unaligned pointers

[Jonathan Larmour]

Shaun Jackman wrote:
> 
> Can GCC generate the code necessary to load from and store to unaligned
> pointers? Ditto for unaligned members of structures.
> In the case of structure members the compiler knows compile-time which are
> aligned and which are unaligned, and genereate the respective code. Although
> it doesn't at the moment. Nor does it warn me of the access to an unaligned
> structure member (w/ -Wall).
> For pointers though, how do I indicate a given pointer can possibly be
> unaligned, and needs odd-alignment safe dereferncing?

In general, if gcc deferences a pointer, then it will assume that what the
pointer points to is aligned appropriately for the type it points to. If it
doesn't, it's your problem :-).

If you want to be able to access unaligned structures, you would have to
copy it first (and use a char * pointer to access it for copying, since
that is the only type guaranteed to be safe for this).

Jifl
-- 
Red Hat, 35 Cambridge Place, Cambridge, UK. CB2 1NS  Tel: +44 (1223) 728762
"Plan to be spontaneous tomorrow."  ||  These opinions are all my own fault

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