From: Fabrice Le Fessant <fabrice.le_fessant@inria.fr>
To: Sylvain Le Gall <sylvain@le-gall.net>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Re: Subtyping structurally-equivalent records, or something like it?
Date: Tue, 04 May 2010 17:18:00 +0200 [thread overview]
Message-ID: <4BE03AA8.30408@inria.fr> (raw)
In-Reply-To: <slrnhu092j.mc9.sylvain@gallu.homelinux.org>
"ocamlopt" does optimize data representation: for example, it can unbox
floats into registers, or into arrays of floats. However, there is a
tradeoff between such optimizations and efficiency: when you do too much
representation optimisation, you might end up performing a lot of tests
because a given type can be represented in multiple formats, and
performing a lot of transformations between the representations,
especially as the FFI (Ocaml interface to C) specifies the
representation of data.
Of course, I am not saying it is not possible to do better: it requires
a lot of energy, the compiler code becomes more complex, and the
improvement on speed is not clear.
--Fabrice
Sylvain Le Gall wrote, On 05/04/2010 03:42 PM:
> On 04-05-2010, rossberg@mpi-sws.org <rossberg@mpi-sws.org> wrote:
>> "Sylvain Le Gall" <sylvain@le-gall.net>:
>>> This is not about optimized compiler in this case but about data
>>> representation. Even if you use an optimized compiler (which is not
>>> really the case with ocamlopt), you won't change datastructure
>>> representation to optimize.
>> What do you mean? There is no reason in general why a compiler cannot
>> optimize data representations, and some do in cases like this.
>>
>
> Anyway, if it comes to data alignement and things like that, the
> compiler should optimize data representations. But in this case, I
> really don't think we are talking about data alignement.
>
> Regards,
> Sylvain Le Gall
>
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--
Fabrice LE FESSANT
Chercheur, Equipe ASAP
(As Scalable As Possible)
http://www.lefessant.net/
INRIA-Futurs, Bat P - 112
Parc Orsay Université
2-4, rue Jacques Monod
F-91893 Orsay Cedex, FRANCE
next prev parent reply other threads:[~2010-05-04 15:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-01 19:55 [Caml-list] " Dario Teixeira
2010-05-01 20:01 ` Sylvain Le Gall
2010-05-04 10:33 ` [Caml-list] " AUGER Cédric
[not found] ` <4429.86797211251$1272970133@news.gmane.org>
2010-05-04 11:53 ` Sylvain Le Gall
2010-05-04 12:47 ` [Caml-list] " rossberg
2010-05-04 13:42 ` Sylvain Le Gall
2010-05-04 15:18 ` Fabrice Le Fessant [this message]
2010-05-05 9:31 ` [Caml-list] " Goswin von Brederlow
2010-05-05 12:12 ` rossberg
2010-05-05 16:46 ` Goswin von Brederlow
2010-05-04 13:37 ` Edgar Friendly
2010-05-05 9:33 ` Goswin von Brederlow
2010-05-05 11:10 ` Yaron Minsky
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