anchor.diff:      (return-from instruction t)))
   
   (define-instruction br (target)
  -  (check-register-class reg :gpr-64)
  +  (check-register-class target :gpr-64)
     (emit-instruction (logior #xd61f0000
                               (ash (register-number target) +rn-shift+)))
     (return-from instruction t))
   
   (define-instruction blr (target)
  -  (check-register-class reg :gpr-64)
  +  (check-register-class target :gpr-64)
     (emit-instruction (logior #xd63f0000
                               (ash (register-number target) +rn-shift+)))
     (return-from instruction t))
  
positive.code:                               (ash (ldb (byte 16 0) imm-value) 5)
                                (ash (register-number dst) +rd-shift+)))
      (return-from instruction t)))
  
negative.code:                  (t
                    (assert (<= 0 amount 31))
                    (check-register-class rhs :gpr-32 :wzr)))
             (emit-instruction (logior #x0a000000
                                       (ash opcode 29)
                                       sf
                                       (if negate-bit
  