LuaJIT does not support 64 bit integers. It uses double NaN tagging for storing object references. That's the basic principle of LuaJIT design and one of the mo

LuaJIT does not support 64 bit integers. It uses double NaN tagging for storing object references. That's the basic principle of LuaJIT design and one of the most important source of its superior performance. In this matter, it is very similar to JS VMs. Support for 64 bit integers would require to abandon this model and completely redesign the LuaJIT VM. Mike opinion about that was very negative. I believe that this was one of the reasons he decided to abandon the project: he was disappointed by Lua creators decision to introduce 64 bit ints and the fact that LuaJIT can't be made Lua 5.3 compatible without rebuilding it from scratch (but that's only my personal impression).