Now you're playing ignorant. Feel free to substitute stack accesses with register reads, but since we're talking "variable args" I feel you're going to run out of those quickly.
I'm not playing ignorant, I'm pointing out a very real difference between reading variadic arguments with va_arg and reading normal arguments with plain code. Normal arguments typically get read straight out of their corresponding registers, whereas va_arg reads from a stack entry. It is not the exact same code and it is not the same calling convention.
Please don't say things like "This is plain false" when you say things like this which are, well, just plain false.
