anchor.diff:  ;;; element to be read.  The third input is assumed to be an unboxed
   ;;; DOUBLE-FLOAT to be stored as an element in the array.
   
  -(defclass double-float-aset-instruction (instruction one-successor-mixin)
  +(defclass double-float-aset-instruction
  +    (instruction one-successor-mixin side-effect-mixin)
     ())
   
   (defun make-double-float-aset-instruction (input1 input2 input3 successor)
  
positive.code: ;;; the element to be read.  The third input is assumed to be an
  ;;; unboxed (UNSIGNED-BYTE 8) to be stored as an element in the array.
  
  (defclass unsigned-byte-8-aset-instruction (instruction one-successor-mixin)
    ())
  
  (defun make-unsigned-byte-8-aset-instruction (input1 input2 input3 successor)
  
negative.code: ;;; and represents the index in the instance of the element to be read.
  ;;; The third input is the element to be stored in the array.
  
  (defclass t-aset-instruction
      (instruction one-successor-mixin side-effect-mixin)
    ())
  
  (defun make-t-aset-instruction (input1 input2 input3 successor)
  