configured with --prefix=/usr/local/gcc6.0 --enable-languages='c c++ fortran' --enable-libgomp --enable-threads=posix --with-dwarf2 --without-libiconv-prefix --without-libintl-prefix --with-system-zlib --disable-werror --without-cloog --without-isl resulting in ../../../libgcc/libgcc2.c: In function ‘__powitf2’: ../../../libgcc/libgcc2.c:1851:1: internal compiler error: in i386_pe_seh_unwind_emit, at config/i386/winnt.c:1137 } ^ ../../../libgcc/libgcc2.c:1851:1: internal compiler error: Bus error mmap: No such device The reference in winnt.c shows: case REG_CFA_EXPRESSION: /* Only emitted with DRAP, which we disable. */ gcc_unreachable (); So it seems there is some unsupported combination here now that more in-line expansion of powers has been added. Does it require a different setting for exception handling? I didn't think seh or tf mode were supported.