Re: octave loop slowness (was "")

[Brendan Drew]

True, there is no requirement that you generate Java bytecode to be fed 
to a JVM to get JIT; however, I am extremely leery of reinventing the 
wheel. Especially when the wheel in question is a very very hairy piece 
of software. 

We didn't really deal much with JIT stuff in my compiler or architecture 
classes, but I can imagine that supporting JIT capabilities puts some 
pretty strong requirements on the VM / interpreter and forces your hand 
in a number of important design issues (such as what your IR looks 
like). First off, you're going to have to be keenly aware of the 
underlying ABI conventions for whatever your implementation language is 
so that you're able to link against JIT compiled code. You might have to 
redo your symbol table to look more like a traditional compiler's symbol 
table so that you can support the assembly phase of the JIT. This is 
just off the top of my head --- I'm sure that there are tons of other 
issues which crop up when you implement JIT.

Java has already (largely) solved these problems, which is why most of 
the JIT research that I'm aware of is all JVM based. There is a set of 
GNU packages which allow a kind of limited (last I checked) JIT -- GNU 
Lightning and one other that I can't recall off the top of my head. 
Maybe LLVM 
(http://developers.slashdot.org/article.pl?sid=04/08/13/2356209) would 
be of interest?


John W. Eaton wrote:

> On 20-Mar-2006, Brendan Drew wrote:
>
> | Doing the JIT "properly" gets to be a mess, because you end up having to 
> | basically throw away your entire interpreter and writing a full-up 
> | compiler which translates Matlab-ish code --> JVM microcode.
>
> By JVM, do you mean Java Virtual Machine?  There is no requirement
> that a just-in-time compiler generate Java bytecodes or have anything
> at all to do with Java.
>
> jwe
>
>
>
> -------------------------------------------------------------
> Octave is freely available under the terms of the GNU GPL.
>
> Octave's home on the web:  http://www.octave.org
> How to fund new projects:  http://www.octave.org/funding.html
> Subscription information:  http://www.octave.org/archive.html
> -------------------------------------------------------------
>
>  



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------