Re: [Texmacs-dev] GCC 3.2 status update

[Igor V. Kovalenko]

Joris van der Hoeven wrote:
> > On PIII-750 unoptimized TeXmacs is rather usable :)
>
>
> Are there any problems left with the unoptimized version
> in the case of gcc-3.2?
It does not crash, and allows me to edit docs and export PS files. I can't say 
more.

> > Gee, you have a foresight of kind :)
> > We can possibly eliminate the GCC/c++ PR 8287 which is fixed as of my current 
> > testing.
> > More to go, I wish GCC team a luck. IMHO they do a nice job.
>
>
> I am afraid that I cannot longer say that they do a good job if something
> which worked fine with the compiler from two years ago does not work fine
> anymore after all "improvements". I do understand that a major change like 3.0
> caused a lot of problems, most of which were fixed in 3.1. However, after that,
> we may expect more stability, considering the fact that the gcc compiler
> is a central piece of software for so many people.
Well, they have exposed some of the subtlier inconsistencies in code. Say, some
violations of standard-defined type aliasing rules may be now catastrophic.
I do not have the latest C++ standard so I again can't be an expert here.

> > Now to the problem update.
> > As of 20021109 the default optimized compilation does a segfault *immediately*
> > if not using TeXmacs own memory allocators. Just run and click in the text area.
> >
> > If using own allocators you are able to invoke Help->Welcome page. Then try to
> > select first paragraph. When you release mouse button you get *triple* deletion
> > of tree object after which memory is guaranteed to be corrupted IMO. Well, with 
> > my
> > debugging patch there are two deletions of tree object that are reported, 
> > implying
> > there was another (the very first) one. 'this' address indicates that tree 
> > object
> > was on stack. When after these reports you click somewhere in the text area you 
> > have
> > another *two* reports (same diagnostics, same 'this' address) followed by a 
> > SIGSEGV.
> >
> > This thing with higher-level optimizations still gets more involved. There is 
> > even
> > a bug in compiler causing debugging information to be generated incorrectly...
>
>
> So if I understand you well, things are rather getting worse than better :^(((

AFAIK this bug should be present in all GCC>=3 versions... Does not affect
compiled code quality though.

>  
>
> > So... I should admit that main Linux distributions still can accept TeXmacs 
> > package
> > along with the requirement to use 'compat'-gcc package and it's libstdc++ 
> > implementation.
> > Anyway, Mozilla project seems to have some problems with GCC-3.2. RedHat (to 
> > name one :)
> > is shipping Mozilla packages compiled with 'compat'-gcc (2.96) package.
>
>
> OK. So the best thing would be to rewrite our configure script such that
>
> 1) We use g++-2.95.3 whenever the "compat" package is installed and
>    we add this as a dependency in the TeXmacs.spec file.
>
> 2) Use non-optimized compilation whenever the compat package is
>    not installed and there is only a bugged g++ compiler on the disc.
>
> 3) Add a line which makes the computer pray that everything will work.
>
> I will also try to provide a compilation option so as to compile with
> Boehme's gc as soon as I have time.
>
>
> > As to my plans regarding this topic, I'm sorry I should be rather busy with my 
> > PhD for
> > about a month from now on. Still, I'll find some time to test with GCC-3.2.1 
> > release :)
>
>
> Well, I wish to thank you thousand times for all the help that you have
> given so far, since debugging requires a lot of skill and patience.
> Good luck for your PhD. in the meantime,
>
> Joris

Thanks!

--
Regards,
Igor V. Kovalenko    mailto: iko at crec dot mipt dot ru