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Re: [LTO merge][8/15] GIMPLE streamer
On Wed, 30 Sep 2009, Richard Guenther wrote:
> On Wed, Sep 30, 2009 at 12:52 AM, Joseph S. Myers
> <joseph@codesourcery.com> wrote:
> > On Mon, 28 Sep 2009, Diego Novillo wrote:
> >
> >> This patch adds the gimple streamer.
> >
> > My comments on this patch relate to the portability of output (to
> > different hosts for the same target), diagnostics and error handling.
> >
> > I can see some issues here with output portability that should be
> > addressed for objects with LTO information to be portable between hosts.
>
> I think trying to make the streamer format portable between hosts
> is not an important goal (though that should be documented).
I think portability between hosts is important as part of the general
principle of identical code on different hosts. If you wish to put LTO
information in GCC's own runtime libraries then you need it for Canadian
cross compilers to work (the runtime libraries are built with or copied
from the build-x-target compiler, then used subsequently with the
host-x-target compiler). Likewise for any library that is built once for
use from multiple hosts, and LTO certainly ought to support building and
distributing binary libraries with LTO information in them (and
unnecessarily building multiple copies of a library means correspondingly
greater validation needed).
--
Joseph S. Myers
joseph@codesourcery.com