I would imagine it would be more things like "This function would optimize so much better if I could assume that the two parameters don't alias. Should I add that restriction to the function's type signature?"
Maybe it would be more productive to make a new language more amenable to optimization rather than trying to clumsily bolt it onto C. It's not like C is a good language, anyway. I find FORTRAN more pleasant in many ways, and that's not quite the state of the art...
