A variable containing the LuaJIT version string. This is LuaJIT 2.0.4 in x32 Garry's Mod, and LuaJIT 2.1.0-beta3 on the x86-64 branch and main with x64 launch option.
LuaJIT 2.0.4
LuaJIT 2.1.0-beta3
x86-64
main