Fortran-related libgomp failures in case of -fno-openmp

Fortran-related libgomp failures in case of -fno-openmp

[Gerald Pfeifer]

On i386-unknown-freebsd7.1 we see the following tests fail:

  FAIL: libgomp.fortran/condinc2.f  -O  (test for excess errors)
  WARNING: libgomp.fortran/condinc2.f  -O  compilation failed to produce executable
  FAIL: libgomp.fortran/condinc4.f90  -O  (test for excess errors)
  WARNING: libgomp.fortran/condinc4.f90  -O  compilation failed to produce executable
  FAIL: libgomp.fortran/omp_cond2.f  -O  (test for excess errors)
  WARNING: libgomp.fortran/omp_cond2.f  -O  compilation failed to produce executable
  FAIL: libgomp.fortran/omp_cond4.F90  -O  (test for excess errors)
  WARNING: libgomp.fortran/omp_cond4.F90  -O  compilation failed to produce executable

Looking into the log files, the pattern is the same in all cases:

  Excess errors:
  /pfeifer/OBJ-0531-2252/i386-unknown-freebsd7.1/./libgomp/.libs/libgomp.so:
  undefined reference to `pthread_create'

And what all of these three testcases have in common is

  { dg-options "-fno-openmp" }

So, it seems -fno-openmp in combination with an attempt to still link
libgomp.so leads to this failure.


Is it possible this is an issue with the testsuite rather than with
the code on FreeBSD?

Gerald

Re: Fortran-related libgomp failures in case of -fno-openmp

[Steve Kargl]

On Mon, Jun 01, 2009 at 07:59:15PM +0200, Gerald Pfeifer wrote:
>   Excess errors:
>   /pfeifer/OBJ-0531-2252/i386-unknown-freebsd7.1/./libgomp/.libs/libgomp.so:
>   undefined reference to `pthread_create'
> 
> And what all of these three testcases have in common is
> 
>   { dg-options "-fno-openmp" }
> 
> So, it seems -fno-openmp in combination with an attempt to still link
> libgomp.so leads to this failure.
> 
> 
> Is it possible this is an issue with the testsuite rather than with
> the code on FreeBSD?
> 

The code is fine.  The problem is with the testsuite.  When
-fopenmp is used on FreeBSD, the additional option -pthread
is added to the list of options.

REMOVE:kargl[28] gfortran -v -fopenmp -c d.f90
Using built-in specs.
Target: i386-portbld-freebsd8.0
Configured with: ./..//gcc-4.3-20081120/configure --disable-nls --with-system-zlib --with-libiconv-prefix=/usr/local --with-gmp=/usr/local --program-suffix=43 --libdir=/usr/local/lib/gcc-4.3.3 --with-gxx-include-dir=/usr/local/lib/gcc-4.3.3/include/c++/ --disable-rpath --prefix=/usr/local --mandir=/usr/local/man --infodir=/usr/local/info/gcc43 --build=i386-portbld-freebsd8.0
Thread model: posix
gcc version 4.3.3 20081120 (prerelease) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-fopenmp' '-c' '-mtune=i386' '-pthread'

If someone uses -fno-openmp and still tries to link to libgomp,
then the -pthread option is missing and hence the test fail
because -lpthread is not included.  On FreeBSD, libgomp.so.1
does not show a dependency on libpthread, so the dynamic linker
can't automagically work.

REMOVE:kargl[30] ldd /usr/home/kargl/work/lib/libgomp.so.1
/usr/home/kargl/work/lib/libgomp.so.1:
        libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x481a8000)
        libc.so.7 => /lib/libc.so.7 (0x4808c000)

-- 
Steve

Re: Fortran-related libgomp failures in case of -fno-openmp

[Janis Johnson]

On Mon, 2009-06-01 at 11:14 -0700, Steve Kargl wrote:
> On Mon, Jun 01, 2009 at 07:59:15PM +0200, Gerald Pfeifer wrote:
> >   Excess errors:
> >   /pfeifer/OBJ-0531-2252/i386-unknown-freebsd7.1/./libgomp/.libs/libgomp.so:
> >   undefined reference to `pthread_create'
> > 
> > And what all of these three testcases have in common is
> > 
> >   { dg-options "-fno-openmp" }
> > 
> > So, it seems -fno-openmp in combination with an attempt to still link
> > libgomp.so leads to this failure.
> > 
> > 
> > Is it possible this is an issue with the testsuite rather than with
> > the code on FreeBSD?
> > 
> 
> The code is fine.  The problem is with the testsuite.  When
> -fopenmp is used on FreeBSD, the additional option -pthread
> is added to the list of options.
> 
> REMOVE:kargl[28] gfortran -v -fopenmp -c d.f90
> Using built-in specs.
> Target: i386-portbld-freebsd8.0
> Configured with: ./..//gcc-4.3-20081120/configure --disable-nls --with-system-zlib --with-libiconv-prefix=/usr/local --with-gmp=/usr/local --program-suffix=43 --libdir=/usr/local/lib/gcc-4.3.3 --with-gxx-include-dir=/usr/local/lib/gcc-4.3.3/include/c++/ --disable-rpath --prefix=/usr/local --mandir=/usr/local/man --infodir=/usr/local/info/gcc43 --build=i386-portbld-freebsd8.0
> Thread model: posix
> gcc version 4.3.3 20081120 (prerelease) (GCC) 
> COLLECT_GCC_OPTIONS='-v' '-fopenmp' '-c' '-mtune=i386' '-pthread'
> 
> If someone uses -fno-openmp and still tries to link to libgomp,
> then the -pthread option is missing and hence the test fail
> because -lpthread is not included.  On FreeBSD, libgomp.so.1
> does not show a dependency on libpthread, so the dynamic linker
> can't automagically work.

Why doesn't libgomp.so.1 show a depedency on libpthread, isn't
that the bug?

> REMOVE:kargl[30] ldd /usr/home/kargl/work/lib/libgomp.so.1
> /usr/home/kargl/work/lib/libgomp.so.1:
>         libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x481a8000)

Janis

Re: Fortran-related libgomp failures in case of -fno-openmp

[Steve Kargl]

On Mon, Jun 01, 2009 at 12:49:42PM -0700, Janis Johnson wrote:
> On Mon, 2009-06-01 at 11:14 -0700, Steve Kargl wrote:
> > 
> > If someone uses -fno-openmp and still tries to link to libgomp,
> > then the -pthread option is missing and hence the test fail
> > because -lpthread is not included.  On FreeBSD, libgomp.so.1
> > does not show a dependency on libpthread, so the dynamic linker
> > can't automagically work.
> 
> Why doesn't libgomp.so.1 show a depedency on libpthread, isn't
> that the bug?
> 

I've never looked at how the authors of libgomp wrote the
build glue nor have I tried to decipher why one would specifically
suppress OpenMP with the -fno-openmp option yet still try to
link to its runtime library.  It does appear that libgomp/configure
looks to see if -pthread (or -lpthread) is required, but then it
may not use that result in actually building libgomp.so.1

-- 
Steve