[llvm-dev] GSoC Interested student

Hamilton Tobon Mosquera via llvm-dev llvm-dev at lists.llvm.org
Tue Apr 7 05:32:27 PDT 2020


Hi Johannes,

In order to create the testcases with the FIXMEs showing how it should 
look after the transformation, I've been trying to come up with a way of 
splitting the runtime call __tgt_target_teams based on Silei's recent 
patch D77005. I like the idea of using its asynchronous version 
__tgt_target_teams_nowait, but I think we would have to modify it, 
either to return the async_info struct:

__tgt_async_info __tgt_target_teams_nowait(...) // This would break the 
current canonical way of returning a status code.

or to receive it as a pointer and modify its content, then waiting on 
that async_info object:

int __tgt_target_teams_nowait(..., __tgt_async_info *async_info = nullptr)

The first way leads to modify the Clang's code generation, and I'm not 
sure if that is a good idea. Concerning the second way, I'm not sure if 
having a default argument would lead also to modify the Clang's code 
generation.

Another possible solution would be to implement another runtime 
function, avoiding the need to modify the _nowait version. This would 
lead to implement new runtime functions for each runtime call that 
implies data transfers, which is perhaps worse. I don't know which 
approach is better, should I look for a way of modifying Clang's code 
generation in case of needed?. I'm trying to be as less disruptive as 
possible. Can you give me some advice?.

Thank you.

Hamilton.

On 28/03/20 11:05 p. m., Doerfert, Johannes wrote:
> On 3/28/20 8:33 PM, Hamilton Tobon Mosquera wrote:
>   > Hi Johannes,
>   >
>   > I've been thinking on how to implement a solution for the problem and
>   > I have some questions:
>   >
>   > 1. You mention in the problem description that the current
>   > asynchronous functions can be used, and probably modified. The problem
>   > is that those runtime functions with _nowait at the end are not
>   > asynchronous. Looking at their implementations, they just wait for
>   > other tasks is there are pending tasks, and then call its synchronous
>   > versions. So, is it a good idea to wrap them in functions that call
>   > them as asynchronous (using std::async), then return an object to wait
>   > on?. Then, waiting on the object returned.
>
> Take a look at D77005. Shilei introduced some real askync versions for a
> different reason already. You can build on top of that patch and extend
> it if needed further.
>
>
>   > 2. I'm thinking on replacing the data transfer inside
>   > __tgt_target_teams with __tgt_target_data_begin. The problem with this
>   > is that __tgt_target_data_begin does not initialize [first]private
>   > variables, and doesn't check for lambda mappings. Therefore, my idea
>   > to go around this problem is to create another wrapper function F,
>   > that calls __tgt_target_data_begin, and executes the necessary code
>   > for lambda mappings check and [first]private variables, and finally,
>   > calling F as the asynchronous function. What is good about this, is
>   > that the code concerning data transfer inside __tgt_target_teams can
>   > be replaced with F.
>
> Interesting. I'll need to see small examples. For now, focus on the
> simple case, we'll get to the rest later. However, we should really
> start by creating test cases that show the initial code and FIXMEs that
> describe how we want it to look like.
>
>
>   > 3. Also, I was wondering if I must to be aware of (split them into
>   > issue and wait) all the other constructs that imply data transfers
>   > (update, data enter/exit), or just focus on __tgt_target[_nowait] and
>   > __tgt_target_teams[_nowait].
>
> We want to eventually split all transfers into two but let's start with
> a single one.
>
>
>   > 4. This might be a dumb question, but just to make sure. Do I have to
>   > move the wait call into the offloaded region just before the data is
>   > used (because I think this would imply analyzing the offloaded
>   > bitcode, which is in another module)?, or move it just before the
>   > kernel is executed?.
>
> We split, then we move them apart. The cannot be moved over instructions
> that might change behavior if we move them, e.g. an aliasing memory
> operation or a kernel call that uses the data.
