[cfe-dev] About commit TILE-Gx backend to community repository and default disabled

Jiong Wang jiwang at tilera.com
Tue Mar 19 20:58:02 PDT 2013

Hi Chris,

could you please comment on committing TILE-Gx backend into community?

========== TILE-Gx Status ===========

Features Supported
1. general function.
2. PIC/TLS/JumpTable.
3. Instructoin Bundling for VLIW.
4. Asm Parser
5. MC Layer (aware of instruction bundle), MCJIT support.
6. Initial regression tests for CodeGen & MC Layer.

Regression Result
Expected Passes : 13363
Expected Failures : 84
Unsupported Tests : 76
Unexpected Failures: 21

20 of the unexpected failures are caused by lack of old jit support.

Test-Suite Result
Expected Passes : 953
Unexpected Failures: 14
(all 14 failures has the same output as tilegx gcc,
most of them are about float precision issue)

于 2013/3/16 2:37, Tom Stellard 写道:
> On Fri, Mar 15, 2013 at 05:38:28PM +0800, Jiong Wang wrote:
>> Hi Chandler,
>> on 2013/3/15 17:15, Chandler Carruth wrote:
>>> On Fri, Mar 15, 2013 at 1:54 AM, Jiong Wang <jiwang at tilera.com
>>> <mailto:jiwang at tilera.com>> wrote:
>>>     I agree that everyone should contribute to keep the community
>>>     active and vigorious. But I think there are difference between
>>>     contributors.
>>>        some are focused and with expertise on middle end, while others
>>>     may on front or back end. so the normal way for a new contributor
>>>     is, find a familiar point to start, then go deeper and wider and
>>>     expand one's contribution during this process.
>>>        For Tilera corporation and me, we would like the keep tilegx
>>>     backend actively maintained and improved, and wish it could be a
>>>     good target to improve and test VLIW, many core features etc.
>>> Inevitably, if you care about LLVM's support for your platform,
>>> you will care about bugs and features in the target-independent
>>> stack of LLVM's software (including the target independent parts
>>> of Clang, etc). There will be bugs which are priorities only for
>>> you and/or your users, features most pressing only for you or your
>>> users, etc. As such, it seems likely that you will need at least a
>>> basic working familiarity with the stack, and the ability to
>>> improve it in at least basic ways. Simple things like finding and
>>> fixing bugs in the target independent code generator, improving
>>> DAG combine optimizations, or looking for compile time hotspots
>>> are almost always approachable by nearly anyone on the project.
>>      I am not quite understand your points here, for a backend
>> maintainer, of course, these things are daily work.
>>> Essentially, you don't need to invent a new middle end
>>> optimization, or improve the subtleties of our alias analysis.
>>> Most of LLVM, and most of our bugs/missing features/areas for
>>> improvement, involve straightforward C++ code and systems that
>>> anyone who cares can go in, hack, and improve. That's what
>>> occupies the majority of the maintenance work as it happens. There
>>> is relatively little deeply detailed work requiring specialized
>>> knowledge.
>>      Anyway, my question is "how could tilegx backend included in
>> community repository?", I am here to seek answer for this. I
>> searched mailinglist archive, and learned R600 and AArch64's request
>> post, but find few things.
> Hi Jiong,
> I am the maintainer of the R600 backend so I have some experience trying to
> get a new backend included in the community repository.
> My recommendation is to contact the project lead, Chris Lattner,
> directly and point him to the reviews that have already been done and ask
> him specifically what you need to do to get the backend approved.
> There is no formal process in place for adding a new backend, and I
> think if you keep posing your question to the list you will have trouble
> getting a clear answer on what needs to be done
> -Tom

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