[Openmp-dev] Linking error with gcc on ppc64le

[Carlo Bertolli via Openmp-dev]

Hi all

I am trying to test extensively libomp on ppc platforms. When compiling on
ppc64le (a P8 node) using gcc 4.8.2 both application and runtime library, I
get the following:

testiompppc64.o: In function `main':
testiompppc64.cpp:(.text+0x154): undefined reference to
`GOMP_parallel_start'
testiompppc64.cpp:(.text+0x168): undefined reference to `GOMP_parallel_end'
testiompppc64.o: In function `main._omp_fn.0':
testiompppc64.cpp:(.text+0x334): undefined reference to
`omp_get_thread_num'
testiompppc64.cpp:(.text+0x354): undefined reference to
`omp_get_num_threads'
testiompppc64.cpp:(.text+0x364): undefined reference to
`omp_get_thread_num'

Inspection of libomp.so shows the following when grepping against
omp_get_num_threads symbol:

000000000005bd40 t __kmp_api_omp_get_num_threads
000000000005d8a0 t __kmp_api_omp_get_num_threads_
000000000005d8a0 t __kmp_api_omp_get_num_threads__10_alias
000000000005bd40 t __kmp_api_omp_get_num_threads_10_alias
000000000005d8a0 T omp_get_num_threads_ at OMP_1.0
000000000005bd40 T omp_get_num_threads at OMP_1.0
000000000005d8a0 T omp_get_num_threads_@@VERSION
000000000005bd40 T omp_get_num_threads@@VERSION


This seems to be happening only when using gcc to build the application. If
I use clang to build the application, then everything is fine even when
building the library with either clang or gcc.
In these successful cases, when checking the symbols used I obtain:

1. The executable:

U omp_get_thread_num@@VERSION

2. The library (in this case I used gcc to build it):

000000000005cde0 T omp_get_thread_num_@@VERSION
000000000005b610 T omp_get_thread_num@@VERSION


It may be that my gcc installation is not appropriate for the platform and
what I am trying to do, but is anyone aware of what kind of problem this
could be and point me in the direction of a solution?


Thanks!

-- Carlo
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