This issue is long standing and with the recent ports tree and POCL 1.4 and LLVM 8.0/LLVM 9.0 it can be reduced to the parallel installation of lang/beignet (beignet-1.3.2_8 as for now). With lang/pocl installed, any OpenCL using application fails with the error:
: CommandLine Error: Option 'limited-coverage-experimental' registered more than once! LLVM ERROR: inconsistency in registered CommandLine options
The problem can be simply reproduced by installing port devel/clinfo and/or benchmarks/clpeak, issuing "clinfo" for instance on the command line, when lang/pocl and lang/beignet are installed parallel.
This issue has been reported since POCL 0.14 (i.e. Bug 219562).
In all cases I've tested, devel/ocl-icd is also installed and used.
This issue has been reported upstream in 2017, see
and has been also dicussed here with the LLVM backend:
Possible workaround: https://salsa.debian.org/opencl-team/beignet/blob/master/debian/patches/static-llvm.patch
lang/beignet expired today, please use lang/intel-compute-runtime instead.