From 27d0ce81a443444e377a11adb719b740789ef60c Mon Sep 17 00:00:00 2001
From: Andrew Myers <atmyers2@gmail.com>
Date: Wed, 26 Jul 2023 14:03:24 -0700
Subject: [PATCH 1/5] use if constexpr in DenseBins

---
 Src/Particle/AMReX_DenseBins.H | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/Src/Particle/AMReX_DenseBins.H b/Src/Particle/AMReX_DenseBins.H
index a4fdc14e038..9bef80ef61b 100644
--- a/Src/Particle/AMReX_DenseBins.H
+++ b/Src/Particle/AMReX_DenseBins.H
@@ -93,18 +93,12 @@ private:
 
     template <typename F, typename I>
     AMREX_GPU_HOST_DEVICE
-    static auto call_f(F const& f, const_pointer_input_type v, I& index)
-        noexcept -> decltype(f(v,index))
-    {
-        return f(v,index);
-    }
-
-    template <typename F, typename I>
-    AMREX_GPU_HOST_DEVICE
-    static auto call_f(F const& f, const_pointer_input_type v, I& index)
-        noexcept -> decltype(f(v[index]))
-    {
-        return f(v[index]);
+    static auto call_f(F const& f, const_pointer_input_type v, I& index) {
+        if constexpr (IsCallable<F, decltype(v), I>::value) {
+            return f(v, index);
+        } else {
+            return f(v[index]);
+        }
     }
 
 public:

From df81d7a7fedc490414bb127ebfb4cf4ca9cc5184 Mon Sep 17 00:00:00 2001
From: Andrew Myers <atmyers2@gmail.com>
Date: Wed, 26 Jul 2023 14:03:42 -0700
Subject: [PATCH 2/5] use if constexpr in ParticleMesh

---
 Src/Particle/AMReX_ParticleUtil.H | 143 ++++--------------------------
 1 file changed, 16 insertions(+), 127 deletions(-)

diff --git a/Src/Particle/AMReX_ParticleUtil.H b/Src/Particle/AMReX_ParticleUtil.H
index 0ddc09b4422..54acdfd6820 100644
--- a/Src/Particle/AMReX_ParticleUtil.H
+++ b/Src/Particle/AMReX_ParticleUtil.H
@@ -58,141 +58,30 @@ auto call_f (F const& f,
     return f(p, i);
 }
 
