GNU bug report logs - #58168
string-lessp glitches and inconsistencies

Previous Next

Full log

Message #116 received at 58168 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 58168 <at> debbugs.gnu.org
Subject: Re: bug#58168: string-lessp glitches and inconsistencies
Date: Fri, 14 Oct 2022 16:39:55 +0200

As performance is more acceptable now I'm not going to take any further action with respect of string<, but let me just answer your questions:

8 okt. 2022 kl. 09.35 skrev Eli Zaretskii <eliz <at> gnu.org>:

> I suggested to use memchr to find whether a string has any
> C0 or C1 bytes, _before_ doing the actual comparison, to find out
> whether a multibyte string includes any raw bytes, which would then
> require slower comparisons.

That isn't practical; we would traverse each argument in full, twice, even if there is a difference early on. While memchr is fast for what it does, it will still need to look at every bit of its input.

> I also suggested to try memmem as yet another possibility

There is no reason to believe that this would help in any way.

> This is me being happy.

Thank you, let's both rejoice then! Again, the improvements and analyses have been worthwhile.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.