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From: " "@deneb.cygnus.argh.org (Florian Weimer)
Subject: Re: GNAT: pragma Ravenscar
Date: 1999/12/01
Message-ID: <877liy2u7d.fsf@deneb.cygnus.argh.org>#1/1
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Jean-Marc Bourguet <bourguet@my-deja.com> writes:

> In article <87vh6j4tpo.fsf@deneb.cygnus.argh.org>,
>   " "@deneb.cygnus.argh.org (Florian Weimer) wrote:
> > Alfred Hilscher <Alfred.Hilscher@icn.siemens.de> writes:
> >
> > > I thought when I build the same program twice, once with this pragma
> > > and again without this pragma then I would get different sized
> > > exe-files (because a smaller runtime included). But when I did so,
> > > I've got both times the same size. Do I missunderstand what the
> > > pragma does or do I miss some GNAT switches ? I've looked to the
> > > documentation but I found no answer there.
> 
> As I understood it, pragma Ravenscar aim was to enforce some
> restrictions, not to reduce the run time size. (I seems to recall
> another pragma Resticted_Run_Time which had this goal). I've never
> used these pragmas so I may be wrong.

The Ravenscar restrictions permit the use of a simplified run time
environment.

The GNAT reference manual says the following (for Resticted_Run_Time,
pragma Ravenscar is similar):

|    This set of restrictions causes the automatic selection of a
|    simplified version of the run time that provides improved
|    performance for the limited set of tasking functionality permitted
|    by this set of restrictions.

But GNAT 3.12p doesn't enforce the restrictions, and the standard run
time library is always used.  Some time ago, I browsed the compiler
sources, and IIRC I found nothing which looks like a handler for these
pragmas, so I think they are a no-op in the public version.