patch applied (ghc): massive changes to add a 'zipper' representation of C--

[Simon Marlow]

Ben Lippmeier wrote:
>  
>> | It would be nice to make Ben's register allocator available for
>> testing on
>> | the 6.8.x series, as it will give better results in some case (albeit
>> only
>> | a few at the moment).  Since most of the code is already in the
>> branch, I
>> | don't think it's a problem to keep pushing patches in.
>>
>> The reason for caution is that Ben and Norman are fiddling with the
>> same code.  So they'll be ok on the head, but Ben's patches (without
>> Norman's) might not apply smoothly to the branch
> 
> About half of the new register allocator code is a generic graph colouring
> library that doesn't ever see the Cmm IR, or even knows what a register is..
> It looks like Norman's mega-patch touched some of the interface between Cmm
> and graph land but not the generic graph stuff itself, which is fairly
> separate.
> 
> I should be able to push improvements to the graph algorithms into 6.8 which
> are separate from what Norman is doing. I'll make sure to validate on 6.8 as
> well as the head - sounds ok?

Sounds fine to me.

Cheers,
	Simon