One LAPACK nonsymmetric eigensolver test fails when using Eigen BLAS with FMA enabled.

When running the LAPACK test suite through the Eigen wrappers in eigen/lapack, a small subset of tests for the non-symmetric eigenvalue problem fail due to the eigenvalues computed with and without eigenvectors differ.

The error occurs with FMA enabled, but not without. I have narrowed it down to the GEBP kernel. The tests pass if I unset EIGEN_HAS_SINGLE_INSTRUCTION_MADD at the top of: https://gitlab.com/libeigen/eigen/-/blob/master/Eigen/src/Core/products/GeneralBlockPanelKernel.h

I will continue digging.