compiler: revert broken reduce par_tile

Author: mloubout

devito/mpi/distributed.py

@@ -91,7 +91,7 @@ def devito_mpi_finalize():
     """
     Finalize MPI, if initialized by Devito.
     """
-    global init_by_devito
+    global init_by_devito  # noqa: F824
     if init_by_devito and MPI.Is_initialized() and not MPI.Is_finalized():
         MPI.Finalize()
 

devito/passes/clusters/blocking.py

@@ -508,9 +508,7 @@ def __init__(self, par_tile):
             # The user has supplied one specific par-tile per blocked nest
             self.umt_small = par_tile
             self.umt_sparse = par_tile
-            # Reduction tiles have to be unbounded.
-            self.umt_reduce = UnboundedMultiTuple(
-                *[UnboundTuple(*p, 1) for p in par_tile])
+            self.umt_reduce = par_tile
         else:
             # Special case 1: a smaller par-tile to avoid under-utilizing
             # computational resources when the iteration spaces are too small