Using OpenMP 4.0 target directives with user libraries

[Grund__Aalexander]

I tried to get an OpenMP 4.0 test case to run where the code calls a user library that is compiled for host and mic (-mmic)
The host library is in current directory (pwd), the MIC lib is in pwd/mic and I set LD_LIBRARY_PATH to pwd and MIC_LD_LIBRARY_PATH to pwd/mic
However the execution fails with "On the sink, dlopen() returned NULL. The result of dlerror() is "/tmp/coi_procs/1/31669/load_lib/iccoutysEa1j: undefined symbol: foo"

The code looks like this:

#include <omp.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include "foo.h"

#pragma omp declare target
int foo();
#pragma omp end declare target

int main()
{
  /* start user code */
#pragma omp target
    {
      foo();
    }
  return 0;
}

Command line is:
icc -shared -fPIC -o libhostlib.so hostlib.c
icc -mmic -shared -fPIC -o mic/libhostlib.so hostlib.c
icc -openmp -o test_mic.o -c test_mic.c
icc -openmp -L. -lhostlib -o test_mic test_mic.o

How can I get something like this to work or is it just impossible to use custom libraries on the target with the offload model?

[Kevin_D_Intel · Accepted solution]

I revised my earlier reply to match all the names you used.

Try building and running like this:

icc -openmp -fpic -shared -o libhostlib.so hostlib.c
icc -openmp -fpic -mmic -shared -o mic/libhostlib.so hostlib.c
icc -openmp -L. -lhostlib -otest_mic test_mic.c -offload-option,mic,ld,"-L./mic -lhostlib"

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:.
export MIC_LD_LIBRARY_PATH=$MIC_LD_LIBRARY_PATH:./mic
./test_mic

[Grund__Aalexander]

This does indeed work.

Thanks for that!

[Kevin_D_Intel]

Great!  Thank you for useful question/post. I expect it will help others in the future.