PureSoA IdCpu fixes (AMReX-Codes#3671)

## Summary

I noticed a few issues in AMReX while trying to update HiPACE++ for
AMReX-Codes#3585.

Additionally, I would like to point out that `ParticleTile` has
`push_back_real` and `push_back_int` functions but for PureSoA there is
no `push_back_idcpu`, however this is not added in this PR.

## Additional background

## Checklist

The proposed changes:
- [x] fix a bug or incorrect behavior in AMReX
- [ ] add new capabilities to AMReX
- [ ] changes answers in the test suite to more than roundoff level
- [ ] are likely to significantly affect the results of downstream AMReX
users
- [ ] include documentation in the code and/or rst files, if appropriate

Src/Particle/AMReX_Particle.H

@@ -24,15 +24,6 @@ namespace
  constexpr Long NoSplitParticleID = GhostParticleID - 4;
  }
 
- /** Used for 32bit int particle Ids, as in pure SoA layout */
- namespace IntParticleIds {
- constexpr int GhostParticleID = 2147483647; // 2**31-1
- constexpr int VirtualParticleID = GhostParticleID - 1;
- constexpr int LastParticleID = GhostParticleID - 2;
- constexpr int DoSplitParticleID = GhostParticleID - 3;
- constexpr int NoSplitParticleID = GhostParticleID - 4;
- }
-
  using namespace LongParticleIds;
 }
 

Src/Particle/AMReX_ParticleTile.H

@@ -458,7 +458,7 @@ SoAParticle<NArrayReal, NArrayInt>::NextID ()
 #endif
  next = the_next_id++;
 
- if (next > IntParticleIds::LastParticleID) {
+ if (next > LongParticleIds::LastParticleID) {
  amrex::Abort("SoAParticle<NArrayReal, NArrayInt>::NextID() -- too many particles");
  }
 
@@ -470,7 +470,7 @@ int
 SoAParticle<NArrayReal, NArrayInt>::UnprotectedNextID ()
 {
  int next = the_next_id++;
- if (next > IntParticleIds::LastParticleID) {
+ if (next > LongParticleIds::LastParticleID) {
  amrex::Abort("SoAParticle<NArrayReal, NArrayInt>::NextID() -- too many particles");
  }
  return next;
@@ -1039,7 +1039,9 @@ struct ParticleTile
 
  void shrink_to_fit ()
  {
- if constexpr (!ParticleType::is_soa_particle) {
+ if constexpr (ParticleType::is_soa_particle) {
+ GetStructOfArrays().GetIdCPUData().shrink_to_fit();
+ } else {
  m_aos_tile().shrink_to_fit();
  }
  for (int j = 0; j < NumRealComps(); ++j)
@@ -1058,7 +1060,9 @@ struct ParticleTile
  Long capacity () const
  {
  Long nbytes = 0;
- if constexpr (!ParticleType::is_soa_particle) {
+ if constexpr (ParticleType::is_soa_particle) {
+ nbytes += GetStructOfArrays().GetIdCPUData().capacity() * sizeof(uint64_t);
+ } else {
  nbytes += m_aos_tile().capacity() * sizeof(ParticleType);
  }
  for (int j = 0; j < NumRealComps(); ++j)
@@ -1077,7 +1081,9 @@ struct ParticleTile
 
  void swap (ParticleTile<ParticleType, NArrayReal, NArrayInt, Allocator>& other)
  {
- if constexpr (!ParticleType::is_soa_particle) {
+ if constexpr (ParticleType::is_soa_particle) {
+ GetStructOfArrays().GetIdCPUData().swap(other.GetStructOfArrays().GetIdCPUData());
+ } else {
  m_aos_tile().swap(other.GetArrayOfStructs()());
  }
  for (int j = 0; j < NumRealComps(); ++j)

Src/Particle/AMReX_StructOfArrays.H

@@ -195,13 +195,12 @@ struct StructOfArrays {
  for (int i = 0; i < int(m_runtime_idata.size()); ++i) { m_runtime_idata[i].resize(count); }
  }
 
- [[nodiscard]] IdCPU* idcpuarray () {
+ [[nodiscard]] uint64_t* idcpuarray () {
  if constexpr (use64BitIdCpu == true) {
  return m_idcpu.dataPtr();
  } else {
  return nullptr;
  }
-
  }
 
  [[nodiscard]] GpuArray<ParticleReal*, NReal> realarray ()