This patch changes TYPE_VECTOR_SUBPARTS to a poly_uint64.  The value is
encoded in the 10-bit precision field and was previously always stored
as a simple log2 value.  The challenge was to use this 10 bits to
encode the number of elements in variable-length vectors, so that
we didn't need to increase the size of the tree.

In practice the number of vector elements should always have the form
N + N * X (where X is the runtime value), and as for constant-length
vectors, N must be a power of 2 (even though X itself might not be).
The patch therefore uses the low 8 bits to encode log2(N) and bit
8 to select between constant-length and variable-length vectors.
Targets without variable-length vectors continue to use the old scheme.

A new valid_vector_subparts_p function tests whether a given number
of elements can be encoded.  This is false for the vector modes that
represent an LD3 or ST3 vector triple (which we want to treat as arrays
of vectors rather than single vectors).

Most of the patch is mechanical; previous patches handled the changes
that weren't entirely straightforward.

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

gcc/
	* tree.h (TYPE_VECTOR_SUBPARTS): Turn into a function and handle
	polynomial numbers of units.
	(SET_TYPE_VECTOR_SUBPARTS): Likewise.
	(valid_vector_subparts_p): New function.
	(build_vector_type): Remove temporary shim and take the number
	of units as a poly_uint64 rather than an int.
	(build_opaque_vector_type): Take the number of units as a
	poly_uint64 rather than an int.
	* tree.c (build_vector_from_ctor): Handle polynomial
	TYPE_VECTOR_SUBPARTS.
	(type_hash_canon_hash, type_cache_hasher::equal): Likewise.
	(uniform_vector_p, vector_type_mode, build_vector): Likewise.
	(build_vector_from_val): If the number of units is variable,
	use build_vec_duplicate_cst for constant operands and
	VEC_DUPLICATE_EXPR otherwise.
	(make_vector_type): Remove temporary is_constant ().
	(build_vector_type, build_opaque_vector_type): Take the number of
	units as a poly_uint64 rather than an int.
	(check_vector_cst): Handle polynomial TYPE_VECTOR_SUBPARTS and
	VECTOR_CST_NELTS.
	* cfgexpand.c (expand_debug_expr): Likewise.
	* expr.c (count_type_elements, categorize_ctor_elements_1): Likewise.
	(store_constructor, expand_expr_real_1): Likewise.
	(const_scalar_mask_from_tree): Likewise.
	* fold-const-call.c (fold_const_reduction): Likewise.
	* fold-const.c (const_binop, const_unop, fold_convert_const): Likewise.
	(operand_equal_p, fold_vec_perm, fold_ternary_loc): Likewise.
	(native_encode_vector, vec_cst_ctor_to_array): Likewise.
	(fold_relational_const): Likewise.
	(native_interpret_vector): Likewise.  Change the size from an
	int to an unsigned int.
	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Handle polynomial
	TYPE_VECTOR_SUBPARTS.
	(gimple_fold_indirect_ref, gimple_build_vector): Likewise.
	(gimple_build_vector_from_val): Use VEC_DUPLICATE_EXPR when
	duplicating a non-constant operand into a variable-length vector.
	* hsa-brig.c (hsa_op_immed::emit_to_buffer): Handle polynomial
	TYPE_VECTOR_SUBPARTS and VECTOR_CST_NELTS.
	* ipa-icf.c (sem_variable::equals): Likewise.
	* match.pd: Likewise.
	* omp-simd-clone.c (simd_clone_subparts): Likewise.
	* print-tree.c (print_node): Likewise.
	* stor-layout.c (layout_type): Likewise.
	* targhooks.c (default_builtin_vectorization_cost): Likewise.
	* tree-cfg.c (verify_gimple_comparison): Likewise.
	(verify_gimple_assign_binary): Likewise.
	(verify_gimple_assign_ternary): Likewise.
	(verify_gimple_assign_single): Likewise.
	* tree-pretty-print.c (dump_generic_node): Likewise.
	* tree-ssa-forwprop.c (simplify_vector_constructor): Likewise.
	(simplify_bitfield_ref, is_combined_permutation_identity): Likewise.
	* tree-vect-data-refs.c (vect_permute_store_chain): Likewise.
	(vect_grouped_load_supported, vect_permute_load_chain): Likewise.
	(vect_shift_permute_load_chain): Likewise.
	* tree-vect-generic.c (nunits_for_known_piecewise_op): Likewise.
	(expand_vector_condition, optimize_vector_constructor): Likewise.
	(lower_vec_perm, get_compute_type): Likewise.
	* tree-vect-loop.c (vect_determine_vectorization_factor): Likewise.
	(get_initial_defs_for_reduction, vect_transform_loop): Likewise.
	* tree-vect-patterns.c (vect_recog_bool_pattern): Likewise.
	(vect_recog_mask_conversion_pattern): Likewise.
	* tree-vect-slp.c (vect_supported_load_permutation_p): Likewise.
	(vect_get_constant_vectors, vect_transform_slp_perm_load): Likewise.
	* tree-vect-stmts.c (perm_mask_for_reverse): Likewise.
	(get_group_load_store_type, vectorizable_mask_load_store): Likewise.
	(vectorizable_bswap, simd_clone_subparts, vectorizable_assignment)
	(vectorizable_shift, vectorizable_operation, vectorizable_store)
	(vectorizable_load, vect_is_simple_cond, vectorizable_comparison)
	(supportable_widening_operation): Likewise.
	(supportable_narrowing_operation): Likewise.
	* tree-vector-builder.c (tree_vector_builder::binary_encoded_nelts):
	Likewise.
	* varasm.c (output_constant): Likewise.

gcc/ada/
	* gcc-interface/utils.c (gnat_types_compatible_p): Handle
	polynomial TYPE_VECTOR_SUBPARTS.

gcc/brig/
	* brigfrontend/brig-to-generic.cc (get_unsigned_int_type): Handle
	polynomial TYPE_VECTOR_SUBPARTS.
	* brigfrontend/brig-util.h (gccbrig_type_vector_subparts): Likewise.

gcc/c-family/
	* c-common.c (vector_types_convertible_p, c_build_vec_perm_expr)
	(convert_vector_to_array_for_subscript): Handle polynomial
	TYPE_VECTOR_SUBPARTS.
	(c_common_type_for_mode): Check valid_vector_subparts_p.
	* c-pretty-print.c (pp_c_initializer_list): Handle polynomial
	VECTOR_CST_NELTS.

gcc/c/
	* c-typeck.c (comptypes_internal, build_binary_op): Handle polynomial
	TYPE_VECTOR_SUBPARTS.

gcc/cp/
	* constexpr.c (cxx_eval_array_reference): Handle polynomial
	VECTOR_CST_NELTS.
	(cxx_fold_indirect_ref): Handle polynomial TYPE_VECTOR_SUBPARTS.
	* call.c (build_conditional_expr_1): Likewise.
	* decl.c (cp_finish_decomp): Likewise.
	* mangle.c (write_type): Likewise.
	* typeck.c (structural_comptypes): Likewise.
	(cp_build_binary_op): Likewise.
	* typeck2.c (process_init_constructor_array): Likewise.

gcc/fortran/
	* trans-types.c (gfc_type_for_mode): Check valid_vector_subparts_p.

gcc/lto/
	* lto-lang.c (lto_type_for_mode): Check valid_vector_subparts_p.
	* lto.c (hash_canonical_type): Handle polynomial TYPE_VECTOR_SUBPARTS.

gcc/go/
	* go-lang.c (go_langhook_type_for_mode): Check valid_vector_subparts_p.

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

From-SVN: r256197