Re: [EXT] Re: Can LTO minor version be updated in backward compatible way ?

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Jul 22, 2019 at 1:15 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Richard Biener:
>
> > On Fri, Jul 19, 2019 at 10:30 AM Florian Weimer <fweimer@redhat.com> wrote:
> >>
> >> * Romain Geissler:
> >>
> >> > That may fly in the open source world, however I expect some vendors
> >> > shipping proprietary code might be fine with assembly/LTO
> >> > representation of their product, but not source.
> >>
> >> They can't ship LTO today anyway due to the format incompatibility, so
> >> that's not really an argument against source-based LTO.
> >
> > Source-based LTO doesn't really work unless you can re-synthesize
> > source from the IL.  At least I don't see how you can do whole-program
> > analysis on source and then cut it into appropriate pieces, duplicating
> > some things and some not to make up for the parallel final compile step.
>
> Oh, I meant using source code only as a portable serialization of the
> program, instead of serializing unstable, compiler-specific IR.  If the
> whole program does not fit into memory, the compiler will still have to
> maintain on-disk data structures, but at least there wouldn't a
> compatibility aspect to those anymore.

OK, but then we'd need to re-do the compile and IPA analysis stage
at each link with the appropriate frontend.  But sure, that would be
possible.

Richard.

> Thanks,
> Florian