From: Bram Stolk <bram AT gig DOT nl>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: I don't understand djgpp's optimizations
Date: 7 Apr 1997 08:36:23 GMT
Organization: EuroNet Internet
Message-ID: <3348B1FF.167E@gig.nl>
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Hi,

BECman wrote:

> He is doing 50,000 calculations in a 'for' loop, not pausing.
> I'm sure this should be in the FAQ, as it's one of the
> important aspects that everyone needs.

When benchmarking:

Make sure, that the result of the calculations is used
afterwards (in a printf or so).

If you don't, a smart compiler will optimize it, and remove
the calculations entirely.

This is what happened to me, after writing a very naive
benchmark :-)
The smart compiler was Sun's cc.

    Bram

> 
> Graham.

-- 
o----------------------------------------------------------------------o
| Bram Stolk, ElectroGIG, Wibautstraat 137c, 1097DN Amsterdam, Holland |
| tel: +31 20 462 462 0   email: bram AT gig DOT nl   home: stolk AT xs4all DOT nl   |
|                                                                      |
| "Real programmers do not comment their code -- it was hard to write, |
|  it should be hard to understand."                                   |
o----------------------------------------------------------------------o