• Subject: RE: "MI" of ILE programs
  • From: Walden Leverich <walden@xxxxxxxxxxxxxxx>
  • Date: Thu, 2 Oct 1997 08:04:52 -0400
  • Organization: Tech Software

While I can't agree with you more about not spending a week to get a 5% 
boost in performance, my question was not driven from a performance need.

I'm one of those sick people that want to see what makes it tick. It has 
actually come in handy to know that the TIME opcode is actually a call to 
QRGXTIME. Or that the SORTA opcode performs a shell sort. Or that even if 
you call a program using a variable for the program name, if the variable 
contains the same value it did last time the call was made the program is 
not re-resolved.

I am looking to get the same internal knowledge about the IBM-supplied code 
in an RPG/ILE program that I have about that code in "good-old" OPM RPG. 
Any chance you can make the program you have to show the human-readable 
version of the W-Code available?

-Walden

-------------------------------
Walden Leverich
Tech Software
walden@techsoftinc.com
www.techsoftinc.com

-----Original Message-----
From:   Hans Boldt [SMTP:hboldt@vnet.IBM.COM]
Sent:   Tuesday, September 30, 1997 12:53 PM
To:     midrange-l@midrange.com
Subject:        RE: "MI" of ILE programs

<snip>
I think the main reason is that it's just not very useful to see the
intermediate language.  First, our intermediate language (W-Code,
which corresponds roughly to MI in OPM) is not easy to read.  Secondly,
the optimizer in the back-end is fairly robust, even at low optimization
levels.  So the W-Code may not fairly represent the final machine code.
The optimizations performed by the ILE back-end are rather good.  Using
C, you should see good improvements just by compiling with the highest
optimizations.  (These days, optimizers can often produce better code
than an experienced assembler programmer.)

Also:  What algorithms are you using?  For example, when sorting, do you
use a bubble sort, a shell sort, or a binary sort?  Depending on your
data, the lowly bubble sort can can sometimes be the best choice!  Choice
of algorithm generally can be the most effective way to speed up your
program.

Another consideration is time:  Is it worth spending a week to get a 5%
improvement in program performance?
<snipping performance, performance and more performance>
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