anchor.diff:  ;;;
   ;;; Instruction ENTER-INSTRUCTION.
   ;;;
  -;;; This instruction is mostly a placeholder for backend to put
  -;;; information that needs to be present right at the beginning of
  -;;; each procedure.  It has a single successor.
  +;;; This instruction encapsulates all the implementation-specific
  +;;; machinery involved in verifying the argument count and parsing the
  +;;; arguments.  It has a single successor.
   
   (defclass enter-instruction (instruction)
  -  ())
  -
  -(defun make-enter-instruction (&optional (successor nil successor-p))
  -  (make-instance 'enter-instruction
  -    :successors (if successor-p (list successor) '())))
  +  ((%lambda-list :initarg :lambda-list :accessor lambda-list)))
  +
  +(defun make-enter-instruction (lambda-list successor)
  +  (let* ((outputs (loop for item in lambda-list
  +			append (cond ((member item lambda-list-keywords) '())
  +				     ((consp item) item)
  +				     (t (list item))))))
  +    (make-instance 'enter-instruction
  +      :lambda-list lambda-list
  +      :outputs outputs
  +      :successors (list successor))))
   
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;;;
  
positive.code: ;;; Datum class SPECIAL-LOCATION.
  ;;;
  ;;; This datum corresponds to a reference to a special variable.
  ;;; The storage is the place where a global value (if any) of the
  ;;; special variable is stored.
  ;;;
  ;;; In later compilation stages, this datum is eliminated.  Instead
  ;;; an EXTERNAL-INPUT is used to hold the storage cell containing the
  ;;; global value, and this cell (together with the name) is passed as
  ;;; argument to a function call that searches for bindings in the
  ;;; dynamic environment.
  
  (defclass special-location (datum)
    ((%name :initarg :name :reader name)))
  
negative.code: ;;;
  ;;; This datum corresponds to a reference to a global FUNCTION,
  ;;; i.e., a function defined in the global environment.  
  
  (defclass global-input (datum)
    ((%name :initarg :name :reader name)))
  
  (defun make-global-input (name)
    (make-instance 'global-input
      :name name))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  