Patches for SI

[Christian König]

Am 21.03.2013 15:02, schrieb Michel Dänzer:
> On Don, 2013-03-21 at 12:37 +0100, Christian König wrote:
>> attached are the next bunch of improvements for the SI llvm backend.
>>
>> Since Tom is on vacation it's probably on us to review them ourself.
>> They are stabilizing the register allocation, and so should make it
>> possible to use RegPressure scheduling again without running out of
>> registers in (for example) lightsmark.
> Sounds good.
>
> Patch 2 makes sense for the intrinsics loading inputs or constants, but
> how is texture sampling not reading from memory? :)

Well also constant loads read from memory, the trick is that this memory 
isn't supposed to change (Well as long as we don't support image write 
functions, but AFAIK we don't want to use them with samplers).

>
> For patch 3, 'switch back to RegPressure' is somewhat misleading, as we
> were originally not setting any scheduling preference, and I don't think
> RegPressure is the default? Also, will this tend to result in using more
> GPRs? Couldn't using fewer GPRs allow dispatching more threads in
> parallel in some cases?

No, RegPressure was indeed the default before you changed it to Source. 
The point is that RegPressure should indeed use less GPRs, but that only 
works if you specify a register pressure, otherwise it seems to just 
schedule pretty much randomly.

>
> Patch 6 is above my head I'm afraid.
>
> The rest looks good to me.
>
>

Christian.