[llvm-dev] GSoC Opportunity
Benson Bin Bin Li via llvm-dev
llvm-dev at lists.llvm.org
Sun Mar 15 20:12:28 PDT 2020
First, thanks a lot for the very detailed response! I watched both of the
videos, and I seem to have a rough idea now of how each of the different
pieces of software maps onto the compilation process. Though I found blogs
such as these two: https://jonasdevlieghere.com/understanding-the-clang-ast/,
https://releases.llvm.org/2.6/docs/tutorial/JITTutorial1.html to be better
for a more in-depth understanding. Anyways, in response to your answers:
The latter can even be problematic if you start applying C++ craziness
> while the first is pretty much always needed when working in a team project.
Ok, that makes sense as you would want the style to be consistent
running the LLVM suite is super easy
Yeah, everything went fine from following your instructions. I do have a
question though: How do I diagnose failed tests? I found the files that
correspond to them, and they seem to be 1 line scripts rather than "code"
But I think every good GSoC proposal includes a biography-like section
Then, try to study it, understand the context and the problem.
But because submitting good patches is one of the best indicators
Ok, so for the application process, basically try to get more info on the
projects I am interested in and from there submit a proposal? Given the
whole coronavirus situation and the time remaining for the application, I
probably do not have the time to get a patch through. Regarding the
projects I am interested in, I have narrowed it down to two(mostly because
I don't think I have the ability to tackle PostDominatorTree project as of
now), and have the following questions about them:
I am following the guide to create a LLVM pass following this guide(
https://llvm.org/docs/WritingAnLLVMPass.html), but it appears
“add_llvm_library” is a macro and not a built-in command. So I have two
questions. 1) In comparing the online repo I found this macro in and my
local, it appears I don’t have the file. Do I need to build it then? 2) How
do I tell CMake to look for this macro?
Is there a specific section of the dragon book that I should read so
that I can at least understand theoretically what it means to create a
LLDB Tab Completion
Is there any resource I can read that explains how lldb is able to
“pause” the executable and map it to a certain line in the source file/in
general how lldb represents the state of the executable?
Where in the source code can I go to see how existing tab completions
3. I built lldb and check-lldb, but it seems that the call path to clang
got messed up, as it is trying to call "Example=Code/llvm-project" rather
than my actual name for the directory "Example-Code/llvm-project". Should I
just clone the repo into a parent directory that doesn't use hyphen?
(Would it be better if I posted this on the forum?)
On Sat, Mar 14, 2020 at 11:10 AM Stefanos Baziotis <
stefanos.baziotis at gmail.com> wrote:
> Hi Benson,
> You're welcome to the LLVM community!
> I'll try to help but note that I'm no formal position to talk about how
> LLVM decides about GSoC (I'm a LLVM newcomer anyway).
> With that said, the rest is _my_ opinion which is partially formed from my
> experience as a GSoC student.
> > But to be up front about this, I have not done any full scale C++
> Depending on how you define "full-scale", a lot of amazing LLVM
> contributors have not done a full-scale C++. So, I think no problem there,
> it's just good to have a relatively good knowledge of C++.
> Talking about C++ skills, I think they're more important if you want to
> contribute to Clang than say LLVM middle or back-end. Because for Clang,
> you have to know a lot of details of the language
> in order to parse it, type-check it and generate LLVM IR. In most other
> parts of LLVM, you're only using the language.
> As a matter of fact, if you have a good knowledge of C++, I believe it's
> more important to be able to understand and adapt to "nearby" code, than to
> be an expert in C++.
> The latter can even be problematic if you start applying C++ craziness
> while the first is pretty much always needed when working in a team project.
> > 1. Do I need to submit a resume/screening/patches?
> As far as the resume, in the way that you may usually apply to jobs, no.
> But I think every good GSoC proposal includes a biography-like section
> where you basically tell your story in programming and how you fit into
> the project (in our case, LLVM).
> I'm not sure what you mean by screening.
> As for patches, I don't think they're required but they're super useful.
> Not because they're some part of unrelated logistics (like "you have to
> have X patches to be considered").
> But because submitting good patches is one of the best indicators (if not
> the best) that you are able to do useful work in this project. :)
> And they don't only show your technical skills. But also communication
> skills, independence etc.
> > 2. Although I do have interests in certain projects posted on you
> website(Implement missing tab completion, createLoopPass, and
> PostDominatorTree), I am uncertain if I have enough expertise to decide
> what would be an appropriate project to contribute to given my current
> knowledge and experience.
