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From: "Martin Dowie" <martin.dowie@baesystems.com>
Newsgroups: comp.lang.ada,comp.realtime,comp.software-eng
Subject: Re: Teaching new tricks to an old dog (C++ -->Ada)
Date: Wed, 9 Mar 2005 09:24:47 -0000
Organization: BAE SYSTEMS
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Xref: g2news1.google.com comp.lang.ada:8917 comp.realtime:1108
 comp.software-eng:4668
Date: 2005-03-09T09:24:47+00:00
List-Id: <comp.lang.ada>

Martin Dowie wrote:
> CTips wrote:
>> Actually, I can verify that: if I look at the computer shootout
>> http://shootout.alioth.debian.org/great/, I find that gcc C beats
>> gnat Ada pretty much across the board; actually, Ada's performance
>> sucks pretty much across the board. One of gcc C or Intel C is
>> generally among the top few programs, while with a couple of
>> exceptions, Gnat Ada is around the middle. In matrix multiply it
>> gets beaten by LISP, Java, and Python!!! (How can you get beaten by
>> Python? The mind boggles!)
>
> It's very easy when you don't switch on _any_ optimizations! :-)
>
> GNAT is being compiled with the equivalent of "-O0" and GCC C is
> getting "-O3".

AdaCore (who maintain GNAT) have long claimed that equivilent Ada
and C code will produce identical results and that they have such examples.
The problem is in generating /equivilent/ programs to start with. E.g. in
the
matrix multiplication test, the writer of the Ada program has chosen to
result
arrays (by value!) from his functions, where as the C program uses
pointer-to-pointer-to-int. A better idiom for the Ada version would have
been
to use a procedure with an 'out' parameter rather than functions.

Cheers

-- Martin