re PR tree-optimization/49038 (-ftree-vectorise introduces reads past end of array)

re PR tree-optimization/49038 (-ftree-vectorise introduces reads past end of array)

	PR tree-optimization/49038
	* tree-vect-loop-manip.c (vect_generate_tmps_on_preheader):
	Ensure at least one epilogue iteration if required by data
	accesses with gaps.
	* tree-vectorizer.h (struct _loop_vec_info): Add new field
	to mark loops that require peeling for gaps.
	* tree-vect-loop.c (new_loop_vec_info): Initialize new field.
	(vect_estimate_min_profitable_iters): Take peeling for gaps into
	account.
	(vect_transform_loop): Generate epilogue if required by data
	access with gaps.
	* tree-vect-data-refs.c (vect_analyze_group_access): Mark the
	loop as requiring an epilogue if there are gaps in the end of
	the strided group.

From-SVN: r174634