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Subject: [OMPI users] OpenMPI with NAG compiler and gcc 4.6
From: Ning Li (ning.li_at_[hidden])
Date: 2011-06-27 05:24:16


Hello,

I built OpenMPI 1.5.3 using NAG compiler v 5.2 on a new system running
Fedora 15 (with gcc 4.6). OpenMPI can be built successfully, but when I
compile a Fortran MPI application I got an error at link stage:

gcc: error: unrecognized option '--export-dynamic'

Note that NAG Fortran compiler generates intermediate C code and
actually calls gcc to build the application.

GCC 4.6 release note contains the following: "GCC now has stricter
checks for invalid command-line options. In particular, when |gcc| was
called to link object files rather than compile source code, it would
previously accept and ignore all options starting with |--|, including
linker options such as |--as-needed| and |--export-dynamic|, although
such options would result in errors if any source code was compiled.
Such options, if unknown to the compiler, are now rejected in all cases;
if the intent was to pass them to the linker, options such as
|-Wl,--as-needed| should be used."

My next step was to track down where the illegal syntax was generated,
using the '-showme' option provided by the OpenMPI compiler wrapper and
'-dryrun' option provided by NAG compiler.

[lining_at_combe pi]$ /home/lining/software/openmpi/1.5.3/nag/bin/mpif90
--showme pi.f90 -o pi.exe_nag
nagfor pi.f90 -o pi.exe_nag
-I/home/lining/software/openmpi/1.5.3/nag/include -pthread
-I/home/lining/software/openmpi/1.5.3/nag/lib
-L/home/lining/software/openmpi/1.5.3/nag/lib -lmpi_f90 -lmpi_f77 -lmpi
-lnsl -lutil -lm -ldl -Wl,--export-dynamic -lnsl -lutil -lm -ldl

[lining_at_combe pi]$ /home/lining/software/openmpi/1.5.3/nag/bin/mpif90
-dryrun pi.f90 -o tpi.exe_nag
NAG Fortran Compiler Release 5.2(721)
Option warning: Unrecognised option -pthread passed to loader
/home/lining/software/NAG_Fortran/lib/forcomp -checkversion 5.2 721
-I/home/lining/software/openmpi/1.5.3/nag/include
-I/home/lining/software/openmpi/1.5.3/nag/lib -library
/home/lining/software/NAG_Fortran/lib -o /tmp/pi.024444.c pi.f90
/usr/bin/gcc -I/home/lining/software/NAG_Fortran/lib -c -DANSI_C
-DINT64=long long -funsigned-char -march=i686 -Wno-pointer-sign -o pi.o
/tmp/pi.024444.c
/usr/bin/gcc -o pi.exe_nag
/home/lining/software/NAG_Fortran/lib/quickfit.o pi.o -pthread
-L/home/lining/software/openmpi/1.5.3/nag/lib -lmpi_f90 -lmpi_f77 -lmpi
-lnsl -lutil -lm -ldl -lnsl -lutil -lm -ldl
-Wl,-rpath,/home/lining/software/NAG_Fortran/lib
/home/lining/software/NAG_Fortran/lib/libf52.so
/home/lining/software/NAG_Fortran/lib/libf52.a -lm --export-dynamic

So OpenMPI generates the '-Wl,--export-dynamic' flag. When this is
passed to NAG compiler, NAG compiler interprets this as "passing the
'--export-dynamic' flag to the linker (gcc)" (which I believe is the
correct behaviour). But gcc 4.6 expects to see '-Wl,--export-dynamic'.

My temporary solution as supplied by NAG compiler developers is to edit
share/openmpi/*-wrapper-data.txt and put flag
'-Wl,-Wl,,--export-dynamic' there.

Ning

--
Ning Li
Technical Consultant
Numerical Algorithms Group
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