nir: Add a new pass to lower array dereferences on vectors

This pass was originally written for lowering TCS output reads and
writes but it is also applicable just about anything including UBOs,
SSBOs, and shared variables.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

src/compiler/nir/nir.h

@@ -2973,6 +2973,16 @@ void nir_fixup_deref_modes(nir_shader *shader);
 
 bool nir_lower_global_vars_to_local(nir_shader *shader);
 
+typedef enum {
+   nir_lower_direct_array_deref_of_vec_load     = (1 << 0),
+   nir_lower_indirect_array_deref_of_vec_load   = (1 << 1),
+   nir_lower_direct_array_deref_of_vec_store    = (1 << 2),
+   nir_lower_indirect_array_deref_of_vec_store  = (1 << 3),
+} nir_lower_array_deref_of_vec_options;
+
+bool nir_lower_array_deref_of_vec(nir_shader *shader, nir_variable_mode modes,
+                                  nir_lower_array_deref_of_vec_options options);
+
 bool nir_lower_indirect_derefs(nir_shader *shader, nir_variable_mode modes);
 
 bool nir_lower_locals_to_regs(nir_shader *shader);