[Mesa-dev] [PATCH] radeon/llvm: Use LLVM C API for compiling LLVM IR to ISA.

[Jose Fonseca]

----- Original Message -----
> On Wed, Apr 24, 2013 at 09:40:44PM +0200, Mathias Fröhlich wrote:
> > 
> > Hi Tom,
> > 
> > On Tuesday, April 23, 2013 20:47:24 Tom Stellard wrote:
> > > First of all, thanks for investigating this.  The information you've
> > > provided has helped me a lot.
> > Good to hear that it helps.
> > 
> > > I took a shot at implementing it this way with private static copies of
> > > llvm.  I've pushed the initial work to this branch:
> > > git://people.freedesktop.org/~tstellar/mesa llvm-build
> > > 
> > > I was able to hide the LLVM symbols by using the --exclude-libs linker
> > > flag and so far I've tested with glxgears, an opencl example and also
> > > eglgears and they all work.  I still need to do some more testing, but
> > > any thoughts on what I've done so far in this branch?
> > 
> > I will look at this as soon as I find time. Probably not before the
> > beginning
> > of next week.
> > 
> 
> I've thought about this some more, and I think that the best solution
> might be to move all LLVM API calls into gallivm and build it as a
> shared object with it's own private copy of LLVM statically linked.  This way
> we
> would still have a private copy of LLVM to work with, but without having
> to statically link every single gallium target with LLVM.  Any thoughts
> about this?

I don't see how this would work -- llvmpipe/draw has LLVMBuildXxxx calls too.  So to prevent symbol collision with apps that use them, we'd need to expose all LLVM calls we need under nome unique prefix.

Also note that gallivm has a lot of function calls. This would also pollute the app's namespace.

In short, for this to work we should do it not for whole gallivm, but with a new module, just for LLVM C calls + the additional helpers, and use an unique prefix (e.g., MesaLLVMXxxx) for everything. 

And we should have a new header, that #defines LLVMFoo MesaLLVMFoo, so that Mesa code doesn't need to be changed all over the place.

Jose