Re: disabled JIT compiler for cpu with no sse2 support

[Mike Pall <mikelu-1003@...>]

Anton Kukura wrote:
> I was under impression that LuaJIT generates x87 instructions for cpu with
> no sse support.

Umm, LuaJIT 2.0 never JIT compiled to x87 code (LuaJIT 1.x did).

The interpreter uses x87 (still the default on x86) or SSE2
(optional on x86, default on x64).

> Unfortunately, the latest git mirror, does not allow to turn JIT engine on
> for cpu without sse2 support.

That's correct. It disables the JIT compiler and falls back to the
interpreter. Previously it simply refused to run at all on a
non-SSE2 CPU. I'd say that's an improvement.

> Mike, do you plan to work on it in near future? 

Not anymore. The number of machines out there without SSE2 is
rapidly shrinking. I'm not sure it's a good investment of my time
to add x87 code generation to the backend. It would be rather
difficult to integrate into the current design and/or won't
perform well, too.

Arguably the Steam hardware survey is biased by their audience:

  http://store.steampowered.com/hwsurvey

But still ... scroll to the bottom, click on "Other Settings" and
you'll see that 98.20% of their users have SSE2. By the time I'd
be finished, it'll be at 99% ...


[BTW: barring unforseen difficulties, beta3 will be out tomorrow
(including x64 support). Anyone testing git HEAD please speak up
now, if you find any issues on any platform. Thank you!]

--Mike