The PHP to C++ compiler hasn't been used for something on the order of 10 years.
At least as of two years ago, pretty much entire web-facing portion of Facebook was written in Hack (which descends from PHP, but has what feels like every syntax feature you could stuff into an Algol-like language). Hack is run on HHVM, which is a bytecode VM that can JIT compile to machine code.
Unsure how extensively they continue to use their PHP to C++ compiler internally.