Add DIM operator to reference model

Signed-off-by: Won Jeon <won.jeon@arm.com>
Change-Id: Iea11ee5d3d98773e9c5e9b827593c05afb41ce3b
diff --git a/reference_model/src/tensor.h b/reference_model/src/tensor.h
index f59a5e1..74f57ed 100644
--- a/reference_model/src/tensor.h
+++ b/reference_model/src/tensor.h
@@ -811,6 +811,13 @@
                         return new Tensor6<int64_t>(tensorName_, dtype_, shape_);
                 }
                 break;
+            case TOSA_REF_TYPE_SHAPE:
+                // if shape information is not already set, set it here.
+                if (shape_.size() == 0)
+                {
+                    shape_ = { 1 };
+                }
+                return new Tensor0<int64_t>(tensorName_, dtype_, shape_);
             case TOSA_REF_TYPE_BOOL:
                 switch (rank)
                 {