anchor.diff:          `(sys.lap-x86:add64 (,+binding-stack-gs-offset+) 16))
     ''nil)
   
  -(defbuiltin sys.int::%%disestablish-block-or-tagbody () ()
  +(defbuiltin sys.int::%%disestablish-block-or-tagbody () (t nil)
     ;; Top entry in the binding stack is a block or tagbody entry.
     ;; It's a environment simple-vector & an offset.
     ;; Pop the stack & set env[offset] = NIL.
  
positive.code:         `(sys.lap-x86:add64 (,+binding-stack-gs-offset+) 16))
    ''nil)
  
  (defbuiltin sys.int::%%disestablish-unwind-protect () ()
    ;; Top entry in the binding stack is an unwind-protect entry.
    ;; It's a function and environment object.
    ;; Pop the stack & call the function with the environment object.
  
negative.code:   (setf *r8-value* (list (gensym))))
  
  ;;; TODO: Check for constants here.
  (defbuiltin sys.int::%%bind (symbol value) (t nil)
    ;; Don't kill here, going to reload & kill later in the function.
    (load-in-reg :r9 symbol)
    (smash-r8)
  