Hi Chris, > > Also > > 5. Within foo, you need to check that nothing too complicated is > > done to P1, for example it isn't stored in a global or passed to > > some other function. > > Actually, worse case, you could just make a trampoline in foo. > However, you're right that this is only worth doing if there are > calls to the fn pointer in foo. OTOH, propagating the trampoline > creation site down to foo will allow it to be further propagated into > functions that foo might call.
that could be very costly. Initializing a trampoline is not very costly. What is costly is using it and then modifying the stack contents where the trampoline was, because you get an icache flush. Eg: if you push the trampoline down into a function called in a loop, then you risk calling the trampoline then dirtying that part of the stack (after function return, due to other local variables using that part of the stack) and thus taking a large hit on every iteration. Ciao, Duncan. _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
