Merge pull request #2230 from devitocodes/msd-pass-fix

compiler: prevent multisubdimension expressions duplicates

Author: mloubout

devito/passes/clusters/implicit.py

@@ -7,6 +7,7 @@
 
 from devito.ir import (Cluster, Interval, IntervalGroup, IterationSpace, Queue,
                        FetchUpdate, PrefetchUpdate, SEQUENTIAL)
+from devito.symbolics import retrieve_dimensions
 from devito.tools import as_tuple, timed_pass
 from devito.types import Eq
 from devito.types.grid import MultiSubDimension, SubDomainSet
@@ -106,6 +107,13 @@ def callback(self, clusters, prefix):
             # The "implicit expressions" created for the MultiSubDomain
             exprs, dims, sub_iterators = make_implicit_exprs(d.msd, c)
 
+            # Make sure the "implicit expressions" aren't scheduled in
+            # an inner loop. E.g schedule both for `t, xi, yi` and `t, d, xi, yi`
+            edims = set(retrieve_dimensions(exprs, deep=True))
+            if dim not in edims and any(d.dim in edims for d in prefix):
+                processed.append(c)
+                continue
+
             # The IterationSpace induced by the MultiSubDomain
             if dims:
                 intervals = [Interval(i) for i in dims]