anchor.diff:    ((%inputs :initarg :inputs :reader mezzano.compiler.backend::instruction-inputs)
      (%outputs :initarg :outputs :reader mezzano.compiler.backend::instruction-outputs)
      (%opcode :initarg :opcode :reader x86-instruction-opcode)
  -   (%operands :initarg :operands :reader x86-instruction-operands)))
  +   (%operands :initarg :operands :reader x86-instruction-operands)
  +   (%clobbers :initarg :clobbers :reader x86-instruction-clobbers))
  +  (:default-initargs :clobbers '()))
  +
  +(defmethod mezzano.compiler.backend::instruction-clobbers ((instruction x86-instruction) (architecture (eql :x86-64)))
  +  (x86-instruction-clobbers instruction))
   
   (defmethod mezzano.compiler.backend::replace-all-registers ((instruction x86-instruction) substitution-function)
     (setf (slot-value instruction '%inputs) (mapcar substitution-function (slot-value instruction '%inputs)))
  
positive.code:                          :opcode 'lap:call
                           :operands (list `(:object :r13 ,sys.int::+fref-entry-point+))
                           :inputs '(:r13 :rax)
                           :outputs (list :r8)))
      (emit (make-instance 'move-instruction
                           :destination result
                           :source :r8))
      (emit out)))
  
  (define-builtin mezzano.runtime::%fixnum-* ((lhs rhs) result)
  
negative.code:     (emit (make-instance 'move-instruction
                           :source :rax
                           :destination result))
      (emit (make-instance 'jump-instruction :target out))
      (emit out)))
  
  (define-builtin mezzano.runtime::%fixnum-truncate ((lhs rhs) (quot rem))
  