[AArch64] Set NUM_POLY_INT_COEFFS to 2

[AArch64] Set NUM_POLY_INT_COEFFS to 2

This patch switches the AArch64 port to use 2 poly_int coefficients
and updates code as necessary to keep it compiling.

One potentially-significant change is to
aarch64_hard_regno_caller_save_mode.  The old implementation
was written in a pretty conservative way: it changed the default
behaviour for single-register values, but used the default handling
for multi-register values.

I don't think that's necessary, since the interesting cases for this
macro are usually the single-register ones.  Multi-register modes take
up the whole of the constituent registers and the move patterns for all
multi-register modes should be equally good.

Using the original mode for multi-register cases stops us from using
SVE modes to spill multi-register NEON values.  This was caught by
gcc.c-torture/execute/pr47538.c.

Also, aarch64_shift_truncation_mask used GET_MODE_BITSIZE - 1.
GET_MODE_UNIT_BITSIZE - 1 is equivalent for the cases that it handles
(which are all scalars), and I think it's more obvious, since if we ever
do use this for elementwise shifts of vector modes, the mask will depend
on the number of bits in each element rather than the number of bits in
the whole vector.

2018-01-11  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* config/aarch64/aarch64-modes.def (NUM_POLY_INT_COEFFS): Set to 2.
	* config/aarch64/aarch64-protos.h (aarch64_initial_elimination_offset):
	Return a poly_int64 rather than a HOST_WIDE_INT.
	(aarch64_offset_7bit_signed_scaled_p): Take the offset as a poly_int64
	rather than a HOST_WIDE_INT.
	* config/aarch64/aarch64.h (aarch64_frame): Protect with
	HAVE_POLY_INT_H rather than HOST_WIDE_INT.  Change locals_offset,
	hard_fp_offset, frame_size, initial_adjust, callee_offset and
	final_offset from HOST_WIDE_INT to poly_int64.
	* config/aarch64/aarch64-builtins.c (aarch64_simd_expand_args): Use
	to_constant when getting the number of units in an Advanced SIMD
	mode.
	(aarch64_builtin_vectorized_function): Check for a constant number
	of units.
	* config/aarch64/aarch64-simd.md (mov<mode>): Handle polynomial
	GET_MODE_SIZE.
	(aarch64_ld<VSTRUCT:nregs>_lane<VALLDIF:mode>): Use the nunits
	attribute instead of GET_MODE_NUNITS.
	* config/aarch64/aarch64.c (aarch64_hard_regno_nregs)
	(aarch64_class_max_nregs): Use the constant_lowest_bound of the
	GET_MODE_SIZE for fixed-size registers.
	(aarch64_const_vec_all_same_in_range_p): Use const_vec_duplicate_p.
	(aarch64_hard_regno_call_part_clobbered, aarch64_classify_index)
	(aarch64_mode_valid_for_sched_fusion_p, aarch64_classify_address)
	(aarch64_legitimize_address_displacement, aarch64_secondary_reload)
	(aarch64_print_operand, aarch64_print_address_internal)
	(aarch64_address_cost, aarch64_rtx_costs, aarch64_register_move_cost)
	(aarch64_short_vector_p, aapcs_vfp_sub_candidate)
	(aarch64_simd_attr_length_rglist, aarch64_operands_ok_for_ldpstp):
	Handle polynomial GET_MODE_SIZE.
	(aarch64_hard_regno_caller_save_mode): Likewise.  Return modes
	wider than SImode without modification.
	(tls_symbolic_operand_type): Use strip_offset instead of split_const.
	(aarch64_pass_by_reference, aarch64_layout_arg, aarch64_pad_reg_upward)
	(aarch64_gimplify_va_arg_expr): Assert that we don't yet handle
	passing and returning SVE modes.
	(aarch64_function_value, aarch64_layout_arg): Use gen_int_mode
	rather than GEN_INT.
	(aarch64_emit_probe_stack_range): Take the size as a poly_int64
	rather than a HOST_WIDE_INT, but call sorry if it isn't constant.
	(aarch64_allocate_and_probe_stack_space): Likewise.
	(aarch64_layout_frame): Cope with polynomial offsets.
	(aarch64_save_callee_saves, aarch64_restore_callee_saves): Take the
	start_offset as a poly_int64 rather than a HOST_WIDE_INT.  Track
	polynomial offsets.
	(offset_9bit_signed_unscaled_p, offset_12bit_unsigned_scaled_p)
	(aarch64_offset_7bit_signed_scaled_p): Take the offset as a
	poly_int64 rather than a HOST_WIDE_INT.
	(aarch64_get_separate_components, aarch64_process_components)
	(aarch64_expand_prologue, aarch64_expand_epilogue)
	(aarch64_use_return_insn_p): Handle polynomial frame offsets.
	(aarch64_anchor_offset): New function, split out from...
	(aarch64_legitimize_address): ...here.
	(aarch64_builtin_vectorization_cost): Handle polynomial
	TYPE_VECTOR_SUBPARTS.
	(aarch64_simd_check_vect_par_cnst_half): Handle polynomial
	GET_MODE_NUNITS.
	(aarch64_simd_make_constant, aarch64_expand_vector_init): Get the
	number of elements from the PARALLEL rather than the mode.
	(aarch64_shift_truncation_mask): Use GET_MODE_UNIT_BITSIZE
	rather than GET_MODE_BITSIZE.
	(aarch64_evpc_trn, aarch64_evpc_uzp, aarch64_evpc_ext)
	(aarch64_evpc_rev, aarch64_evpc_dup, aarch64_evpc_zip)
	(aarch64_expand_vec_perm_const_1): Handle polynomial
	d->perm.length () and d->perm elements.
	(aarch64_evpc_tbl): Likewise.  Use nelt rather than GET_MODE_NUNITS.
	Apply to_constant to d->perm elements.
	(aarch64_simd_valid_immediate, aarch64_vec_fpconst_pow_of_2): Handle
	polynomial CONST_VECTOR_NUNITS.
	(aarch64_move_pointer): Take amount as a poly_int64 rather
	than an int.
	(aarch64_progress_pointer): Avoid temporary variable.
	* config/aarch64/aarch64.md (aarch64_<crc_variant>): Use
	the mode attribute instead of GET_MODE.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r256533