[LLVMdev] Scheduler Roadmap

[dag at cray.com]

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.
 
> 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