+static inline nir_deref_instr *
+nir_build_deref_var(nir_builder *build, nir_variable *var)
+{
+ nir_deref_instr *deref =
+ nir_deref_instr_create(build->shader, nir_deref_type_var);
+
+ deref->mode = var->data.mode;
+ deref->type = var->type;
+ deref->var = var;
+
+ nir_ssa_dest_init(&deref->instr, &deref->dest, 1, 32, NULL);
+
+ nir_builder_instr_insert(build, &deref->instr);
+
+ return deref;
+}
+
+static inline nir_deref_instr *
+nir_build_deref_array(nir_builder *build, nir_deref_instr *parent,
+ nir_ssa_def *index)
+{
+ assert(glsl_type_is_array(parent->type) ||
+ glsl_type_is_matrix(parent->type) ||
+ glsl_type_is_vector(parent->type));
+
+ nir_deref_instr *deref =
+ nir_deref_instr_create(build->shader, nir_deref_type_array);
+
+ deref->mode = parent->mode;
+ deref->type = glsl_get_array_element(parent->type);
+ deref->parent = nir_src_for_ssa(&parent->dest.ssa);
+ deref->arr.index = nir_src_for_ssa(index);
+
+ nir_ssa_dest_init(&deref->instr, &deref->dest,
+ parent->dest.ssa.num_components,
+ parent->dest.ssa.bit_size, NULL);
+
+ nir_builder_instr_insert(build, &deref->instr);
+
+ return deref;
+}
+
+static inline nir_deref_instr *
+nir_build_deref_array_wildcard(nir_builder *build, nir_deref_instr *parent)
+{
+ assert(glsl_type_is_array(parent->type) ||
+ glsl_type_is_matrix(parent->type));
+
+ nir_deref_instr *deref =
+ nir_deref_instr_create(build->shader, nir_deref_type_array_wildcard);
+
+ deref->mode = parent->mode;
+ deref->type = glsl_get_array_element(parent->type);
+ deref->parent = nir_src_for_ssa(&parent->dest.ssa);
+
+ nir_ssa_dest_init(&deref->instr, &deref->dest,
+ parent->dest.ssa.num_components,
+ parent->dest.ssa.bit_size, NULL);
+
+ nir_builder_instr_insert(build, &deref->instr);
+
+ return deref;
+}
+
+static inline nir_deref_instr *
+nir_build_deref_struct(nir_builder *build, nir_deref_instr *parent,
+ unsigned index)
+{
+ assert(glsl_type_is_struct(parent->type));
+
+ nir_deref_instr *deref =
+ nir_deref_instr_create(build->shader, nir_deref_type_struct);
+
+ deref->mode = parent->mode;
+ deref->type = glsl_get_struct_field(parent->type, index);
+ deref->parent = nir_src_for_ssa(&parent->dest.ssa);
+ deref->strct.index = index;
+
+ nir_ssa_dest_init(&deref->instr, &deref->dest,
+ parent->dest.ssa.num_components,
+ parent->dest.ssa.bit_size, NULL);
+
+ nir_builder_instr_insert(build, &deref->instr);
+
+ return deref;
+}
+
+static inline nir_deref_instr *
+nir_build_deref_cast(nir_builder *build, nir_ssa_def *parent,
+ nir_variable_mode mode, const struct glsl_type *type)
+{
+ nir_deref_instr *deref =
+ nir_deref_instr_create(build->shader, nir_deref_type_cast);
+
+ deref->mode = mode;
+ deref->type = type;
+ deref->parent = nir_src_for_ssa(parent);
+
+ nir_ssa_dest_init(&deref->instr, &deref->dest,
+ parent->num_components, parent->bit_size, NULL);
+
+ nir_builder_instr_insert(build, &deref->instr);
+
+ return deref;
+}
+
+/** Returns a deref that follows another but starting from the given parent
+ *
+ * The new deref will be the same type and take the same array or struct index
+ * as the leader deref but it may have a different parent. This is very
+ * useful for walking deref paths.
+ */
+static inline nir_deref_instr *
+nir_build_deref_follower(nir_builder *b, nir_deref_instr *parent,
+ nir_deref_instr *leader)
+{
+ /* If the derefs would have the same parent, don't make a new one */
+ assert(leader->parent.is_ssa);
+ if (leader->parent.ssa == &parent->dest.ssa)
+ return leader;
+
+ UNUSED nir_deref_instr *leader_parent = nir_src_as_deref(leader->parent);
+
+ switch (leader->deref_type) {
+ case nir_deref_type_var:
+ unreachable("A var dereference cannot have a parent");
+ break;
+
+ case nir_deref_type_array:
+ case nir_deref_type_array_wildcard:
+ assert(glsl_type_is_matrix(parent->type) ||
+ glsl_type_is_array(parent->type));
+ assert(glsl_get_length(parent->type) ==
+ glsl_get_length(leader_parent->type));
+
+ if (leader->deref_type == nir_deref_type_array) {
+ assert(leader->arr.index.is_ssa);
+ return nir_build_deref_array(b, parent, leader->arr.index.ssa);
+ } else {
+ return nir_build_deref_array_wildcard(b, parent);
+ }
+
+ case nir_deref_type_struct:
+ assert(glsl_type_is_struct(parent->type));
+ assert(glsl_get_length(parent->type) ==
+ glsl_get_length(leader_parent->type));
+
+ return nir_build_deref_struct(b, parent, leader->strct.index);
+
+ default:
+ unreachable("Invalid deref instruction type");
+ }
+}
+