https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86393
--- Comment #7 from MCCCS <mcccs at gmx dot com> --- The problem was that the LLVM assembler required -mavx512f. I've researched it and found that this LLVM bug was fixed months and shipped with LLVM 7. Apple updates Xcode's LLVM with one year delay, and it should be fixed the next year with 10.15. To sum up: this is llvm 6 bug https://bugs.llvm.org/show_bug.cgi?id=36202 https://llvm.org/viewvc/llvm-project?view=revision&revision=324106
