Date: Sun, 12 Nov 2006 15:52:24 +0100 From: Giorgos Keramidas <keramida@FreeBSD.org> To: Ruslan Ermilov <ru@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: [head tinderbox] failure on arm/arm Message-ID: <20061112145223.GE2331@kobe.laptop> In-Reply-To: <20061112144618.GB49703@rambler-co.ru> References: <20061112133929.9194773068@freebsd-current.sentex.ca> <20061112140010.GA47660@rambler-co.ru> <20061112142710.GE91556@wombat.fafoe.narf.at> <20061112144618.GB49703@rambler-co.ru>
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On 2006-11-12 17:46, Ruslan Ermilov <ru@freebsd.org> wrote:
>On Sun, Nov 12, 2006 at 03:27:10PM +0100, Stefan Farfeleder wrote:
>>> This looks like a GCC bug to me. The following code snippet,
>>> when compiled on FreeBSD/arm, causes a -Wcast-align warning
>>> which doesn't look right:
>>>
>>> %%%
>>> $ cat a.c
>>> struct foo {
>>> char x;
>>> };
>>>
>>> struct foo *
>>> bubu(char *s)
>>> {
>>>
>>> return (struct foo *)s;
>>> }
>>> $ cc -c -Wcast-align a.c
>>> a.c: In function `bubu':
>>> a.c:9: warning: cast increases required alignment of target type
>>> %%%
>>>
>>> (None of other supported architecutes see the issue here.)
>>
>> What is sizeof(struct foo)? If it's > 1 it makes sense.
>
> Yes, it's four bytes on ARM. But why?
Probably because GCC thinks accessing 4-byte quantities is much much
cheaper than 1-byte accesses on this ARM board. I'm not sure why GCC
thinks so, though.
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