Re: PATCH: `__norestrict' type qualifier

[Jamie Lokier <egcs at tantalophile dot demon dot co dot uk>]

Andreas Schwab wrote:
> I was wrong.  If pl is not correctly aligned for a long then the behaviour
> is undefined.
> 
> >From C9x, 6.3.2.3 Pointers
> 
>        [#7]  A  pointer  to  an  object  or  incomplete type may be
>        converted to a pointer to a different object  or  incomplete
>        type.   If the resulting pointer is not correctly aligned50)
>        for  the  pointed-to  type,  the  behavior   is   undefined.
>        Otherwise,  when  converted  back  again,  the  result shall
>        compare equal to the original pointer.

Thanks.  That text's quite useful: it tells me the standard
distinguishes aligned pointers from unaligned pointers, and that
pointers to the wrong type of object already have semantics for the
aligned case but undefined behaviour for the unaligned case.  You can't
dereference them but you can convert and then dereference them.

That's almost what we need to pin down the alignment semantics of
__norestrict.  Unfortunately I don't have a copy of C9X -- is a
reasonably up to date one publicly available?

-- Jamie