I agree; that does look indeed a good reason to set it to zero. Once the end of the function code is reached, ret is either zero or undefined, so there is no need to keep track of the value of ret; just assume that it is zero.

Now I can see how x86 C ABIs is working; thank you for explaining because I did not know much about that before, but now I know, and indeed it is making sense. (On a different instruction set, something else might make sense; I don't really know.)