OpenACC parallel directives fail to run, libgomp error

[stuberl@laposte.net]

I manage to compile simple openACC programs with gcc on POWER8 + Nvidia K40.
But when launching the executable, I get this error:

    libgomp: Cannot map target functions or variables (expected 0, have 1)

More specifically, this error is triggered everytime the directives
    #pragma acc parallel
    #pragma acc kernels
are met at runtime.

for example this code won't work:

    #pragma acc parallel loop
    for(int i=0;i<10;i++) a[i]=0;

However I succesfully managed to use other acc functions: acc_get_num_devices, 
acc_malloc, #pragma acc enter data, #pragma acc update. They have the correct
behaviour (update for example will correctly update data on GPU).

Strangely, #pragma acc enter data crashes when there is a parallel directive in
the same code, but works otherwise. (See test.cpp for details)

My command line to compile is
gcc -fopenacc -foffload=nvptx-none main.c /lib/gcc/powerpc64le-unknown-linux-gnu/6.0.0/crtoffloadbegin.o /lib/gcc/powerpc64le-unknown-linux-gnu/6.0.0/crtoffloadend.o

The libgomp.so.1 used by the executable is the right one. I can see it with ldd.
(it is in [gcc 6 install dir]/lib64)

I installed gcc using the April 23th release candidate.
nvptx with configure --target=nvptx-none
configure --target=nvptx-none --enable-as-accelerator-for="powerpc64le-unknown-linux-gnu"
configure --enable-offload-targets=nvptx-none=$GCC6ROOT/install\

Any clue what can be wrong ?
Thanks !

Louis
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