mesh: Complete facet labels after adding overlaps

This will be used for grabbing DirichletBC nodes from section data.

firedrake/cython/dmcommon.pyx

@@ -1022,6 +1022,18 @@ def label_facets(PETSc.DM plex, label_boundary=True):
             CHKERR(DMLabelSetValue(lbl_int, facet, 1))
     CHKERR(DMLabelDestroyIndex(lbl_ext))
 
+
+def complete_facet_labels(PETSc.DM dm):
+    """Transfer label values from the facet labels to everything in
+    the closure of the facets."""
+    cdef PETSc.DMLabel label
+
+    for name in [FACE_SETS_LABEL, "exterior_facets", "interior_facets"]:
+        if dm.hasLabel(name):
+            label = dm.getLabel(name)
+            CHKERR( DMPlexLabelComplete(dm.dm, label.dmlabel) )
+
+
 @cython.boundscheck(False)
 @cython.wraparound(False)
 def cell_facet_labeling(PETSc.DM plex,

firedrake/cython/petschdr.pxi

@@ -41,6 +41,7 @@ cdef extern from "petscdmplex.h" nogil:
     int DMPlexDistributeData(PETSc.PetscDM,PETSc.PetscSF,PETSc.PetscSection,MPI.MPI_Datatype,void*,PETSc.PetscSection,void**)
     int DMPlexSetAdjacencyUser(PETSc.PetscDM,int(*)(PETSc.PetscDM,PetscInt,PetscInt*,PetscInt[],void*),void*)
     int DMPlexCreatePointNumbering(PETSc.PetscDM,PETSc.PetscIS*)
+    int DMPlexLabelComplete(PETSc.PetscDM, PETSc.PetscDMLabel)
 
 cdef extern from "petscdmlabel.h" nogil:
     struct _n_DMLabel

firedrake/mesh.py

@@ -738,6 +738,7 @@ def callback(self):
             del self._callback
             if self.comm.size > 1:
                 add_overlap()
+            dmcommon.complete_facet_labels(self.topology_dm)
 
             if reorder:
                 with timed_region("Mesh: reorder"):