[Mesa-dev] [RFC PATCH 00/16] A new IR for Mesa

[John Kessenich]

> So, I don't suppose it is possible to have multiple side-by-side  llvm's?

They each go in their own subdirectory, with the version number in the path.

> I don't really look forward to having to recompile llvm when switching
between branches.

LLVM would sit next to mesa, fully compiled, as many versions as you want,
waiting for anything else to link against it.  Changes in other projects in
other locations has no effect on the already compiled LLVM directories.

Different versions of Mesa can point at different LLVM paths, to pick up
which ever already compiled version of LLVM that version wants to pick up.
 Should just be a natural part of the re-link you do when switching between
branches.

JohnK




On Wed, Aug 27, 2014 at 1:57 PM, Rob Clark <robdclark at gmail.com> wrote:

> On Wed, Aug 27, 2014 at 2:26 PM, John Kessenich <johnk at lunarg.com> wrote:
> > Hi,
> >
> > If Mesa used an LLVM IR for it's shader compiler stack, it would most
> likely
> >
> > Pick a specific shipped version.  Shipped versions are stable and
> > unchanging.  Upgrading to a newer version would be done only by choice,
> on
> > Mesa's schedule.
> > Not bring the source into mesa: it works perfectly well sitting next to
> > Mesa.
> > Link it in statically so there are no distro/versioning issues and no
> > interactions with other components of the system that independently use
> LLVM
> > however they wish.  This is also quite small compared to other uses of
> LLVM
> > people sometimes discuss.
> >
> > Externally, no one could even tell some helper functions within the
> compiler
> > stack came from LLVM or a specific version of LLVM.
> >
> >> Packaging and ABI stability...
> >
> > These don't even exist with linking statically to a chosen version.
>
> So, I don't suppose it is possible to have multiple side-by-side
> llvm's?  Ie. I wonder what happens when I'm switching back and forth
> between latest stable mesa branch, vs master which has moved on to
> llvm n+1?
>
> I guess that is less of packaging issue.. but I don't really look
> forward to having to recompile llvm when switching between branches.
>
> BR,
> -R
>
>
> > JohnK
> >
> >
> >
> > On Tue, Aug 26, 2014 at 10:25 PM, Greg Fischer <greg at lunarg.com> wrote:
> >>
> >> My apologies for a too-brief response to this question.
> >>
> >> GlassyMesa links LLVM statically into Mesa. I believe that previous
> >> posters to this thread have already done a pretty good job of arguing
> that
> >> this is at least a workable approach.
> >>
> >> Best regards,
> >> Greg
> >>
> >>
> >>
> >> On Tue, Aug 26, 2014 at 7:14 PM, Kenneth Graunke <kenneth at whitecape.org
> >
> >> wrote:
> >>>
> >>> On Tuesday, August 26, 2014 06:45:42 PM Greg Fischer wrote:
> >>> > The GlassyMesa effort is ongoing despite the lack of recent activity.
> >>> > We
> >>> > continue to embrace LLVM as a basis for shader compilation in Mesa
> and
> >>> > elsewhere.
> >>> >
> >>> > We agree that translating from LLVM back "up" to GLSL IR is
> problematic
> >>> > and
> >>> > that an architecture that supports LLVM backends would be desirable.
> >>> >
> >>> > The current published code is a work-in-progress. We are currently
> >>> > working
> >>> > on tuning of compilation time and code generation quality, and some
> of
> >>> > that
> >>> > work will likely be appearing soon. There have also been recent
> >>> > improvements in glslang, the parser for this stack.
> >>> >
> >>> > Packaging and ABI stability have not been an issue for us.
> >>>
> >>> As far as I know, you haven't actually shipped your software in any
> Linux
> >>> distribution yet, so a lack of packaging problems sort of goes without
> >>> saying...
> >>>
> >>> --Ken
> >>
> >>
> >>
> >> _______________________________________________
> >> mesa-dev mailing list
> >> mesa-dev at lists.freedesktop.org
> >> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >>
> >
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >
>
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