This patch changes GET_MODE_NUNITS from unsigned char
to poly_uint16, although it remains a macro when compiling
target code with NUM_POLY_INT_COEFFS == 1.

We can handle permuted loads and stores for variable nunits if
the number of statements is a power of 2, but not otherwise.

The to_constant call in make_vector_type goes away in a later patch.

2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* machmode.h (mode_nunits): Change from unsigned char to
	poly_uint16_pod.
	(ONLY_FIXED_SIZE_MODES): New macro.
	(pod_mode::measurement_type, scalar_int_mode::measurement_type)
	(scalar_float_mode::measurement_type, scalar_mode::measurement_type)
	(complex_mode::measurement_type, fixed_size_mode::measurement_type):
	New typedefs.
	(mode_to_nunits): Return a poly_uint16 rather than an unsigned short.
	(GET_MODE_NUNITS): Return a constant if ONLY_FIXED_SIZE_MODES,
	or if measurement_type is not polynomial.
	* genmodes.c (ZERO_COEFFS): New macro.
	(emit_mode_nunits_inline): Make mode_nunits_inline return a
	poly_uint16.
	(emit_mode_nunits): Change the type of mode_nunits to poly_uint16_pod.
	Use ZERO_COEFFS when emitting initializers.
	* data-streamer.h (bp_pack_poly_value): New function.
	(bp_unpack_poly_value): Likewise.
	* lto-streamer-in.c (lto_input_mode_table): Use bp_unpack_poly_value
	for GET_MODE_NUNITS.
	* lto-streamer-out.c (lto_write_mode_table): Use bp_pack_poly_value
	for GET_MODE_NUNITS.
	* tree.c (make_vector_type): Remove temporary shim and make
	the real function take the number of units as a poly_uint64
	rather than an int.
	(build_vector_type_for_mode): Handle polynomial nunits.
	* dwarf2out.c (loc_descriptor, add_const_value_attribute): Likewise.
	* emit-rtl.c (const_vec_series_p_1): Likewise.
	(gen_rtx_CONST_VECTOR): Likewise.
	* fold-const.c (test_vec_duplicate_folding): Likewise.
	* genrecog.c (validate_pattern): Likewise.
	* optabs-query.c (can_vec_perm_var_p, can_mult_highpart_p): Likewise.
	* optabs-tree.c (expand_vec_cond_expr_p): Likewise.
	* optabs.c (expand_vector_broadcast, expand_binop_directly): Likewise.
	(shift_amt_for_vec_perm_mask, expand_vec_perm_var): Likewise.
	(expand_vec_cond_expr, expand_mult_highpart): Likewise.
	* rtlanal.c (subreg_get_info): Likewise.
	* tree-vect-data-refs.c (vect_grouped_store_supported): Likewise.
	(vect_grouped_load_supported): Likewise.
	* tree-vect-generic.c (type_for_widest_vector_mode): Likewise.
	* tree-vect-loop.c (have_whole_vector_shift): Likewise.
	* simplify-rtx.c (simplify_unary_operation_1): Likewise.
	(simplify_const_unary_operation, simplify_binary_operation_1)
	(simplify_const_binary_operation, simplify_ternary_operation)
	(test_vector_ops_duplicate, test_vector_ops): Likewise.
	(simplify_immed_subreg): Use GET_MODE_NUNITS on a fixed_size_mode
	instead of CONST_VECTOR_NUNITS.
	* varasm.c (output_constant_pool_2): Likewise.
	* rtx-vector-builder.c (rtx_vector_builder::build): Only include the
	explicit-encoded elements in the XVEC for variable-length vectors.

gcc/ada/
	* gcc-interface/misc.c (enumerate_modes): Handle polynomial
	GET_MODE_NUNITS.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r256195