Hi,

The reason I add this is that TGSI doesn't allow indirect indexing of inputs 
and outputs. Consider this:

MOV OUT[ADDR[0]-1000], IMM[0]

There is no way to know where the output array starts here. It could be for 
example OUT[6]=GENERIC4 or anything else. The problem is some outputs are 
physically stored in a different memory domain than others. Per-patch 
(tessellation) outputs are one such example. Does the MOV instruction write a 
per-vertex or per-patch output? There is no way to know.

The problem can be avoided by using carefully-generated unoptimized TGSI where 
the relative index is the same as the base of the array, which is OUT[6] here:

UADD TEMP[0].x, TEMP[0].x, -1006
UARL ADDR[0], TEMP[0].x
MOV OUT[ADDR[0]+6], IMM[0]

This hack helps for this case, but the drivers which do move outputs to temps 
are still unable to allocate registers efficiently, because there is no way to 
know the actual array size.

This patch series adds proper TGSI support for IN/OUT arrays. It works in the 
same way as temp arrays and it's a requirement for tessellation.

Please review.

Marek
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