Merge pull request #2452 from devitocodes/hotfix-halo-buf

compiler: Hotfix and simplify minimize_symbols

devito/ir/iet/visitors.py

@@ -1229,7 +1229,10 @@ def visit_Iteration(self, o):
         dimension = uxreplace(o.dim, self.mapper)
         limits = [uxreplace(i, self.mapper) for i in o.limits]
         pragmas = self._visit(o.pragmas)
+
         uindices = [uxreplace(i, self.mapper) for i in o.uindices]
+        uindices = filter_ordered(i for i in uindices if isinstance(i, Dimension))
+
         return o._rebuild(nodes=nodes, dimension=dimension, limits=limits,
                           pragmas=pragmas, uindices=uindices)
 

devito/passes/iet/misc.py

@@ -5,9 +5,9 @@
 import sympy
 
 from devito.finite_differences import Max, Min
-from devito.ir import (Any, Forward, Iteration, List, Prodder, FindApplications,
-                       FindNodes, FindSymbols, Transformer, Uxreplace,
-                       filter_iterations, retrieve_iteration_tree, pull_dims)
+from devito.ir import (Any, Forward, List, Prodder, FindApplications, FindNodes,
+                       FindSymbols, Transformer, Uxreplace, filter_iterations,
+                       retrieve_iteration_tree, pull_dims)
 from devito.passes.iet.engine import iet_pass
 from devito.ir.iet.efunc import DeviceFunction, EntryFunction
 from devito.symbolics import (ValueLimit, evalrel, has_integer_args, limits_mapper,
@@ -246,31 +246,20 @@ def remove_redundant_moddims(iet):
     if not mds:
         return iet
 
-    # ModuloDimensions are defined in Iteration headers, hence they must be
-    # removed from there first of all
-    mapper = {}
-    for n in FindNodes(Iteration).visit(iet):
-        candidates = [d for d in n.uindices if d in mds]
-
-        degenerates, others = split(candidates, lambda d: d.modulo == 1)
-        subs = {d: sympy.S.Zero for d in degenerates}
-
-        redundants = as_mapper(others, key=lambda d: d.offset % d.modulo)
-        for k, v in redundants.items():
-            chosen = v.pop(0)
-            subs.update({d: chosen for d in v})
-
-        if subs:
-            # Expunge the ModuloDimensions from the Iteration header
-            uindices = [d for d in n.uindices if d not in subs]
-            iteration = n._rebuild(uindices=uindices)
+    degenerates, others = split(mds, lambda d: d.modulo == 1)
+    subs = {d: sympy.S.Zero for d in degenerates}
 
-            # Replace the ModuloDimensions in the Iteration body
-            iteration = Uxreplace(subs).visit(iteration)
+    redundants = as_mapper(others, key=lambda d: d.offset % d.modulo)
+    for k, v in redundants.items():
+        chosen = v.pop(0)
+        subs.update({d: chosen for d in v})
 
-            mapper[n] = iteration
-
-    iet = Transformer(mapper, nested=True).visit(iet)
+    # Transform the `body`, rather than `iet`, to avoid applying substitutions
+    # to `iet.parameters`, so e.g. `..., t0, t1, t2, ...` remains unchanged
+    # instead of becoming `..., t0, t1, t1, ...`. The IET `engine` will then
+    # take care of cleaning up the `parameters` list
+    body = Uxreplace(subs).visit(iet.body)
+    iet = iet._rebuild(body=body)
 
     return iet