[llvm-dev] Want to contribute in LLVM.

[amit kumar via llvm-dev]

Thanks, I'll check them out.

On Wed, 16 Dec 2020, 11:49 am Stephen Neuendorffer, <
stephen.neuendorffer at gmail.com> wrote:

> Another option would be to take some existing passes and reimplement them
> in a useful way in MLIR.  Even some
>  elatively simple passes (like mem2reg/reg2mem) could be useful in the
> MLIR standard dialect, for instance,
> but no one has taken the time to do the implementation.
>
> Steve
>
> On Tue, Dec 15, 2020 at 7:27 PM amit kumar via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Thank you so know to guide me towards my first step, I'm going through
>> your suggested step and will let you know if I face any problem. and
>> last but not least these kinds of quick help/replies really give
>> motivation to beginners like me towards open-source contribution.
>>
>> Thanks and regards
>> Amit Kumar
>>
>> On Wed, Dec 16, 2020 at 8:12 AM Armand Behroozi <armandb at umich.edu>
>> wrote:
>> >
>> > Hey Amit,
>> >
>> > EECS583 at Umich also has a homework assignment or two that you could
>> give a go if you wanted.
>> > HW2 asks you to extend the loop invariant code motion pass and do
>> frequent path LICM (hoist almost invariant code).
>> >
>> > Link below.
>> > https://web.eecs.umich.edu/~mahlke/courses/583f18/homeworks.html
>> >
>> > It's just another resource.
>> >
>> > Best of luck.
>> >
>> > Regards,
>> >
>> > Armand
>> >
>> > On Tue, Dec 15, 2020 at 4:18 PM Stefanos Baziotis via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>> >>
>> >> Hi Amit,
>> >>
>> >> There are the bugs tagged beginner but last time I checked, IMHO, they
>> were not that "beginner-friendly" after all.
>> >>
>> >> The way I would recommend that you start with LLVM is by rewriting a
>> pass. One thing to note here is that this is not really a contribution (i.e.
>> >> a commit won't result immediately from that), so if you're only
>> interested in contributing something with your first try, that won't do it.
>> >>
>> >> But a common theme I see among beginners, including myself when I
>> started, is that when you're obsessed with landing a commit,
>> >> unavoidably you're going to "hack your way towards it". That basically
>> means that you'll just gather relatively shallow knowledge, maybe
>> >> with some breadth, but that limited too, just to commit something.
>> That's bad and it will probably not serve you in the long run.
>> >>
>> >> This is why for example, in courses which use LLVM as a teaching tool,
>> the assignments don't ask you to do something
>> >> shallow like that but instead they ask for something that requires
>> some kind of deep knowledge and thought (which you develop along).
>> >>
>> >> To that end, I recommend rewriting a pass (which is btw somewhat
>> common in courses). Now, that might sound scary but it's not.
>> >> The _actual_ goal is not to actually rewrite the pass. Neither all of
>> it, nor at the production level of LLVM. Rewriting
>> >> the pass is just an "artificial goal" only to have something to move
>> towards. The _actual_ goal is what you'll learn by moving
>> >> towards this goal. And what you'll learn will probably be both deep
>> and broad.
>> >>
>> >> You only need to start simple, like "OK, how do I query this
>> analysis?". Just that, then you try something like "hmm, how can I inspect
>> / traverse
>> >> the results of this analysis" etc. (and the good thing is that for a
>> lot of these first steps, multiple other passes will have done the exact
>> >> same thing and you should feel free to copy code shamelessly as you're
>> starting out).
>> >>
>> >> After some time doing that, you'll find that you start understanding
>> the system in some detail and _then_, you'll be equipped to do actual
>> commits.
>> >>
>> >> Now, the question is with which pass to start with? Again, because of
>> the above, that doesn't really matter, but in any case, it depends on what
>> you like.
>> >> For example, if you're interested in loops, I'd start with LCSSA (and
>> along with it, I'd give a try to the LLVM Loop Terminology). If you're
>> interested
>> >> in inter-procedural optimizations, I'd start with Sparse Conditional
>> Constant Propagation (SCCP).
>> >>
>> >> If you have no idea where to start or what you like, you might start
>> with Scalar Replacement of Aggregates (SROA), just because I saw it
>> >> in a cool course on UIUC recently and it seems to guide you relatively
>> well. Here's the link:
>> http://misailo.web.engr.illinois.edu/courses/526-sp20/,
>> >> it's project 1 (again, don't need to even do the whole thing, do the
>> parts that motivate you; I mean please don't treat that as an _actual_
>> assignment,
>> >> you probably have enough of those already :) ).
>> >>
>> >> So, this got very long, sorry for that, I hope it helps. Please don't
>> hesitate to reach me for questions.
>> >>
>> >> Best,
>> >> Stefanos
>> >>
>> >> Στις Τρί, 15 Δεκ 2020 στις 9:12 μ.μ., ο/η amit kumar via llvm-dev <
>> llvm-dev at lists.llvm.org> έγραψε:
>> >>>
>> >>> Respected Sir/Ma'am,
>> >>>                        I'm Amit Kumar, a 3rd-year undergraduate
>> >>> student in Computer Science Engineering (CSE) from IIIT Nagpur, India.
>> >>> I am new to open source only contributed to HactoberFest in the past 2
>> >>> years and I came across LLVM through GSoC and interested in
>> >>> building some new features in the newer version's LLVM and contribute
>> >>> to the language. I had studied Compiler Design in our courses.
>> >>>
>> >>> Please help me and show me direction towards starting my journey to
>> >>> the open-source contribution.
>> >>> Thanks and Regards
>> >>> Amit Kumar
>> >>> _______________________________________________
>> >>> LLVM Developers mailing list
>> >>> llvm-dev at lists.llvm.org
>> >>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> >>
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