[Mesa-dev] 761131ce4591e5f55f38d13f2c4d2194bc9cb0fd build regression with llvm 2.8

[Jose Fonseca]

----- Original Message -----
> On Thu, 2012-07-26 at 07:52 -0700, Jose Fonseca wrote:
> > ----- Original Message -----
> > > On 7/21/12 5:53 AM, Jose Fonseca wrote:
> > > > ----- Original Message -----
> > > >> Hi guys
> > > >>
> > > >> LLVM 2.8 doesn't appear to have mcjit, so we end up with no
> > > >> llvm
> > > >> libs
> > > >> defined,
> > > >
> > > > Yes, mcjit is only used/necessary from llvm-3.1 onwards, so the
> > > > autoconf code should check conditiionally.
> > > >
> > > > BTW, I'll soon commit a change that will stop using mcjit from
> > > > 3.2
> > > > onwards (as with the current LLVM 3.2 trunk, AVX is supported
> > > > by
> > > > the old jit, which is more stable/polished).
> 
> Can you clarify the scope of "will stop using mcjit from 3.2
> onwards"?

What I meant by that was already done in commit c30bf68946433d26f672c741a763bba4712aada7.

> Is that specific to (the Intel AVX extensions?) related matters, or
> is
> that a mesa-wide statement?    (I am specifically interested in the
> llvmpipe related parts that Adam touched on below).

The MC-JIT vs old JIT is currently a build time choice (based on #ifdef's). Essentially, we only use MC-JIT for LLVM 3.1, if AVX support hasn't been backported (ie. when not using my backports_31 branch below).

It could be made into a runtime choice if you prefer, ie., based of the availability of AVX. Or we could just disable MC-JIT altogether, and wait until it replaces the old jit upstream.

BTW, for best results using llvmpipe on 3.1, please consider using http://cgit.freedesktop.org/~jrfonseca/llvm/log/?h=backports_31 as it includes some backports of bugs/enhacements that affect llvmpipe to LLVM 3.1.

Jose