llvm-project/openmp/docs/remarks/OMP130.rst

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.. _omp130:
Removing unused state machine from generic-mode kernel. [OMP130]
================================================================
This optimization remark indicates that an unused state machine was removed from
a target region. This occurs when there are no parallel regions inside of a
target construct. Normally, a state machine is required to schedule the threads
inside of a parallel region. If there are no parallel regions, the state machine
is unnecessary because there is only a single thread active at any time.
Examples
--------
This optimization should occur on any target region that does not contain any
parallel work.
.. code-block:: c++
void copy(int N, double *X, double *Y) {
#pragma omp target teams distribute map(tofrom: X[0:N]) map(tofrom: Y[0:N])
for (int i = 0; i < N; ++i)
Y[i] = X[i];
}
.. code-block:: console
$ clang++ -fopenmp -fopenmp-targets=nvptx64 -O2 -Rpass=openmp-opt omp130.cpp
omp130.cpp:2:1: remark: Removing unused state machine from generic-mode kernel. [OMP130]
#pragma omp target teams distribute map(tofrom: X[0:N]) map(tofrom: Y[0:N])
^
Diagnostic Scope
----------------
OpenMP target offloading optimization remark.