Re: Loop jamming!?

genew@netcom.com (Gene Wagenbreth)
28 Jul 1997 09:31:24 -0400

          From comp.compilers
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[3 earlier articles]
Re: Loop jamming!? sven@customized.com (Sven) (1997-07-13)
Re: Loop jamming!? n8tm@aol.com (1997-07-16)
Re: Loop jamming!? cdg@nullstone.com (Christopher Glaeser) (1997-07-18)
Re: Loop jamming!? schow@nortel.ca (Stanley Chow) (1997-07-21)
Re: Loop jamming!? cdg@nullstone.com (Christopher Glaeser) (1997-07-22)
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Re: Loop jamming!? genew@netcom.com (1997-07-28)
Re: Loop jamming!? simmons@nortel.ca (Steve Simmons) (1997-07-29)
Re: Loop jamming!? schow@nortel.ca (Stanley Chow) (1997-07-31)
Re: Loop jamming!? jan@fsnif.neuroinformatik.ruhr-uni-bochum.de (Jan Vorbrueggen) (1997-07-31)
Re: Loop jamming!? cliff.click@Eng.Sun.COM (cliffc) (1997-08-07)
Re: Loop jamming!? mkent@acm.org (Mike Kent) (1997-08-07)
Re: Loop jamming!? schow@nortel.ca (Stanley Chow) (1997-08-09)
| List of all articles for this month |
From: genew@netcom.com (Gene Wagenbreth)
Newsgroups: comp.compilers
Date: 28 Jul 1997 09:31:24 -0400
Organization: Applied Parallel Rsch (Topanga)
References: 97-07-089 97-07-102 97-07-108
Keywords: Fortran, optimize

If you are after high performance, f90 array syntax can get in your way. The
compiler must translate the f90 to the equivalent of an f77 DO loop while
generating code. It must perform loop jamming, and sometimes array demotion.
Performance depends on how the compiler does this. The user has no control,
and usually can not find out what the compiler has done. Rewriting the code
by hand in f77 Do loops is often the best thing to do.


Gene W
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Gene Wagenbreth Programming for Dollars
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