On Fri, Jan 05, 2018 at 10:25:35AM +0000, Richard Sandiford wrote:
> Jakub Jelinek <ja...@redhat.com> writes:
> > On Fri, Jan 05, 2018 at 09:49:56AM +0000, Richard Sandiford wrote:
> >> Is the patch OK as a compromise for GCC 8? We don't speculatively
> >> increase the user alignment in increase_alignment, but do still increase
> >> it if it helps to vectorise a particular loop access?
> >
> > I'd be a little bit worried about code that puts some variables into user
> > sections with specific alignment, i.e.
> > __attribute__((section ("whatever"), aligned(N)))
> > where data is collected from different TUs into the user section and
> > any padding added there breaks this. E.g. Linux kernel and other programs
> > use this technique heavily.
>
> Looking again, it seems we already prevent increasing alignment for
> the "used" attribute (with or without "aligned"). Is that good enough?
>
> That kind of construct is used without "aligned" too, and I think it
> should have "used" to stop it being removed as dead.
Yeah, that should be likely good enough.
Jakub
