ia32 inter-unit move fixes, part 1

[Chris Lattner]

On Feb 6, 2007, at 11:16 AM, Jan Hubicka wrote:

>>> In this patch, I rename the existing Y constraint to Y2, so that
>>> I can add a Yi constraint for use when inter-unit moves are
>>> allowed.  In the balance of the patch, I adjust the md files
>>> to match.  No uses of Yi are yet included, only renaming from
>>> the old name.  For the insn patterns that require SSE2 in the
>>> predicate, I rename to 'x', rather than use the conditional 'Y2',
>>> which should be reserved for when SSE2 might not be available.
>>
>> Does this break inline asm that uses the Y constraint?
>
> It does, but 'Y' was never documented and is meant internal only
> (ie it is enabled only when SSE2 is available, 'x' is in charge for  
> xmm
> registers). So if some users used 'Y' they should switch to 'x',  
> perhaps
> we can mention that in the news webpage.

Okay, makes sense!  Thanks,

-Chris