PHP 5.1 execution models... what's the deal?

[bubblenut]

Hey, I was reading this blog post today and found it all very interesting but at no point did it shed any light on the differences between the execution models and I can't seem to find anything about it. Anyone know anything?

The Link

[Weedpacket]

I'm browsing the Zend2 CVS right now, in case there's something there. My guess is that it refers to three ways in which PHP function calls can be implemented in bytecode: whether it uses the current approach of pushing the current scope onto a stack and issuing a CALL instruction so that control jumps to the relevant section of code; or whether it lists all the function bodies in a big SWITCH; or whether it uses a rats-nest of GOTOs to hop around the place. If I hadn't already seen the benchmark results my guesses would have been about right (GOTOs would be the fastest, but the current CALL would be the default (and more robust)).

So far:
http://lxr.php.net/source/ZendEngine2/README.ZEND_VM

[bubblenut]

WOOT!! Thanks weed. Not that it's really going to make a difference to me, I just wanted to know.