>
>
>   > 5. Do you have a template for the GSoC proposal. That is, is it plain
>   > text or pdf or ...?. Also, do you have sort of a structure that we
>   > have to follow?, for example, Abstract -> Benefits -> Deliverables
>   > ..., or do we have freedom on that?. Your post in hte GSoC page only
>   > mentions that we must include our background, but nothing about the
>   > format of the proposal.
>
> I do not have one. I thought they might or they have an FAQ that
> describes what to do. I know they have some required things, so check
> their webpage. I think you have to use google docs, I might be wrong.
> Your categories look good, make the deliverables not too specific but
> describe more ideas to work on. We'll make tasks as we go as you are not
> the only one working on this general area.
>
> Feel free to send me a draft of the proposal for feedback.
>
> Cheers,
>     Johannes
>
>   > Thank you.
>   >
>   > Hamilton.
>   >
>   >
>   > On``` 25/03/20 11:41 a. m., Doerfert, Johannes wrote:
>   >> On 3/25/20 5:51 AM, Hamilton Tobon Mosquera wrote:
>   >>   > Hi Johannes,
>   >>   >
>   >>   > Sorry about the failing tests. I completely forgot about running all
>   >>   > of them, I only ran the tests for the openmp ipo transforms.
>   >>
>   >> No worries, it happens.
>   >>
>   >>
>   >>   > I found the GH issue in cache. I can post it here if you want.
>   >>
>   >> Yes, please.
>   >>
>   >>
>   >>   > I analyzed these runtime calls, __tgt_target_teams_[nowait]. What I
>   >>   > don't understand about the problem we want to solve (splitting the
>   >>   > memory transfer into issue and wait and legally moving code
> inside) is
>   >>   > that the memory transfer is made inside those runtime calls.
>   >>   > Therefore, the runtime calls to the memory transfer cannot be
> analyzed
>   >>   > in the IR. Could you please explain a bit further if the memory
>   >>   > transfer should split in the IR? or split
> __tgt_target_teams_[nowait]
>   >>   > in such a way that the memory transfer is made in the first
> part, and
>   >>   > the wait in the second part.
>   >>
>   >> Exactly what you said in the last sentence. Split the runtime call into
>   >> two, issue and wait. Then we move issue "up" the execution path and wait
>   >> "down".
>   >>
>   >> Cheers,
>   >>     Johannes
>   >>
>   >>
>   >>   > Thanks.
>   >>   >
>   >>   > Hamilton.
>   >>   >
>   >>   > On 23/03/20 2:21 p. m., Doerfert, Johannes wrote:
>   >>   >>
>   >>   >> On 3/23/20 11:22 AM, Hamilton Tobon Mosquera wrote:
>   >>   >>   > Hi Johannes,
>   >>   >>   >
>   >>   >>   > Yes, I'm highly interested, I already started. It would be nice
>   >> if you
>   >>   >>   > post the details again. I didn't take note of them, I was
> always
>   >>   >>   > looking at the issue in GH.
>   >>   >>
>   >>   >> I asked if we can make the readonly but unsure yet. I can write
> it again
>   >>   >> but it'll take ma some time.
>   >>   >>
>   >>   >>
>   >>   >>   > The problem I'm facing right now is this:
>   >>   >>   > The first task is identifying OpenMP API calls referred to
>   >> device memory
>   >>   >>   > allocation. I first understood how the compiler driver
>   >> orchestrates the
>   >>   >>   > process of offloading OpenMP regions to devices, and now I'm
>   >> looking at
>   >>   >>   > the step of the pipeline that generates LLVM IR for both
> host and
>   >>   >>   > device. I wrote a simple C program that uses OpenMP to map a
>   >> local array
>   >>   >>   > to the device main memory. Then I'm looking at the device and
>   >> host LLVM
>   >>   >>   > IR representation of this program, but I can't find any
> runtime call
>   >>   >>   > referred to device memory allocation. In the host IR I see
> that the
>   >>   >>   > array is passed to the outlined function and stored in a
>   >> register inside
>   >>   >>   > the outlined function, but there's no memory allocation runtime
>   >> call.
>   >>   >>   > And in the device IR the array is passed to the main offloading
>   >>   >>   > function.
