[R-pkg-devel] Compiler choice on CRAN (R-windows-oldrel)

[Mark van der Loo]

Thanks Uwe. Very clear.

I'll post the solution I chose, so people can find it later. The problem is
that GCC <= 4.6.3 (at least) does not implement OpenMP reduction statements.

So now I do something like this:

#ifdef _OPENMP
#include <omp.h>
#endif

#ifdef __GNUC__
#if __GNUC__ <= 4 & __GNUC_MINOR__ <= 6
#else
#define HAS_REDUCTION
#endif
#endif

/* more code */

  #ifdef HAS_REDUCTION
  #pragma omp parallel for reduction(min:imin), reduction(max:imax)
  #endif
  for (int i=0; i<nx; i++){
    /*loop content*/
  }


This means that the loop does not get parallelized on systems compiling
with gcc <= 4.6.x

Best,
Mark






Op do 25 aug. 2016 om 14:44 schreef Uwe Ligges <
ligges at statistik.tu-dortmund.de>:

>
>
> On 25.08.2016 13:14, Mark van der Loo wrote:
> > Thank you Peter, good points.
> >
> > Good to know for sure (or a.s.) that compiler specification at CRAN is
> not
> > an option. The 4th option is interesting as well. I may just do that.
> >
> > Thanks again!
> > Mark
>
> For Windows, indeed, you are tight to gcc 4.6.3 for R < 3.3.0 and to gcc
> 4.9.3 for R >= 3.3.0. If your package fails for gcc 4.6.3 we can live
> with it.
>
> Same for the other platform CRAN runs checks for, typically there is one
> compiler (as specified on the CRAN web pages).
>
> Best,
> Uwe Ligges
>
>
>
>
>
> >
> >
> >
> >
> >
> >
> >
> >
> > Op do 25 aug. 2016 om 12:17 schreef peter dalgaard <pdalgd at gmail.com>:
> >
> >> I don't have hard info on ABI compatibility between gcc versions, but
> >> there have been issues in the past, at least with with gfortran.
> >>
> >> Now, many people/schools will have R-3.2.x installed, built with gcc
> >> 4.6.y. We cannot retroactively recompile their installation, nor expect
> >> them to install a new version built with gcc 4.9.z. This raises a
> specific
> >> question and a generic one:
> >>
> >> - specific: Will a package binary of gower built with 4.9 work with R
> >> built with 4.6?
> >> - generic: Is is sufficiently likely that a given package if compiled
> with
> >> a different compiler version that CRAN would consider having a
> mechanism to
> >> specify a particular compiler version?
> >>
> >> I suspect that the answer to the second question is no.
> >>
> >> Whether to condition on R >= 3.3 is a good idea largely depends on two
> >> things
> >>
> >> - the user base (would they upgrade R anyways?)
> >> - are there other packages that depends on gower? (CRAN keeps only the
> >> newest version of a package so requiring a newer R could affect users
> with
> >> less aggressive update policies. This already happened when the pbkrtest
> >> package update rendered the car package unloadable.)
> >>
> >> You do have a 4th option: conditionalize the _code_ on the R version,
> then
> >> remove old-style code when 3.2.x becomes history.
> >>
> >> -pd
> >>
> >> On 25 Aug 2016, at 11:20 , Mark van der Loo <mark.vanderloo at gmail.com>
> >> wrote:
> >>
> >>> Dear listers,
> >>>
> >>>
> >>> Compilation of my gower pkg fails on R-oldrel-windows. I am pretty sure
> >>> that this is because it uses gcc 4.6.3 which has limited support for
> >> OpenMP
> >>> (the errors are the same as I got on the old travis-ci build
> environment,
> >>> see my related question[1]).
> >>>
> >>> Now, according to the Rtools page[2], since R3.2.2 "Both the gcc 4.6.3
> >>> toolchain and a toolchain based on gcc 4.9.3 and mingw-w64 v3 are now
> >>> included." Not sure what that says about CRAN, but I'm hoping/guessing
> it
> >>> uses Rtools the same way as we do.
> >>>
> >>> So I guess I have the following options:
> >>>
> >>> - make my package depend on R>=3.3
> >>> - Alter my code (as kindly suggested by Ott Toomet in [1])
> >>> - Tell CRAN to use the modern compiler.
> >>>
> >>> Obviously, the latter would be easiest. Is this is even possible? For a
> >>> local installation I could set an environment variable[3], but how
> about
> >>> doing this at CRAN?
> >>>
> >>> Thanks,
> >>> Mark
> >>>
> >>>
> >>> [1] https://stat.ethz.ch/pipermail/r-package-devel/2016q3/000983.html
> >>> [2] https://cran.r-project.org/bin/windows/Rtools/
> >>> [3]
> >>>
> >>
> https://cran.r-project.org/doc/manuals/r-release/R-admin.html#Customizing-package-compilation
> >>>
> >>>       [[alternative HTML version deleted]]
> >>>
> >>> ______________________________________________
> >>> R-package-devel at r-project.org mailing list
> >>> https://stat.ethz.ch/mailman/listinfo/r-package-devel
> >>
> >> --
> >> Peter Dalgaard, Professor,
> >> Center for Statistics, Copenhagen Business School
> >> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> >> Phone: (+45)38153501
> >> Office: A 4.23
> >> Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
> >>
> >>
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-package-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-package-devel
> >
>

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