search for: uaddo_portable

.../ the best possible machine instruction. Here are docs about these builtins: https://clang.llvm.org/docs/LanguageExtensions.html#checked-arithmetic-builtins . With unsigned types this is easy: int uaddo_native(unsigned a, unsigned b, unsigned* s) { return __builtin_add_overflow(a, b, s); } int uaddo_portable(unsigned a, unsigned b, unsigned* s) { *s = a + b; return *s < a; } We get exactly the same assembly: uaddo_native: # @uaddo_native xor eax, eax add edi, esi setb al mov dword ptr [rdx], edi ret uaddo_portable: # @uaddo_portable xor eax, eax add edi, esi setb al mov dword ptr [rdx], edi ret Bu...