>   >>   >>   > Any suggestion or documentation on how that memory transfer is
>   >>   >>   > achieved?, and how to track its API calls. It might be that
> I'm not
>   >>   >>   > using the proper omp directive, so here is C code:
>   >>   >>
>   >>   >> Take a look at
>   >>
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgodbolt.org%2Fz%2FE9VoVx&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=yM9OaHxEHZBkU9HNFiMvQFv9zveVQp3kS%2FB4W9qkxKA%3D&reserved=0
>   >> , the mapping request,
>   >>   >>
>   >>   >> which may or may not cause data-transfers, are part of the call to
>   >>   >> __tgt_target_teams[_nowait] and
> __tgt_target_data_update[_nowait]. Start
>   >>   >> by reading the impl. of those two functions in the openmp runtime
>   >>   >> (llvm-project/openmp/...).
>   >>   >>
>   >>   >> Let me know if this helps and once you have new questions.
>   >>   >>
>   >>   >> Cheers,
>   >>   >>     Johannes
>   >>   >>
>   >>   >> P.S. I merged your first patch. You didn't run all test before.
> I did
>   >>   >> and noticed that we failed one because of type mismatches.
> Fixed them
>   >>   >> before I merged your patch.
>   >>   >>
>   >>   >>   >
>   >>   >>   > #include <omp.h>
>   >>   >>   > #include <stdio.h>
>   >>   >>   >
>   >>   >>   > #define size 1000000
>   >>   >>   > double a[size];
>   >>   >>   >
>   >>   >>   > int main() {
>   >>   >>   >
>   >>   >>   >   #pragma omp target map(to: a[0:size])
>   >>   >>   >   #pragma omp teams distribute
>   >>   >>   >   for (int i = 0; i < size; ++i) {
>   >>   >>   >     a[i] = a[i]*(i*i)/2;
>   >>   >>   >   }
>   >>   >>   >
>   >>   >>   >   return 0;
>   >>   >>   > }
>   >>   >>   >
>   >>   >>   >
>   >>   >>   > PD: The command to compile is this:
>   >>   >>   >     clang -v -save-temps \
>   >>   >>   >     -I/path/to/llvm/release/9.x/include -fopenmp \
>   >>   >>   >     -fopenmp-targets=nvptx64-nvidia-cuda -Xopenmp-target \
>   >>   >>   >         -march=sm_61 memory_transfer.c -o memory_transfer
>   >>   >>   >
>   >>   >>   > Thanks.
>   >>   >>   > Hamilton.
>   >>   >>   >
>   >>   >>   > On 23/03/20 11:11 a. m., Doerfert, Johannes wrote:
>   >>   >>   >> On 3/22/20 12:33 PM, Hamilton Tobon Mosquera wrote:
>   >>   >>   >>   > Ahhh I understand. So I believe the project you posted
> is still
>   >>   >>   >> opened. Do you any advice on the question I posted before?.
>   >>   >>   >>
>   >>   >>   >> Yes. Still open. You should use this as the main part of
> the GSoC
>   >>   >>   >> proposal (if you are interested). Can you repeat the question?
>   >>   >>   >>
>   >>   >>   >>   >
>   >>   >>   >>   > Thank you.
>   >>   >>   >>   >
>   >>   >>   >>   > On 22/03/20 1:26 p. m., Doerfert, Johannes wrote:
>   >>   >>   >>   >> I did not. The issues sections on GH was removed.
>   >>   >>   >>   >>
>   >>   >>   >>   >> ________________________________________
>   >>   >>   >>   >> From: Hamilton Tobon Mosquera <htobonm at eafit.edu.co>
>   >>   >>   >>   >> Sent: Sunday, March 22, 2020 12:21
>   >>   >>   >>   >> To: llvm-dev at lists.llvm.org
>   >>   >>   >>   >> Cc: Doerfert, Johannes
>   >>   >>   >>   >> Subject: Re: [llvm-dev] GSoC Interested student
>   >>   >>   >>   >>
>   >>   >>   >>   >> Hi there Johannes!,
>   >>   >>   >>   >>
>   >>   >>   >>   >> I was checking out the issue (about latency hiding when
>   >>   >> transferring
>   >>   >>   >>   >> memory from host to device) you posted about a week
> ago, but
>   >>   >> it's not
>   >>   >>   >>   >> there anymore. Did you remove it?.
