new register allocator and HARD_REGNO_CALL_PART_CLOBBERED

[Joern Rennecke]

Michael Matz wrote:
> I want to ensure that I understand the problem correctly, so please
> correct me if I'm wrong.
> 
> The problem is, that some hardregs are not allowed for pseudos live
> over calls, i.e. a subset of the caller-saved-regs-problem, _but_:
>  1) this set depends on the mode of the actual pseudo, and

Yes.

>  2) this set can change for each call, i.e. depends on the actual call.

It's not really the call that might be different, but if a different pseudo
is tracked across a different call, you have to consider the mode of that
other pseudo.  This is relevant if you want to merge webs for different
pseudos.
	
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