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From: Andi Kleen <ak@muc.de>
Subject: Re: GNAT versions ( was :Ada compiler for PC?)
Date: 1999/05/06
Message-ID: <m3so9aci9g.fsf@fred.muc.de>#1/1
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Sender: andi@fred.muc.de
References: <7fndu7$im4$1@nnrp1.dejanews.com> <7gbjhg$s98$1@rtl.cygnus.com>
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X-Trace: 6 May 1999 17:45:13 +0100, 195.180.232.64
Newsgroups: comp.lang.ada,gnu.misc.discuss
Date: 1999-05-06T00:00:00+00:00
List-Id: <comp.lang.ada>

Robert Dewar <robert_dewar@my-dejanews.com> writes:

> I did the design and implementation of the exception handling in
> Ada, so I am pretty familiar with what was and was not done. Yes
> there were early discussions about trying to deal with commonality
> between the languages, but unfortunately these did not result in
> a common facility. I tried to understand what had been done for
> C++ but failed. Others here at ACT are still trying to do more
> merging here, but it is not easy. I found no high level interface
> oriented description of the mechanism used for C++. Perhaps I
> simply did not look hard enough, or just did not know how to read
> the code correctly. I find the back end of GCC rather difficult
> to navigate (and indeed in a recent email Per Bothner (hope I
> remembered the spelling right) claimed that the entire gcc compiler
> was ill-documented so why single out the exception handling). I
> find that position FAR too pessimistic, and indeed in general the
> gcc backend is documented a lot better than many proprietary
> compilers with which I am familiar, but in this particular case,
> we have not yet achieved the ideal of merging the exception handling
> of C++ and Ada. I believe this could only have been achieved if we
> had started with a fully documented high level design.

As a first impression the GNAT 3.11 "zero-cost" EH implementation 
seems to usually generate smaller unwind tables than the egcs C++ 
EH implementation

(IMNSHO that is the main problem with the current egcs EH - too much
executable bloat)

It would be great if the best points of both could be merged.

-Andi