HipHop transforms your PHP source code into highly optimized C++ and then compiles it with g++ to build binary files. You keep coding in simplerPHP, then HipHop executes your source code in a semantically equivalent manner and sacrifices some rarely used features – such as eval() – in exchange for improved performance
Platform: Cross-platform; License: PHP License
Reference: https://github.com/facebook/hiphop-php/wiki