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Message-Id: <20100901.094607.1753910472605096940.Christophe.Troestler+ocaml@umons.ac.be>
To: dmitry.bely@gmail.com
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Subject: Re: [Caml-list] Re: Question about float refs.
From: Christophe TROESTLER <Christophe.Troestler+ocaml@umh.ac.be>
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X-Spam: no; 0.00; christophe:01 troestler:01 christophe:01 troestler:01 ocaml:01 printf:01 printf:01 compiler:01 unboxed:01 wrote:01 dmitry:01 caml-list:01 minor:01 umh:01 bely:01 

On Wed, 1 Sep 2010 11:18:05 +0400, Dmitry Bely wrote:
> 
> >> Some black magic is needed:
> >>
> >> let r = ref 0.0 in
> >> for i = 0 to 1000_000_000 do r := float i done;
> >> Printf.printf "%f\n" (!r +. 0.);
> >> Printf.printf "words: %f\n" (Gc.stat ()).Gc.minor_words
> 
> Do you have any idea why the optimizer needs that?

It helps the compiler to figure out that “r” must be unboxed.
See also http://caml.inria.fr/mantis/view.php?id=5133

C.