I think you would also need to ban threading and reentrancy (from signals)? Also, if you had function pointers, you would have to pessimize to storing each such

I think you would also need to ban threading and reentrancy (from signals)? Also, if you had function pointers, you would have to pessimize to storing each such function's stack memory separately I think (since the compiler wouldn't be able to figure out the call graph, in general)