Re: Fortran libraries on the Blue Gene with mpi

[John R. Cary]

Ralf Wildenhues wrote:
> Hello John,
>
> * John R. Cary wrote on Mon, Apr 13, 2009 at 10:19:49PM CEST:
>   
> > I am trying to link some Fortran code on the Blue Gene (P) using
> > the xl compilers.
> >     
>
> Probably Libtool needs to be ported fully to this system first, or,
> just the name matching be adjusted (libtool matches compilers by their
> names).  Can you point us to documentation of the compiler and linker
> suite of this system?  Would you be willing to go through the porting
> effort with us (you'll have to answer a few questions and try out some
> things on this system while we work on a patch).
Sure, I would be happy to do this.



First, the compilers are those at



http://www.alcf.anl.gov/support/usingALCF/bgl/appdocs.php



But I think it is the linking that gets to be a pain.  This is a 
cross-compile

situation, in which one compiles on 64-bit login nodes but runs on 32-bit

compute nodes.  The former can have shared objects, but the latter cannot.

The parallel compilers, e.g., mpixlf95_r, are wrappers over the

cross compilers, such as



login3.intrepid$ \ls /opt/ibmcmp/xlf/bg/11.1/bin/bg*

/opt/ibmcmp/xlf/bg/11.1/bin/bgf2003    
/opt/ibmcmp/xlf/bg/11.1/bin/bgxlf2003_r

/opt/ibmcmp/xlf/bg/11.1/bin/bgf77      /opt/ibmcmp/xlf/bg/11.1/bin/bgxlf90

/opt/ibmcmp/xlf/bg/11.1/bin/bgf90      /opt/ibmcmp/xlf/bg/11.1/bin/bgxlf90_r

/opt/ibmcmp/xlf/bg/11.1/bin/bgf95      /opt/ibmcmp/xlf/bg/11.1/bin/bgxlf95

/opt/ibmcmp/xlf/bg/11.1/bin/bgfort77   /opt/ibmcmp/xlf/bg/11.1/bin/bgxlf95_r

/opt/ibmcmp/xlf/bg/11.1/bin/bgxlf      /opt/ibmcmp/xlf/bg/11.1/bin/bgxlf_r

/opt/ibmcmp/xlf/bg/11.1/bin/bgxlf2003



which are probably also wrappers that ensure that one generates

32-bit code and does not link   So in the end, I think these are all just

regular xl compilers.



My solution, btw, is simply to pull any '-R' args out after libtool:



AC_PROG_LIBTOOL

echo Cleaniing up FCLIBS for xlf

case $SERIALFC in

*mpixlf* | *bgxlf*)

  OLDFCLIBS=$FCLIBS

  unset FCLIBS

  for i in $OLDFCLIBS; do

    case $i in

      -R*) ;;

      *) FCLIBS="$FCLIBS $i";;

    esac

  done

  ;;

esac



John Cary