RE: MI, W-Code and OS/400

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Joe Pluta
Sent: Friday, May 23, 2003 4:56 PM
To: RPG programming on the AS400 / iSeries
Subject: MI, W-Code and OS/400

>The NMI is then subject to MASSIVE amounts of optimization when being
>finally translated to executable code.  When I did some research on the
>optimizer, my brain nearly exploded.  But that's just me.

I have not done the research, but I did have an online discussion with Jon
Paris and an IBM technical heavy where I was scolded but still came out
ahead because I learned some things re: optimization.  At least I think I
did because the heavy never responded to my "this is how I understand what
your saying, is it correct" post.

The CPU wants to keep data in registers and also execute stmts in parallel.
The problem is that when an exception occurs the contents of the actual
program variables may not match with what is stored in the registers.  So
exceptions are bad for optimizing code.  But a running program does not have
many exception boundaries, and that is good for the optimizer.  Basically
the proc is the exception boundary, so all code from bgnProc to EndProc can
be optimized without concern for exceptions exposing variables that have not
been updated in unison.

Anyway, I suspect that the great optimizing secrets of IBM are a lot of
hype. One of the ways that the ibm man keeps the independent software
developer down by not releasing the source code of their languages.

What the heck is IBM in the language business for anyway? IBM should provide
ILE and a W-Code compiler.  The rest should be left to the independents.
Developing RPG, CODE400, Java, C++ must be very expensive, how much revenue
can it bring in? and I think it dampens innovation on the platform.

-Steve

.