This patch changes GET_MODE_BITSIZE from an unsigned short
to a poly_uint16.

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_to_bits): Return a poly_uint16 rather than an
	unsigned short.
	(GET_MODE_BITSIZE): Return a constant if ONLY_FIXED_SIZE_MODES,
	or if measurement_type is polynomial.
	* calls.c (shift_return_value): Treat GET_MODE_BITSIZE as polynomial.
	* combine.c (make_extraction): Likewise.
	* dse.c (find_shift_sequence): Likewise.
	* dwarf2out.c (mem_loc_descriptor): Likewise.
	* expmed.c (store_integral_bit_field, extract_bit_field_1): Likewise.
	(extract_bit_field, extract_low_bits): Likewise.
	* expr.c (convert_move, convert_modes, emit_move_insn_1): Likewise.
	(optimize_bitfield_assignment_op, expand_assignment): Likewise.
	(store_expr_with_bounds, store_field, expand_expr_real_1): Likewise.
	* fold-const.c (optimize_bit_field_compare, merge_ranges): Likewise.
	* gimple-fold.c (optimize_atomic_compare_exchange_p): Likewise.
	* reload.c (find_reloads): Likewise.
	* reload1.c (alter_reg): Likewise.
	* stor-layout.c (bitwise_mode_for_mode, compute_record_mode): Likewise.
	* targhooks.c (default_secondary_memory_needed_mode): Likewise.
	* tree-if-conv.c (predicate_mem_writes): Likewise.
	* tree-ssa-strlen.c (handle_builtin_memcmp): Likewise.
	* tree-vect-patterns.c (adjust_bool_pattern): Likewise.
	* tree-vect-stmts.c (vectorizable_simd_clone_call): Likewise.
	* valtrack.c (dead_debug_insert_temp): Likewise.
	* varasm.c (mergeable_constant_section): Likewise.
	* config/sh/sh.h (LOCAL_ALIGNMENT): Use as_a <fixed_size_mode>.

gcc/ada/
	* gcc-interface/misc.c (enumerate_modes): Treat GET_MODE_BITSIZE
	as polynomial.

gcc/c-family/
	* c-ubsan.c (ubsan_instrument_shift): Treat GET_MODE_BITSIZE
	as polynomial.

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

From-SVN: r256200