From c49940a4ea6eb37faaf52cb91fa3f80741f788eb Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Sat, 18 Sep 2021 21:58:18 +0200
Subject: [PATCH] Do not build inner face data if not requested

---
 include/deal.II/matrix_free/face_setup_internal.h   | 4 ++++
 include/deal.II/matrix_free/matrix_free.templates.h | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/include/deal.II/matrix_free/face_setup_internal.h b/include/deal.II/matrix_free/face_setup_internal.h
index 504bd6dc63..5499c18300 100644
--- a/include/deal.II/matrix_free/face_setup_internal.h
+++ b/include/deal.II/matrix_free/face_setup_internal.h
@@ -82,6 +82,7 @@ namespace internal
         const dealii::Triangulation<dim> &triangulation,
         const unsigned int                mg_level,
         const bool                        hold_all_faces_to_owned_cells,
+        const bool                        build_inner_faces,
         std::vector<std::pair<unsigned int, unsigned int>> &cell_levels);
 
       /**
@@ -165,6 +166,7 @@ namespace internal
       const dealii::Triangulation<dim> &triangulation,
       const unsigned int                mg_level,
       const bool                        hold_all_faces_to_owned_cells,
+      const bool                        build_inner_faces,
       std::vector<std::pair<unsigned int, unsigned int>> &cell_levels)
     {
       use_active_cells = mg_level == numbers::invalid_unsigned_int;
@@ -583,6 +585,8 @@ namespace internal
               if (dcell->at_boundary(f) && !dcell->has_periodic_neighbor(f))
                 face_is_owned[dcell->face(f)->index()] =
                   FaceCategory::locally_active_at_boundary;
+              else if (!build_inner_faces)
+                continue;
 
               // treat boundaries of cells of different refinement level
               // inside the domain in case of multigrid separately
diff --git a/include/deal.II/matrix_free/matrix_free.templates.h b/include/deal.II/matrix_free/matrix_free.templates.h
index 053eef26ca..4f7666d93e 100644
--- a/include/deal.II/matrix_free/matrix_free.templates.h
+++ b/include/deal.II/matrix_free/matrix_free.templates.h
@@ -1029,6 +1029,7 @@ namespace internal
     const std::vector<unsigned int> &cell_vectorization_category,
     const bool                       cell_vectorization_categories_strict,
     const bool                       do_face_integrals,
+    const bool                       build_inner_faces,
     const bool                       overlap_communication_computation,
     MatrixFreeFunctions::TaskInfo &  task_info,
     std::vector<std::pair<unsigned int, unsigned int>> &cell_level_index,
@@ -1041,6 +1042,7 @@ namespace internal
       face_setup.initialize(dof_handler[0]->get_triangulation(),
                             mg_level,
                             hold_all_faces_to_owned_cells,
+                            build_inner_faces,
                             cell_level_index);
 
     const unsigned int n_dof_handlers = dof_handler.size();
@@ -1740,6 +1742,7 @@ MatrixFree<dim, Number, VectorizedArrayType>::initialize_indices(
     additional_data.cell_vectorization_category,
     additional_data.cell_vectorization_categories_strict,
     do_face_integrals,
+    additional_data.mapping_update_flags_inner_faces != update_default,
     additional_data.overlap_communication_computation,
     task_info,
     cell_level_index,
-- 
2.39.5