A few simple DImode improvements

[Jeff Law]

On 06/28/10 12:20, Bernd Schmidt wrote:
> I don't know
>> whether this a concern with IRA; can IRA allocate a DImode pseudo to a
>> floating point register if there are SImode SUBREGs of it?  The old
>> register allocator wouldn't, and you could wind up with a bunch of
>> reloads.
>>      
> I don't know whether IRA would do that or whether it can determine the
> costs correctly; I can't find anything right now which would deal with
> this case.
>    
It should be merely a question of consulting CANNOT_CHANGE_MODE_CLASS 
(for correctness) and costing models.  It shouldn't really need special 
handling.

jeff