GHC-8.10.3 segfaults with FFI code.
apt-get install libtestu01-0-dev git clone https://github.com/haskellari/splitmix.git cd splitmix cabal run splitmix-testu01
GHC-8.10.2 and other GHCs before (since GHC-7.0.4) work (at least on x86_64 Linux).
See tests step in https://github.com/haskellari/splitmix/pull/52/checks?check_run_id=1634618901 (the link might die in the future though).
The splitmix-testu01 has both FFI exports and imports. It imports C-functions which uses exports. I have no idea whether that is supposed to work, but it did before.