HHVM
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| Developer(s) | |
|---|---|
| Initial release | December 9, 2011 |
| Stable release | 3.15.0 (7 September 2016) |
| Repository | github |
| Development status | Active |
| Written in | C++ and OCaml |
| License | PHP License and Zend License |
| Website | www |
HipHop Virtual Machine (HHVM) is an open-source virtual machine based on just-in-time (JIT) compilation that serves as an execution engine for the PHP and Hack programming languages. By using the principle of JIT compilation, executed PHP or Hack code is first transformed into intermediate HipHop bytecode (HHBC), which is then dynamically translated into x86-64 machine code, optimized, and natively executed. This contrasts with PHP's usual interpreted execution, in which the Zend Engine transforms PHP source code into opcodes that serve as a form of bytecode, and executes the opcodes directly on the Zend Engine's virtual CPU.
HHVM is developed by Facebook, with the project's source code hosted on GitHub; it is licensed under the terms of the PHP License and Zend License.
HHVM was created as the successor of the HipHop for PHP (HPHPc) PHP execution engine, which is a PHP-to-C++ transpiler that has also been created by Facebook. Based on the gained experience and aiming to solve issues introduced by HPHPc, Facebook decided in early 2010 to create a JIT-based PHP virtual machine. Issues associated with HPHPc included its reaching of a plateau for further performance improvements, lack of full support for all features of the PHP language, and difficulties arising from specific time- and resource-consuming development and deployment processes required for PHP projects that used HPHPc. In Q1 2013, the production version of facebook.com website stopped using HPHPc and switched to HHVM.
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