>   >>   >>   >>   >>
>   >>   >>   >>   >> Thanks.
>   >>   >>   >>   >>
>   >>   >>   >>   >> Hamilton.
>   >>   >>   >>   >>
>   >>   >>   >>   >> On 21/03/20 10:04 p. m., Hamilton Tobon Mosquera via
> llvm-dev
>   >>   >> wrote:
>   >>   >>   >>   >>> Hi there!,
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> Right now I'm starting with the project proposed by
>   >> Johannes here:
>   >>   >>   >>   >>>
>   >>   >>   >>
>   >>   >>
>   >>
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fllvm%2Fllvm-project%2Fissues%2F180&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=CVDD7HCzFVsPwSpZLOeiO5%2BMNX78sGrDd2eYJ5dWzyE%3D&reserved=0.
>   >>   >>   >>   >>>
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> The first task is identifying OpenMP API calls referred
>   >> to device
>   >>   >>   >> memory
>   >>   >>   >>   >>> allocation. I first understood how the compiler driver
>   >>   >> orchestrates the
>   >>   >>   >>   >>> process of offloading OpenMP regions to devices, and
> now I'm
>   >>   >> looking at
>   >>   >>   >>   >>> the step of the pipeline that generates LLVM IR for both
>   >> host and
>   >>   >>   >>   >>> device. I wrote a simple C program that uses OpenMP to
>   >> map a local
>   >>   >>   >> array
>   >>   >>   >>   >>> to the device main memory. Then I'm looking at the
> device and
>   >>   >> host LLVM
>   >>   >>   >>   >>> IR representation of this program, but I can't find any
>   >>   >> runtime call
>   >>   >>   >>   >>> referred to device memory allocation. In the host IR
> I see
>   >>   >> that the
>   >>   >>   >>   >>> array is passed to the outlined function and stored in a
>   >> register
>   >>   >>   >> inside
>   >>   >>   >>   >>> the outlined function, but there's no memory allocation
>   >>   >> runtime call.
>   >>   >>   >>   >>> And in the device IR the array is passed to the main
>   >> offloading
>   >>   >>   >>   >>> function. Any suggestion or documentation on how
> that memory
>   >>   >>   >> transfer is
>   >>   >>   >>   >>> achieved?, and how to track its API calls. It might
> be that
>   >>   >> I'm not
>   >>   >>   >>   >>> using the proper omp directive, so here is C code:
>   >>   >>   >>   >>>
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> #include <omp.h>
>   >>   >>   >>   >>> #include <stdio.h>
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> #define size 1000000
>   >>   >>   >>   >>> double a[size];
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> int main() {
>   >>   >>   >>   >>>
>   >>   >>   >>   >>>    #pragma omp target map(to: a[0:size])
>   >>   >>   >>   >>>    #pragma omp teams distribute
>   >>   >>   >>   >>>    for (int i = 0; i < size; ++i) {
>   >>   >>   >>   >>>      a[i] = a[i]*(i*i)/2;
>   >>   >>   >>   >>>    }
>   >>   >>   >>   >>>    return 0;
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> PD: The command to compile is this: clang -v -save-temps
>   >>   >>   >>   >>> -I/path/to/llvm/release/9.x/include -fopenmp
>   >>   >>   >>   >>> -fopenmp-targets=nvptx64-nvidia-cuda -Xopenmp-target
>   >> -march=sm_61
>   >>   >>   >>   >>> memory_transfer.c -o memory_transfer
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> Thank you all.
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> Hamilton.
>   >>   >>   >>   >>>
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> On 18/03/20 9:21 p. m., Doerfert, Johannes wrote:
>   >>   >>   >>   >>>> 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://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FzfiHaPaoQPc&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=hN9WGEO%2F3quio7A9tvtIDHxznURuITYVBszFSmqM5M8%3D&reserved=0
>   >>   >>   >>   >>>> and the OpenMPOpt pass.
