[Ffmpeg-devel] Stack alignment warning

[Loren Merritt]

On Fri, 15 Dec 2006, M?ns Rullg?rd wrote:
> Loren Merritt <lorenm at u.washington.edu> writes:
>> On Sat, 16 Dec 2006, Uoti Urpala wrote:
>>>> 2006/12/15, Ismail Donmez <ismail at pardus.org.tr>:
>>>
>>>>  (support stack aligned local arrays)
>>>
>>> The warning test in ffmpeg does not use arrays (it's a single int
>>> variable), and the alignment does seem to work for arrays too in gcc
>>> 4.1.
>>
>> In particular, gcc 3.4.3 completely ignores __attribute__((aligned(...)))
>> for scalar variables and 1-element arrays, but obeys it on multi-element
>> arrays (given the aligned-stack abi assumption, which was the original
>> problem). Thus it miscompiles ff_check_alignment even though the other
>> instances of alignment are ok.
>
> Is that saying that the check should be changed to test an array
> larger than 1 element?

Yes, that would fix this particular case. Though for all I know, different 
versions of gcc might be broken in different ways.

--Loren Merritt