Re: very slow archive-mode

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

>>>>> On Thu, 13 Mar 2008 11:08:52 -0400, Stefan Monnier <monnier@iro.umontreal.ca> said:

>>> I reported a similar problem.  I believe set-buffer-multibyte is
>>> *a lot* slower now, and may even have a time complexity of O(N^2).

>> I suspect so too.  Now set-buffer-multibyte must convert more 8-bit
>> bytes to mutlibyte forms and that results in more movement and
>> increasing of the gap.  This code:

> Also, IIUC the 8-bit bytes that are not represented as a single byte
> and not only more numerous, but they also take up more space (they
> used to take up just 2 bytes but now they take up what 3? 4? 5
> bytes?).

IIUC, it still takes up just 2 bytes by cleverly using vacant UTF-8
area (see character.h).

I think code_convert_region in Emacs 22 tried to avoid the repeated
reallocations and copies by estimating the necessary buffer size from
the intermediate result of conversion in progress. (And there were a
cast problem that affected its performance:
http://lists.gnu.org/archive/html/emacs-pretest-bug/2004-12/msg00197.html)

Does the code conversion in Emacs 23 include such estimation?

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp