Dear Anton Soldatov,
This looks wonderful! I'm glad you worked on it and put it out there. I know a lot of people who had problems with the 2GB memory limit.
As a side note, there were some problems with LuaJIT and Mac OSX, where on 64-bit builds LuaJIT would twiddle bits in the 32-bit range. This required people to build their applications with -pagezero_size=(something much smaller than the default 2^32) and -image_base=(something much smaller than 2^32, which is the default). This ruined people who wanted to inject Lua extensions as part of a dylib extension to a main application which did not change their image_base/pagezero_size.
Does 64-bit "clean" mean that, if this makes it to Mac OSX, this would no longer be a problem?