Re: More on Lisp structures performance

On 23 Jan 2026, at 19:30, Tim Bradshaw (as tfb at tfeb dot org) <[email protected]> wrote:
> 
> (defun decoded-object-address (o)
>  (let ((tag-mask (load-time-value
>                   (1- (expt 2 (if 64-bit 4 3)))))
>        (tagged-address (sys:object-pointer o)))
>    (let ((address (logandc2 tagged-address tag-mask))
>          (tag (logand tagged-address tag-mask)))
>      (assert (= address (sys:object-address o))) ;sanity
>      (values address tag))))
> 


Sorry, old version of that fn, here is the right one:

(defun decoded-object-address (o)
  (let ((tag-mask (load-time-value
                   (1- (expt 2 (if 64-bit 4 3)))))
        (tagged-address (sys:object-pointer o)))
    (let ((address (logandc2 tagged-address tag-mask))
          (tag (logand tagged-address tag-mask)))
      (unless (sys:immediatep o)
        (assert (= address (sys:object-address o))))
      (values address tag))))

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