Could not internalize function. Some optimizations may not be possible. [OMP140]

This analysis remark indicates that function internalization failed for the given function. Internalization occurs when a call to a function that ordinarily has external visibility is replaced with a call to a copy of that function with only internal visibility. This allows the compiler to make strong static assertions about the context a function is called in. Without internalization this analysis would always be invalidated by the possibility of someone calling the function in a different context outside of the current translation unit. This is necessary for optimizations like OMP111 and OMP120. If a function failed to be internalized it most likely has linkage that cannot be copied. Internalization is currently only enabled by default for OpenMP target offloading.

Examples

This will occur for any function declaration that has incompatible linkage.

__attribute__((weak)) void setup();

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

$ clang++ -fopenmp -fopenmp-targets=nvptx64 -O1 -Rpass-analysis=openmp-opt omp140.cpp
omp140.cpp:1:1: remark: Could not internalize function. Some optimizations may not
be possible. [OMP140]
__attribute__((weak)) void setup() {
^

Diagnostic Scope

OpenMP analysis remark.