🚀 go-pugleaf

Juan writes ..
>Now that the EXECMOD discussion is progressing past the "where can I get
>it" phase, into performance considerations, how well does an EXECMODed
>exec stack up against a compiled one (using IBM's REXX compiler) ?

An EXECMODed file is simply a file that has been loaded into a MODULE
with a miniscule amount of code to call the EXEC processor with the
(now) in-core file.  When invoked, the EXEC processor must still process
the EXEC statements into meta-code and then execute (interpret) the
result, line-by-(meta)line.

A compiled EXEC has been transformed into machine code.  Presumably, the
highly processed machine code is more efficient than interpreted code.

Compiled REXX, in my experience, is 2 to 12 or so times faster than
interpreted REXX depending on what the EXEC does.  If there is little
REXX code, but lots of expensive commands (CMS, CP, XEDIT, etc), then
little or no difference in performance will be seen.

Compiled REXX is almost always larger than an EXECMODed or source EXEC
file, especially if extraneous blanks and comments are excluded.  See
the COMPREXX program (there are others) to remove comments etc from
EXECs.

When we use EXECMOD, or similar programs, we generally preprocess the
file with COMPREXX.  Even simply processing a source file with COMPREXX
will speed up the loading and execution of an (interpreted) EXEC.

Wayne Smith
Systems Group - CAPS              BITNET/CREN:  wts@maine
University of Maine System        internet:     wts@maine.maine.edu

P.S.  As I recall, EXECMOD significantly speeded up EXEC2, but not REXX,
as EXEC2 seems (seemed?) to be read a line at a time whereas REXX is
loaded in one swell foop.

PPS IBM has shot itself in the foot by requiring a licensed run-time
library to execute compiled EXECs.  It is my understanding that the
"new" REXX compiler (not yet on HESC) has the same characteristic.
Also, the Systems Center PROREXX is executable without separate run-time
system (and license).

Hope this helps!