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From: gl8f@astsun9.astro.Virginia.EDU (Greg Lindahl)
Newsgroups: comp.lang.misc
Subject: Re: Aggressive optimization
Message-ID: <1990Nov16.022829.19283@murdoch.acc.Virginia.EDU>
Date: 16 Nov 90 02:28:29 GMT
References: <5494:Nov1519:06:3790@kramden.acf.nyu.edu> <6063@lanl.gov> <9576:Nov1523:11:0990@kramden.acf.nyu.edu>
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Organization: Department of Astronomy, University of Virginia
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In article <9576:Nov1523:11:0990@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:

>Matt pointed out that gcc did much better.

My name is spelled "Greg". Matt Crawford may also be an astronomer,
but my hair is much longer. Trivial to tell us apart.

> gcc, however, will produce suboptimal code for
>
>  for (j = 0;j < 100;j++)
>    a[i * j] = ...;

If you forget to turn on strength reduction, you deserve what you get.

>Even good Fortran
>optimizers don't do very well on moderately complex code.

I showed you code in which FORTRAN does well, and you have to
hand-optimize C to beat it. Please don't forget history, or you will
have to repeat it. The best part of "discussing" anything with you is
that you refuse to learn.