Re: GNOME vs GNU gcc & glibc

[Ronald de Man <deman win tue nl>]

On Wed, Apr 07, 1999 at 11:13:09AM -0400, Gleef wrote:
> 
> On Wed, 7 Apr 1999, Sergio Brandano wrote:
> [snip]
> > >   Note that the latest compilers (egcs, pgcc, gcc 2.8) may do Bad
> > >Things while compiling your kernel, particularly if absurd
> > >optimizations (like -O9) are used.
> 
> Note that the "Bad Things" with optimization issue also carries over to
> GNOME.  I have seen some buggy binaries where the bugs were in the
> compiler's optimization, rather than in GNOME.

I've had some problems that went away after recompiling with less
aggresive optimization. A couple of times (in the case of gmc) the
reason was broken dependencies that got fixed by a clean recompile.

There was a period that I had to compile ORBit with gcc-2.7 to get it
working. But nowadays I'm using pgcc again with -O6 and I'm having
no problems. If you ask me, it was probably not a bug in pgcc, but
something like an uninitialized variable in ORBit that got a different
value when compiled with pgcc -O6.

I've experienced this myself in a 10-line program that I once wrote.
It worked perfectly with -O2, and crashed with -O6. It took me quite
a while to understand that the problem was in my code (which taught me
to read the description of library functions before using them).

About the Linux kernel: Linus officially only supports gcc-2.7.2.3.
I compile with pgcc-1.1 and -O2 -fomit-frame-pointer without experiencing
problems, but there are problems with this combination, it's just that
my particular configuration apparently doesn't suffer from them.

Anyway, I agree that if you have a certain problem that nobody else seems
to have, it is worth the trouble of doing a clean recompile without
optimization, or with a different compiler.

Ronald