Amesos2: try avoiding shallow-copy of a local-view

packages/amesos2/src/Amesos2_Kokkos_View_Copy_Assign.hpp

@@ -88,6 +88,30 @@ implement_copy_or_assign_same_mem_check_types(bool bInitialize, dst_t & dst, con
   bAssigned = true;
 }
 
+
+// deep-copy version (no checking)
+// bInitialize:
+//   If bInitialize is false, then the data needs to be allocated but not initialized.
+//   If we are about to solve into x we don't care about setting the original values.
+//   In this case, we are allocating so we first make the memory via update_dst_size.
+//   Then we only copy from the source if bInitialize is true.
+// bAssigned:
+//   bAssigned tells the caller if the data was simply assigned, so it is set false in this case.
+template<class dst_t, class src_t> // actual implementation
+void deep_copy_only(bool bInitialize, dst_t & dst, const src_t & src, bool & bAssigned) {
+  update_dst_size(dst, src); // allocates if necessary
+  if(bInitialize) { // bInitialize false would be for solver getting x, where the actual values are not needed
+    Kokkos::deep_copy(dst, src); // full copy
+  }
+  bAssigned = false;
+}
+
+template<class dst_t, class src_t> // actual implementation
+void deep_copy_only(dst_t & dst, const src_t & src) {
+  bool bAssigned;
+  deep_copy_only(true, dst, src, bAssigned);
+}
+
 // now handle type mismatch for same memory space - now types are different
 // bInitialize:
 //   If bInitialize is false, then the data needs to be allocated but not initialized.

packages/amesos2/src/Amesos2_TpetraMultiVecAdapter_def.hpp

@@ -264,7 +264,8 @@ namespace Amesos2 {
     if ( num_vecs == 1 && this->getComm()->getRank() == 0 && this->getComm()->getSize() == 1 ) {
       if(mv_->isConstantStride()) {
         bool bAssigned;
-        deep_copy_or_assign_view(bInitialize, kokkos_view, mv_->getLocalViewDevice(Tpetra::Access::ReadOnly), bAssigned);
+        //deep_copy_or_assign_view(bInitialize, kokkos_view, mv_->getLocalViewDevice(Tpetra::Access::ReadOnly), bAssigned);
+        deep_copy_only(bInitialize, kokkos_view, mv_->getLocalViewDevice(Tpetra::Access::ReadOnly), bAssigned);
         return bAssigned; // if bAssigned is true we are accessing the mv data directly without a copy
       }
       else {
@@ -525,7 +526,8 @@ namespace Amesos2 {
 
       // If this is the optimized path then kokkos_new_data will be the dst
       auto mv_view_to_modify_2d = mv_->getLocalViewDevice(Tpetra::Access::OverwriteAll);
-      deep_copy_or_assign_view(mv_view_to_modify_2d, kokkos_new_data);
+      //deep_copy_or_assign_view(mv_view_to_modify_2d, kokkos_new_data);
+      deep_copy_only(mv_view_to_modify_2d, kokkos_new_data);
     }
     else {