> This is kind of a generic sentence.
> I'd say, start with finding a project that you're truly interested in.
> Then, try to study it, understand the context and the problem.
> You don't need to get very far, that's totally ok. You can then do a post
> (either here or on Discourse:
> for this specific project (you can do posts for multiple projects).
> Hopefully, by discussing with people (and mentors) and understanding what
> the project is asking better,
> you can find if you want to do it or not. Certainly, the mentors of the
> project can guide you through.
> 3. The GCC GSoC website suggested checking out their source code,
> compiling and running their test suite. Can I do something similar for
> Yes, totally. I'm not familiar with GCC internals but running the LLVM
> suite is super easy (so easy that you don't really learn anything by doing
> it :P )
> So, the LLVM project has moved to a common repository:
> You can clone the project and then use CMake to build it. The cmake
> configuration for LLVM has a bunch of flags:
> and you may get lost. So, I'll say start simple:
> Go to the llvm-project dir (the one you cloned) and do:
> cmake ./llvm -DLLVM_ENABLE_PROJECTS="clang" -DCMAKE_BUILD_TYPE=Release
> -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_TARGETS_TO_BUILD="X86"
> In the link above you can read what the flags do. llvm middle / back-end
> (i.e. opt / llc, ask if you don't know what these mean) is always built.
> But to build clang
> we have to enable it explicitly. We set build type to release because
> doing a debug build will take a lot of time and a lot of space. Also, when
> starting out,
> you probably don't need it. We enable assertions mostly because you can
> use the -debug option say in opt and see debug prints.
> Finally, we only build for x86 arch because that's probably what you have
> and you don't need any other for now.
> Hit enter and once the configuration is complete you can do:
> make -j<number of threads> <-- this is faster but limit it depending on
> your systemS
> When that's finished, the llvm-project/bin/ dir will have executables like
> clang, clang++, opt, llc etc.
> Which you can run (also ask if you don't know what to do with them. With
> clang you probably will know, it's like invoking
> most compilers like gcc to compile .c / .cpp files).
> To run the test suite, you can go to llvm-project/llvm/test and do:
> <dir of llvm-project>/bin/llvm-lit .
> That will run only llvm's test suite but you'll get an idea.
> Also, you can watch these videos:
> Hope this helped!
> Kind regards,
> Stefanos Baziotis
> Στις Σάβ, 14 Μαρ 2020 στις 2:04 π.μ., ο/η Benson Bin Bin Li via llvm-dev <
> llvm-dev at lists.llvm.org> έγραψε:
>> Dear LLVM Team,
>> I would like to contribute to/participate in LLVM’s GSOC, because I would
>> very much like to combine my knowledge of graph theory/algorithms and my
>> interest in C++ together. Contributing to the LLVM code seems like a
>> fantastic challenge and learning experience for these two interests of
>> mine, as well as computer science in general (For example, the use of a new
>> syntactic category to disambiguate a grammar demonstrates 1) indirection 2)
>> the power of naming things).
>> But to be up front about this, I have not done any full scale C++
>> project(Although we had to modify the Linux kernel in my OS class, that was
>> in C). However, I do believe my C++ skills are at an intermediate level, as
>> C++, like Python, is a language in which I will spend my free time learning
>> more about. Like vim, there is always more to learn in C++, and to that end
>> I will watch CppCon Videos or peruse blogs such as Fluent C++(which is a
>> treasure trove of material to nerd out on) in my free time. I also have a
>> layman’s knowledge of CMake, from using it to configure ccls to lint C++
>> code with specific flags, and am aware of Google’s Test framework. Finally,
>> I am currently taking Professor Stroustrap’s C++ class, and the compilers
>> course here at Columbia.
>> Regarding the logistics:
>> 1. Do I need to submit a resume/screening/patches?
>> 2. Although I do have interests in certain projects posted on you
>> website(Implement missing tab completion, createLoopPass, and
>> PostDominatorTree), I am uncertain if I have enough expertise to decide
>> what would be an appropriate project to contribute to given my current
>> knowledge and experience.
>> 3. The GCC GSoC website suggested checking out their source code,
>> compiling and running their test suite. Can I do something similar for LLVM?
>> Anyways, thank you for taking the time to read this email, and I hope to
>> hear back!
>> Best regards,
>> Benson Li
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
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