Article View: comp.lang.fortran
Article #4653Re: better ratfor ?
From: Joseph P. Larson
Date: Tue, 02 Dec 1986 14:51
Date: Tue, 02 Dec 1986 14:51
30 lines
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2102 bytes
In article <1768@ncoast.UUCP> btb@ncoast.UUCP (Brad Banko) writes:
>...
> ( if (.not. (a.le.n) ) ..., should go to:
> if ( a.gt.n ) ... ),
>
> I don't know much about compilers. Our Fortran compiler is
>Vax Fortran ...
>second, if the ratfor ( if (.not. (a.le.n))...) is hand optimized to
>( if (a.gt.n) ...) the resulting executable file runs twice as fast.
Hmm. I've looked at the code VAX/VMS FORTRAN produces in the past.
The optimization always struck me as being very good. Is this the
FORTRAN you are using, or do you use UNIX/Eunice? Also, I assume
that either you are doing more hand-optimizations than just this
one line, or this is almost your entire routine in order for there
to be a difference-factor of 2 for this trivial change. Could you be
so nice as to send us (or at least me) the Macro-11 the code produces?
I'm curious. (In VAX/VMS FORTRAN, I think you want the /MACH option.
Don't do a /FULL list or anything like that).
Of course, it could be possible you've stumbled across just the right
combination of boolean operators to negate the compiler's ability to
optimize, at which point DEC would probably love to receive a fairly
detailed description....
--
UUCP: ihnp4!rosevax!dayton!joe Joe Larson
ATT : (612) 375-3537 Dayton Hudson Department Store Company
(standard disclaimer...) 700 on the Mall
Mpls, Mn. 55408
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!rutgers!dayton!joe From: joe@dayton.UUCP (Joseph P. Larson) Newsgroups: comp.lang.fortran Subject: Re: better ratfor ? Message-ID: <235@dayton.UUCP> Date: Tue, 2-Dec-86 09:51:19 EST Article-I.D.: dayton.235 Posted: Tue Dec 2 09:51:19 1986 Date-Received: Tue, 2-Dec-86 22:42:57 EST References: <1724@ncoast.UUCP> <5401@brl-smoke.ARPA> <1355@ttrdc.UUCP> <1768@ncoast.UUCP> Reply-To: joe@dayton.UUCP (Joseph P. Larson) Distribution: comp.org.decus Organization: Dayton-Hudson Dept. Store Co. Lines: 30 Keywords: ratfor, fortran, optimize, f77