Test transform optimisation

Author: garth-wells

cpp/dolfinx/fem/FiniteElement.h

@@ -435,13 +435,7 @@ class FiniteElement
   dof_transformation_fn(doftransform ttype, bool scalar_element = false) const
   {
     if (!needs_dof_transformations())
-    {
-      // If no permutation needed, return function that does nothing
-      return [](std::span<U>, std::span<const std::uint32_t>, std::int32_t, int)
-      {
-        // Do nothing
-      };
-    }
+      return nullptr;
 
     if (!_sub_elements.empty())
     {
@@ -541,13 +535,7 @@ class FiniteElement
                               bool scalar_element = false) const
   {
     if (!needs_dof_transformations())
-    {
-      // If no permutation needed, return function that does nothing
-      return [](std::span<U>, std::span<const std::uint32_t>, std::int32_t, int)
-      {
-        // Do nothing
-      };
-    }
+      return nullptr;
     else if (!_sub_elements.empty())
     {
       if (!_reference_value_shape) // Mixed element

cpp/dolfinx/fem/assemble_matrix_impl.h

@@ -153,8 +153,10 @@ void assemble_cells_matrix(
            nullptr, nullptr);
 
     // Compute A = P_0 \tilde{A} P_1^T (dof transformation)
-    P0(Ae, cell_info0, cell0, ndim1);  // B = P0 \tilde{A}
-    P1T(Ae, cell_info1, cell1, ndim0); // A =  B P1_T
+    if (P0)
+      P0(Ae, cell_info0, cell0, ndim1); // B = P0 \tilde{A}
+    if (P1T)
+      P1T(Ae, cell_info1, cell1, ndim0); // A =  B P1_T
 
     // In lifting mode only BC dofs are assembled, while in standard mode these
     // row/column dofs are zeroed.
@@ -333,8 +335,10 @@ void assemble_entities(
     std::ranges::fill(Ae, 0);
     kernel(Ae.data(), &coeffs(f, 0), constants.data(), cdofs_b.data(),
            &local_entity, &perm, nullptr);
-    P0(Ae, cell_info0, cell0, ndim1);
-    P1T(Ae, cell_info1, cell1, ndim0);
+    if (P0)
+      P0(Ae, cell_info0, cell0, ndim1);
+    if (P1T)
+      P1T(Ae, cell_info1, cell1, ndim0);
 
     // Don't clear rows/cols in LiftingMode
     if constexpr (!LiftingMode)
@@ -586,16 +590,15 @@ void assemble_interior_facets(
     // where each block is element tensor of size (dmap0, dmap1).
 
     // Only apply transformation when cells exist
-    if (cells0[0] >= 0)
+    if (P0 and cells0[0] >= 0)
       P0(Ae, cell_info0, cells0[0], num_cols);
-    if (cells0[1] >= 0)
+    if (P1T and cells0[1] >= 0)
     {
       std::span sub_Ae0(Ae.data() + bs0 * dmap0_size * num_cols,
                         bs0 * dmap0_size * num_cols);
-
       P0(sub_Ae0, cell_info0, cells0[1], num_cols);
     }
-    if (cells1[0] >= 0)
+    if (P1T and cells1[0] >= 0)
       P1T(Ae, cell_info1, cells1[0], num_rows);
 
     if (cells1[1] >= 0)

cpp/dolfinx/fem/assemble_vector_impl.h

@@ -105,7 +105,8 @@ void assemble_cells(
     std::ranges::fill(be, 0);
     kernel(be.data(), &coeffs(index, 0), constants.data(), cdofs_b.data(),
            nullptr, nullptr, nullptr);
-    P0(be, cell_info0, c0, 1);
+    if (P0)
+      P0(be, cell_info0, c0, 1);
 
     // Scatter cell vector to 'global' vector array
     auto dofs = md::submdspan(dmap, c0, md::full_extent);
@@ -200,7 +201,8 @@ void assemble_entities(
     std::ranges::fill(be, 0);
     kernel(be.data(), &coeffs(f, 0), constants.data(), cdofs_b.data(),
            &local_entity, &perm, nullptr);
-    P0(be, cell_info0, cell0, 1);
+    if (P0)
+      P0(be, cell_info0, cell0, 1);
 
     // Add to global vector
     auto dofs = md::submdspan(dmap, cell0, md::full_extent);