From: Vincent Aravantinos <vincent.aravantinos@gmail.com>
To: Ethan Burns <burns.ethan@gmail.com>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Comparing variant types
Date: Thu, 28 Apr 2011 23:07:38 +0200 [thread overview]
Message-ID: <2E33DAF4-C496-41ED-9208-61E66BD1AB82@gmail.com> (raw)
In-Reply-To: <BANLkTi=55g=rwiRm03_eS=uyGGDCoi4ezg@mail.gmail.com>
Hi,
without entering any details, probably the following links would be
interesting to you:
http://ocaml.janestreet.com/?q=node/33
http://ocaml.janestreet.com/?q=node/35
V.
Le 28 avr. 11 à 21:16, Ethan Burns a écrit :
> Hi,
>
> I have a program that uses variant types as an enumeration. While
> profiling, I noticed that compare_val was being called a bunch. When
> I went to inspect why this was the case, it turns out that it was
> being called to compare equality of my variants. I am a bit confused,
> however, because my understanding was that variants that are declared
> without an 'of' clause were just represented as integers and therefore
> a type containing only these simple elements should be directly
> comparable (no compare_val).
>
> While looking further into this, I found a little example where the
> compiler seems to produce a simple comparison in one case and not in
> another:
>
> type dir = Left | Right | Up | Down | No_op
>
> (* performs a simple comparison *)
> let f a = a <> Right
>
> (* calls out to C to do compare_val *)
> let g (a:dir) b = a <> b
>
> There is the -dlambda output:
>
> (seq
> (let (f/69 (function a/70 (!= a/70 1a)))
> (setfield_imm 0 (global Test!) f/69))
> (let (g/71 (function a/72 b/73 (caml_notequal a/72 b/73)))
> (setfield_imm 1 (global Test!) g/71))
> 0a)
>
> Since both functions know that the types of the elements being compare
> is 'dir', which contains only simple elements, why does the g function
> still use compare_val? Does the compiler not perform this particular
> optimization?
>
>
> Best,
> Ethan
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa-roc.inria.fr/wws/info/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
next prev parent reply other threads:[~2011-04-28 21:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-28 19:16 Ethan Burns
2011-04-28 21:07 ` Vincent Aravantinos [this message]
2011-04-28 22:56 ` Ethan Burns
[not found] ` <354087020.772283.1304031467793.JavaMail.root@zmbs4.inria.fr>
2011-04-29 8:46 ` Fabrice Le Fessant
2011-04-29 8:57 ` Dmitry Bely
[not found] ` <164004794.892685.1304067487325.JavaMail.root@zmbs2.inria.fr>
2011-04-29 9:33 ` luc.maranget
2011-04-29 10:54 ` Andrew
2011-04-29 11:17 ` Dmitry Bely
2011-04-29 12:15 ` Jon Harrop
2011-04-30 16:38 ` Andrew
2011-04-29 11:32 ` Dmitry Bely
2011-04-30 13:43 ` craff73
2011-04-30 19:26 ` Andrew
2011-04-30 20:19 ` Gabriel Scherer
2011-04-30 20:57 ` Yaron Minsky
[not found] <fa.FGXk5PCsQgS8TidmFkgljpqbLZo@ifi.uio.no>
2011-04-29 11:54 ` Ethan Burns
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