Make SoftQuad faster

src/elements/SoftQuad.H

@@ -192,9 +192,25 @@ namespace SoftQuadrupoleData
         /** Push all particles */
         using BeamOptic::operator();
 
+        /** Compute and cache the constants for the push.
+         *
+         * In particular, used to pre-compute and cache variables that are
+         * independent of the individually tracked particle.
+         *
+         * @param refpart reference particle
+         */
+        void compute_constants (RefPart const & refpart)
+        {
+            using namespace amrex::literals; // for _rt and _prt
+
+            Alignment::compute_constants(refpart);
+        }
+
         /** This is a soft-edge quadrupole functor, so that a variable of this type can be used
          *  like a soft-edge quadrupole function.
          *
+         * The @see compute_constants method must be called before pushing particles through this operator.
+         *
          * @param x particle position in x
          * @param y particle position in y
          * @param t particle position in t
@@ -213,7 +229,7 @@ namespace SoftQuadrupoleData
             amrex::ParticleReal & AMREX_RESTRICT py,
             amrex::ParticleReal & AMREX_RESTRICT pt,
             uint64_t & AMREX_RESTRICT idcpu,
-            [[maybe_unused]] RefPart const & refpart
+            RefPart const & AMREX_RESTRICT refpart
         ) const
         {
             using namespace amrex::literals; // for _rt and _prt
@@ -500,6 +516,11 @@ namespace SoftQuadrupoleData
         amrex::ParticleReal* m_sin_h_data = nullptr; //! non-owning pointer to host sine coefficients
         amrex::ParticleReal* m_cos_d_data = nullptr; //! non-owning pointer to device cosine coefficients
         amrex::ParticleReal* m_sin_d_data = nullptr; //! non-owning pointer to device sine coefficients
+
+      private:
+        // constants that are independent of the individually tracked particle,
+        // see: compute_constants() to refresh
+        amrex::ParticleReal ...;
     };
 
 } // namespace impactx