[patch] h8300: Improve loads of certain constants.

[Kazu Hirata]

Hi Toshi,

> > On H8/300, if one wants to load a constant whose upper and lower part
> > are the same like 0x12341234, then gcc generates
> > 
> > 	mov.w	#4660,r0
> > 	mov.w	#4660,r1
> > 
> > This can be improved as
> > 
> > 	mov.w	#4660,r0
> > 	mov.w	r0,r1
> 
> 
> Is this done post-reload?        
>
> We should give CSE/GCSE a chance to optimize redundant constants before   
> optimizing the constant loads into registers.

This is done at final, so I don't think I am interfering with CSE or
GCSE.

Kazu Hirata