Re: Mi vs C (was calling RPG ILE with parameter list from MI)

Hi, Jon:

 > Jon Paris wrote:
 > This got me thinking. Has anyone here done any tests to compare the 
execution speed of MI programs vs comparable C programs? IBM doesn't 
write in MI any
 > more and by sticking with MI you lose most of the optimization 
options that are available to ILE programs. The vast majority of MI 
instructions are surfaced in the
 > C compiler and if I recall correctly are not called as functions (as 
they would be if called from RPG) but replaced by in-line code streams 
which should be a lot
 > more efficient.

There are a large number of OPM MI instructions that are not available 
as ILE built-ins. As to performance, it depends on the algorithms used 
and how they are coded. In many cases, OPM MI can perform very well.

 > C code has to be a lot more maintainable than MI and there are many 
more tools to work with it.

It is certainly possible to write very obtuse code in C, almost as 
cryptic and unreadable as some examples I have seen in APL.

 > SO is there really any reason to use MI for new code? Does it really 
perform any better?

 > Jon Paris
 > www.Partner400.com
 > www.SystemiDeveloper.com

There is still one issue that IBM has not yet resolved. If you make any 
syntax or semantic errors using any of the MI built-in functions in any 
ILE language, instead of getting a meaningful and helpful error message, 
you get a "dump" and an ugly message that says "compiler internal error 
- call support" and  it opens up a "problem". For this reason, I use the 
OPM MI QPRCRTPG API to "debug" any MI code I write, before ever 
attempting to use equivalent embedded MI built-in functions, to make 
sure I have the arguments to the instructions coded correctly, etc.  
Until IBM "fixes" this, there will still be a need for the OPM MI 
compiler, IMHO.

Mark S. Waterbury
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