The relative-addressed case in shader_register_normalise_arrayed_addressing()
leaves the control point id in idx[0], while for constant register
indices it is placed in idx[1]. The latter case could be fixed instead,
but placing the control point count in the outer dimension is more
logical.
The FXC optimiser sometimes converts a local array of input values into
direct array addressing of the inputs, which can result in a
dcl_indexrange instruction spanning input elements with different masks.
For example, this occurred in a shader:
reg_idx write_mask
0 xyz
1 xyzw
2 xyzw
3 xyz
The dcl_indexrange instruction covered only xyz, so once merged, searching for
xyzw failed.
It is impossible to declare an input array where elements have different
component counts, but the optimiser can create this case. One way for
this to occur is to dynamically index input values via a local array
containing copies of the input values. The optimiser converts this to
dynamically indexed inputs.
