> This is a fun benchmark in C++, where you can see that GCC has a more restrictive small string optimization Wouldn't this be on the choice of stl (libstdc++

> This is a fun benchmark in C++, where you can see that GCC has a more restrictive small string optimization Wouldn't this be on the choice of stl (libstdc++ vs libc++) rather than compiler? Anyway, on my system, (llvm/clang 10.0, gcc 10.1), both take ~360ms. > None of the compilers can see that the loop can be optimized out I was interested in this, so decided to investigate. I'm actually not sure why that's happening. This is the definition of to_string on my system: inline string to_string(long __val) { const bool __neg = __val < 0; const unsigned long __uval = __neg ? (unsigned long)~__val + 1ul : __val; const auto __len = __detail::__to_chars_len(__uval); string __str(__neg + __len, '-'); __detail::__to_chars_10_impl(&__str[__neg], __len, __uval); return __str; } __to_chars_len() is marked as 'constexpr', but __to_chars_10_impl is not, and the latter modifies an allocated buffer; maybe that's why?