This patch enables targets to describe DR_TARGET_ALIGNMENT as a compile-time
variable.  It does so by turning the variable into a 'poly_uint64'.

gcc/ChangeLog:
2018-11-13  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* config/aarch64/aarch64.c
	(aarch64_vectorize_preferred_vector_alignment): Change return type to
	poly_uint64.
	(aarch64_simd_vector_alignment_reachable): Adapt to preferred vector
	alignment being a poly int.
	* doc/tm.texi (TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT): Change
	return type to poly_uint64.
	* target.def (default_preferred_vector_alignment): Likewise.
	* targhooks.c (default_preferred_vector_alignment): Likewise.
	* targhooks.h (default_preferred_vector_alignment): Likewise.
	* tree-vect-data-refs.c (vect_calculate_target_alignment): Likewise.
	(vect_compute_data_ref_alignment): Adapt to vector alignment being a
	poly int.
	(vect_update_misalignment_for_peel): Likewise.
	(vect_enhance_data_refs_alignment): Likewise.
	(vect_find_same_alignment_drs): Likewise.
	(vect_duplicate_ssa_name_ptr_info): Likewise.
	(vect_setup_realignment): Likewise.
	(vect_can_force_dr_alignment_p): Change alignment parameter type to
	poly_uint64.
	* tree-vect-loop-manip.c (get_misalign_in_elems): Learn to construct a
	mask with a compile time variable vector alignment.
	(vect_gen_prolog_loop_niters): Adapt to vector alignment being a poly
	int.
	(vect_do_peeling): Exit early if vector alignment is not constant.
	* tree-vect-stmts.c (ensure_base_align): Adapt to vector alignment being
	a poly int.
	(vectorizable_store): Likewise.
	(vectorizable_load): Likweise.
	* tree-vectorizer.h (struct dr_vec_info): Make target_alignment field a
	poly_uint64.
	(vect_known_alignment_in_bytes): Adapt to vector alignment being a
	poly int.
	(vect_can_force_dr_alignment_p): Change alignment parameter type to
	poly_uint64.

From-SVN: r266072