The hook is passed the promoted mode instead of the original type mode.

The expr.h reference in the documentation is no longer correct, but
pointing to calls.h or calls.c doesn't help much either.  I just left
this as-is since it's not related to the point of the series.

After previous changes, most places already pass arg.mode and arg.type.
Only i386 and mcore needed to construct a new one out of nothing.
rs6000 needs to construct one slightly earlier than before.

2019-08-20  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* target.def (must_pass_in_stack): Take a function_arg_info instead
	of a mode and a type.
	* doc/tm.texi: Regenerate.
	* calls.h (must_pass_in_stack_var_size): Take a function_arg_info
	instead of a mode and a type.
	(must_pass_in_stack_var_size_or_pad): Likewise.
	* calls.c (must_pass_in_stack_var_size): Likewise.
	(must_pass_in_stack_var_size_or_pad): Likewise.
	(initialize_argument_information): Update call to
	targetm.calls.must_pass_in_stack.
	(must_pass_va_arg_on_stack): Likewise.
	* function.c (assign_parm_find_entry_rtl): Likewise.
	* targhooks.c (hook_pass_by_reference_must_pass_in_stack): Likewise.
	* config/alpha/alpha.c (alpha_function_arg): Likewise.
	(alpha_function_arg_advance): Likewise.
	* config/cr16/cr16.c (cr16_function_arg): Likewise.
	(cr16_function_arg_advance): Likewise.
	* config/cris/cris.c (cris_pass_by_reference): Likewise.
	(cris_arg_partial_bytes): Likewise.
	* config/iq2000/iq2000.c (iq2000_pass_by_reference): Likewise.
	* config/lm32/lm32.c (lm32_function_arg): Likewise.
	* config/mcore/mcore.c (mcore_num_arg_regs): Likewise.
	(mcore_function_arg, mcore_arg_partial_bytes): Likewise.
	* config/mips/mips.c (mips_pass_by_reference): Likewise.
	* config/mmix/mmix.c (mmix_function_arg_advance): Likewise.
	(mmix_function_arg_1, mmix_pass_by_reference): Likewise.
	* config/sh/sh.c (sh_pass_by_reference): Likewise.
	* config/stormy16/stormy16.c (xstormy16_function_arg): Likewise.
	* config/xtensa/xtensa.c (xtensa_function_arg_advance): Likewise.
	* config/arm/arm.c (arm_must_pass_in_stack): Take a function_arg_info
	instead of a mode and a type.
	* config/fr30/fr30.c (fr30_must_pass_in_stack): Likewise.
	(fr30_num_arg_regs): Likewise.
	(fr30_setup_incoming_varargs): Update calls accordingly.
	(fr30_arg_partial_bytes, fr30_function_arg): Likewise.
	(fr30_function_arg_advance): Likewise.
	* config/frv/frv.c (frv_must_pass_in_stack): Take a function_arg_info
	instead of a mode and a type.
	* config/gcn/gcn.c (num_arg_regs): Likewise.
	(gcn_function_arg, gcn_function_arg_advance): Update calls to
	num_arg_regs and targetm.calls.must_pass_in_stack.
	(gcn_arg_partial_bytes): Likewise.
	* config/i386/i386.c (ix86_must_pass_in_stack): Take a
	function_arg_info instead of a mode and a type.
	(classify_argument): Update call accordingly.
	* config/nds32/nds32.c (nds32_must_pass_in_stack): Take a
	function_arg_info instead of a mode and a type.
	* config/rs6000/rs6000-internal.h (rs6000_must_pass_in_stack):
	Likewise.
	* config/rs6000/rs6000-call.c (rs6000_must_pass_in_stack): Likewise.
	(rs6000_parm_needs_stack): Update call accordingly.
	(setup_incoming_varargs): Likewise.

From-SVN: r274703