anchor.diff:      (cond ((constant-type-p x 'fixnum)
              (load-in-r8 y t)
              (fixnum-check :r8)
  +           (smash-r8)
              ;; Small integers can be encoded directly into the instruction.
              (if (typep (second x) '(signed-byte 28))
                  (emit `(sys.lap-x86:add64 :r8 ,(fixnum-to-raw (second x))))
  
positive.code: 	      (typep (second x) 'fixnum))
  	 (load-in-r8 y t)
  	 (fixnum-check :r8)
  	 ;; Small integers can be encoded directly into the instruction.
  	 (if (typep (second x) '(signed-byte 28))
  	     (emit `(sys.lap-x86:or64 :r8 ,(fixnum-to-raw (second x))))
  
negative.code:            (fixnum-check :r9)
             (load-in-reg :r8 x t)
             (fixnum-check :r8)
             (smash-r8)
             (emit `(sys.lap-x86:xor64 :r8 :r9))
             (setf *r8-value* (list (gensym))))))
  
  