pr11135: make PIC register a pseudo

[Mike Stump]

On May 13, 2007, at 3:32 AM, Rask Ingemann Lambertsen wrote:
> On Fri, Jan 06, 2006 at 02:48:30PM -0800, Richard Henderson wrote:
>>
>> What they're looking for is, for functions that don't use
>> the pic register, to not reserve the pic register so that
>> it's available for computation.  This is harder.  In theory,
>> ppc has some scheme for this, where they eliminate the pic
>> register to itself.  I've never really understood how that's
>> supposed to work.
>
>   Suppose you tell reload that %rpic can be eliminated as %rpic + 0.  
> Reload
> will start out by assuming that the elimination is possible and  
> %rpic will
> be available for reloads. If no insns mention %rpic at all, it  
> should just
> work, and you will have recovered a register.

Hum...  Could this work on the i386 port (32-bit) to get another  
register?  If so, we'd love to have the extra register when  
possible.  :-)