nir: treat per-view outputs as arrayed IO

This is needed for implementing multiview in panvk, where the address
calculation for multiview outputs is not well-represented by lowering to
nir_intrinsic_store_output with a single offset.

The case where a variable is both per-view and per-{vertex,primitive} is
now unsupported. This would come up with drivers implementing
NV_mesh_shader or using nir_lower_multiview on geometry, tessellation,
or mesh shaders. No drivers currently do either of these. There was some
code that attempted to handle the nested per-view case by unwrapping
per-view/arrayed types twice, but it's unclear to what extent this
actually worked.

ANV and Turnip both rely on per-view outputs being assigned a unique
driver location for each view, so I've added on option to configure that
behavior rather than removing it.

Signed-off-by: Benjamin Lee <benjamin.lee@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31704>

src/compiler/nir/nir_opt_vectorize_io.c

@@ -520,9 +520,11 @@ nir_opt_vectorize_io(nir_shader *shader, nir_variable_mode modes)
 
             case nir_intrinsic_load_output:
             case nir_intrinsic_load_per_vertex_output:
+            case nir_intrinsic_load_per_view_output:
             case nir_intrinsic_load_per_primitive_output:
             case nir_intrinsic_store_output:
             case nir_intrinsic_store_per_vertex_output:
+            case nir_intrinsic_store_per_view_output:
             case nir_intrinsic_store_per_primitive_output:
                if (!(modes & nir_var_shader_out))
                   continue;