-// These next several functions are used by ParticleToMesh and MeshToParticle
-
-// Lambda takes a Particle
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const& plo,
-             GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
-    -> decltype(f(p.m_aos[i], fabarr, plo, dxi))
-{
-    return f(p.m_aos[i], fabarr, plo, dxi);
-}
-
-// Lambda takes a Particle
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const&,
-             GpuArray<Real,AMREX_SPACEDIM> const&) noexcept
-    -> decltype(f(p.m_aos[i], fabarr))
-{
-    return f(p.m_aos[i], fabarr);
-}
-
-// Lambda takes a Particle
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<const T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const& plo,
-             GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
-    -> decltype(f(p.m_aos[i], fabarr, plo, dxi))
-{
-    return f(p.m_aos[i], fabarr, plo, dxi);
-}
-
-// Lambda takes a Particle
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<const T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const&,
-             GpuArray<Real,AMREX_SPACEDIM> const&) noexcept
-    -> decltype(f(p.m_aos[i], fabarr))
-{
-    return f(p.m_aos[i], fabarr);
-}
-
-// Lambda takes a SuperParticle
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI,
-          typename std::enable_if<(NAR != 0) || (NAI != 0), int>::type = 0>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const& plo,
-             GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
-    -> decltype(f(p.getSuperParticle(i), fabarr, plo, dxi))
-{
-    return f(p.getSuperParticle(i), fabarr, plo, dxi);
-}
-
-// Lambda takes a SuperParticle
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI,
-          typename std::enable_if<(NAR != 0) || (NAI != 0), int>::type = 0>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const&,
-             GpuArray<Real,AMREX_SPACEDIM> const&) noexcept
-    -> decltype(f(p.getSuperParticle(i), fabarr))
-{
-    return f(p.getSuperParticle(i), fabarr);
-}
-
-// Lambda takes a ConstParticleTileData
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const&,
-             GpuArray<Real,AMREX_SPACEDIM> const&) noexcept
-    -> decltype(f(p, i, fabarr))
-{
-    return f(p, i, fabarr);
-}
-
-// Lambda takes a ConstParticleTileData
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
+// This function is used by ParticleToMesh and MeshToParticle
+template <typename F, typename T, typename T_ParticleType, template<class, int, int> class PTDType, int NAR, int NAI>
 AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
 auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
+             const PTDType<T_ParticleType, NAR, NAI>& p,
              const int i, Array4<T> const& fabarr,
              GpuArray<Real,AMREX_SPACEDIM> const& plo,
              GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
-    -> decltype(f(p, i, fabarr, plo, dxi))
 {
-    return f(p, i, fabarr, plo, dxi);
-}
-
-// Lambda takes a ParticleTileData
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<const T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const& plo,
-             GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
-    -> decltype(f(p, i, fabarr, plo, dxi))
-{
-    return f(p, i, fabarr, plo, dxi);
-}
-
-// Lambda takes a ParticleTileData
-template <typename F, typename T, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<const T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const&,
-             GpuArray<Real,AMREX_SPACEDIM> const&) noexcept
-    -> decltype(f(p, i, fabarr))
-{
-    return f(p, i, fabarr);
+    if constexpr (IsCallable<F, decltype(p.m_aos[i]), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
+        return f(p.m_aos[i], fabarr, plo, dxi);
+    } else if constexpr (IsCallable<F, decltype(p.m_aos[i]), decltype(fabarr)>::value) {
+        return f(p.m_aos[i], fabarr);
+    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i)), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
+        return f(p.getSuperParticle(i), fabarr, plo, dxi);
+    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i)), decltype(fabarr)>::value) {
+        return f(p.getSuperParticle(i), fabarr);
+    } else if constexpr (IsCallable<F, decltype(p), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
+        return f(p, i, fabarr, plo, dxi);
+    } else {
+        return f(p, i, fabarr);
+    }
 }
 
-
 }
 
 /**

From f39d78e5b26f5c12649f74e8e1dd461b451b5b15 Mon Sep 17 00:00:00 2001
From: Andrew Myers <atmyers2@gmail.com>
Date: Wed, 26 Jul 2023 14:22:59 -0700
Subject: [PATCH 3/5] also do ParticleReduce

---
 Src/Particle/AMReX_ParticleUtil.H | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/Src/Particle/AMReX_ParticleUtil.H b/Src/Particle/AMReX_ParticleUtil.H
index 54acdfd6820..45853ff4466 100644
--- a/Src/Particle/AMReX_ParticleUtil.H
+++ b/Src/Particle/AMReX_ParticleUtil.H
@@ -22,8 +22,23 @@ namespace amrex
 
 namespace particle_detail {
 
-// The next several functions are used by ParticleReduce
+// This function is used by ParticleReduce
+template <typename F, typename T_ParticleType, int NAR, int NAI>
+AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+auto call_f (F const& f,
+             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
+             const int i) noexcept
+{
+    if constexpr (IsCallable<F, decltype(p.m_aos[i])>::value) {
+        return f(p.m_aos[i]);
+    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i))>::value) {
+        return f(p.getSuperParticle(i));
+    } else {
+        return f(p, i);
+    }
+}
 
+    /*
 // Lambda takes a Particle
 template <typename F, typename T_ParticleType, int NAR, int NAI>
 AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
@@ -57,6 +72,7 @@ auto call_f (F const& f,
 {
     return f(p, i);
 }
+    */
 