>   >>   >>   >>   >>>> There are multiple bigger tasks towards better
>   >> offloading, one of
>   >>   >>   >>   >>>> which is described here
>   >>   >>   >>   >>>>
>   >>   >>   >>
>   >>   >>
>   >>
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fllvm%2Fllvm-project%2Fissues%2F180&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=CVDD7HCzFVsPwSpZLOeiO5%2BMNX78sGrDd2eYJ5dWzyE%3D&reserved=0
>   >>   >>   >>   >>>> 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://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Freviews.llvm.org%2FD29250&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=lycF%2FQ2WOJtIzRuGEgAu%2BOEw9220%2FnqslSkJMKFENJw%3D&reserved=0.
>   >>   >>   >>   >>>> 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://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%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=gAMSEONp%2F8cMDuO0IckxHPXbBnUllJMWVfLHwa6UsBc%3D&reserved=0<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%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=gAMSEONp%2F8cMDuO0IckxHPXbBnUllJMWVfLHwa6UsBc%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://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.llvm.org%2Fshow_bug.cgi%3Fid%3D40253&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=Wye5YuFLVUPPESqTRnwsZtimjF0wdUxDetwoCNCib64%3D&reserved=0<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%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=Wye5YuFLVUPPESqTRnwsZtimjF0wdUxDetwoCNCib64%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.
>   >>   >>   >>   >>>>
>   >>   >>   >>   >>>> _______________________________________________
>   >>   >>   >>   >>>> LLVM Developers mailing list
>   >>   >>   >>   >>>> llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
>   >>   >>   >>   >>>>
>   >>   >>   >>
>   >>   >>
>   >>
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.llvm.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fllvm-dev&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=7CKfLhJkFKsjWn97SBMgKMz9nxRV1iZp305G9rsVLoA%3D&reserved=0<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.llvm.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fllvm-dev&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=7CKfLhJkFKsjWn97SBMgKMz9nxRV1iZp305G9rsVLoA%3D&reserved=0>
>   >>   >>   >>   >>>>
>   >>   >>   >>   >>>> La información contenida en este correo electrónico
> está
>   >> dirigida
>   >>   >>   >>   >>>> únicamente a su destinatario y puede contener
> información
>   >>   >>   >>   >>>> confidencial, material privilegiado o información
>   >> protegida por
>   >>   >>   >>   >>>> derecho de autor. Está prohibida cualquier copia,
>   >> utilización,
>   >>   >>   >>   >>>> indebida retención, modificación, difusión,
> distribución o
>   >>   >>   >>   >>>> reproducción total o parcial. Si usted recibe este
> mensaje
>   >>   >> por error,
>   >>   >>   >>   >>>> por favor contacte al remitente y elimínelo. La
>   >> información aquí
>   >>   >>   >>   >>>> contenida es responsabilidad exclusiva de su remitente
>   >> por lo
>   >>   >> tanto
>   >>   >>   >>   >>>> la Universidad EAFIT no se hace responsable de lo
> que el
>   >> mensaje
>   >>   >>   >>   >>>> contenga. The information contained in this email is
>   >>   >> addressed to its
>   >>   >>   >>   >>>> recipient only and may contain confidential
> information,
>   >>   >> privileged
>   >>   >>   >>   >>>> material or information protected by copyright. Its
>   >>   >> prohibited any
>   >>   >>   >>   >>>> copy, use, improper retention, modification,
> dissemination,
>   >>   >>   >>   >>>> distribution or total or partial reproduction. If you
>   >> receive
>   >>   >> this
>   >>   >>��  >>   >>>> message by error, please contact the sender and delete
>   >> it. The
>   >>   >>   >>   >>>> information contained herein is the sole
> responsibility of
>   >>   >> the sender
>   >>   >>   >>   >>>> therefore Universidad EAFIT is not responsible for
> what the
>   >>   >> message
>   >>   >>   >>   >>>> contains.
