From: Yaro Pollak <yarop@altair-semi.com>
To: David Edelsohn <dje@watson.ibm.com>
Cc: gcc-help@gcc.gnu.org
Subject: Re: Unaligned access to packed structs on ppc405
Date: Mon, 30 Jan 2006 12:03:00 -0000 [thread overview]
Message-ID: <43DE006E.2040803@altair-semi.com> (raw)
In-Reply-To: <200601291716.k0THGPD31684@makai.watson.ibm.com>
David Edelsohn wrote:
>>>>>>Yaro Pollak writes:
>>>>>>
>>>>>>
>
>
>
>>I am cross-compiling on GCC 3.4.1 for the PowerPC 405, which can handle
>>unaligned accesses in hardware.
>>Whenever I am accessing members of a packed bit-struct by pointer, the
>>compiler produces byte accesses, instead of 4-byte acceses.
>>I've tried to use |-mstrict-align but to no avail.
>>
>>
>
> What does "|-mstrict-align" mean? -mstrict-align means "do not
>assume that unaligned accesses are handled by the system." You are
>requesting that the compiler assume the target requires strict alignment
>and then questioning why it is accessing a packed bit-struct assuming the
>least alignment.
>
>David
>
>
>
Yes, I actually couldn't tell whether I should use -mno-strict-align or
-mstrict-align from the explanation in GCC documentation (thank you for
your explanation) so I tried both, but it didn't matter at all. I guess
I should have mentioned that before. Perhaps any other ideas? I feel it
is something fundamental that I keep missing.
Yaro
next prev parent reply other threads:[~2006-01-30 12:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-29 17:16 David Edelsohn
2006-01-30 12:03 ` Yaro Pollak [this message]
2006-02-02 16:13 ` David Edelsohn
-- strict thread matches above, loose matches on Subject: below --
2006-02-05 18:35 John Yates
2006-02-05 21:02 ` David Edelsohn
2006-02-06 10:18 ` Yaro Pollak
2006-02-01 12:03 [Re: Unaligned access to packed structs on ppc405] Yaro Pollak
2006-02-04 4:25 ` Unaligned access to packed structs on ppc405 David Edelsohn
2006-01-30 16:18 Matthew Jones
2006-01-30 16:26 ` Yaro Pollak
2006-01-29 10:00 Yaro Pollak
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