Re: SGI compiler options

From: Roberto Gomperts <roberto at.at demilo.boston.sgi.com>
Subject: Re: SGI compiler options
Date: Wed, 21 Jul 93 14:52:39 EDT
 Hi Bruce,
 Your message dated: Wed, 21 Jul 93 08:50:30 EDT
 |>  Howdy Netters,
 |>
 |>  Dan Severance recently wrote regarding SGI machines -
 |>
 |>  >If you have an R4000 or R4400 machine, you need to add the
 "-mips2"
 |>  >option, since "-mips1" is the default (compatibility mode,
 will run on
 |>  >both R3000 and R4000 machines).  (The fast square-root is
 incorporated
 |>  >when you specify -mips2) ...
 |>  >
 |>  >   Another compiler option (fairly new) to try is the -sopt, and is
 |>  >documented in the f77 man page, and under the "fopt"
 manpage (-sopt
 |>  >runs the program fopt).  One user got a 40% speedup, we don't; it
 |>  >depends on your code.
 |>
 |>  I and several other users attempted this and were not able to get either
 |>  of these options to work. I have an Indigo XS24 R4000 with the F77
 compiler
 |>  3.4.1, Development option 4.0.1, and Irix 4.0.5 so I believe I have most
 |>  (but apparently not all) the goodies.
 |>
 |>  When trying to make using the -mips2 option I received the following note
 -
 |>
 |>       f77: Error: malformed or unknown option -mips2
 |>       *** Error code 2
 	I am afraid you are not up to date with the system software for your
 	machine. The "latest-and-greatest" for your equipment is Development
 	Option (IDO) 4.1.1 and Compilers (Fortran) 3.5.1 (aka 3.10.1 compilers)
 	To expand a little on Dan's notes concerning the benefits of the -mips2
 	flag: On the average I have seen +/- 20% improvement when used on a large
 	variaty of chemistry codes. Also, to have the benefit of the "fast
 sqrt"
 	you ought to link with -mips2 (as well as compile).
 |>
 |>  I checked my cdroms to see if I had all the options installed and it
 'appears'
 |>  I do.  What am I doing wrong or what isn't installed?
 |>
 |>  Regarding -sopt, when this option was included in the makefile the
 compiler
 |>  seemed to go into hibernation after it encountered the first routine to
 |>  compile.  After awhile (ca. 10 minutes) I lost patience and aborted the
 make.
 |>  Again, any suggestions what went wrong or I didn't do correctly?
 |>
 |>  Thanks in advance to Dan and any others with responses,
 |>
 |>  Bruce
 |>
 ____________________________________________________________________________
 |>  |                                      |
 |
 |>  |"You can't always get what you want,  | Dr. Bruce A. Luxon
 |
 |>  |   But if you try sometimes,          | Chemistry Department
 |
 |>  |     You'll get what you need ..."    | Purdue University
 |
 |>  |                                      | W. Lafayette, IN  47907
 |
 |>  |                          Mick Jagger | (317)494-5289; Fax (317)494-0239
 |
 |>  |                                      | bruce at.at
 dggpi2.chem.purdue.edu      |
 |>
 |______________________________________|___________________________________|
 |>
 |>
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 				-- Roberto
 						Roberto Gomperts
 						roberto at.at sgi.com
 						phone: (508) 562 4800
 						Fax:   (508) 562 4755
 "Gracias a la vida,
 que me ha dado tanto ..."
         Violeta Parra