It should be simply the function name. If you need to specify the precise module (if you have several static functions in several modules with the same name for instance) you can prefix the function name with the module name (e.g. foo.o: myFunc). I think (if memory serves) that you can even use a wildcard character (e.g. foo.o: *). Things get rather complex if we are talking about C++. I didn't test this but I guess you will have to use the mangled name, which is not especially nice, but at least you have a mean of getting things done.
