Jan Oravec
f0dcca8b29
Continuation's m_received field is used to transfer values and exceptions to the Continuation by send() and raise() methods. It has a valid value only for a short duration of time, between ContNext/ContSend/ContRaise and UnpackCont opcodes, when no other operations could possibly occur. Let's free these 16 bytes of memory and pass the value thru the VM stack. To achieve this goal, ContEnter was modified to accept a value to be transferred on the stack. The existence of the value on the stack is then acknowledged by the UnpackCont opcode, which is the first opcode executed after ContEnter enters the continuation body. ContNext then becomes a trivial Null and is thus removed, ContSend just teleports the value from local 0 to the stack (I will experiment in a follow up diff with replacing ContSent by CGetL+UnsetL). ContRaise has to update the label, but the eventual plan is to enter into unwinder directly from the raise() method.
HipHop VM for PHP 
HipHop VM (HHVM) is a new open-source virtual machine designed for executing programs written in PHP. HHVM uses a just-in-time compilation approach to achieve superior performance while maintaining the flexibility that PHP developers are accustomed to. HipHop VM (and before it HPHPc) has realized > 5x increase in throughput for Facebook compared with Zend PHP 5.2.
HipHop is most commonly run as a standalone server, replacing both Apache and modphp.
Installing
You can install a prebuilt package or compile from source.
Running
You can run standalone programs just by passing them to hhvm: hhvm my_script.php.
HipHop bundles in a webserver. So if you want to run on port 80 in the current directory:
sudo hhvm -m server
For anything more complicated, you'll want to make a config.hdf and run sudo hhvm -m server -c config.hdf.
Contributing
We'd love to have your help in making HipHop better. If you run into problems, please open an issue, or better yet, fork us and send a pull request. Join us on #hhvm on freenode.
If you want to help but don't know where to start, try fixing some of the Zend tests that don't pass. You can run them with hphp/test/run. When they work, move them to zend/good and send a pull request.
Before changes can be accepted a Contributors Licensing Agreement (pdf - print, sign, scan, link) must be signed.
Licence
HipHop VM is licensed under the PHP and Zend licenses except as otherwise noted.