anchor.diff:  
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;;;
  -;;; LIR instruction SIGNED-SUB-INSTRUCTION
  +;;; MIR instruction SIGNED-SUB-INSTRUCTION
   
   (defclass signed-sub-instruction (instruction two-successors-mixin)
     ())
  
positive.code: 
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; LIR instruction MEMSET1-INSTRUCTION
  ;;;
  ;;; This instruction stores an item in a memory location.  It takes
  ;;; two inputs.  The first input is the address of a location in
  
negative.code: 
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; MIR instruction MEMREF2-INSTRUCTION
  ;;;
  ;;; This instruction loads a memory location.  It takes a two inputs.
  ;;; The first input contains the base address of the datum to load.
  