https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80859
--- Comment #19 from Thorsten Kurth <thorstenkurth at me dot com> --- Thanks you very much. I am sorry that I do not have a simpler test case. The kernel which is executed is in the same directory as ABecLaplacian and called MG_3D_cpp.cpp. We have seen similar problems with the fortran kernels (they are scattered across multiple files) but the fortran kernels and our C++ ports give the same performance with the original OpenMP parallelization. In any case, I wonder why the compiler honors the target region even if -march=knl is specified. However, please let me know if you have further questions. I can guide you through that code. The code is big but the relevant files are technically 2 or 3 and the relevant lines of code also not very many.
