glsl: Fix null return coverity warning

Add an assert on the result of as_dereference() not being NULL:

>>>     CID 1324978:  Null pointer dereferences  (NULL_RETURNS)
>>>     Dereferencing a null pointer "deref_record->record->as_dereference()".

Since we are introducing a new variable to hold the result of
as_dereference(), take the opportunity to rename deref_record_type to
interface_type and just name the new variable interface_deref, which is
less confusing.

Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>

diff --git a/src/glsl/lower_ubo_reference.cpp b/src/glsl/lower_ubo_reference.cpp
index 4e09b080e623ed3462895e02e8e2ec2ac02a85af..e581306019b5619488da64101786dc8ff53b01cb 100644 (file)
--- a/src/glsl/lower_ubo_reference.cpp
+++ b/src/glsl/lower_ubo_reference.cpp
@@ -922,12 +922,14 @@ lower_ubo_reference_visitor::calculate_unsized_array_stride(ir_dereference *dere
    case ir_type_dereference_record:
    {
       ir_dereference_record *deref_record = (ir_dereference_record *) deref;
-      const struct glsl_type *deref_record_type =
-         deref_record->record->as_dereference()->type;
-      unsigned record_length = deref_record_type->length;
+      ir_dereference *interface_deref =
+         deref_record->record->as_dereference();
+      assert(interface_deref != NULL);
+      const struct glsl_type *interface_type = interface_deref->type;
+      unsigned record_length = interface_type->length;
       /* Unsized array is always the last element of the interface */
       const struct glsl_type *unsized_array_type =
-         deref_record_type->fields.structure[record_length - 1].type->fields.array;
+         interface_type->fields.structure[record_length - 1].type->fields.array;
 
       const bool array_row_major =
          is_dereferenced_thing_row_major(deref_record);