bugGNU Common Lisp - Bugs: bug #35325, make-array with initial-contents...


bug #35325: make-array with initial-contents is slow

Submitted by:  None
Submitted on:  Tue 17 Jan 2012 11:59:19 PM UTC  
Category:  None Severity:  3 - Normal
Item Group:  None Status:  Fixed
Privacy:  Public Assigned to:  None
Open/Closed:  Closed

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Thu 21 Nov 2013 02:59:55 PM UTC, comment #1:

Greetings, and thanks for your report! This should be fixced now in the master branch of the git repository, and find its way to the next official release.

Camm Maguire <camm>
Project Administrator
Tue 17 Jan 2012 11:59:19 PM UTC, original submission:

Calling make-array with a list for initial-contents is
poorly implemented. The list is traversed with elt, so
that copying the contents is order n^2. This is prohibitively
slow for large lists.

Maybe something like this: (not tested)

(when initial-contents-supplied-p
(if (listp initial-conents)
(do* ( (e initial-conents (cdr e))
(i 0 (1+ i))
(y (car initial-contents) (car e)))
( (null e) x)
(declare (fixnum i))
(setf (elt x i) y))

(do ((n (car dimensions))
(i 0 (1+ i)))
((>= i n))
(declare (fixnum n i))
(si:aset x i (elt initial-contents i))))



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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2013-11-21 camm StatusNone => Fixed
        Open/ClosedOpen => Closed

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