AD fixes for RegisterVariables (however, it needs more maintenance).

Author: oleburghardt

Common/include/CConfig.hpp

@@ -1899,6 +1899,12 @@ class CConfig {
    */
   su2double GetPressure_FreeStreamND(void) const { return Pressure_FreeStreamND; }
 
+  /*!
+   * \brief Get a reference to the non-dimensionalized freestream pressure (used for AD tracking).
+   * \return Reference to non-dimensionalized freestream pressure.
+   */
+  su2double& GetPressure_FreeStreamND(void) { return Pressure_FreeStreamND; }
+
   /*!
    * \brief Get the value of the thermodynamic pressure.
    * \return Thermodynamic pressure.
@@ -1924,6 +1930,12 @@ class CConfig {
    */
   su2double GetTemperature_FreeStreamND(void) const { return Temperature_FreeStreamND; }
 
+  /*!
+   * \brief Get a reference to the non-dimensionalized freestream temperature (used for AD tracking).
+   * \return Reference to non-dimensionalized freestream temperature.
+   */
+  su2double& GetTemperature_FreeStreamND(void) { return Temperature_FreeStreamND; }
+
   /*!
    * \brief Get the value of the non-dimensionalized vibrational-electronic freestream temperature.
    * \return Non-dimensionalized vibrational-electronic freestream temperature.

Common/include/basic_types/ad_structure.hpp

@@ -276,6 +276,12 @@ inline void SetIndex(Identifier& index, const su2double& data) {}
  */
 inline void SetTag(int tag) {}
 
+/*!
+ * \brief Sets the tag of a variable to 0.
+ * \param[in] v - the variable whose tag is cleared.
+ */
+inline void ClearTagOnVariable(su2double& v) {}
+
 /*!
  * \brief Pushes back the current tape position to the tape position's vector.
  */
@@ -684,8 +690,10 @@ FORCEINLINE void ResumePreaccumulation(bool wasActive) {
 
 #ifdef CODI_TAG_TAPE
 FORCEINLINE void SetTag(int tag) { AD::getTape().setCurTag(tag); }
+FORCEINLINE void ClearTagOnVariable(su2double& v) { AD::getTape().clearTagOnVariable(v); }
 #else
 FORCEINLINE void SetTag(int tag) {}
+FORCEINLINE void ClearTagOnVariable(su2double& v) {}
 #endif
 
 #endif  // CODI_REVERSE_TYPE

SU2_CFD/src/solvers/CDiscAdjSolver.cpp

@@ -184,13 +184,16 @@ void CDiscAdjSolver::RegisterVariables(CGeometry *geometry, CConfig *config, boo
     Alpha                  = config->GetAoA()*PI_NUMBER/180.0;
     Beta                   = config->GetAoS()*PI_NUMBER/180.0;
     Mach                   = config->GetMach();
-    Pressure               = config->GetPressure_FreeStreamND();
-    Temperature            = config->GetTemperature_FreeStreamND();
+    su2double& Pressure    = config->GetPressure_FreeStreamND();
+    su2double& Temperature = config->GetTemperature_FreeStreamND();
 
     su2double SoundSpeed = 0.0;
 
+    AD::StopRecording();
+    AD::ClearTagOnVariable(config->GetVelocity_FreeStreamND()[0]);
     if (nDim == 2) { SoundSpeed = config->GetVelocity_FreeStreamND()[0]*Velocity_Ref/(cos(Alpha)*Mach); }
     if (nDim == 3) { SoundSpeed = config->GetVelocity_FreeStreamND()[0]*Velocity_Ref/(cos(Alpha)*cos(Beta)*Mach); }
+    AD::StartRecording();
 
     if (!reset) {
       AD::RegisterInput(Mach);