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_get_known_peeling_cost): 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: r174265