Call may contain unknown parallel regions. Use [[omp::assume("omp_no_parallelism")]] to override. [OMP133]

.. _omp133:

This analysis remark identifies calls that prevented :ref:OMP131 <omp131> from providing the generic-mode kernel with a fully specialized state machine. This remark will identify each call that may contain unknown parallel regions that caused the kernel to require a fallback.

Examples

This will occur for any generic-mode kernel that may contain unknown parallel regions. This is typically coupled with the :ref:OMP132 <omp132> remark.

.. code-block:: c++

extern void setup();

void foo() { #pragma omp target { setup(); #pragma omp parallel { work(); } } }

.. code-block:: console

$ clang++ -fopenmp -fopenmp-targets=nvptx64 -O2 -Rpass-analysis=openmp-opt omp133.cpp omp133.cpp:6:5: remark: Call may contain unknown parallel regions. Use [[omp::assume("omp_no_parallelism")]] to override. [OMP133] setup(); ^

The remark suggests marking the function with the assumption that it contains no parallel regions. If this is done then the kernel will be rewritten with a fully specialized state machine.

.. code-block:: c++

[[omp::assume("omp_no_parallelism")]] extern void setup();

void foo() { #pragma omp target { setup(); #pragma omp parallel { work(); } } }

.. code-block:: console

$ clang++ -fopenmp -fopenmp-targets=nvptx64 -O2 -Rpass=openmp-opt omp133.cpp omp133.cpp:4:1: remark: Rewriting generic-mode kernel with a customized state machine. [OMP131] #pragma omp target ^

Diagnostic Scope

OpenMP target offloading analysis remark.