NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part2/16989

Internet Message Format | 1996-08-05 | 1.8 KB

Path: mail2news.demon.co.uk!genesis.demon.co.uk
From: Lawrence Kirby <[e-mail]>
Newsgroups: comp.lang.c++,comp.lang.c,comp.os.ms-windows.programmer.misc
Subject: Re: fastest code
Date: Fri, 12 Apr 96 23:42:15 GMT
Organization: none
Message-ID: <[e-mail]>
References: <[e-mail]> <4kgu7g$[e-mail]> <[e-mail]> <4kjdus$[e-mail]> <[e-mail]>
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In article <[e-mail]>
           [e-mail] "Kazimir Kylheku" writes:

>In article <4kjdus$[e-mail]>,
>Oliver Hellwig  <[e-mail]> wrote:
> >Well it did!  I did not turn on full optimizations but I just used the
> >compiler in it's default mode.  However, when I turned off all optimizations
> >then it compiled correctly.  I verified that it left the loop but removed
>
>Ah well. What can be said? Don't use Watcom to compile Linux drivers or any
>other portion. Use a freeware compiler that works.

Not to mention that the gcc version of that compiled code, in addition to
working, looks better optimised. What I did find curious was that on
the compilers I tried:

    prom[i] = prom[i+i];

produces different code to:

    prom[i] = prom[2*i];

where the code for the latter certainly looks more efficient (although
it is difficult to guess the exact instruction timings). I wonder if
Watcom compiles the 2nd version correctly.

--
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Lawrence Kirby | [e-mail]
Wilts, England | [e-mail]
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