2 ms·

Odd that GCC is emitting an xor eax, eax before popcount (in both the intrinsic and pattern cases!): popcnt(unsigned int): xor eax, eax

Odd that GCC is emitting an xor eax, eax before popcount (in both the intrinsic and pattern cases!): popcnt(unsigned int): xor eax, eax popcnt eax, edi ret

wahern 6y ago
It's a workaround for a bug in Intel CPUs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62011 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62011
- mmastrac 6y ago
  Interesting, thanks for the pointer.