From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,56525db28240414a
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.180.96.42 with SMTP id dp10mr201719wib.2.1343094365913;
        Mon, 23 Jul 2012 18:46:05 -0700 (PDT)
Path: 
 ge7ni52415029wib.0!nntp.google.com!volia.net!news2.volia.net!feed-A.news.volia.net!border1.nntp.ams2.giganews.com!border3.nntp.ams.giganews.com!ramfeed-2.ams.xsnews.nl!feed.xsnews.nl!border-2.ams.xsnews.nl!feeder3.cambriumusenet.nl!feed.tweaknews.nl!216.40.29.245.MISMATCH!novia!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!ctu-peer!news.nctu.edu.tw!csnews.cs.nctu.edu.tw!news.cs.nctu.edu.tw!feeder.erje.net!nuzba.szn.dk!news.jacob-sparre.dk!munin.jacob-sparre.dk!pnx.dk!.POSTED!not-for-mail
From: Jacob Sparre Andersen <sparre@nbi.dk>
Newsgroups: comp.lang.ada
Subject: Re: Efficient Sequential Access to Arrays
Date: Mon, 16 Jul 2012 13:34:33 +0200
Organization: Jacob Sparre Andersen Research & Innovation
Message-ID: <87394saqie.fsf@adaheads.sparre-andersen.dk>
References: <01983f1c-f842-4b1f-a180-bcef531dad4c@googlegroups.com>
	<kpltof5a8xvm.arygetd4esmc.dlg@40tude.net>
	<44f2bfd0-75ed-4b9c-982e-61d5308f9c01@googlegroups.com>
	<b23dec87-cfa4-4d32-9ac9-da6bfe6d0c85@googlegroups.com>
NNTP-Posting-Host: 79.138.241.140.bredband.3.dk
Mime-Version: 1.0
X-Trace: munin.nbi.dk 1342438477 17850 79.138.241.140 (16 Jul 2012 11:34:37
 GMT)
X-Complaints-To: news@jacob-sparre.dk
NNTP-Posting-Date: Mon, 16 Jul 2012 11:34:37 +0000 (UTC)
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux)
Cancel-Lock: sha1:2bAeEOXeElXKfTkEYURtgt3L46E=
X-Original-Bytes: 1852
Content-Type: text/plain; charset=us-ascii
Date: 2012-07-16T13:34:33+02:00
List-Id: <comp.lang.ada>

Keean Schupke wrote:

> for J in S .. E loop
>     Y := Y + X(J).Z;
> end loop;
>
> Where S and E are random numbers in the index range of the array and
> where S < E, and the array is an array of records (in this case 28
> bytes long) containing the integer Z.
>
> imul   $0x1c,%r9,%r10
> add    0x48(%rsp,%r10,1),%edi
>
> So you can see the multiplication is executed for every iteration.

Your example is probably too simple for your actual application, but (in
Ada 2012) you could also write it (untested):

   for J of X (S .. E) loop
      Y := Y + J.Z;
   end loop;

Greetings,

Jacob
-- 
"Never interrupt your enemy when he is making a mistake."