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: 103376,7767a311e01e1cd
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Date: Fri, 20 Oct 2006 14:52:34 +0200
From: Gautier <gautier@fakeaddress.nil>
User-Agent: Thunderbird 1.5.0.7 (Windows/20060909)
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Subject: Re: GNAT compiler switches and optimization
References: <1161341264.471057.252750@h48g2000cwc.googlegroups.com>
In-Reply-To: <1161341264.471057.252750@h48g2000cwc.googlegroups.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
NNTP-Posting-Host: 83.77.182.167
X-Original-NNTP-Posting-Host: 83.77.182.167
Message-ID: <4538c67e$1_2@news.bluewin.ch>
X-Trace: news.bluewin.ch 1161348734 83.77.182.167 (20 Oct 2006 14:52:14 +0200)
Organization: Bluewin AG
Complaints-To: abuse@bluewin.ch
X-Original-NNTP-Posting-Host: 127.0.0.1
Path: 
 g2news2.google.com!news3.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!wns13feed!worldnet.att.net!164.128.36.58!news.ip-plus.net!newsfeed.ip-plus.net!news.bluewin.ch!not-for-mail
Xref: g2news2.google.com comp.lang.ada:7077
Date: 2006-10-20T14:52:34+02:00
List-Id: <comp.lang.ada>

tkrauss wrote:

>    N := Positive'Value (Argument (1));
...
>    for I in A'range(1) loop
>       for J in A'range(2) loop
probably you have a penalty there against
>    do I = 1,N
>       do J = 1,N
I guess the GNAT compiler can't tell that due to
 >   A := new Real_Matrix(1..N, 1..N);
esp. because alloc. is dynamic, you indeed have:
   for I in 1..N loop
Then you should try that and even
   for I in reverse 1..N loop
Perhaps g95 does that optimization when Ada has to stick with the mentioned 
direction.
Also, compiling with -S and looking at the assembler code helps a lot...
HTH, Gautier
______________________________________________________________
Ada programming -- http://www.mysunrise.ch/users/gdm/gsoft.htm

NB: For a direct answer, e-mail address on the Web site!