https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108240
--- Comment #7 from Segher Boessenkool <segher at gcc dot gnu.org> --- -m64 requires 64-bit instructions. We will ICE if we try to generate code for -m64 without support for 64-bit insns enabled in the compiler. For example, the stdu insn is required to implement the ABI sanely. If the user said they want a -mcpu= for a CPU that has no 64-bit insns, but also wants to use -m64, we should just say sorry, that won't fly.
