This patch changes the type of aff_tree::offset from widest_int to
poly_widest_int and adjusts the function interfaces in the same way.

2017-12-20  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-affine.h (aff_tree::offset): Change from widest_int
	to poly_widest_int.
	(wide_int_ext_for_comb): Delete.
	(aff_combination_const, aff_comb_cannot_overlap_p): Take the
	constants as poly_widest_int rather than widest_int.
	(aff_combination_constant_multiple_p): Return the multiplier
	as a poly_widest_int.
	(aff_combination_zero_p, aff_combination_singleton_var_p): Handle
	polynomial offsets.
	* tree-affine.c (wide_int_ext_for_comb): Make original widest_int
	version static and add an overload for poly_widest_int.
	(aff_combination_const, aff_combination_add_cst)
	(wide_int_constant_multiple_p, aff_comb_cannot_overlap_p): Take
	the constants as poly_widest_int rather than widest_int.
	(tree_to_aff_combination): Generalize INTEGER_CST case to
	poly_int_tree_p.
	(aff_combination_to_tree): Track offsets as poly_widest_ints.
	(aff_combination_add_product, aff_combination_mult): Handle
	polynomial offsets.
	(aff_combination_constant_multiple_p): Return the multiplier
	as a poly_widest_int.
	* tree-predcom.c (determine_offset): Return the offset as a
	poly_widest_int.
	(split_data_refs_to_components, suitable_component_p): Update
	accordingly.
	(valid_initializer_p): Update call to
	aff_combination_constant_multiple_p.
	* tree-ssa-address.c (addr_to_parts): Handle polynomial offsets.
	* tree-ssa-loop-ivopts.c (get_address_cost_ainc): Take the step
	as a poly_int64 rather than a HOST_WIDE_INT.
	(get_address_cost): Handle polynomial offsets.
	(iv_elimination_compare_lt): Likewise.
	(rewrite_use_nonlinear_expr): Likewise.

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

From-SVN: r255888