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.

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];
}

$ 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.