Summary
WarpX::FillBoundaryAux(int lev, amrex::IntVect) (Parallelization/WarpXComm.cpp:1121-1132) always forwards the caller-supplied ng to ablastr::utils::communication::FillBoundary.- Every other FillBoundary helper first checks
m_safe_guard_cells and upgrades the requested ng to the full MultiFab::nGrowVect() when safe-guard mode is active, ensuring all allocated guard cells stay synchronized during debugging runs.
- Because the aux helper skipped that copy-pasted guard, enabling
warpx.safe_guard_cells=1 still leaves Efield_aux/Bfield_aux guard regions partially stale, defeating the point of the safety mode and making aux gathers behave differently from the main E/B grids.
Impact
- Developers rely on
m_safe_guard_cells to detect missing guard exchanges; aux grids now silently skip that enforcement, so particle gathers can still read garbage on the aux MultiFabs even though the rest of the code is running in "safe" mode.
- Diagnostics and solvers that alias
Efield_aux see different guard widths refreshed compared to Efield_fp, which is confusing and makes it harder to compare auxiliary grids against their sources when debugging guard overruns.
Suggested patch
--- a/Parallelization/WarpXComm.cpp
+++ b/Parallelization/WarpXComm.cpp
@@
WarpX::FillBoundaryAux (int lev, IntVect ng)
{
ablastr::fields::MultiLevelVectorField Efield_aux = m_fields.get_mr_levels_alldirs(FieldType::Efield_aux, finest_level);
ablastr::fields::MultiLevelVectorField Bfield_aux = m_fields.get_mr_levels_alldirs(FieldType::Bfield_aux, finest_level);
const amrex::Periodicity& period = Geom(lev).periodicity();
- ablastr::utils::communication::FillBoundary(*Efield_aux[lev][0], ng, WarpX::do_single_precision_comms, period);
- ablastr::utils::communication::FillBoundary(*Efield_aux[lev][1], ng, WarpX::do_single_precision_comms, period);
- ablastr::utils::communication::FillBoundary(*Efield_aux[lev][2], ng, WarpX::do_single_precision_comms, period);
- ablastr::utils::communication::FillBoundary(*Bfield_aux[lev][0], ng, WarpX::do_single_precision_comms, period);
- ablastr::utils::communication::FillBoundary(*Bfield_aux[lev][1], ng, WarpX::do_single_precision_comms, period);
- ablastr::utils::communication::FillBoundary(*Bfield_aux[lev][2], ng, WarpX::do_single_precision_comms, period);
+ auto fill_aux = [this, &period, &ng](amrex::MultiFab* mf)
+ {
+ const amrex::IntVect& nghost = (m_safe_guard_cells) ? mf->nGrowVect() : ng;
+ ablastr::utils::communication::FillBoundary(*mf, nghost, WarpX::do_single_precision_comms, period);
+ };
+ fill_aux(Efield_aux[lev][0]);
+ fill_aux(Efield_aux[lev][1]);
+ fill_aux(Efield_aux[lev][2]);
+ fill_aux(Bfield_aux[lev][0]);
+ fill_aux(Bfield_aux[lev][1]);
+ fill_aux(Bfield_aux[lev][2]);
}Prepared by Codex
Summary
WarpX::FillBoundaryAux(int lev, amrex::IntVect)(Parallelization/WarpXComm.cpp:1121-1132) always forwards the caller-suppliedngtoablastr::utils::communication::FillBoundary.m_safe_guard_cellsand upgrades the requestedngto the fullMultiFab::nGrowVect()when safe-guard mode is active, ensuring all allocated guard cells stay synchronized during debugging runs.warpx.safe_guard_cells=1still leavesEfield_aux/Bfield_auxguard regions partially stale, defeating the point of the safety mode and making aux gathers behave differently from the main E/B grids.Impact
m_safe_guard_cellsto detect missing guard exchanges; aux grids now silently skip that enforcement, so particle gathers can still read garbage on the aux MultiFabs even though the rest of the code is running in "safe" mode.Efield_auxsee different guard widths refreshed compared toEfield_fp, which is confusing and makes it harder to compare auxiliary grids against their sources when debugging guard overruns.Suggested patch
Prepared by Codex