aggressive-loop-optimization warnings

We get those pesky warnings, that seem like they are potentially harmful, but I have no idea where they come from:

/home/dkempf/build-avx512/dune-perftool-paperplots/skylake-poisson/skylake_poisson_h4_v2_deg2_opcount_rOperator_file.hh: In constructor ‘rOperator<GFSU, GFSV, RF>::rOperator(const GFSU&, const GFSV&, const Dune::ParameterTree&) [with GFSU = Dune::PDELab::GridFunctionSpace<Dune::GridView<Dune::DefaultLeafGridViewTraits<const Dune::YaspGrid<3, Dune::EquidistantCoordinates<oc::OpCounter<double>, 3> > > >, Dune::PDELab::QkDGLocalFiniteElementMap<oc::OpCounter<double>, oc::OpCounter<double>, 2, 3>, Dune::PDELab::NoConstraints, Dune::PDELab::ISTL::VectorBackend<(Dune::PDELab::ISTL::Blocking)2, 27> >; GFSV = Dune::PDELab::GridFunctionSpace<Dune::GridView<Dune::DefaultLeafGridViewTraits<const Dune::YaspGrid<3, Dune::EquidistantCoordinates<oc::OpCounter<double>, 3> > > >, Dune::PDELab::QkDGLocalFiniteElementMap<oc::OpCounter<double>, oc::OpCounter<double>, 2, 3>, Dune::PDELab::NoConstraints, Dune::PDELab::ISTL::VectorBackend<(Dune::PDELab::ISTL::Blocking)2, 27> >; RF = oc::OpCounter<double>]’:
/home/dkempf/build-avx512/dune-perftool-paperplots/skylake-poisson/skylake_poisson_h4_v2_deg2_opcount_rOperator_file.hh:82:9: warning: iteration 3 invokes undefined behavior [-Waggressive-loop-optimizations]
         quad_points_dim2_num4_3_dir0[quadiname_dim2_num4_3_localdim0 + 4 * quadiname_dim2_num4_3_localdim1] = qp_num3[quadiname_dim2_num4_3_localdim0];