S/390: -march= and -mcpu= options

[Ulrich Weigand]

David Edelsohn wrote:

>First there are backward compatibility issues in a complete s390
>port.

Which issues are you thinking of?  Up to now, the s390 port has
never accepted any of the options under discussion now, so there
are no old options to be compatible with ...

>Second, the people who participated in the earlier discussion
>agreed that there should be a shorthand.

Why shouldn't -march=z900 be enough?  The compiler has to 
select *some* scheduling model, and it would be silly to
schedule for a CPU the generated code cannot run on, thus
it would be reasonable to default to -mtune=z900 if
-march=z900 is given.  What should then be the difference 
between -mcpu=z900 and -march=z900?

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de