	(vect_analyze_data_refs): For possible gathers or scatters do
	not create an alternate DR, just check their possible validity
	and mark them.  Adjust DECL_NONALIASED handling to not rely
	on DR_BASE_ADDRESS.
	* tree-vect-loop-manip.c (vect_update_inits_of_drs): Do not
	update inits of gathers or scatters.
	* tree-vect-patterns.c (vect_recog_mask_conversion_pattern):
	Also copy gather/scatter flag to pattern vinfo.

From-SVN: r261834