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- Subject: Re: any plan about luajit2 support 5.2!
- From: Mike Pall <mikelu-1011@...>
- Date: Wed, 17 Nov 2010 18:12:29 +0100
Alex Bradbury wrote:
> Do you envisage that this same FFI interface could be provided for
> standard Lua for compatibility reasons?
Unlikely. It's tightly integrated into the VM, esp. the garbage
> It's significantly easier to port an FFI to
> another platform than to port LuaJIT (judging by libffi at least, I'm
> not sure what your FFI includes)
Oooh, don't get me started about FFI portability. You'd think that
writing a C parser is tough, but the real challenge was handling
all the little platform differences (packed structs with aligned
members and bitfields, anyone?).
And I haven't even implemented the plethora of calling conventions
yet ... the first release of the FFI will only allow you to create
and use native data structures, but not call C functions (yet).
Already quite useful and helps on benchmarks, too. ;-)
> [...] so those on platforms where LuaJIT is not supported [...]
I'm sure this will be resolved over time. After x86/x64, PPC, ARM
and MIPS -- what's left? And I mean platforms suitable for a
dynamic language with a JIT compiler _and_ with some outlook for
the future plus a market share to speak of.
[Platforms which prohibit runtime code-generation can still
benefit from the faster LuaJIT interpreter. E.g. the PPC/e500 port
of the LuaJIT interpreter is complete now. It outruns the Lua
interpreter by a factor of 2x - 4x and in some cases up to 6x.
The sponsor is rather happy with this performance.]