Better handling for multi-word values?

[Bernd Schmidt]

> 
> An alternate solution woul be to introduce a target macro that takes
> a register class and a mode, and tells if a register group actually needs
> to use consecutive registers.

Actually, in my current patch, the machine description gets to decide whether
a given mode is allocated as a MULTIWORD, or as a normal single pseudo reg.

The requirement might differ between different instructions: consider the
i386 mulsidi3 pattern, which does need consecutive registers, although none
of the other DImode operations do.  So there needs to be a way for reload to
decide per operand whether a group is needed or not, the macro is only a hint.

Are there any machine descriptions which actually require multi-word integer
values to be in consecutive hard regs (except for special cases like the i386
mulsidi3)?

Bernd