Analysis of OpenMP 4.5 Offloading in Implementations: Correctness and Overhead.

•Identify the extent of OpenMP 4.5 offload support in implementations from GCC, Clang, and XL.•Identifying and reporting inconsistencies or bugs in specific compiler implementations.•Evaluate the available OpenMP 4.5 compiler implementations on ORNL Summit and other systems.•Defining a testing methodology to evaluate overhead of directives across different OpenMP 4.5 implementations.•Demonstrate how the OpenMP compilers use CUDA driver and CUDA runtime APIs via execution traces.•Evaluate changes in runtime overhead while using combined constructs vs. nested constructs.•Evaluate effect of changing the number of teams/threads on the overhead.