From: Richard Biener <richard.guenther@gmail.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Romain Geissler <romain.geissler@amadeus.com>,
GCC Development <gcc@gcc.gnu.org>
Subject: Re: Can LTO minor version be updated in backward compatible way ?
Date: Thu, 18 Jul 2019 11:40:00 -0000 [thread overview]
Message-ID: <CAFiYyc1OYMBQ3ADLs6GuHp8YfegHTYQ7Lwj=Hwbf5Pk3cZNcbQ@mail.gmail.com> (raw)
In-Reply-To: <87ftn4in6x.fsf@linux.intel.com>
On Wed, Jul 17, 2019 at 7:30 PM Andi Kleen <ak@linux.intel.com> wrote:
>
> Romain Geissler <romain.geissler@amadeus.com> writes:
> >
> > I have no idea of the LTO format and if indeed it can easily be updated
> > in a backward compatible way. But I would say it would be nice if it
> > could, and would allow adoption for projects spread on many teams
> > depending on each others and unable to re-build everything at each
> > toolchain update.
>
> Right now any change to an compiler option breaks the LTO format
> in subtle ways.
Indeed - that one is quite awkward. I wonder if we could try mitigating
that by streaming some hash in front of the actual data for optimization/target
nodes we can verify is correct. Such change would be local to
optc-save-gen.awk and materialize in cl_*_stream_{in,out}.
I think that's the only place where streaming is auto-generated.
Richard.
> In fact even the minor changes that are currently
> done are not frequent enough to catch all such cases.
>
> So it's unlikely to really work.
>
> -Andi
>
prev parent reply other threads:[~2019-07-18 11:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 14:12 Romain Geissler
2019-07-17 16:15 ` Michael Matz
2019-07-17 17:30 ` Andi Kleen
2019-07-17 18:10 ` Jeff Law
2019-07-18 16:13 ` Florian Weimer
2019-07-18 23:00 ` [EXT] " Romain Geissler
2019-07-19 8:30 ` Florian Weimer
2019-07-22 7:52 ` Richard Biener
2019-07-22 11:15 ` Florian Weimer
2019-07-22 11:20 ` Richard Biener
2019-07-22 14:25 ` Martin Liška
2019-07-22 14:31 ` Jeff Law
2019-07-23 8:49 ` Martin Liška
2019-07-23 13:17 ` Jeff Law
2019-07-22 17:57 ` Jeffrey Walton
2019-07-18 11:40 ` Richard Biener [this message]
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