* calls.c (initialize_argument_information): If an argument has no
	stack space associated with it, and BLOCK_REG_PADDING is defined,
	use it to decide at which end the argument should be padded.
	* function.c (assign_parms): Allocate BLKmode stack slots.
	* config/mips/mips-protos.h (mips_pad_arg_upward): Declare.
	(mips_pad_reg_upward): Declare.
	* config/mips/mips.h (PAD_VARARGS_DOWN): Use FUNCTION_ARG_PADDING.
	(CUMULATIVE_ARGS): Remove num_adjusts and adjusts.
	(FUNCTION_ARG_PADDING): Use mips_pad_arg_upward.
	(BLOCK_REG_PADDING): Use mips_pad_reg_upward.
	* config/mips/mips.c (struct mips_arg_info): Remove struct_p.
	(mips_expand_call): Remove code for generating structure shifts.
	(mips_arg_info): Don't set struct_p.  Don't set fpr_p for non-float
	types unless using the EABI.
	(function_arg_advance): Don't generate shift instructions.
	(function_arg): Don't return them.  Don't short-circuit the
	check for double structure chunks for DFmode arguments.
	(mips_pad_arg_upward, mips_pad_reg_upward): New functions.
	(mips_expand_prologue): Remove code to emit structure shifts.
	* config/mips/irix6-libc-compat.c: Remove workarounds for buggy
	structure passing (inet_ntoa, inet_lnaof, inet_netof).  Update
	comments to say that only structure returns are a problem.

From-SVN: r70843