From octave-maintainers-request at bevo dot che dot wisc dot edu Mon Dec  9 11:34:49 2002
Subject: Re: Possible starting point for Octave Compiler?
From: JD Cole <jdcole at san dot rr dot com>
To: Paul Kienzle <pkienzle at jazz dot ncnr dot nist dot gov>,    Randy Gober <GoberR@Bellsouth.net>
CC: octave-maintainers at bevo dot che dot wisc dot edu
Date: Mon, 09 Dec 2002 09:46:00 -0800

Initially I was considering do a straight m-file to octave C++ 
translation. I haven't had any experience with compiling Matlab scripts 
so I was wondering, when compiling a script, does it decend into each 
function, emitting code for those as well, or does it only emit the 
script provided?

Thanks,
JD

Paul Kienzle wrote:

>You will want to look at tree_walker in the octave/src directory, which
>allows you to walk the parse tree.  It is used in pt-check, pt-pr-code
>and pt-bp.  It walks the parse tree for a function, visiting each node
>in turn.  You need to write the action you want for each node type.
>
>As a first step I would like Octave to spit out a byte code for the likes
>of Parrot or some other virtual machine.  Parrot in particular because
>it is intended to be used by scripting languages, but Java byte code or
>.NET CLR would also be interesting.
>
>All of these machines have JITs available for compiling the byte code.
>
>A couple of years ago I did an experiment in which I translated the
>an m-file version of cumsum to C++ by hand:
>
>	y = zeros(size(x));
>	total = 0;
>	for i=1:length(x)
>	   total = total + x(i);
>	   y(i) = total;
>	endfor
>
>IIRC, I got a 6x speedup from a direct translation using octave_value
>for x,y,i and total.  As optimized C, this loop was about 5000x faster.
>In Python, this loop was 100x faster.
>
>  
>