[LLVMdev] Scheduler Roadmap

[Hal Finkel]

On Fri, 11 May 2012 10:26:41 -0500
<dag at cray.com> wrote:

> Hal Finkel <hfinkel at anl.gov> writes:
> 
> >> Actually, we don't have any problem releasing tests.  We have done
> >> so before when sending patches.  The problem is the people we got
> >> the tests from.  Some are from proprietary test suites, others are
> >> from sensitive codes, etc.  It's often not up to us at all.
> >
> > I completely understand. Why don't we start by having you prepare
> > LLVM IR files, and associated outputs, for x86_64 from your
> > frontends only from open-source codes. As a first step, you could
> > even just generate LLVM IR files for us from the codes in the LLVM
> > test suite. We could setup a buildbot based on those files (which I
> > believe would be easy to do), and then we can actively test trunk
> > LLVM against those files.
> 
> I like this idea.  It'll work for C/C++ but not Fortran.  Since there
> is no Fortran ABI one has to link with our Fortran compiler &
> libraries to get an executable that actually works.
> 
> But let me think about this some more.  I would really like to expand
> the LLVM testbase if we can.  It will be a long process since I'll
> have to get all these tests approved for release.  I can't give a
> timeline on that at all.  I think it will be a very gradual process.

Out of curiosity, what is your current thinking on this?

 -Hal

>  
> > To be fair, the reason that my patch was not accepted was because it
> > caused test-suite failures on x86. Does the patch work for you? 
> 
> I'm hopefully going to try it within the next few days.
> 
> > If it does, then maybe the situation has changed, and we should
> > reconsider the status of the patch. The patch actually had two
> > parts: the IR->DAG modifications and the changes to the ILP
> > scheduling heuristic. Changes to the ILP scheduling heuristic may
> > be required regardless of how or where the critical chain is
> > relaxed.
> 
> Ok, I will take a look at that.
> 
> > Given that the patch caused test-suite failures on x86, I did not
> > want to commit it as-is. 
> 
> Yes, I understand that.  But from the discussion I got the impression
> that the patch wasn't wanted because ScheduleDAG is going to be
> deprecated.  If that's not the case I will certainly work to get it
> going!
> 
> > I would have loved if someone else had worked to
> > diagnose and/or fix the remaining problems (which may have been
> > scattered among different backends), but it is hard to ask people
> > to do that for a feature that would be deprecated in six months
> > time.
> 
> Yeah, I understand.  But for those of us working off releases it would
> not be deprecated in six months.  That's probably moot now since 3.1
> is almost out the door but I think the patch will still be useful for
> us.
> 
> Believe me, I would really like to be able to work off trunk but I
> have to convince a lot of people here that that is possible.
> Starting with myself.  :)
> 
>                                 -Dave



-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory