[RFA, PATCH, PowerPC] Implements PowerPC e500mc core support

[Mark Mitchell]

David Edelsohn wrote:

> 	Why is it not sufficient to configure GCC with e500 support if one
> wants ISEL?  In other words, e500mc will work and produced code with
> tuning, but ISEL only will be generated if configured for e500.

I don't think this should be an unconditionally static property of the 
compiler at configure time.  We have users that want to use a single 
Power compiler to target a wide variety of Power CPUs, ranging from 603s 
to e500mc to G5s.

(In fact, I think we should be moving to more dynamism, not less.  I 
would like to be able to target (say) ARM EABI and ARM GNU/Linux from 
the same compiler.  However, that's a very big change.)

However, it seems reasonable to have (say) powerpc-* target all possible 
CPUs, while powerpc<something>-* targets only those CPUs indicated by 
<something>.  For example, powerpcibm could target only IBM CPUs, or 
powerpcserver could target only server CPUs, or something.  Or maybe we 
could do --with-cpus=603,440 to mean "only support the CPUs I've listed".

I don't have any preconceived notion about how to spell these things, or 
how'd they map to anything.  I'm just trying to find a way that we can 
have both an uber-Power configuration in which all CPUs can be selected 
dynamically and a more-specific configuration that provides a smaller, 
faster compiler for a subset of CPUs.

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713