From: Ramsay Jones <ramsay@ramsay1•demon.co.uk>
To: Jeff King <peff@peff•net>
Cc: "Junio C Hamano" <gitster@pobox•com>,
"Stefan Beller" <stefanbeller@gmail•com>,
"Arjun Sreedharan" <arjun024@gmail•com>,
"Git Mailing List" <git@vger•kernel.org>,
"Christian Couder" <chriscool@tuxfamily•org>,
"Nguyễn Thái Ngọc Duy" <pclouds@gmail•com>
Subject: Re: [PATCH] bisect: save heap memory. allocate only the required amount
Date: Tue, 26 Aug 2014 13:59:52 +0100 [thread overview]
Message-ID: <53FC84C8.1020300@ramsay1.demon.co.uk> (raw)
In-Reply-To: <20140826124344.GF29180@peff.net>
On 26/08/14 13:43, Jeff King wrote:
> On Tue, Aug 26, 2014 at 01:37:44PM +0100, Ramsay Jones wrote:
>
>>> On my 64-bit system using gcc, sizeof() returns 16; it has to pad the
>>> whole thing to 64-bit alignment in case I put two of them in an array.
>>> But offsetof(name) is 12, since the array of char does not need the same
>>> alignment; it can go right after the type and make use of the padding
>>> bits.
>>
>> Hmm, interesting. I must re-read the standard. I was convinced that the
>> standard *requires* any alignment padding to come *before* the name field.
>> (how would you put a, non-trivial, variable data structure into an array?)
>
> I think you don't. How would you compute a[1] if a[0] has a variable
> size?
>
> You can put a flex-array structure into an array, but then each element
> has the flex member as zero-size (and you should not access it, of
> course).
Exactly. ;-)
ATB,
Ramsay Jones
next prev parent reply other threads:[~2014-08-26 13:00 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-24 14:17 [PATCH] bisect: save heap memory. allocate only the required amount Arjun Sreedharan
2014-08-24 15:10 ` Stefan Beller
2014-08-24 23:39 ` Junio C Hamano
2014-08-25 13:07 ` Jeff King
2014-08-25 21:36 ` Junio C Hamano
2014-08-26 11:03 ` Jeff King
2014-08-26 11:57 ` Ramsay Jones
2014-08-26 12:14 ` Jeff King
2014-08-26 12:37 ` Ramsay Jones
2014-08-26 12:43 ` Jeff King
2014-08-26 12:59 ` Ramsay Jones [this message]
2014-08-24 15:32 ` Ramsay Jones
2014-08-24 21:55 ` Arjun Sreedharan
2014-08-25 13:35 ` Jeff King
2014-08-25 14:06 ` Christian Couder
2014-08-25 15:00 ` Jeff King
2014-08-25 18:26 ` Junio C Hamano
2014-08-25 19:35 ` Jeff King
2014-08-25 20:27 ` Arjun Sreedharan
2014-08-25 21:11 ` Junio C Hamano
2014-08-26 10:20 ` [PATCH 0/3] name_decoration cleanups Jeff King
2014-08-26 10:23 ` [PATCH 1/3] log-tree: make add_name_decoration a public function Jeff King
2014-08-26 11:48 ` Ramsay Jones
2014-08-26 12:17 ` Jeff King
2014-08-26 10:23 ` [PATCH 2/3] log-tree: make name_decoration hash static Jeff King
2014-08-26 17:40 ` Junio C Hamano
2014-08-26 17:43 ` Jeff King
2014-08-26 19:25 ` Junio C Hamano
2014-08-26 10:24 ` [PATCH 3/3] log-tree: use FLEX_ARRAY in name_decoration Jeff King
2014-08-27 0:30 ` Eric Sunshine
2014-08-25 21:14 ` [PATCH] bisect: save heap memory. allocate only the required amount Junio C Hamano
2014-08-26 7:30 ` Arjun Sreedharan
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