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From: Junio C Hamano <gitster@pobox.com>
To: "René Scharfe" <l.s.r@web.de>
Cc: Jeff King <peff@peff.net>, Stephan Beyer <s-beyer@gmx.net>,
	Paul Tan <pyokagan@gmail.com>,
	"brian m. carlson" <sandals@crustytoothpaste.net>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	git@vger.kernel.org
Subject: Re: [PATCH] Fix maybe-uninitialized warnings found by gcc 9 -flto
Date: Thu, 05 Sep 2019 12:25:41 -0700	[thread overview]
Message-ID: <xmqqr24upmtm.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <b4f53049-ff50-8143-1653-d321cce6421c@web.de> (=?utf-8?Q?=22R?= =?utf-8?Q?en=C3=A9?= Scharfe"'s message of "Thu, 5 Sep 2019 21:09:27 +0200")

René Scharfe <l.s.r@web.de> writes:

> Am 05.09.19 um 19:53 schrieb Jeff King:
>>>> int cmd__read_cache(int argc, const char **argv)
>>>> {
>>>> -       int i, cnt = 1, namelen;
>>>> +       int i, cnt = 1, namelen = 0;
>>
>> I actually saw this one the other day, because it triggered for me when
>> compiling with SANITIZE=address. AFAICT it's a false positive. "name" is
>> always NULL unless skip_prefix() returns true, in which case we always
>> set "namelen". And we only look at "namelen" if "name" is non-NULL.
>>
>> This one doesn't even require LTO, because skip_prefix() is an inline
>> function. I'm not sure why the compiler gets confused here.
>
> Yes, that's curious.
>
>> I don't mind
>> initializing namelen to 0 to silence it, though (we already set name to
>> NULL, so this would just match).
>
> Pushing the strlen() call into the loop and getting rid of namelen should
> work as well -- and I'd be surprised if this had a measurable performance
> impact.

Yeah, we are making strlen() call on a constant "name" in a loop
over argv[].  I do not think it matters in this case, either.


  reply	other threads:[~2019-09-05 19:25 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05  8:24 [PATCH] Fix maybe-uninitialized warnings found by gcc 9 -flto Stephan Beyer
2019-09-05 17:08 ` René Scharfe
2019-09-05 17:53   ` Jeff King
2019-09-05 19:09     ` René Scharfe
2019-09-05 19:25       ` Junio C Hamano [this message]
2019-09-05 19:39         ` René Scharfe
2019-09-05 19:50           ` Junio C Hamano
2019-09-05 17:41 ` Junio C Hamano
2019-09-05 17:56 ` Junio C Hamano
2019-09-05 18:03   ` Jeff King
2019-09-05 18:22     ` Junio C Hamano
2019-09-05 22:48 ` Jeff King
2019-09-05 22:50   ` [PATCH 1/6] git-am: handle missing "author" when parsing commit Jeff King
2019-09-05 22:52   ` [PATCH 2/6] pack-objects: use object_id in packlist_alloc() Jeff King
2019-09-05 22:52   ` [PATCH 3/6] bulk-checkin: zero-initialize hashfile_checkpoint Jeff King
2019-09-05 22:53   ` [PATCH 4/6] diff-delta: set size out-parameter to 0 for NULL delta Jeff King
2019-09-05 22:53   ` [PATCH] Fix maybe-uninitialized warnings found by gcc 9 -flto Stephan Beyer
2019-09-05 22:58     ` Jeff King
2019-09-05 23:10       ` Stephan Beyer
2019-09-06  1:24         ` Jeff King
2019-09-06  1:36           ` [PATCH v2 6/6] pack-objects: drop packlist index_pos optimization Jeff King
2019-09-05 22:54   ` [PATCH 5/6] test-read-cache: drop namelen variable Jeff King
2019-09-05 22:56   ` [PATCH 6/6] pack-objects: drop packlist index_pos optimization Jeff King

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