https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98709
Bug ID: 98709 Summary: gcc optimizes bitwise operations, but doesn't optimize logical ones Product: gcc Version: 10.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: vanyacpp at gmail dot com Target Milestone: --- GCC 10.2 produces very good code for this function noticing that both sides of conjuntion are the same: unsigned foo_bitwise(unsigned a, unsigned b) { return (~a ^ b) & ~(a ^ b); } foo_bitwise(unsigned int, unsigned int): xor edi, esi mov eax, edi not eax ret But when I write a similar function with logical operations it doesn't notice that: bool foo_logical(bool a, bool b) { return (!a ^ b) & !(a ^ b); } foo_logical(bool, bool): mov eax, esi xor eax, edi xor eax, 1 cmp dil, sil sete dl and eax, edx ret I believe that in a similar manner it can be optimized to something like this: foo_logical(bool, bool): xor edi, esi mov eax, edi xor eax, 1 ret