[uae] Re: JIT and AMD64
- From: Richard Drummond <evilrich@xxxxxxxxxxxxxx>
- To: uae@xxxxxxxxxxxxx
- Date: Wed, 23 Aug 2006 16:32:04 -0400
Hi Pete
On Wednesday 23 August 2006 07:52, Peter Gordon wrote:
> Speaking of JITs, i'm not saying it would be worth doing, but purely
> hypothetically, would a 68k -> 68k JIT be easy to do?
It would be fairly straightforward, I would imagine, to add 68k host support
to the JIT. Anyway, it'd be easier than PPC support (mainly because the 68k
processor is more like the x86 than its the PPC).
> I'd imagine that 99% of the time its a 1:1 conversion, with maybe address
> conversion (which is done at recompilation time, not execution, so
> therefore still 1:1 instruction mapping), and probably only possible for
> code in userstate, but you'd get near full speed performance on real Amiga
> systems.
If you wanted to do it this way - a virtualisation of the 68k CPU - it would
be a re-write of the current JIT. The current JIT doesn't attempt to maintain
any kind of 1:1 mapping between host CPU registers and 68k registers, for
example (of course, it's not possible on the x86 and AMD64 anyway).
Cheers,
Rich
Other related posts:
