Re: [gccsdk] Unaligned loads etc

On Sun, Mar 08, 2015 at 01:59:08PM +0000, John Ballance wrote:
> Hi.
>
> I'd appreciate a bit of a pointer.
>
> I'm compiling all sorts of things from the autobuilder tree, but
> would like to make sure that unaligned loads and saves are not
> generated. Whilst current riscos machines can have the alignment
> exception turned off, it isn't good practice to rely on the results
> of a 'bypassed' alignment exception.
>
> It seems logical that there will be a simple flag to add to things,
> but what flag please, and where best to add it.. and on a module by
> module basis, or a whole compile basis?

I think this is one for John, but AFAIAA GCC's default options won't emit
unaligned loads and saves. That wasn't always the case - before ARMv7 came
along some packages were built unaligned. The output should be ARMv3 to
ARMv7 safe (ARMv2 is a bit trickier).

Do you have a counterexample of recently-compiled code?

Theo

(apologies for the riscos.info downtime this weekend - it got wedged, I
moved it to a new server, and then had some awkward transatlantic disc
juggling to get everything working which took much longer than expected.
Should all be up and reliable now)

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