[Bug c++/80859] Performance Problems with OpenMP 4.5 support

[thorstenkurth at me dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80859

--- Comment #13 from Thorsten Kurth <thorstenkurth at me dot com> ---
Hello Jakub,

the compiler options are just -fopenmp. I am sure it does not have to do
anything with vectorization as I compare the code runtime with and without the
target directives and thus vectorization should be the same between them. The
remaining OpenMP sections are the same. In our work we have not seen 10x
because of insufficient vectorization, it is usually because of cache locality
but that is the same for OMP 4.5 and OMP 3 because the loops are not touched.
I do not specify an ISA choice, but I will try specifying KNL now and will tell
you what the compiler is going to do.

Best
Thorsten