[llvm-dev] GSoC Interested student

Wed Mar 18 18:21:33 PDT 2020

Hi Hamilton,

I personally don't believe the effort to make the IR "parallelism-aware" is worth it right now.
What I propose is something else, see for example https://youtu.be/zfiHaPaoQPc and the OpenMPOpt pass.
There are multiple bigger tasks towards better offloading, one of which is described here https://github.com/llvm/llvm-project/issues/180
It might be interesting to add the transfer functions used for memory transfer to the OMPKinds.def file so they are known in the OpenMPOpt.cpp pass.
Another small task would be to eliminate trivially redundant ones, that is if you have copy X from A to B directly followed by copy X from B to A, remove both.

Does this make sense?

Cheers,
  Johannes

---------------------------------------
Johannes Doerfert
Researcher

Argonne National Laboratory
Lemont, IL 60439, USA

jdoerfert at anl.gov

________________________________________
From: Hamilton Tobon Mosquera <htobonm at eafit.edu.co>
Sent: Wednesday, March 18, 2020 19:14
To: llvm-dev at lists.llvm.org
Cc: Doerfert, Johannes
Subject: Re: [llvm-dev] GSoC Interested student

Hi there!,

I think I'm done with this patch: D76058. If that is everything concerning that, could you please assign me another task.

I've been reading about Concurrent Control Flow Graphs, which would be awesome for LLVM because it would be kind of a starting point for optimizations for parallel programs in general. The thing is that it seems more complicated than it is presented in the papers, I think that's why it's not implemented in LLVM yet. So, I think I'll try searching for something else. Nevertheless, don't you think that implementing this is worth the effort?. The papers I'm reading are from 1990s, I don't understand why they aren't widely implemented in big compilers xd.

I saw this commit from you: https://reviews.llvm.org/D29250. Is there something I can help with concerning this?.

I would like to do contribute to the OpenMP target offloading. Is there anything I can help with?.

On 11/03/20 8:51 a. m., Hamilton Tobon Mosquera via llvm-dev wrote:

Hi there!,

As part of my application process to the next GSoC I'm working on the TODO in OpenMPOpt.cpp line 437:

    // TODO: We should validate the declaration agains the types we expect.

    Link: https://github.com/llvm/llvm-project/blob/master/llvm/lib/Transforms/IPO/OpenMPOpt.cpp#L437<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fllvm%2Fllvm-project%2Fblob%2Fmaster%2Fllvm%2Flib%2FTransforms%2FIPO%2FOpenMPOpt.cpp%23L437&data=01%7C01%7Chtobonm%40eafit.edu.co%7C60068814c014449f011808d7c5bafa38%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=LN1PaCRL7EasnWgZYoc1GzdXHL2NqTwgFuqMj196HSQ%3D&reserved=0>

I have a question. When there is a mismatch in the types (return type or argument types) between the function declaration found and the runtime library function, what should I do?. Show an error or a warning?, continuing with the pass or exiting the program?.

Thanks.

On 10/03/20 7:12 p. m., Stefanos Baziotis wrote:
Hi Hamilton,

Thanks for your interest in LLVM!

IMHO you have a good start. I'll try to help by CC'ing Johannes. Note that it's difficult for LLVM developers
(including GSoC mentors and including Johannes) to keep up with every discussion on llvm-dev.
So, you can CC them to make their life easier. :)

Johannes, I see a lot of people interested in this project. Maybe a list of starting points, patches etc.
could help.

Best,
Stefanos

Στις Τρί, 10 Μαρ 2020 στις 1:04 π.μ., ο/η Hamilton Tobon Mosquera via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> έγραψε:
Greetings,

I'm an LLVM newcomer interested in participating in the next GSoC under
the project "Improve parallelism-aware analyses and optimizations". I've
already read "Compiler Optimizations for OpenMP" and "Compiler
Optimizations for Parallel Programs" both by Doerfert and Finkel. Also,
I've watched their two LLVM meeting developers conferences "Representing
parallelism within LLVM" and "Optimizing indirections, using
abstractions without ...", so I have some background in the problems
they are trying to tackle. Also, I'm close to solve one of the bugs
posted in bugzilla, which has given me a broader idea of how the OpenMP
pragmas are translated. The bus is this:
https://bugs.llvm.org/show_bug.cgi?id=40253<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.llvm.org%2Fshow_bug.cgi%3Fid%3D40253&data=01%7C01%7Chtobonm%40eafit.edu.co%7C60068814c014449f011808d7c5bafa38%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=6LOTde6O8f2dbq8EkNxKv%2FNa%2BOrBXL%2FNqgqj8mGqn9o%3D&reserved=0>.

I tried contacting you Johannes but with your Argonne email, I suppose
that's why you couldn't answer. Could you tell me more about the
project?, what variants do you have?, or what can I focus my application
on?. Should I start with what you recommended to Emanuel?.

Thank you.

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