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From: ak@muc.de
Subject: Re: Beginner's questions
Date: 1999/05/08
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In article <37332A6D.B0D02309@aasaa.ofe.org>,
David Starner <dstarner98@aasaa.ofe.org> writes:
> Robert Dewar wrote:
>> This is nothing to do with fashion, it is to do with user requirements.
>> All that is needed to make garbage collection appear in GNAT for example
>> is some customer who really needs it and is willing to fund at least part
>> of the development cost.

> One thing that may make this easier is that EGCS snapshot now includes a
> conservative garbage collector for the Java compiler, so it shouldn't be
> that hard to connect GNAT to that garbage collector when it runs on
> EGCS. Trying that is on my list for my first EGCS project (hopefull
> sometime in the next few years.)

I only see a slightly hacked version of the Boehm GC in the libgcj repository.
The egcs CVS server seems to also carry a separate "egcs_gc_branch" where some 
experimental work is going on to replace some of the obstack usage in gcc with a GC
scheme. 

Both things are not very helpful for implementing GC in the Ada runtime I think.

>> Note that it is perfectly posssible to use any one of several conservative
>> garbage collectors with GNAT. 
> Like writing an interface for the Boehem GC for each class? Is there a
> better conservative GC to use with Ada, or a more Ada-native interface?

What is wrong with the Boehm GC? 

>> Why don't these meet your needs?
> Because we're lazy, and it's much easier just to set a compiler switch.
> Also, the documentation offers no clues that it is safe to use such
> garbage collectors. It would be nice to have a statement in the compiler
> docs that it should be fairly safe to use a conservative garbage
> collector.

With the conservative boehm gc it would most likely be only a "-lgc" switch.
 
Of course it could do better with some compiler cooperation, but is there
any strong reason why a conservative GC cannot just be plugged in?

-Andi