https://bugzilla.redhat.com/show_bug.cgi?id=2121490
--- Comment #18 from Fabio Valentini decathorpe@gmail.com --- This means that either the code is invalid and gets simplified down to an "ud2" x86 instruction by LLVM (i.e. "this is invalid"), or you're running code that requires a newer instruction set (like AVX2 or AVX512) on an older CPU that doesn't support it.