Use vec<> in build_vector

Use vec<> in build_vector

This patch makes build_vector take the elements as a vec<> rather
than a tree *.  This is useful for SVE because it bundles the number
of elements with the elements themselves, and enforces the fact that
the number is constant.  Also, I think things like the folds can be used
with any generic GNU vector, not just those that match machine vectors,
so the arguments to XALLOCAVEC had no clear limit.

2017-09-14  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree.h (build_vector): Take a vec<tree> instead of a tree *.
	* tree.c (build_vector): Likewise.
	(build_vector_from_ctor): Update accordingly.
	(build_vector_from_val): Likewise.
	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Likewise.
	* tree-ssa-forwprop.c (simplify_vector_constructor): Likewise.
	* tree-vect-generic.c (add_rshift): Likewise.
	(expand_vector_divmod): Likewise.
	(optimize_vector_constructor): Likewise.
	* tree-vect-slp.c (vect_get_constant_vectors): Likewise.
	(vect_transform_slp_perm_load): Likewise.
	(vect_schedule_slp_instance): Likewise.
	* tree-vect-stmts.c (vectorizable_bswap): Likewise.
	(vectorizable_call): Likewise.
	(vect_gen_perm_mask_any): Likewise.  Add elements in order.
	* expmed.c (make_tree): Likewise.
	* fold-const.c (fold_negate_expr_1): Use auto_vec<tree> when building
	a vector passed to build_vector.
	(fold_convert_const): Likewise.
	(exact_inverse): Likewise.
	(fold_ternary_loc): Likewise.
	(fold_relational_const): Likewise.
	(const_binop): Likewise.  Use VECTOR_CST_ELT directly when operating
	on VECTOR_CSTs, rather than going through vec_cst_ctor_to_array.
	(const_unop): Likewise.  Store the reduction accumulator in a
	variable rather than an array.
	(vec_cst_ctor_to_array): Take the number of elements as a parameter.
	(fold_vec_perm): Update calls accordingly.  Use auto_vec<tree> for
	the new vector, rather than constructing it after the input arrays.
	(native_interpret_vector): Use auto_vec<tree> when building
	a vector passed to build_vector.  Add elements in order.
	* tree-vect-loop.c (get_initial_defs_for_reduction): Use
	auto_vec<tree> when building a vector passed to build_vector.
	(vect_create_epilog_for_reduction): Likewise.
	(vectorizable_induction): Likewise.
	(get_initial_def_for_reduction): Likewise.  Fix indentation of
	case statements.
	* config/sparc/sparc.c (sparc_handle_vis_mul8x16): Change n_elts
	to a vec<tree> *.
	(sparc_fold_builtin): Use auto_vec<tree> when building a vector
	passed to build_vector.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r252760