Yes, more or less. I'm not sure if push and pop is significantly faster than a mov and add. But there are also instructions like leave and ret that follow this

Yes, more or less. I'm not sure if push and pop is significantly faster than a mov and add. But there are also instructions like leave and ret that follow this same fully descending stack convention. So if you deviate from that you can't use any of those. It's worth mentioning what fully descending means here. I'm surprised the article didn't mention it. "Fully" means that the stack pointer points to the last entry on the stack (the top). "Empty" means it points to the next entry just after the last (top) entry. That is, it points to where the next push would be written to. Anyway, you can have whatever calling convention you want, really. All you need is a way to pass arguments, return values, and to know where to return to. You could have a linked list of frames allocated by malloc() with the head pointer in EBP, for example. Say the return address and caller frame pointer is stored in the start of the frame. Then you would return by mov ebx, [ebp]; mov ebp, [ebp+4]; jmp ebx. Or something lile that. This is a pretty ridiculous calling convention though, but it'd work.