anchor.diff:  ;;;
   ;;; Instruction NON-SIMPLE-T-AREF-INSTRUCTION.
   ;;;
  -;;; This instruction takes two inputs.  The first input is assumed
  -;;; to be a general array.  The second is assumed to be a FIXNUM
  -;;; and represents the index in the instance of the element to be read.
  -;;; This instruction produces a single output, the element read.
  +;;; This instruction takes two inputs.  The first input is assumed to
  +;;; be an unspecialized non-simple array.  The second is assumed to be
  +;;; a FIXNUM and represents the index in the instance of the element
  +;;; to be read.  This instruction produces a single output, the
  +;;; element read.
   
   (defclass non-simple-t-aref-instruction (instruction one-successor-mixin)
     ())
  
positive.code: ;;; Instruction SIMPLE-T-ASET-INSTRUCTION.
  ;;;
  ;;; This instruction takes three inputs.  The first input is assumed
  ;;; to be a general array.  The second is assumed to be a FIXNUM
  ;;; 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 simple-t-aset-instruction
      (instruction one-successor-mixin side-effect-mixin)
  
negative.code: ;;; Instruction NON-SIMPLE-T-ASET-INSTRUCTION.
  ;;;
  ;;; This instruction takes three inputs.  The first input is assumed
  ;;; to be an unspecialized non-simple array.  The second is assumed to
  ;;; be a FIXNUM 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 non-simple-t-aset-instruction
      (instruction one-successor-mixin side-effect-mixin)
  