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From: jloup@nocturne.chorus.fr (Jean-Loup Gailly)
Newsgroups: comp.lang.ada
Subject: Re: Reducing size of Ada's EXE files
Message-ID: <9348@chorus.fr>
Date: 16 Apr 91 08:47:05 GMT
References: <437@wrdis01.af.mil> <1991Apr12.235101.7245@jpl-devvax.jpl.nasa.gov> <3049@sparko.gwu.edu>
Sender: jloup@chorus.fr
Reply-To: jloup@nocturne.chorus.fr (Jean-Loup Gailly)
Organization: Chorus systemes, Saint Quentin en Yvelines, France
List-Id: <comp.lang.ada>

In article <3049@sparko.gwu.edu>, mfeldman@seas.gwu.edu (Michael Feldman)
writes:

| In article <1991Apr12.235101.7245@jpl-devvax.jpl.nasa.gov>
| larryc@poe.jpl.nasa.gov (Larry Carroll) writes:

> Agreed, it takes a smart linker to know just what part of a package you need.
> For instance, any variables global to a package which are used by the desired
> subprogram will need to be linked in. Any initialization code you include at 
> the end of the package, & all the subprograms & global variables they use,
> must be linked.  And so on.  But eventually such smart linkers must become 
> available if Ada is to compete successfully with other languages.
>
> Anyone know which vendors supply such linkers?

| Three I am familiar with are the TeleSoft, Meridian, and Janus/Ada families.
| Indeed they throw away unused subprograms. In my experience, invoking this
| global optimization, as it's usually called, requires both compiling and
| linking with a command-line switch set, because preparing for and doing this
| optimization takes time and space, and one doesn't want to do it unnecessarily.

All Alsys compilers remove unused subprograms by default, but you can
set a bind time option to keep them. On the 370, we found that it was often
*cheaper* to remove unused subprograms, because the bind time was dominated
by the IO, and the binder had less IO to perform when unused subprograms
were eliminated. Alsys does not require a compile time option. The call
graph is kept systematically because it is stored in a very compact form.

Jean-loup Gailly
(formally within Alsys)

Chorus systemes, 6 av G. Eiffel, 78182 St-Quentin-en-Yvelines-Cedex, France
email: jloup@chorus.fr    Tel: +33 (1) 30 64 82 79 Fax: +33 (1) 30 57 00 66