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Call may contain unknown parallel regions. Use `__attribute__((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
`__attribute__((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++
__attribute__((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.
|
