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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,c4cb2c432feebd9d
X-Google-Thread: 1094ba,c4cb2c432feebd9d
X-Google-Attributes: gid103376,gid1094ba,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!cyclone1.gnilink.net!spamkiller.gnilink.net!gnilink.net!trnddc08.POSTED!87bf9b22!not-for-mail
From: Dan Nagle <dannagle@verizon.net>
Reply-To: dnagle@erols.com
Organization: Purple Sage Computing Solutions, Inc.
User-Agent: Thunderbird 1.5.0.2 (X11/20060420)
MIME-Version: 1.0
Newsgroups: comp.lang.ada,comp.lang.fortran
Subject: Re: Bounds Check Overhead
References: <mubcg.13522$fb2.853@newssvr27.news.prodigy.net>
	<epcs4e.qb8.ln@hunter.axlog.fr>
 <tHkcg.6937$kR6.484@trnddc05>	<0ugu4e.4i7.ln@hunter.axlog.fr>
	<PkHcg.90575$Fs1.7198@bgtnsc05-news.ops.worldnet.att.net>
	<To_cg.10095$S7.4017@news-server.bigpond.net.au>
	<%P_cg.155733$eR6.26337@bgtnsc04-news.ops.worldnet.att.net>
	<6H9dg.10258$S7.9150@news-server.bigpond.net.au>
	<XVadg.76594$_S7.45873@newssvr14.news.prodigy.com>
	<1hfv5wb.1x4ab1tbdzk7eN%nospam@see.signature>
	<pan.2006.05.25.12.11.52.919554@linuxchip.demon.co.uk.uk.uk>
	<4475DA61.3080001@comcast.net>
 <m2mzd569l9.fsf@grendel.local>	<44762F55.4050106@cits1.stanford.edu>
 <87hd3d1472.fsf@ludovic-brenta.org>
In-Reply-To: <87hd3d1472.fsf@ludovic-brenta.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Message-ID: <3cBdg.6255$oa3.2407@trnddc08>
Date: Fri, 26 May 2006 10:59:11 GMT
NNTP-Posting-Host: 70.108.4.182
X-Complaints-To: abuse@verizon.net
X-Trace: trnddc08 1148641151 70.108.4.182 (Fri, 26 May 2006 06:59:11 EDT)
NNTP-Posting-Date: Fri, 26 May 2006 06:59:11 EDT
Xref: g2news2.google.com comp.lang.ada:4489 comp.lang.fortran:10285
Date: 2006-05-26T10:59:11+00:00
List-Id: <comp.lang.ada>

Hello,

Ludovic Brenta wrote:

<snip>

> And that's why Ada specifies that I cannot change inside the loop, and
> is undefined outside the loop; see ARM 5.5 (9, 10).
> 
> You seem to imply that Fortran has a similar rule, but that compilers
> do not enforce that rule, and therefore have to perform range checking
> to enforce a non-existent language rule about array access.  I am
> confused.  Could you clarify?

A loop index cannot be changed within the loop.
Some compilers may have an option to allow older code
to work without modification by allowing modification
within the loop.  (Basically, this is to avoid re-certification
costs incurred when the code is modified in any way.)

The value at loop termination is defined to be the last value
within the loop, plus the increment.  For a concurrent loop
or for a forall, the index values are undefined outside
the loop.

-- 
Cheers!

Dan Nagle
Purple Sage Computing Solutions, Inc.