https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119468
--- Comment #4 from Jens Seifert <jens.seifert at de dot ibm.com> --- clang is emitting extended mnemonics. On gcc, I only can enforce this by using inline assembly: unsigned long long parityfast(unsigned long long in) { __asm__("popcntd %0,%1":"+r"(in)); return in & 1; } parityfast(unsigned long long): popcntd 3,3 rldicl 3,3,0,63 blr