Another small trick is to use a "reversed" bump allocator, that starts handing out the memory from the end with the larger addresses. Since AST structures are almost always created bottom-up, children before the parents, the root node at the very end on the return from parseProgram/parseModule/etc. function, you will end up with the AST that has most its pointers pointing forward. This means that during AST walks, you'll be going from lower addresses to the higher ones which I think is actually somewhat faster than the reverse order.
Comments
Another small trick is to use a "reversed" bump allocator, that starts handing out the memory from the end with the larger addresses. Since AST structures are almost always created bottom-up, children before the parents, the root node at the very end on the return from parseProgram/parseModule/etc. function, you will end up with the AST that has most its pointers pointing forward. This means that during AST walks, you'll be going from lower addresses to the higher ones which I think is actually somewhat faster than the reverse order.