Advance step on device (#32198)

Author: dschwen

framework/include/neml2/userobjects/NEML2ModelExecutor.h

@@ -41,6 +41,7 @@ class NEML2ModelExecutor : public NEML2ModelInterface<GeneralUserObject>
   void finalize() override;
 
   void initialSetup() override;
+  void timestepSetup() override;
 
   /// Get the batch index for the given element ID
   std::size_t getBatchIndex(dof_id_type elem_id) const;
@@ -87,6 +88,9 @@ class NEML2ModelExecutor : public NEML2ModelInterface<GeneralUserObject>
   /// The NEML2BatchIndexGenerator used to generate the element-to-batch-index map
   const NEML2BatchIndexGenerator & _batch_index_generator;
 
+  /// Advance state on device (rather than via MOSOE material properties)
+  const bool _advance_step_on_device;
+
   /// flag that indicates if output data has been fully computed
   bool _output_ready;
 

framework/src/neml2/userobjects/NEML2ModelExecutor.C

@@ -31,6 +31,12 @@ NEML2ModelExecutor::actionParams()
       "List of NEML2 variables to skip error checking when setting up the model input. If an "
       "input variable is skipped, its value will stay zero. If a required input variable is "
       "not skipped, an error will be raised.");
+  params.addParam<bool>(
+      "advance_step_on_device",
+      false,
+      "Keep state and forces on the device and advance it to old_state and old_forces without a "
+      "roundtrip through MOOSE materials. This is only recommended for explicit time integration "
+      "or when absolutely no restepping occurs (e.g. failed timesteps).");
   return params;
 }
 
@@ -68,6 +74,7 @@ NEML2ModelExecutor::NEML2ModelExecutor(const InputParameters & params)
 #ifdef NEML2_ENABLED
     ,
     _batch_index_generator(getUserObject<NEML2BatchIndexGenerator>("batch_index_generator")),
+    _advance_step_on_device(getParam<bool>("advance_step_on_device")),
     _output_ready(false),
     _error_message("")
 #endif
@@ -167,6 +174,20 @@ NEML2ModelExecutor::initialSetup()
           "those called `NEML2To*MOOSEMaterialProperty`.");
 }
 
+void
+NEML2ModelExecutor::timestepSetup()
+{
+  if (_advance_step_on_device && _t_step > 0)
+  {
+    // Set old state variables and old forces
+    if (model().input_axis().has_subaxis("old_state") && model().output_axis().has_subaxis("state"))
+      _in.slice("old_state").fill(_out.slice("state"));
+    if (model().input_axis().has_subaxis("old_forces") &&
+        model().input_axis().has_subaxis("forces"))
+      _in.slice("old_forces").fill(_in.slice("forces"));
+  }
+}
+
 std::size_t
 NEML2ModelExecutor::getBatchIndex(dof_id_type elem_id) const
 {