From: Robert A Duff <bobduff@shell01.TheWorld.com>
Subject: Re: Efficiency of code generated by Ada compilers
Date: Sun, 08 Aug 2010 11:49:29 -0400
Date: 2010-08-08T11:49:29-04:00 [thread overview]
Message-ID: <wccr5i985py.fsf@shell01.TheWorld.com> (raw)
In-Reply-To: f208e17c-0511-4397-a13a-39a3da6eef5e@q22g2000yqm.googlegroups.com
Gene <gene.ressler@gmail.com> writes:
> In some cases, a built-in Ada construct will generate better code than
> a "hand-coded" equivalent in C++. An example I ran into recently was
> incrementing a modular type. In Ada, you say I := I + 1;, and the
> compiler takes care of "wrapping" to zero. In C++, I've frequently
> seen people write i = (i + 1) % n; to simulate the same operation in
> the absence of modular types.
You will see me writing "I := (I + 1) mod N;" (for signed
integer I) in Ada. ;-)
>...In this case, GCC/C++ generates a div/
> mod instruction, which is very expensive.
That's surprising. It wouldn't be hard to optimize the
"I := (I + 1) mod N;" case (which would apply to both
C and Ada).
And it would be desirable, because in most cases the explicit
"mod" (or "%") is more readable.
- Bob
next prev parent reply other threads:[~2010-08-08 15:49 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-06 20:21 Efficiency of code generated by Ada compilers Elias Salomão Helou Neto
2010-08-06 20:24 ` (see below)
2010-08-06 23:14 ` Shark8
2010-08-07 7:53 ` Dmitry A. Kazakov
2010-08-10 13:52 ` Elias Salomão Helou Neto
2010-08-10 14:24 ` Shark8
2010-08-10 14:28 ` Shark8
2010-08-10 15:01 ` Robert A Duff
2010-08-10 15:14 ` Yannick Duchêne (Hibou57)
2010-08-10 18:32 ` Robert A Duff
2010-08-10 15:10 ` Georg Bauhaus
2010-08-10 15:32 ` Dmitry A. Kazakov
2010-08-10 22:26 ` Randy Brukardt
2010-08-20 7:22 ` Yannick Duchêne (Hibou57)
2010-08-08 14:03 ` Gene
2010-08-08 15:49 ` Robert A Duff [this message]
2010-08-08 17:13 ` Charles H. Sampson
2010-08-08 18:11 ` Dmitry A. Kazakov
2010-08-08 20:51 ` Robert A Duff
2010-08-08 22:10 ` (see below)
2010-08-08 22:22 ` Robert A Duff
2010-08-09 4:46 ` Yannick Duchêne (Hibou57)
2010-08-09 5:52 ` J-P. Rosen
2010-08-09 13:28 ` Robert A Duff
2010-08-09 18:42 ` Jeffrey Carter
2010-08-09 19:05 ` Robert A Duff
2010-08-10 10:00 ` Jacob Sparre Andersen
2010-08-10 12:39 ` Robert A Duff
2010-08-09 19:33 ` Yannick Duchêne (Hibou57)
2010-08-09 21:42 ` Robert A Duff
2010-08-10 12:26 ` Phil Clayton
2010-08-10 12:57 ` Yannick Duchêne (Hibou57)
2010-08-10 14:03 ` Elias Salomão Helou Neto
2010-08-10 14:27 ` Yannick Duchêne (Hibou57)
2010-08-10 22:50 ` anon
2010-08-10 23:28 ` Yannick Duchêne (Hibou57)
2010-08-10 23:38 ` Yannick Duchêne (Hibou57)
2010-08-11 7:06 ` Niklas Holsti
2010-08-11 11:58 ` anon
2010-08-11 12:37 ` Georg Bauhaus
2010-08-11 13:13 ` Robert A Duff
2010-08-11 23:49 ` Randy Brukardt
2010-08-10 14:31 ` Shark8
2010-08-11 7:14 ` Charles H. Sampson
2010-08-11 6:42 ` Charles H. Sampson
2010-08-08 22:35 ` tmoran
2010-08-09 13:53 ` Robert A Duff
2010-08-09 17:59 ` tmoran
2010-08-09 19:36 ` Yannick Duchêne (Hibou57)
2010-08-09 21:38 ` Robert A Duff
2010-08-11 7:42 ` Charles H. Sampson
2010-08-11 13:38 ` Robert A Duff
2010-08-12 7:48 ` Charles H. Sampson
2010-08-12 8:08 ` Ludovic Brenta
2010-08-12 17:10 ` Charles H. Sampson
2010-08-12 18:06 ` Jeffrey Carter
2010-08-11 18:49 ` Simon Wright
2010-08-12 7:54 ` Charles H. Sampson
2010-08-12 8:36 ` Dmitry A. Kazakov
2010-08-12 11:04 ` Brian Drummond
2010-08-12 19:23 ` Simon Wright
2010-08-12 20:21 ` (see below)
2010-08-13 15:08 ` Elias Salomão Helou Neto
2010-08-13 15:10 ` Elias Salomão Helou Neto
2010-08-13 18:01 ` Georg Bauhaus
2010-08-13 19:52 ` Robert A Duff
2010-08-14 9:44 ` Georg Bauhaus
2010-08-13 20:22 ` Robert A Duff
2010-08-14 1:34 ` Randy Brukardt
2010-08-14 7:18 ` anon
2010-08-13 21:57 ` Jeffrey Carter
2010-08-13 22:37 ` Yannick Duchêne (Hibou57)
2010-08-13 22:43 ` Yannick Duchêne (Hibou57)
2010-08-13 23:29 ` tmoran
2010-08-14 0:02 ` Yannick Duchêne (Hibou57)
2010-08-14 0:16 ` (see below)
2010-08-14 10:47 ` Brian Drummond
2010-08-14 13:58 ` Yannick Duchêne (Hibou57)
2010-08-15 0:23 ` Brian Drummond
2010-08-14 14:51 ` (see below)
2010-08-15 0:58 ` Brian Drummond
2010-08-15 1:58 ` (see below)
2010-08-15 10:31 ` Brian Drummond
2010-08-13 15:37 ` Dmitry A. Kazakov
2010-08-16 13:29 ` Elias Salomão Helou Neto
2010-08-16 14:09 ` Dmitry A. Kazakov
2010-08-18 14:00 ` Elias Salomão Helou Neto
2010-08-18 16:38 ` Dmitry A. Kazakov
2010-08-19 18:52 ` Elias Salomão Helou Neto
2010-08-19 19:48 ` Dmitry A. Kazakov
2010-08-13 16:58 ` (see below)
2010-08-14 16:13 ` Charles H. Sampson
2010-08-16 13:45 ` Elias Salomão Helou Neto
2010-08-15 12:32 ` Florian Weimer
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