Rewriting generic-mode kernel with a customized state machine. [OMP131]

.. _omp131:

This optimization remark indicates that a generic-mode kernel on the device was specialized for the given target region. When offloading in generic-mode, a state machine is required to schedule the work between the parallel worker threads. This optimization specializes the state machine in cases where there is a known number of parallel regions inside the kernel. A much simpler state machine can be used if it is known that there is no nested parallelism and the number of regions to schedule is a static amount.

Examples

This optimization should occur on any generic-mode kernel that has visibility on all parallel regions, but cannot be moved to SPMD-mode and has no nested parallelism.

.. code-block:: c++

#pragma omp declare target int TID; #pragma omp end declare target

void foo() { #pragma omp target { TID = omp_get_thread_num(); #pragma omp parallel { work(); } } }

.. code-block:: console

$ clang++ -fopenmp -fopenmp-targets=nvptx64 -O2 -Rpass=openmp-opt omp131.cpp omp131.cpp:8:1: remark: Rewriting generic-mode kernel with a customized state machine. [OMP131] #pragma omp target ^

Diagnostic Scope

OpenMP target offloading optimization remark.