[Webkit-unassigned] [Bug 24986] ARM JIT port

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=24986





------- Comment #8 from zherczeg at inf.u-szeged.hu  2009-04-03 12:55 PDT -------
> Congratulations on getting this working!, great job.

Thank you for your encouraging words!

I probably mentioned some time ago, that we have already tried to put nanojit
(Tamarin jit engine) under JavaScriptCore. That does exactly the same thing as
your MacroAssembler: it has a LIR (low-level intermediate language), and
generates machine code from that language. At first sight it looks great, only
we have to generate lir, and nanojit will do the rest of the work.
Unfortunately, the results were disappointing. Why? Because that common
low-level language totally misses platform specific optimizations. Even x86 and
x86-64 has major differences. ARM is something totally different, because the
instruction size is constant: 1 word (4 bytes).

We must sacrifice either the easly maintanable code or great performance. We
chose the second one, we want a fast jit. We hope we can maintain the arm port
in the future, and we can implement all the neccessary changes, new byte-codes,
etc. But we see your points as well. We had actually talked a lot about them.


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