anchor.diff:                           :opcode 'lap:call
                            :operands (list `(:object :r13 ,sys.int::+fref-entry-point+))
                            :inputs '(:r13 :rax)
  -                         :outputs (list :r8)))
  +                         :outputs (list :r8)
  +                         :clobbers '(:rax :rcx :rdx :rsi :rdi :rbx :r8 :r9 :r10 :r11 :r12 :r13 :r14 :r15
  +                                     :mm0 :mm1 :mm2 :mm3 :mm4 :mm5 :mm6 :mm7
  +                                     :xmm0 :xmm1 :xmm2 :xmm3 :xmm4 :xmm5 :xmm6 :xmm7 :xmm8
  +                                     :xmm9 :xmm10 :xmm11 :xmm12 :xmm13 :xmm14 :xmm15)))
       (emit (make-instance 'move-instruction
                            :destination result
                            :source :r8))
  +    (emit (make-instance 'jump-instruction :target out))
       (emit out)))
   
   (define-builtin mezzano.runtime::%fixnum-* ((lhs rhs) result)
  
positive.code:                          :opcode 'lap:call
                           :operands (list `(:object :r13 ,sys.int::+fref-entry-point+))
                           :inputs (list :r13 :rax :rdx)
                           :outputs (list :r8)))
      (emit (make-instance 'move-instruction
                           :source :r8
                           :destination result))
  
negative.code:   ((%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)
     (%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)))
  