Hi Martin,
We actually are planning a large project (350) hours, as Ethan plans to
work essentially full time over the summer. Sorry for the confusion. I
had the terminology a bit confused, and thought "large" was closer to a
6-month commitment.
We will be submitting the proposal shortly.
Take care,
-Tuck
On Mon, Mar 24, 2025 at 10:02 PM Tucker Taft <tucker.t...@gmail.com> wrote:
> Thanks, Martin. We expect it to be a medium size project. And we will be
> sure that Ethan can build, test, and debug the GNAT-FE and other GCC
> components.
>
> Take care,
> -Tuck
>
> On Mon, Mar 24, 2025 at 7:23 PM Martin Jambor <mjam...@suse.cz> wrote:
>
>> Hello,
>>
>> in general the project proposal looks very good. A few comments inline:
>>
>> On Tue, Mar 18 2025, Tucker Taft via Gcc wrote:
>> >
>> [...]
>> > The GNAT front end is organized into three basic phases, a parser, a
>> > semantic analyzer, and an expander. In the sources, these are
>> represented
>> > by source files par-ch*.adb, sem_ch*.{ads,adb}, and exp_ch*.{ads,adb},
>> > where "ch*" is short-hand for the various chapters of the Ada reference
>> > manual. For this project the intent is to augment primarily the
>> "chapter
>> > 5" components, given that loop and parallel-do statements are defined in
>> > chapter 5 of the Ada reference manual. For example, the function
>> > Par.Ch5.P_Loop_Statement is where most of the parsing of the loop
>> statement
>> > takes place, while Par.Ch5.P_Parallel_Do_Statement would be a new local
>> > function of Par.Ch5. Similarly, Sem_Ch5.Analyze_Loop_Statement would be
>> > augmented, while Sem_Ch5.Analyze_Parallel_Do_Statement would be new.
>> And
>> > finally, Exp_Ch5.Expand_Loop_Statement would be augmented, while
>> > Exp_Ch5.Expand_Parallel_Do_Statement would be new.
>> >
>> > The project would begin with the parser, simply recognizing the new
>> syntax,
>> > and producing debug output to report on whether the parse was
>> successful.
>> > The next phase would be to construct the appropriate tree
>> representations,
>> > which would mean updating the gen_il* set of files to include new fields
>> > and node types to support the parallel for-loop and parallel do
>> statement.
>> > As part of doing this, pseudo-code would be developed for the semantic
>> and
>> > expansion phases, to ensure that the new tree components created meet
>> the
>> > needs of these later phases. Finally the semantic and expansion phases
>> > would be implemented in Ada, using the new tree components available.
>> >
>> >
>> > For the expansion phase, the job is primarily to transform the syntax
>> into
>> > the appropriate calls on out-of-line runtime components providing
>> > light-weight-thread management. These routines have already been
>> developed
>> > and debugged, and are available on the GitHub site for the ParaSail
>> > parallel programming language (
>> > https://github.com/parasail-lang/parasail/tree/main/lwt).
>> >
>> > As far as effort involved, the parsing functions in the GNAT Front End
>> tend
>> > to be quite short, often less than a page of code, making heavy use of
>> > shared parsing components. The semantic phase tends to be significantly
>> > more complex, but for this effort relatively little additional code
>> will be
>> > required, because the additional static semantics for these new features
>> > are pretty simple. The major effort will be in the expansion phase,
>> > primarily because the out-of-line light-weight-threading library expects
>> > the loop body to be represented as a procedure. In fact the GNAT-FE
>> > frequently creates simple out-of-line routines as part of implementing
>> > certain existing Ada features, so there should be plenty of models to
>> work
>> > from to turn the loop body into an out-of-line routine. Similarly,
>> > generating calls to run-time routines is also quite common as part of
>> > various GNAT-FE expansion routines, so we can use those as models as
>> well.
>> >
>> >
>> > One feature of the light-weight-threading library we will be interfacing
>> > with is that it sits on top of the existing Ada runtime, as well as the
>> GCC
>> > implementation of OpenMP, without any need to alter these underlying
>> > components.
>> >
>> > Overall we would estimate a couple of weeks for the parsing and initial
>> > semantic analysis for these two features, with the bulk of the summer
>> spent
>> > on the expansion phase, finalizing the semantic analysis, and if there
>> is
>> > time, working on error recovery.
>>
>> Do you envision this as a medium-sized (approx. 175 hours) or large (350
>> hours) project?
>>
>> >
>> > As far as mentors, Tucker Taft had agreed to be a mentor. Tucker was
>> the
>> > lead designer of Ada 2022, and has implemented the
>> light-weight-threading
>> > library that we will be interfacing with. Richard Wai has also agreed
>> to
>> > be a mentor. Richard is an active member of the ISO-WG9 committee on
>> Ada
>> > and its Ada Rapporteur Group (ARG), and has also made contributions to
>> GCC
>> > components, in particular the GNAT front end, in the past.
>> >
>> > The contributor will be Ethan Luis McDonough. Ethan is currently
>> finishing
>> > his last semester in the Penn State University online Software
>> Engineering
>> > program, and is also finishing up an internship at the Lawrence
>> Livermore
>> > Laboratory focused on open source LLVM development. Ethan spent his
>> time
>> > at the lab working on LLVM’s Fortran frontend as well as GPU
>> > instrumentation tools. Most recently Ethan has been implementing a code
>> > generator for a hardware description language built on top of the
>> ParaSail
>> > Programming Language, using an API he implemented in Ada providing
>> access
>> > to the tree representation used by the ParaSail front end (which is
>> written
>> > in Ada). He looks forward to making a contribution to the open-source
>> GNAT
>> > FE component of the GCC compiler collection.
>>
>> That definitely looks like solid experience that proves that Ethan has
>> what it takes to work on the project. Still, the general rules apply,
>> please look at the "Before you apply" section of our GSoC page at
>> https://gcc.gnu.org/wiki/SummerOfCode#Before_you_apply and make sure you
>> are able to build, install, test and debug GCC. I am not familiar with
>> Ada FE myself but in this instance finding the correct dumps but also to
>> get a gdb session going and inspect the compiler internals from within.
>>
>> Good luck!
>>
>> Martin
>>
>