 // This function is used by ParticleToMesh and MeshToParticle
 template <typename F, typename T, typename T_ParticleType, template<class, int, int> class PTDType, int NAR, int NAI>

From 5132971d02baf33e734fa11e06e8f457e12eb347 Mon Sep 17 00:00:00 2001
From: Andrew Myers <atmyers2@gmail.com>
Date: Wed, 26 Jul 2023 15:23:54 -0700
Subject: [PATCH 4/5] a little cleanup

---
 Src/Particle/AMReX_ParticleMesh.H   | 27 +++++++++-
 Src/Particle/AMReX_ParticleReduce.H | 19 ++++++-
 Src/Particle/AMReX_ParticleUtil.H   | 83 +----------------------------
 3 files changed, 45 insertions(+), 84 deletions(-)

diff --git a/Src/Particle/AMReX_ParticleMesh.H b/Src/Particle/AMReX_ParticleMesh.H
index 148df384ee1..75d2cdb4838 100644
--- a/Src/Particle/AMReX_ParticleMesh.H
+++ b/Src/Particle/AMReX_ParticleMesh.H
@@ -6,8 +6,33 @@
 #include <AMReX_MultiFab.H>
 #include <AMReX_ParticleUtil.H>
 
-namespace amrex
+namespace amrex {
+
+namespace particle_detail {
+
+template <typename F, typename T, typename T_ParticleType, template<class, int, int> class PTDType, int NAR, int NAI>
+AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+auto call_f (F const& f,
+             const PTDType<T_ParticleType, NAR, NAI>& p,
+             const int i, Array4<T> const& fabarr,
+             GpuArray<Real,AMREX_SPACEDIM> const& plo,
+             GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
 {
+    if constexpr (IsCallable<F, decltype(p.m_aos[i]), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
+        return f(p.m_aos[i], fabarr, plo, dxi);
+    } else if constexpr (IsCallable<F, decltype(p.m_aos[i]), decltype(fabarr)>::value) {
+        return f(p.m_aos[i], fabarr);
+    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i)), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
+        return f(p.getSuperParticle(i), fabarr, plo, dxi);
+    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i)), decltype(fabarr)>::value) {
+        return f(p.getSuperParticle(i), fabarr);
+    } else if constexpr (IsCallable<F, decltype(p), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
+        return f(p, i, fabarr, plo, dxi);
+    } else {
+        return f(p, i, fabarr);
+    }
+}
+}
 
 template <class PC, class MF, class F, std::enable_if_t<IsParticleContainer<PC>::value, int> foo = 0>
 void
diff --git a/Src/Particle/AMReX_ParticleReduce.H b/Src/Particle/AMReX_ParticleReduce.H
index 8a93dba94d7..2c1df48fd0e 100644
--- a/Src/Particle/AMReX_ParticleReduce.H
+++ b/Src/Particle/AMReX_ParticleReduce.H
@@ -13,8 +13,25 @@
 
 #include <limits>
 
-namespace amrex
+namespace amrex {
+
+namespace particle_detail {
+
+template <typename F, typename T_ParticleType, int NAR, int NAI>
+AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+auto call_f (F const& f,
+             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
+             const int i) noexcept
 {
+    if constexpr (IsCallable<F, decltype(p.m_aos[i])>::value) {
+        return f(p.m_aos[i]);
+    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i))>::value) {
+        return f(p.getSuperParticle(i));
+    } else {
+        return f(p, i);
+    }
+}
+}
 
 /**
  * \brief A general reduction method for the particles in a ParticleContainer that can run on either CPUs or GPUs.
diff --git a/Src/Particle/AMReX_ParticleUtil.H b/Src/Particle/AMReX_ParticleUtil.H
index 45853ff4466..0d7f9af776b 100644
--- a/Src/Particle/AMReX_ParticleUtil.H
+++ b/Src/Particle/AMReX_ParticleUtil.H
@@ -17,88 +17,7 @@
 
