Hi Luc,
> > Indeed it looks like a problem.
> > Thanks for pointing it out.
> > Was able to reproduce it with gcc 11 (clang 13 seems fine).
> > Actually, adding ' __attribute__ ((__may_alias__))' for both dst and src
> > didn't quire the problem.
>
> __may_alias__ works if it's applied to a typ
Hi Konstantin,
> Indeed it looks like a problem.
> Thanks for pointing it out.
> Was able to reproduce it with gcc 11 (clang 13 seems fine).
> Actually, adding ' __attribute__ ((__may_alias__))' for both dst and src
> didn't quire the problem.
__may_alias__ works if it's applied to a typedef, see
> > Not sure I understand the problem you are referring to.
> > Are you saying that original rte_memcpy() code breaks strict aliasing?
> > If so, could you point where exactly?
>
> As far as I understand, yes, it does break strict aliasing. For
> example, in the following line:
>
> *(uint64_t *)d
Hi Konstantin,
> > Thanks for your input Konstantin. Much appreciated. Just to make sure
> > I understand, can you please confirm that we do not want to fix the
> > fact that unaligned access in C is undefined behaviour?
>
> Yes, I don't think it is a real problem in that particular case.
Perfect
Hi Luc,
> > > Calls to rte_memcpy_generic could result in unaligned loads/stores for
> > > 1 < n < 16. This is undefined behavior according to the C standard,
> > > and it gets flagged by the clang undefined behavior sanitizer.
> > >
> > > rte_memcpy_generic is called with unaligned src and dst ad
> > Calls to rte_memcpy_generic could result in unaligned loads/stores for
> > 1 < n < 16. This is undefined behavior according to the C standard,
> > and it gets flagged by the clang undefined behavior sanitizer.
> >
> > rte_memcpy_generic is called with unaligned src and dst addresses.
> > When 1
04/02/2022 18:16, Ananyev, Konstantin:
>
> > Calls to rte_memcpy_generic could result in unaligned loads/stores for
> > 1 < n < 16. This is undefined behavior according to the C standard,
> > and it gets flagged by the clang undefined behavior sanitizer.
> >
> > rte_memcpy_generic is called with
> Calls to rte_memcpy_generic could result in unaligned loads/stores for
> 1 < n < 16. This is undefined behavior according to the C standard,
> and it gets flagged by the clang undefined behavior sanitizer.
>
> rte_memcpy_generic is called with unaligned src and dst addresses.
> When 1 < n < 16
Hi,
It's been several days and I haven't received any additional feedback
on this patch (and the other patch related to this one:
http://mails.dpdk.org/archives/dev/2022-January/232491.html). I would
welcome any kind of feedback. Ideally, I'm hoping an authoritative
voice would indicate if there's
Calls to rte_memcpy_generic could result in unaligned loads/stores for
1 < n < 16. This is undefined behavior according to the C standard,
and it gets flagged by the clang undefined behavior sanitizer.
rte_memcpy_generic is called with unaligned src and dst addresses.
When 1 < n < 16, the code wou
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