>   >>   >>   >>   >>>> La información contenida en este correo electrónico
> está
>   >> dirigida
>   >>   >>   >>   >>>> únicamente a su destinatario y puede contener
> información
>   >>   >>   >>   >>>> confidencial, material privilegiado o información
>   >> protegida por
>   >>   >>   >>   >>>> derecho de autor. Está prohibida cualquier copia,
>   >> utilización,
>   >>   >>   >>   >>>> indebida retención, modificación, difusión,
> distribución o
>   >>   >>   >>   >>>> reproducción total o parcial. Si usted recibe este
> mensaje
>   >>   >> por error,
>   >>   >>   >>   >>>> por favor contacte al remitente y elimínelo. La
>   >> información aquí
>   >>   >>   >>   >>>> contenida es responsabilidad exclusiva de su remitente
>   >> por lo
>   >>   >> tanto
>   >>   >>   >>   >>>> la Universidad EAFIT no se hace responsable de lo
> que el
>   >> mensaje
>   >>   >>   >>   >>>> contenga. The information contained in this email is
>   >>   >> addressed to its
>   >>   >>   >>   >>>> recipient only and may contain confidential
> information,
>   >>   >> privileged
>   >>   >>   >>   >>>> material or information protected by copyright. Its
>   >>   >> prohibited any
>   >>   >>   >>   >>>> copy, use, improper retention, modification,
> dissemination,
>   >>   >>   >>   >>>> distribution or total or partial reproduction. If you
>   >> receive
>   >>   >> this
>   >>   >>   >>   >>>> message by error, please contact the sender and delete
>   >> it. The
>   >>   >>   >>   >>>> information contained herein is the sole
> responsibility of
>   >>   >> the sender
>   >>   >>   >>   >>>> therefore Universidad EAFIT is not responsible for
> what the
>   >>   >> message
>   >>   >>   >>   >>>> contains.
>   >>   >>   >>   >>>>
>   >>   >>   >>   >>>>
>   >>   >>   >>   >>>> _______________________________________________
>   >>   >>   >>   >>>> LLVM Developers mailing list
>   >>   >>   >>   >>>> llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
>   >>   >>   >>   >>>>
>   >>   >>   >>
>   >>   >>
>   >>
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.llvm.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fllvm-dev&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=7CKfLhJkFKsjWn97SBMgKMz9nxRV1iZp305G9rsVLoA%3D&reserved=0
>   >>   >>   >>   >>>>
>   >>   >>   >>   >>>>
>   >>   >>   >>   >>>> La información contenida en este correo electrónico
> está
>   >> dirigida
>   >>   >>   >>   >>>> únicamente a su destinatario y puede contener
> información
>   >>   >>   >>   >>>> confidencial, material privilegiado o información
>   >> protegida por
>   >>   >>   >>   >>>> derecho de autor. Está prohibida cualquier copia,
>   >> utilización,
>   >>   >>   >>   >>>> indebida retención, modificación, difusión,
> distribución o
>   >>   >>   >>   >>>> reproducción total o parcial. Si usted recibe este
> mensaje
>   >>   >> por error,
>   >>   >>   >>   >>>> por favor contacte al remitente y elimínelo. La
>   >> información aquí
>   >>   >>   >>   >>>> contenida es responsabilidad exclusiva de su remitente
>   >> por lo
>   >>   >> tanto
>   >>   >>   >>   >>>> la Universidad EAFIT no se hace responsable de lo
> que el
>   >> mensaje
>   >>   >>   >>   >>>> contenga. The information contained in this email is
>   >>   >> addressed to its
>   >>   >>   >>   >>>> recipient only and may contain confidential
> information,
>   >>   >> privileged
>   >>   >>   >>   >>>> material or information protected by copyright. Its
>   >>   >> prohibited any
>   >>   >>   >>   >>>> copy, use, improper retention, modification,
> dissemination,
>   >>   >>   >>   >>>> distribution or total or partial reproduction. If you
>   >> receive
>   >>   >> this
>   >>   >>   >>   >>>> message by error, please contact the sender and delete
>   >> it. The
>   >>   >>   >>   >>>> information contained herein is the sole
> responsibility of
>   >>   >> the sender
>   >>   >>   >>   >>>> therefore Universidad EAFIT is not responsible for
> what the
>   >>   >> message
>   >>   >>   >>   >>>> contains.
