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Re: alignment errors on armel: what to do?

On 09/29/2009 04:16 PM, Paul Brook wrote:
>> char f[4];
>> ...
>> any idea why gcc would lay out the memory differently for armel than for
>> i386?  i haven't tried it on the old arm architecture.
> The alignment of "f" is entirely arbitrary.
> It could be effected by any number of things, including but not limited to 
> where other variables happen to be placed, ABI differences, how aggressively 
> the compiler chooses speed over size, exact compiler versions and, if you're 
> really unlucky, phase of the moon.

true, i'm not saying it's non-compliant that it's char-aligned.  it's
just interesting to observe that in i386, it seems to be guaranteed to
be word-aligned, even if i do:

char g;
char f[4];

both &g and f are 32-bit aligned on i386.  not so when i build on armel.

given armel's failures on alignment errors (and i386's apparent ability
to handle them gracefully -- try passing f+1 to test() ) i find it
curious that gcc would be *more* cautious about over-alignment on i386
than on armel.


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