* genmodes.c, mode-classes.def: New files.

	* genmodes.c, mode-classes.def: New files.
	* machmode.def: Rewritten to genmodes.c interface.
	* Makefile.in (extra_modes_file): New substitution variable.
	(MACHMODE_H): No longer includes machmode.def or
	@extra_modes_file@; instead, mode-classes.def and insn-modes.h.
	(BUILD_RTL): Add $(BUILD_PREFIX)insn-modes.o.
	(OBJS-common): Add insn-modes.o.
	(STAGESTUFF): Add insn-modes.c, insn-modes.h, s-modes, and
	genmodes$(build_exeext).
	(insn-modes.o, insn-modes.c, insn-modes.h, s-modes, genmodes.o,
	genmodes$(build_exeext), $(BUILD_PREFIX_1)insn-modes.o): New targets.
	(s-genrtl): Don't depend on $(RTL_BASE_H).
	(gengenrtl.o): Don't depend on coretypes.h, $(GTM_H), real.h,
	or $(RTL_BASE_H); just rtl.def.
	* gengenrtl.c: Don't include coretypes.h, tm.h, rtl.h, or
	real.h.  Give fake definition of CONST_DOUBLE_FORMAT and
	substitute definition of NUM_RTX_CODE.  Add casts to avoid
	warnings.
	* machmode.h: Include insn-modes.h, not machmode.def.  Include
	mode-classes.def to define enum mode_class.  Tweak definitions
	of GET_MODE_CLASS, GET_MODE_SIZE, GET_MODE_BITSIZE, GET_MODE_MASK,
	GET_MODE_INNER, GET_MODE_WIDER_MODE, GET_CLASS_NARROWEST_MODE.
	(inner_mode_array): Renamed mode_inner.
	(mode_base_align): New.
	* rtl.c (mode_name, mode_class, mode_bitsize, mode_size,
	mode_unit_size, mode_wider_mode, mode_mask_array,
	inner_mode_array, class_narrowest_mode): Delete definitions.
	* stor-layout.c (get_mode_alignment): Use mode_base_align.
	* real.h: Use MIN_MODE_FLOAT and MAX_MODE_FLOAT, not QFmode
	and TFmode, in real_format_for_mode and REAL_MODE_FORMAT.

	* config/ip2k/ip2k.h, config/iq2000/iq2000.h:
	No need to define BITS_PER_UNIT.

	* stor-layout.c (compute_record_mode): Don't force BLKmode if
	field is zero-length BLKmode.
	* expr.c (expand_expr, case COMPONENT_REF): Handle case of BLKmode
	zero-size references.

	* combine.c (distribute_links): Properly test for REG being set.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@72314 138bc75d-0d04-0410-961f-82ee72b054a4