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

[Matt Turner]

On Wed, Aug 20, 2014 at 11:13 AM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> Gentoo has also had trouble updating for similar reasons; Matt (the Gentoo Mesa package mantainer) can probably comment more.

Yes, at one point we were stuck two releases behind current Mesa (and
this is Gentoo!) because we couldn't get the appropriate version of
LLVM stabilized because a number of reverse dependencies didn't work
with the new LLVM version.

Having multiple versions installed in parallel breaks down pretty
easily. Where do the headers go? Where do all the executables go? Do
you version all of them and install one for each version? Do other
distros allow multiple versions of LLVM to be installed in parallel?
How do they manage?

> I've also heard stories from friends of mine who use radeonsi that they couldn't get new GL features or compiler fixes unless they upgrade both Mesa /and/ LLVM, and that LLVM was usually either not released or not available in their distribution for a few months.

I get the sense that this is a problem that a backend in LLVM would
cause, but maybe not so if we just used LLVM IR for the GLSL compiler.
I think the C API is suitable for this kind of thing as well. Tom?