HipHop started out with a static (a.k.a. ahead of time, AOT) compiler. Over time, this approach turned out to be undesirable and a VM with JIT compiler, HHVM, was developed under the same name and in the same repo. The static compiler, HPHPc, as well as a related interpreter, HPHPi, was phased out. This has happened over the last year or so at least. By now, everything but HHVM has been dropped completely and even mentions of it in the wiki at GitHub have been removed. The last revision that still mentioned it is two months old: https://github.com/facebook/hiphop-php/wiki/Home/bb5c90c860bf87315c1981641c2aa5a318192a9a#hhvm-versus-older-hiphop-execution-engines
HipHop currently contains only one PHP implementation, which is a JIT compiler.