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From: Jeff King <peff@peff.net>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: git@vger.kernel.org, "Stefan Beller" <sbeller@google.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Jakub Narębski" <jnareb@gmail.com>,
	"Jacob Keller" <jacob.keller@gmail.com>
Subject: Re: [PATCH 5/8] xdl_change_compact(): fix compaction heuristic to adjust io
Date: Thu, 11 Aug 2016 00:16:03 -0400	[thread overview]
Message-ID: <20160811041603.xtkagaluyntawwue@sigill.intra.peff.net> (raw)
In-Reply-To: <7dea0a1e-a1b4-efe4-c86d-152f6c96604a@alum.mit.edu>

On Wed, Aug 10, 2016 at 06:58:06PM +0200, Michael Haggerty wrote:

> > And it looks like rchgo[io] always ends the loop on a 0. So it seems
> > like we would just hit that condition again.
> 
> Correct...in this loop. But there is another place where `io` is
> incremented unconditionally. In the version before my changes, it is via
> the preincrement operator in this while statement conditional:
> 
> https://github.com/mhagger/git/blob/a28705da929ad746abcb34270947f738549d3246/xdiff/xdiffi.c#L502
> 
> After my changes, the unconditional increment is more obvious because I
> took it out of the while condition:
> 
> https://github.com/mhagger/git/blob/39a135da93834fd72ee923d95d0cebfe525dfe7a/xdiff/xdiffi.c#L541
> 
> (BTW, I think this is a good example of how patch 2/8 makes the code
> easier to reason about.)

Ah, yeah, I totally missed that case (and I agree the code after your
2/8 makes it much more obvious).

> I didn't do the hard work to determine whether `io` could *really* walk
> off the end of the array, but I don't see an obvious reason why it
> *couldn't*.

Yeah, I'm in agreement.

-Peff

  parent reply	other threads:[~2016-08-11  4:16 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-03 22:00 [PATCH 0/8] Better heuristics make prettier diffs Michael Haggerty
2016-08-03 22:00 ` [PATCH 1/8] xdl_change_compact(): rename some local variables for clarity Michael Haggerty
2016-08-04  7:06   ` Jeff King
2016-08-04 18:24     ` Junio C Hamano
2016-08-13 19:38     ` Michael Haggerty
2016-08-14 12:26       ` Jeff King
2016-08-03 22:00 ` [PATCH 2/8] xdl_change_compact(): clarify code Michael Haggerty
2016-08-03 22:11   ` Stefan Beller
2016-08-03 23:14     ` Michael Haggerty
2016-08-03 23:50       ` Stefan Beller
2016-08-04  7:13         ` Jeff King
2016-08-10 16:39         ` Michael Haggerty
2016-08-10 16:58           ` Stefan Beller
2016-08-03 22:00 ` [PATCH 3/8] xdl_change_compact(): rename i to end Michael Haggerty
2016-08-04  7:16   ` Jeff King
2016-08-03 22:00 ` [PATCH 4/8] xdl_change_compact(): do one final shift or the other, not both Michael Haggerty
2016-08-03 22:00 ` [PATCH 5/8] xdl_change_compact(): fix compaction heuristic to adjust io Michael Haggerty
2016-08-04  7:27   ` Jeff King
2016-08-10 16:58     ` Michael Haggerty
2016-08-10 17:09       ` Michael Haggerty
2016-08-11  4:16       ` Jeff King [this message]
2016-08-04 18:43   ` Junio C Hamano
2016-08-10 17:13     ` Michael Haggerty
2016-08-03 22:00 ` [PATCH 6/8] xdl_change_compact(): keep track of the earliest end Michael Haggerty
2016-08-04 18:46   ` Junio C Hamano
2016-08-10 17:16     ` Michael Haggerty
2016-08-03 22:00 ` [PATCH 7/8] is_blank_line: take a single xrecord_t as argument Michael Haggerty
2016-08-04 18:48   ` Junio C Hamano
2016-08-03 22:00 ` [PATCH 8/8] diff: improve positioning of add/delete blocks in diffs Michael Haggerty
2016-08-03 22:29   ` Jacob Keller
2016-08-03 22:36     ` Michael Haggerty
2016-08-04  4:47       ` Jacob Keller
2016-08-04 19:39       ` Junio C Hamano
2016-08-10 19:01         ` Michael Haggerty
2016-08-10 21:28           ` Junio C Hamano
2016-08-03 22:30   ` Stefan Beller
2016-08-03 22:41     ` Michael Haggerty
2016-08-03 22:51       ` Stefan Beller
2016-08-03 23:30         ` Michael Haggerty
2016-08-04  0:04           ` Stefan Beller
2016-08-10 19:12             ` Michael Haggerty
2016-08-04  7:56   ` Jeff King
2016-08-04 16:55     ` Stefan Beller
2016-08-04 19:47       ` Junio C Hamano
2016-08-13  0:09       ` Michael Haggerty
2016-08-12 23:25     ` Michael Haggerty
2016-08-13  8:59       ` Jeff King
2016-08-13 15:59         ` Junio C Hamano
2016-08-14  7:21           ` Jacob Keller
2016-08-15  6:33         ` Stefan Beller
2016-08-15 20:24           ` Junio C Hamano
2016-08-04 19:52   ` Junio C Hamano
2016-08-13  0:11     ` Michael Haggerty
2016-08-03 22:08 ` [PATCH 0/8] Better heuristics make prettier diffs Michael Haggerty
2016-08-04  7:38 ` Jeff King
2016-08-04 19:54   ` Junio C Hamano
2016-08-04 20:01     ` Jeff King

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