(struct attr_desc): Add unsigned_p field.

	(struct function_unit_op): Add issue_delay, conflict_exp, and
	issue_exp fields.  Drop busyexp field.
	(struct function_unit): Add needs_blockage_function,
	needs_range_function, issue_delay, and max_blockage fields.  Drop
	costexp, and busy delay fields.
	(enum operator): Add POS_MINUS_OP, EQ_OP, MIN_OP, RANGE_OP.
	(operate_exp): Implement new ops.
	(make_internal_attr): Set unsigned_p based on the value of SPECIAL.
	(write_attr_get): Function is unsigned when unsigned_p is true.
	(write_attr_valueq): Write hex value of large constants in a comment.
	(simplify_by_exploding): Check for EXP having no EQ_ATTR expressions
	and for all values as the default.
	(find_and_mark_used_attributes): Add TERMS and NTERMS parameters.
	(max_attr_value): Allow IF_THEN_ELSE.
	(simplify_knowing, write_complex_function, extend_range): New
	functions.
	(gen_unit): Use local variables to name the fields.  Change the
	meaning of busy-delay to issue-delay.
	(expand_units): Compute issue_exp.  Write attributes for computing
	`<name>_unit_blockage' and `<name>_unit_blockage_range' functions.
	Compute max_blockage, and the needs_*_function values.
	(write_function_unit_info): Write blockage function and conflict cost
	functions using write_complex_function.  Write new function_unit_desc
	fields.
(expand_units): Use the normalized values of the
	unit's CONDEXP and BUSYEXP.

From-SVN: r1952