[llvm-dev] [mlir] Re: "MLIR meets LLVM" Round-Table at the LLVM Dev Meeting

[Mehdi AMINI via llvm-dev]

Hi all,

As a reminder, the round-table will be Tuesday, Oct 22, 10:20-11:30, see
here: http://llvm.org/devmtg/2019-10/#round

Here is a potential list of all the topics I gathered from everyone, let me
know if I missed anything.

- Intro, practical aspect of the integration (repository, etc.)
- Can we have a machine-readable definition of LLVM IR in LLVM itself:
instructions, tracking changes, altering the semantics in the dialect wrt
LLVM IR. We could reuse this for the MLIR LLVM Dialect.
- Clang: would the static analyzer be a good candidate for a project to be
playing with a MLIR Dialect?
- Using MLIR for SCEV, VPLAN, etc. Isn’t SCEV an IR?
- MIR: could/should it be reimplemented as a MLIR dialect?
- What about Alive? (If Alive folks are around?)
- Representing parallelism in MLIR
- Heterogeneous compilation: this includes GPU of course, but also more
exotic platforms / third-party accelerator: how to plug all this into a
codegen story?
- Using MLIR dialects as a testbed for proposed LLVM IR changes (there were
proposals of tensor types for LLVM for example).
- Using MLIR for loop optimization and other higher-level transformations,
e.g. doing LLVM->Polly->MLIR Affine->LLVM.-

Note also that at shortly after the round-table, at 12:05pm the talk about An
MLIR Dialect for High-Level Optimization of Fortran
<https://llvm.org/devmtg/2019-10/talk-abstracts.html#tech19> will take
place.

Best,

-- 
Mehdi


On Fri, Oct 18, 2019 at 7:21 AM 'James Molloy' via MLIR <mlir at tensorflow.org>
wrote:

> > Some existing bits in LLVM that could have used MLIR are ScalarEvolution
> expressions, VPlan, SelectionDAG.  Moving these would be a lot of work
> obviously but what are some new things under development that could use
> MLIR from day one?
>
> I'd add to this list the MIR format, which is clearly crying out for
> MLIR-ification.
>
> On Fri, 18 Oct 2019 at 14:00, Lei Zhang <antiagainst at google.com> wrote:
>
>> FYI: related to GPU compilation, there will also be a "Challenges using
>> LLVM for GPU compilation" roundtable covering
>>
>>  - Canonicalization vs. GPUs: Type mutation;
>>  - Control flow mutation (graphics shaders are more sensitive to this);
>>  - Divergence/reconvergence sensitivity;
>>  - Address-space awareness;
>>
>> Time slot hasn't been finalized but preliminary planned for Tue 3-4pm or
>> Wed 2-3pm.
>>
>> http://lists.llvm.org/pipermail/llvm-dev/2019-October/136033.html
>>
>> Thanks,
>> Lei
>>
>>
>> On Tue, Oct 15, 2019 at 12:01 PM Sanjoy Das <sanjoy at google.com> wrote:
>>
>>> I won't be present during the round table, but it might be interesting
>>> to discuss if there are ways to use MLIR within LLVM.
>>>
>>> Some existing bits in LLVM that could have used MLIR are ScalarEvolution
>>> expressions, VPlan, SelectionDAG.  Moving these would be a lot of work
>>> obviously but what are some new things under development that could use
>>> MLIR from day one?
>>>
>>> -- Sanjoy
>>>
>>> On Tue, Oct 15, 2019 at 3:59 AM 'Alex Zinenko' via MLIR <
>>> mlir at tensorflow.org> wrote:
>>>
>>>> I would be interested in practical aspects:
>>>> - practical connection between MLIR's LLVM dialect and actual LLVM IR:
>>>> having a machine-readable definition of instructions, tracking changes,
>>>> altering the semantics in the dialect wrt LLVM IR;
>>>> - using MLIR dialects as a testbed for proposed LLVM IR changes (there
>>>> were proposals of tensor types for LLVM for example).
>>>>
>>>> This may be partially orthogonal, but may be interesting:
>>>> - using MLIR for loop optimization and other higher-level
>>>> transformations, e.g. doing LLVM->Polly->MLIR Affine->LLVM.
>>>>
>>>>
>>>> On Tue, Oct 15, 2019 at 1:27 AM Mehdi Amini <aminim at google.com> wrote:
>>>>
>>>>> Hey all,
>>>>>
>>>>> FYI the round-table will be Tuesday, Oct 22, 10:20-11:30, see here:
>>>>> http://llvm.org/devmtg/2019-10/#round
>>>>>
>>>>> It would be nice to have an agenda now, what are your thoughts on
>>>>> topics we should cover?
>>>>>
>>>>> Cheers,
>>>>>
>>>>> --
>>>>> Mehdi
>>>>>
>>>>>
>
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