>   >>   >>   >>   >>> _______________________________________________
>   >>   >>   >>   >>> LLVM Developers mailing list
>   >>   >>   >>   >>> llvm-dev at lists.llvm.org
>   >>   >>   >>   >>>
>   >>   >>   >>
>   >>   >>
>   >>
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.llvm.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fllvm-dev&data=01%7C01%7Chtobonm%40eafit.edu.co%7C3e9ac7a8643c4dbe405e08d7d38dfd75%7C99f7b55e9cbe467b8143919782918afb%7C0&sdata=7CKfLhJkFKsjWn97SBMgKMz9nxRV1iZp305G9rsVLoA%3D&reserved=0
>   >>   >>   >>   >>>
>   >>   >>   >>   >>> La información contenida en este correo electrónico está
>   >> dirigida
>   >>   >>   >>   >>> únicamente a su destinatario y puede contener
> información
>   >>   >>   >>   >>> confidencial, material privilegiado o información
>   >> protegida por
>   >>   >>   >>   >>> derecho de autor. Está prohibida cualquier copia,
>   >> utilización,
>   >>   >>   >>   >>> indebida retención, modificación, difusión,
> distribución o
>   >>   >>   >>   >>> reproducción total o parcial. Si usted recibe este
>   >> mensaje por
>   >>   >> error,
>   >>   >>   >>   >>> por favor contacte al remitente y elimínelo. La
>   >> información aquí
>   >>   >>   >>   >>> contenida es responsabilidad exclusiva de su
> remitente por lo
>   >>   >> tanto la
>   >>   >>   >>   >>> Universidad EAFIT no se hace responsable de lo que
> el mensaje
>   >>   >>   >>   >>> contenga. The information contained in this email is
>   >> addressed
>   >>   >> to its
>   >>   >>   >>   >>> recipient only and may contain confidential information,
>   >>   >> privileged
>   >>   >>   >>   >>> material or information protected by copyright. Its
>   >> prohibited any
>   >>   >>   >>   >>> copy, use, improper retention, modification,
> dissemination,
>   >>   >>   >>   >>> distribution or total or partial reproduction. If you
>   >> receive this
>   >>   >>   >>   >>> message by error, please contact the sender and delete
>   >> it. The
>   >>   >>   >>   >>> information contained herein is the sole responsibility
>   >> of the
>   >>   >> sender
>   >>   >>   >>   >>> therefore Universidad EAFIT is not responsible for
> what the
>   >>   >> message
>   >>   >>   >>   >>> contains.
>   >>   >>   >>   >> La información contenida en este correo electrónico está
>   >> dirigida
>   >>   >>   >> únicamente a su destinatario y puede contener información
>   >> confidencial,
>   >>   >>   >> material privilegiado o información protegida por derecho de
>   >> autor. Está
>   >>   >>   >> prohibida cualquier copia, utilización, indebida retención,
>   >>   >>   >> modificación, difusión, distribución o reproducción total o
>   >> parcial. Si
>   >>   >>   >> usted recibe este mensaje por error, por favor contacte al
>   >> remitente y
>   >>   >>   >> elimínelo. La información aquí contenida es responsabilidad
>   >> exclusiva de
>   >>   >>   >> su remitente por lo tanto la Universidad EAFIT no se hace
>   >> responsable de
>   >>   >>   >> lo que el mensaje contenga. The information contained in this
>   >> email is
>   >>   >>   >> addressed to its recipient only and may contain confidential
>   >>   >>   >> information, privileged material or information protected by
>   >> copyright.
>   >>   >>   >> Its prohibited any copy, use, improper retention,
> modification,
>   >>   >>   >> dissemination, distribution or total or partial reproduction.
>   >> If you
>   >>   >>   >> receive this message by error, please contact the sender and
>   >> delete it.
>   >>   >>   >> The information contained herein is the sole
> responsibility of the
>   >>   >>   >> sender therefore Universidad EAFIT is not responsible for
> what the
>   >>   >>   >> message contains.