 #include <limits>
 
-namespace amrex
-{
-
-namespace particle_detail {
-
-// This function is used by ParticleReduce
-template <typename F, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i) noexcept
-{
-    if constexpr (IsCallable<F, decltype(p.m_aos[i])>::value) {
-        return f(p.m_aos[i]);
-    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i))>::value) {
-        return f(p.getSuperParticle(i));
-    } else {
-        return f(p, i);
-    }
-}
-
-    /*
-// Lambda takes a Particle
-template <typename F, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i) noexcept
-    -> decltype(f(p.m_aos[i]))
-{
-    return f(p.m_aos[i]);
-}
-
-// Lambda takes a SuperParticle
-template <typename F, typename T_ParticleType, int NAR, int NAI,
-          typename std::enable_if<NAR != 0 || NAI != 0, int>::type = 0>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i) noexcept
-    -> decltype(f(p.getSuperParticle(i)))
-{
-    return f(p.getSuperParticle(i));
-}
-
-// Lambda takes a ConstParticleTileData
-template <typename F, typename T_ParticleType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const ConstParticleTileData<T_ParticleType, NAR, NAI>& p,
-             const int i) noexcept
-    -> decltype(f(p, i))
-{
-    return f(p, i);
-}
-    */
-
-// This function is used by ParticleToMesh and MeshToParticle
-template <typename F, typename T, typename T_ParticleType, template<class, int, int> class PTDType, int NAR, int NAI>
-AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-auto call_f (F const& f,
-             const PTDType<T_ParticleType, NAR, NAI>& p,
-             const int i, Array4<T> const& fabarr,
-             GpuArray<Real,AMREX_SPACEDIM> const& plo,
-             GpuArray<Real,AMREX_SPACEDIM> const& dxi) noexcept
-{
-    if constexpr (IsCallable<F, decltype(p.m_aos[i]), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
-        return f(p.m_aos[i], fabarr, plo, dxi);
-    } else if constexpr (IsCallable<F, decltype(p.m_aos[i]), decltype(fabarr)>::value) {
-        return f(p.m_aos[i], fabarr);
-    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i)), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
-        return f(p.getSuperParticle(i), fabarr, plo, dxi);
-    } else if constexpr (IsCallable<F, decltype(p.getSuperParticle(i)), decltype(fabarr)>::value) {
-        return f(p.getSuperParticle(i), fabarr);
-    } else if constexpr (IsCallable<F, decltype(p), decltype(fabarr), decltype(plo), decltype(dxi)>::value) {
-        return f(p, i, fabarr, plo, dxi);
-    } else {
-        return f(p, i, fabarr);
-    }
-}
-
-}
+namespace amrex {
 
 /**
  * \brief Returns the number of particles that are more than nGrow cells

From e682522dd7bf3e63fe7251140955f723633e2a68 Mon Sep 17 00:00:00 2001
From: Andrew Myers <atmyers2@gmail.com>
Date: Wed, 26 Jul 2023 15:38:41 -0700
Subject: [PATCH 5/5] Update Src/Particle/AMReX_DenseBins.H

---
 Src/Particle/AMReX_DenseBins.H | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Src/Particle/AMReX_DenseBins.H b/Src/Particle/AMReX_DenseBins.H
index 9bef80ef61b..67ff2c1c9c5 100644
--- a/Src/Particle/AMReX_DenseBins.H
+++ b/Src/Particle/AMReX_DenseBins.H
@@ -93,7 +93,7 @@ private:
 
     template <typename F, typename I>
     AMREX_GPU_HOST_DEVICE
-    static auto call_f(F const& f, const_pointer_input_type v, I& index) {
+    static auto call_f (F const& f, const_pointer_input_type v, I& index) {
         if constexpr (IsCallable<F, decltype(v), I>::value) {
             return f(v, index);
         } else {