From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail1-relais-roc.national.inria.fr (mail1-relais-roc.national.inria.fr [192.134.164.82])
	by walapai.inria.fr (8.13.6/8.13.6) with ESMTP id p0VICxXJ025148
	for <caml-list@sympa-roc.inria.fr>; Mon, 31 Jan 2011 19:12:59 +0100
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: Al0BAAOKRk3B/BfVkWdsb2JhbAClDQEBAQEJCwoHEQMhvWeFTgSMIYNFiEw
X-IronPort-AV: E=Sophos;i="4.60,405,1291590000"; 
   d="scan'208";a="98949889"
Received: from msa04.smtpout.orange.fr (HELO msa.smtpout.orange.fr) ([193.252.23.213])
  by mail1-smtp-roc.national.inria.fr with ESMTP; 31 Jan 2011 19:12:54 +0100
Received: from [192.168.1.63] ([83.199.112.88])
	by mwinf5d33 with ME
	id 2JCs1g00U1uVNnn03JCtNf; Mon, 31 Jan 2011 19:12:53 +0100
Message-ID: <4D46FB9E.5040805@lexifi.com>
Date: Mon, 31 Jan 2011 19:12:46 +0100
From: Alain Frisch <alain.frisch@lexifi.com>
Organization: LexiFi
User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7
MIME-Version: 1.0
To: Nicolas Ojeda Bar <nojb@math.harvard.edu>
CC: caml-list@yquem.inria.fr
References: <476C4EB3-59D2-4756-927C-C1697E7AE4D8@math.harvard.edu>
In-Reply-To: <476C4EB3-59D2-4756-927C-C1697E7AE4D8@math.harvard.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Caml-list] reference cells

On 01/31/2011 05:29 PM, Nicolas Ojeda Bar wrote:
> I am translating an imperative language into Ocaml. Right now I am
> translating mutable variables into ref cells. Will they be optimized
> when I compile the corresponding Ocaml program? Or will they be heap
> allocated? If this is the case, I will have to translate my language
> into some sort of SSA form before, and I would like to avoid that.

Mutable variables which are used only internally in a function's body
are not heap allocated.

If you write:

    let r = ref e0 in e1

and r only appears in e1 under the form:

     r := ...
     !r

and not under a local abstraction, then the reference is kept in a local 
variable.

You can use the -dlambda switch to the compilers and toplevel to see that.


-- Alain