compiler: Fix toposort to account for fences

devito/ir/clusters/cluster.py

@@ -14,7 +14,7 @@
 from devito.mpi.reduction_scheme import DistReduce
 from devito.symbolics import estimate_cost
 from devito.tools import as_tuple, flatten, infer_dtype
-from devito.types import WeakFence, CriticalRegion
+from devito.types import Fence, WeakFence, CriticalRegion
 
 __all__ = ["Cluster", "ClusterGroup"]
 
@@ -239,42 +239,46 @@ def is_sparse(self):
         """
         return any(a.is_irregular for a in self.scope.accesses)
 
-    @property
+    @cached_property
     def is_wild(self):
         """
         True if encoding a non-mathematical operation, False otherwise.
         """
-        return self.is_halo_touch or self.is_dist_reduce or self.is_fence
+        return (self.is_halo_touch or
+                self.is_dist_reduce or
+                self.is_weak_fence or
+                self.is_critical_region)
 
-    @property
+    @cached_property
     def is_halo_touch(self):
         return self.exprs and all(isinstance(e.rhs, HaloTouch) for e in self.exprs)
 
-    @property
+    @cached_property
     def is_dist_reduce(self):
         return self.exprs and all(isinstance(e.rhs, DistReduce) for e in self.exprs)
 
-    @property
+    @cached_property
     def is_fence(self):
-        return self.is_weak_fence or self.is_critical_region
+        return (self.exprs and all(isinstance(e.rhs, Fence) for e in self.exprs) or
+                self.is_critical_region)
 
-    @property
+    @cached_property
     def is_weak_fence(self):
         return self.exprs and all(isinstance(e.rhs, WeakFence) for e in self.exprs)
 
-    @property
+    @cached_property
     def is_critical_region(self):
         return self.exprs and all(isinstance(e.rhs, CriticalRegion) for e in self.exprs)
 
-    @property
+    @cached_property
     def is_async(self):
         """
         True if an asynchronous Cluster, False otherwise.
         """
         return any(isinstance(s, (WithLock, PrefetchUpdate))
                    for s in flatten(self.syncs.values()))
 
-    @property
+    @cached_property
     def is_wait(self):
         """
         True if a Cluster waiting on a lock (that is a special synchronization

devito/passes/clusters/misc.py

@@ -340,6 +340,8 @@ def is_cross(source, sink):
                 return t0 < v <= t1 or t1 < v <= t0
 
             for cg1 in cgroups[n+1:]:
+                n1 = cgroups.index(cg1)
+
                 # A Scope to compute all cross-ClusterGroup anti-dependences
                 scope = Scope(exprs=cg0.exprs + cg1.exprs, rules=is_cross)
 
@@ -355,14 +357,16 @@ def is_cross(source, sink):
                     break
 
                 # Any anti- and iaw-dependences impose that `cg1` follows `cg0`
-                # and forbid any sort of fusion
-                elif any(scope.d_anti_gen()) or\
-                        any(i.is_iaw for i in scope.d_output_gen()):
+                # and forbid any sort of fusion. Fences have the same effect
+                elif (any(scope.d_anti_gen()) or
+                      any(i.is_iaw for i in scope.d_output_gen()) or
+                      any(c.is_fence for c in flatten(cgroups[n:n1+1]))):
                     dag.add_edge(cg0, cg1)
 
                 # Any flow-dependences along an inner Dimension (i.e., a Dimension
                 # that doesn't appear in `prefix`) impose that `cg1` follows `cg0`
-                elif any(not (i.cause and i.cause & prefix) for i in scope.d_flow_gen()):
+                elif any(not (i.cause and i.cause & prefix)
+                         for i in scope.d_flow_gen()):
                     dag.add_edge(cg0, cg1)
 
                 # Clearly, output dependences must be honored