anchor.diff:  ;;; param 0
   ;;; Silly slot for the benefit of apply
   ;;; Return address
  -;;; Saved %bp <--- %bp
  -;;; func slot (filled by callee) <--- (+ %sp (* frame-base value-size))
  +;;; Saved %bp <--- %bp (and (+ %sp (* frame-base value-size)))
  +;;; %func
   ;;; Local var 0
   ;;; ...
   ;;; Local var N
  
positive.code: 
  ;;; Functions
  
  (define function-in-frame-base 0)
  (define function-out-frame-base -1)
  
  (define (emit-function-prologue out)
    (emit-push out %bp)
  
negative.code:   (dispmem 0 (* value-size (+ 3 index)) %bp))
  
  (define (local-slot index frame-base)
    (dispmem (* value-size (+ 1 index)) 0 %bp))
  
  (define (varrec-operand varrec frame-base)
    (let* ((mode (varrec-attr varrec 'mode))
  