an_extern_func      6 apps/c_backend/pipeline_generator.cpp HalideExtern_2(int, an_extern_func, int, int);
an_extern_func     17 apps/c_backend/pipeline_generator.cpp         g(x, y) = cast<uint16_t>(f(y, x) + f(x, y) + an_extern_func(x, y) + h());