>   >>   >>   >>   >
>   >>   >>   >>
>   >>   >>   >>
>   >>   >>   >> La información contenida en este correo electrónico está
> dirigida
>   >>   >> únicamente a su destinatario y puede contener información
> confidencial,
>   >>   >> material privilegiado o información protegida por derecho de
> autor. Está
>   >>   >> prohibida cualquier copia, utilización, indebida retención,
>   >>   >> modificación, difusión, distribución o reproducción total o
> parcial. Si
>   >>   >> usted recibe este mensaje por error, por favor contacte al
> remitente y
>   >>   >> elimínelo. La información aquí contenida es responsabilidad
> exclusiva de
>   >>   >> su remitente por lo tanto la Universidad EAFIT no se hace
> responsable de
>   >>   >> lo que el mensaje contenga. The information contained in this
> email is
>   >>   >> addressed to its recipient only and may contain confidential
>   >>   >> information, privileged material or information protected by
> copyright.
>   >>   >> Its prohibited any copy, use, improper retention, modification,
>   >>   >> dissemination, distribution or total or partial reproduction.
> If you
>   >>   >> receive this message by error, please contact the sender and
> delete it.
>   >>   >> The information contained herein is the sole responsibility of the
>   >>   >> sender therefore Universidad EAFIT is not responsible for what the
>   >>   >> message contains.
>   >>   >>   >
>   >>   >>
>   >>   >>
>   >>   >> La información contenida en este correo electrónico está dirigida
>   >> únicamente a su destinatario y puede contener información confidencial,
>   >> material privilegiado o información protegida por derecho de autor. Está
>   >> prohibida cualquier copia, utilización, indebida retención,
>   >> modificación, difusión, distribución o reproducción total o parcial. Si
>   >> usted recibe este mensaje por error, por favor contacte al remitente y
>   >> elimínelo. La información aquí contenida es responsabilidad exclusiva de
>   >> su remitente por lo tanto la Universidad EAFIT no se hace responsable de
>   >> lo que el mensaje contenga. The information contained in this email is
>   >> addressed to its recipient only and may contain confidential
>   >> information, privileged material or information protected by copyright.
>   >> Its prohibited any copy, use, improper retention, modification,
>   >> dissemination, distribution or total or partial reproduction. If you
>   >> receive this message by error, please contact the sender and delete it.
>   >> The information contained herein is the sole responsibility of the
>   >> sender therefore Universidad EAFIT is not responsible for what the
>   >> message contains.
>   >>   >
>   >>
>   >>
>   >> La información contenida en este correo electrónico está dirigida
> únicamente a su destinatario y puede contener información confidencial,
> material privilegiado o información protegida por derecho de autor. Está
> prohibida cualquier copia, utilización, indebida retención,
> modificación, difusión, distribución o reproducción total o parcial. Si
> usted recibe este mensaje por error, por favor contacte al remitente y
> elimínelo. La información aquí contenida es responsabilidad exclusiva de
> su remitente por lo tanto la Universidad EAFIT no se hace responsable de
> lo que el mensaje contenga. The information contained in this email is
> addressed to its recipient only and may contain confidential
> information, privileged material or information protected by copyright.
> Its prohibited any copy, use, improper retention, modification,
> dissemination, distribution or total or partial reproduction. If you
> receive this message by error, please contact the sender and delete it.
> The information contained herein is the sole responsibility of the
> sender therefore Universidad EAFIT is not responsible for what the
> message contains.
>   >
>
>
> La información contenida en este correo electrónico está dirigida únicamente a su destinatario y puede contener información confidencial, material privilegiado o información protegida por derecho de autor. Está prohibida cualquier copia, utilización, indebida retención, modificación, difusión, distribución o reproducción total o parcial. Si usted recibe este mensaje por error, por favor contacte al remitente y elimínelo. La información aquí contenida es responsabilidad exclusiva de su remitente por lo tanto la Universidad EAFIT no se hace responsable de lo que el mensaje contenga. The information contained in this email is addressed to its recipient only and may contain confidential information, privileged material or information protected by copyright. Its prohibited any copy, use, improper retention, modification, dissemination, distribution or total or partial reproduction. If you receive this message by error, please contact the sender and delete it. The information contained herein is the sole responsibility of the sender therefore Universidad EAFIT is not responsible for what the message contains.


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