I just watched Jason Turners C++ Code Smells talk from the last CppCon'19 and paused at 7.37m, where he talks about output parameters.
https://youtu.be/f_tLQl0wLUM?t=457
The function in question (see GodBolt link), has a return value. His question is, how many parameters does this function take and the answer is 1. I am trying to understand what that means.
std::string get_value();
int main()
{
const auto value = get_value();
}
The resulting (and interesting part of that) assembly is this:
...
mov rdi, rsp
...
He said rdi is the register for the first parameter, but I don't know what the point of this code piece is. Does that mean the compiler created a hidden [out] parameter instead of the return value? Could someone elaborate what that means?
