Re: [PATCH] Optimize rename detection for a huge diff

From: David Kastrup <dak@gnu.org>
Date: Feb 13, 2008, 10:19 UTC
Message-ID: <864pcd9n0e.fsf@lola.quinscape.zz>
In-Reply-To: <7vodalqj0s.fsf@gitster.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 7 quoted lines

> The first hunk is about shrinking the diff_score structure;
> before the patch, it was O(NxM) where N and M are number of
> rename source and destination candidates, but after the patch it
> is now O(M), so this shrinkage should not matter, but score is
> capped to MAX_SCORE (60000) and name_score is actually 0 or 1.
> We cannot make it 1-bit unsigned bitfield as there is a qsort
> comparison callback that does (b->name_score - a->name_score).

Hm?  Can't that be changed into

(b->name_score > a->name_score ? 1 
 : b->name_score < a->name_score ? -1 : 0)

or something?  Or perhaps just

  ((int)b->name_score - (int)a->name_score)

or so?

It sounds like a factor 2 is in question here, and that would seem like an easy fix?

-- 
David Kastrup