GCC 4.0 vs. 3.5

[Geert Bosch]

On Apr 16, 2004, at 21:04, Mark Mitchell wrote:
> I think that tree-ssa is a big deal, but it's not a feature -- it's an 
> implementation detail.  New and/or better optimizations would be new 
> features.
>
> So, if we're switching to 4.0 it should be because the code we 
> generate is far better.

It seems reasonable to call a "major update" one where a lot changes.
Even though from a narrow C/C++ point of view, one might argue that we
still implement pretty much the same language and generate code for
the same targets, this is only one axis.

The reality is that many things change. New languages are added
(Fortran 95), others are dropped (Fortran 77, maybe Ada temporarily).
Compiler behavior will be different. The compiler will do much better
on some code, worse on others. More so than with ordinary releases.

> So, calling it 4.0 would be patting ourselves on the back, but 
> miscommunicating with the users.

No, it warns uses: a lot has changed. This is a .0 release with lots
of code that has not previously been tested by actual use. Releasing
a new major version communicates this risk better than anything else.

As a large part of GCC has been rewritten to incorporate a modern
compiler infrastructure, there also is a reason to fly the flags
and celebrate. Quite a few people may be nominated for a pat
on the back too.

   -Geert