Performance benefits from inlining simple functions might be significant, since function call in PHP is not cheap. We'd have some potential problems there.

Included in the list are things like:

• Variable scoping - we don't want function variables to mess with our scope, so we'd probably rename them or something.
• Then we might get a problem if function messing with current scope is called indirectly so we can't really know.
• And then some may use end-of-scope for destruction of variables that have dtors, so when we'd clean up these variables?