[oi-dev] Compiler migration #2

[Bob Friesenhahn]

On Sat, 26 Jan 2013, Peter Tribble wrote:

> Adam,
>
>> I am continuing on completing studio -> gcc compiler migration. As this is
>> something, which will take a century to complete, I have come to a
>> conclusion that I will directly update stuff and make sure it is buildable
>> by gcc44.
>
> Just one question - why gcc44? In other words, why not jump straight
> to gcc 4.7?

I agree that there is no (or should be no) technical reason to prefer 
4.4.4 (4.4.0 was released on April 21, 2009) for user-space code 
outside of core Illumos.  In fact, there is good reason to keep up 
with GCC major releases and use a similar GCC for building user-space 
code as popular stable Linux distributions use.  This would ease 
porting of Linux applications which are typically developed/tested 
with the GCC provided with Linux.  On open-source development lists, I 
am seeing considerable interest from developers to use the latest C 
and C++ standards which implies that the code they write will prefer 
compilers implementing those standards.

The main concern is with C++ ABIs, which may require that 
libraries/applications depending on a particular C++ standard library 
and ABI be updated in a consistent way on a periodic basis (e.g. every 
two years).  If there is actual instability (yet to be demonstrated), 
then this has consequences for independently packaged software.

Illumos uses (patched) 4.4.4 because that is what there was available 
developer time to use and the kernel has special needs.

GCC 4.4 does not produce code for modern CPUs whereas GCC is 
continually enhanced to be able to produce code which targets modern 
CPUs.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/