From roberto@demilo.boston.sgi.com  Wed Jul 21 10:52:39 1993
Message-Id: <9307211852.AA25464@demilo.boston.sgi.com>
To: bruce@dggpi2.chem.purdue.edu (Bruce Luxon)
Subject: Re: SGI compiler options 
Date: Wed, 21 Jul 93 14:52:39 EDT
From: Roberto Gomperts <roberto@demilo.boston.sgi.com>


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@dggpi2.chem.purdue.edu      |
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|>  
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				-- Roberto


						Roberto Gomperts
						roberto@sgi.com
						phone: (508) 562 4800
						Fax:   (508) 562 4755

"Gracias a la vida,
que me ha dado tanto ..."
        Violeta Parra