https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114088
--- Comment #5 from Thiago Macieira <thiago at kde dot org> --- (In reply to Jonathan Wakely from comment #4) > (In reply to Xi Ruoyao from comment #2) > > But __builtin_strlen *does* get optimized when the input is a string > > literal. > > But so does strlen, because GCC knows about it. That's my point. And if POSIX or ISO C had c16slen() and c32slen(), I might use them. But this request would stand that you do implement built-ins for those. They don't. Even if they did, I would not want to call them everywhere unless I knew the compiler had an intrinsic to match and thus replace with a constant value when the string is known to be constant. The code we currently have using `std::char_traits<char16_t>::length()` would have a small regression in performance if the compiler always inserted out-of-line calls. Therefore, what really matters to me is that the compiler have an intrinsic.
