Re: LuaJIT library syncing

["Andrew Wilson" <agrwagrw@...>]

Thanks Mike, that clarifies everything.  AGRW

On Fri, Dec 19, 2008 at 2:21 AM, Mike Pall <mikelu-0812@mike.de> wrote:
> Andrew Wilson wrote:
>> I wanted to load the plain lua51.dll to avoid duplicating lua51.dll.
>> So if I'd like to have only one lua51.dll, is it best to just
>> substitute lua51.dll from LuaJIT compilation or statically link LuaJIT
>> or have LuaJit check version of plain lua51.dll directly?
>
> Err, I think you're missing something important. The DLL contains
> the VM, not the EXE! Both lua.exe and luajit.exe are only small
> programs (~10K) that parse the command line and invoke the Lua VM
> (luajit.exe offers a couple more options).
>
> The lua51.dll of both VMs are *different* (check the file sizes).
> In the case of LuaJIT it also contains the JIT compiler, which is
> an unseparable part of the VM.
>
> The DLL of both VMs must have the same name, because all C modules
> reference it. All lua_*/luaL_* symbols are tagged during linking
> with the DLL they resolve with, i.e. "lua51.dll".
>
> You cannot load both DLLs in the same process. And you cannot
> statically link LuaJIT because then all C modules would implicitly
> load the other DLL and call its functions -- chaos ensues.
>
>> The directory structure, lua modules, lua files, examples, docs etc
>> already exist in Lua for Windows setup. What is your opinion on how
>> LuaJIT would best be included in a Lua distribution?
>
> It's a drop-in replacement. So just remove lua.exe/lua51.dll and
> replace with the luajit.exe/lua51.dll from LuaJIT. Add the files
> from jit/*.lua to the Lua module directory. Explain to users they
> should invoke "luajit -O foo.lua" instead and that's it.
>
> Note that you can turn off the JIT compiler with -j off, if needed.
> Then you end up with more or less the same VM as used by Lua 5.1.4
> plus the Coco patchset. (Not that there's a good reason to do so,
> except for debugging.)
>
> --Mike
>