Intall Octave with amdblis and amdlibflame with Spack

 spack install octave+hdf5+fftw ^hdf5~mpi ^fftw~mpi ^amdblis threads=openmp ^amdlibflame threads=openmp

To enable threading you need to set OMP_NUN_THREADS=4 (e.g. with 4 cores).