https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66509
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> --- The assembly test in configure failed: configure:24880: checking assembler for filds and fists mnemonics configure:24889: /usr/bin/as -o conftest.o conftest.s >&5 clang -cc1as: fatal error: error in backend: 32-bit absolute addressing is not supported in 64-bit mode configure:24892: $? = 1 configure: failed program was filds mem; fists mem So maybe it is just a matter of changing configure.ac to use a slightly different test on it.