From: lutz@iks-jena.de (Lutz Donnerhacke)
Subject: Re: efficient vector/matrix operations in Ada
Date: Tue, 14 Aug 2001 08:56:51 +0000 (UTC)
Date: 2001-08-14T08:56:51+00:00 [thread overview]
Message-ID: <slrn9nhpui.ht.lutz@taranis.iks-jena.de> (raw)
In-Reply-To: bebbba07.0108132046.53d265dc@posting.google.com
* Russ wrote:
>Larry Hazel <lhazel@mindspring.com> wrote in message news:<3B783732.A3A1EB82@mindspring.com>...
>> Seems to me if a compiler can't generate the most efficient code for
>> A = B + C + D
>> or
>> A := B + C + D
>> in any language, you need a different compiler.
>
>I'm no compiler expert, but I seriously doubt that you are correct here.
>Come to think of it, I'll just say that you are flat out wrong--and I'll
>eat crow if you are right. The difference (in C++) between
>
> A = B + C + D;
>and
> A = B; A += C; A += D;
>
>is more fundamental than a compiler can account for. Don't forget that
>"+" and "+=" are user-defined operators to start with. The former says
>to add B, C, and D, place the result in a temporary matrix, and copy
>that matrix by value back into A.
Even the dragon book contains a chapter about data flow analysis, which is
invented to remove unnecessary temporary copies and does a wonderful job on
this subject.
next prev parent reply other threads:[~2001-08-14 8:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-07 1:13 efficient vector/matrix operations in Ada Russ
2001-08-07 2:18 ` Dale Stanbrough
2001-08-07 2:21 ` tmoran
2001-08-07 3:04 ` Russ P.
2001-08-10 16:54 ` B.Gaffney
2001-08-13 7:50 ` Dmitry Kazakov
2001-08-13 19:45 ` Russ
2001-08-13 20:23 ` Larry Hazel
2001-08-13 21:26 ` Ted Dennison
2001-08-14 4:46 ` Russ
2001-08-14 5:28 ` David Starner
2001-08-14 8:17 ` Alexander Boucke
2001-08-14 8:56 ` Lutz Donnerhacke [this message]
2001-08-14 10:54 ` Jacob Sparre Andersen
2001-08-13 21:30 ` Ted Dennison
2001-08-14 4:56 ` Russ
2001-08-14 7:32 ` efficient vector/matrix operations in Fortran, was Re: ... " tmoran
2001-08-14 14:05 ` efficient vector/matrix operations " Ted Dennison
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2001-08-07 11:36 Gautier Write-only-address
2001-08-14 12:37 Gautier Write-only-address
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