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[Caml-list] factor 5 speed increase for natively compiled camlp4 parsers
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Date: -- (:)
From: Michel Mauny <Michel.Mauny@i...>
Subject: Re: [Caml-list] factor 5 speed increase for natively compiled camlp4 parsers
Dear Henrik,

Hendrik Tews wrote/écrivait (Tue, Jun 08, 2004 at 01:17:27AM +0200):

> QUESTIONS TO EXPERTS AND CAMLP4 MAINTAINERS:

> 1. Why is the -linkall neccessary? Its clear to me that one needs
>    the -linkall when building camlp4o. However, I don't
>    understand why camlp4o.opt needs the -linkall.

It is because of the programming style used in the modules to be
linked: some of them are not referenced (and therefore not linked in
without -linkall), but have useful actions in their initialisation
code, such as fill in an external reference with a function they've
just defined. The -linkall option makes sure that all initialisation
codes are executed.

Now I agree with you that it looks strange. What I did (in the CVS)
is to use -linkall for building camlp4.cmxa: this way your recipe
works even without -linkall.

> 2. Is the process that generates pa_o_fast.ml applicable to all
>    camlp4 grammars?

No: it relies on the particular structure of files pa_o.ml and
pa_op.ml.

>    Why is it not used for the revised syntax?

I suspect the revised syntax is meant to stay extensible, and this
extensibility would be lost if the parser was compiled `as much as'
the one obtained in pa_o_fast. This is just a guess: I don't master all
Camlp4 secrets (yet) ;-)

>    What is the option -meta_action of pa_extend.cmo doing?

It decides wether actions are to be interpreted as expressions or
meta-expressions (expressions at the meta-level). In short, it decides
wether "2+3" is parsed as the expression 2+3 or the expression
<:expr<2+3>>.

> 3. Would it be possible to include a ``mknativecamlp4'' script
>    that automates the described procedure in the next
>    distribution?

I'll see what I can do, but note that this not a top priority right now.

>    Would it be possible to build and install pa_o.cmx, pa_op.cmx,
>    pa_o_fast.cmx, and odyl.cmx? 

Done in the CVS.

Thanks,

-- Michel

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