I wonder if a relatively easy starting point would be enabling the declaration of do concurrent construct variables:
do concurrent (integer :: i = 1:n) It’s a minor convenience and less exciting than adding locality specifiers but possibly a good first exercise. Damian On Thu, Feb 23, 2023 at 07:08 Tobias Burnus <tob...@codesourcery.com> wrote: > Hi, > > and welcome to the GCC / gfortran community. > > On 23.02.23 14:15, varma datla via Fortran wrote: > > I am willing to contribute to the project idea "Fortran – DO CONCURRENT". > > I hope the following helps a bit – it is admittedly a bit chaotic, but I > try to write something cleaner later. > > But to have something to think of and to startwith, it should be > sufficient: > > I think there are two parts to it: First, to add the changes of newer > Fortran to gfortran and then to actually use them to generate > concurrently running code. (Internally, gfortran currently handles 'do > concurrent' to run mostly like a normal loop – except that it annotates > the loops are independent. – Real parallelization would be useful, > however.) > > If you want to see examples, see do_concurrent_1.f90 to > do_concurrent_6.f90 in gfortran's testsuite, i.e. > gcc/testsuite/gfortran.dg/ in the GCC sources. That's at > > https://gcc.gnu.org/git/?p=gcc.git;a=tree;f=gcc/testsuite/gfortran.dg;hb=refs/heads/master > / But it is best to download GCC yourself via Git as described at > https://gcc.gnu.org/git.html > > I want to note that the DO CONCURRENT syntax also permits a mask > argument, like in 'do concurrent (i=1:5, j=1:5, (i/=j))' where the last > argument selects a subset. > > For the Fortran standard, see https://gcc.gnu.org/wiki/GFortranStandards > > Fortran 2018 (= 18-007r1) adds for locality specifiers: LOCAL, > LOCAL_INIT, SHARED and DEFAULT(NONE). > > Fortran 202x alias 2023 adds 'reduce' as in 'do concurrent (i = 1, n) > reduce(+:a, b, c) reduce(max:d, e, f)' > > I think the first step is to add parsing support for those new features, > i.e. store them, check for issues (diagnostic) and then fail with a > 'sorry not yet implemented'. > > The next step would be to implement LOCAL/LOCAL_INIT for running on the > host. > > And then, finally, would be to translate into code which can then be run > concurrently. I was thinking of mapping it internally to OpenMP or > OpenACC, to be toggled via a commandline option like > -fdo-concurrent=<openmp,openmp-target,openacc,...>. > > * * * > > I think the first step would be to download GCC and build it. Something > like "git clone" as described above, then "mkdir build" (some > directory); "cd build" and then "../configure --prefix=where-to-install" > followed by "make -j12" and "make install". The "-j12" runs 12 build > jobs in parallel. How much to use depends on your system. > > You probably need to install some development versions of libraries such > as ISL, gmp, mpfr and mpc. If you don't have them readily, an option is > to run ./contrib/download_prerequisites to download those and build them > automatically alongside GCC. > > So far for now. If you have questions, please ask. — And I will try to > write something more structured later. > > Tobias > > -- > Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, > 80634 Münch > <https://www.google.com/maps/search/:+Arnulfstra%C3%9Fe+201,+80634+M%C3%BCnch?entry=gmail&source=g>en; > Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, > Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB > 106955 > > ----------------- > Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, > 80634 Münch > <https://www.google.com/maps/search/:+Arnulfstra%C3%9Fe+201,+80634+M%C3%BCnch?entry=gmail&source=g>en; > Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, > Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB > 106955 >
