compiler: Misc compiler tweaks and improvements

devito/core/cpu.py

@@ -60,6 +60,9 @@ def _normalize_kwargs(cls, **kwargs):
         o['par-dynamic-work'] = oo.pop('par-dynamic-work', cls.PAR_DYNAMIC_WORK)
         o['par-nested'] = oo.pop('par-nested', cls.PAR_NESTED)
 
+        # Distributed parallelism
+        o['dist-drop-unwritten'] = oo.pop('dist-drop-unwritten', cls.DIST_DROP_UNWRITTEN)
+
         # Misc
         o['expand'] = oo.pop('expand', cls.EXPAND)
         o['optcomms'] = oo.pop('optcomms', True)

devito/core/gpu.py

@@ -75,6 +75,9 @@ def _normalize_kwargs(cls, **kwargs):
         o['gpu-fit'] = as_tuple(oo.pop('gpu-fit', cls._normalize_gpu_fit(**kwargs)))
         o['gpu-create'] = as_tuple(oo.pop('gpu-create', ()))
 
+        # Distributed parallelism
+        o['dist-drop-unwritten'] = oo.pop('dist-drop-unwritten', cls.DIST_DROP_UNWRITTEN)
+
         # Misc
         o['expand'] = oo.pop('expand', cls.EXPAND)
         o['optcomms'] = oo.pop('optcomms', True)

devito/core/operator.py

@@ -100,6 +100,12 @@ class BasicOperator(Operator):
     The supported MPI modes.
     """
 
+    DIST_DROP_UNWRITTEN = True
+    """
+    Drop halo exchanges for read-only Function, even in presence of
+    stencil-like data accesses.
+    """
+
     INDEX_MODE = "int64"
     """
     The type of the expression used to compute array indices. Either `int64`
@@ -281,7 +287,7 @@ def _specialize_iet(cls, graph, **kwargs):
         # from HaloSpot optimization)
         # Note that if MPI is disabled then this pass will act as a no-op
         if 'mpi' not in passes:
-            passes_mapper['mpi'](graph)
+            passes_mapper['mpi'](graph, **kwargs)
 
         # Run passes
         applied = []
@@ -300,17 +306,17 @@ def _specialize_iet(cls, graph, **kwargs):
         if 'init' not in passes:
             passes_mapper['init'](graph)
 
-        # Enforce pthreads if CPU-GPU orchestration requested
-        if 'orchestrate' in passes and 'pthreadify' not in passes:
-            passes_mapper['pthreadify'](graph, sregistry=sregistry)
-
         # Symbol definitions
         cls._Target.DataManager(**kwargs).process(graph)
 
         # Linearize n-dimensional Indexeds
         if 'linearize' not in passes and options['linearize']:
             passes_mapper['linearize'](graph)
 
+        # Enforce pthreads if CPU-GPU orchestration requested
+        if 'orchestrate' in passes and 'pthreadify' not in passes:
+            passes_mapper['pthreadify'](graph, sregistry=sregistry)
+
         return graph
 
 

devito/ir/clusters/cluster.py

@@ -9,7 +9,7 @@
                                DataSpace, Guards, Properties, Scope, detect_accesses,
                                detect_io, normalize_properties, normalize_syncs,
                                sdims_min, sdims_max)
-from devito.mpi.halo_scheme import HaloTouch
+from devito.mpi.halo_scheme import HaloScheme, HaloTouch
 from devito.symbolics import estimate_cost
 from devito.tools import as_tuple, flatten, frozendict, infer_dtype
 
@@ -26,7 +26,7 @@ class Cluster(object):
     exprs : expr-like or list of expr-like
         An ordered sequence of expressions computing a tensor.
     ispace : IterationSpace, optional
-        The cluster iteration space.
+        The Cluster iteration space.
     guards : dict, optional
         Mapper from Dimensions to expr-like, representing the conditions under
         which the Cluster should be computed.
@@ -37,9 +37,12 @@ class Cluster(object):
         Mapper from Dimensions to lists of SyncOps, that is ordered sequences of
         synchronization operations that must be performed in order to compute the
         Cluster asynchronously.
+    halo_scheme : HaloScheme, optional
+        The halo exchanges required by the Cluster.
     """
 
-    def __init__(self, exprs, ispace=None, guards=None, properties=None, syncs=None):
+    def __init__(self, exprs, ispace=None, guards=None, properties=None, syncs=None,
+                 halo_scheme=None):
         ispace = ispace or IterationSpace([])
 
         self._exprs = tuple(ClusterizedEq(e, ispace=ispace) for e in as_tuple(exprs))
@@ -57,6 +60,8 @@ def __init__(self, exprs, ispace=None, guards=None, properties=None, syncs=None)
                     properties = properties.drop(d)
         self._properties = properties
 
+        self._halo_scheme = halo_scheme
+
     def __repr__(self):
         return "Cluster([%s])" % ('\n' + ' '*9).join('%s' % i for i in self.exprs)
 
@@ -91,7 +96,9 @@ def from_clusters(cls, *clusters):
             raise ValueError("Cannot build a Cluster from Clusters with "
                              "non-compatible synchronization operations")
 
-        return Cluster(exprs, ispace, guards, properties, syncs)
+        halo_scheme = HaloScheme.union([c.halo_scheme for c in clusters])
+
+        return Cluster(exprs, ispace, guards, properties, syncs, halo_scheme)
 
     def rebuild(self, *args, **kwargs):
         """
@@ -110,7 +117,8 @@ def rebuild(self, *args, **kwargs):
                               ispace=kwargs.get('ispace', self.ispace),
                               guards=kwargs.get('guards', self.guards),
                               properties=kwargs.get('properties', self.properties),
-                              syncs=kwargs.get('syncs', self.syncs))
+                              syncs=kwargs.get('syncs', self.syncs),
+                              halo_scheme=kwargs.get('halo_scheme', self.halo_scheme))
 
     @property
     def exprs(self):
@@ -144,6 +152,10 @@ def properties(self):
     def syncs(self):
         return self._syncs
 
+    @property
+    def halo_scheme(self):
+        return self._halo_scheme
+
     @cached_property
     def free_symbols(self):
         return set().union(*[e.free_symbols for e in self.exprs])

devito/ir/iet/nodes.py

@@ -288,10 +288,13 @@ def functions(self):
                             retval.append(s.function)
                     except AttributeError:
                         continue
+
         if self.base is not None:
             retval.append(self.base.function)
+
         if self.retobj is not None:
             retval.append(self.retobj.function)
+
         return tuple(filter_ordered(retval))
 
     @cached_property
@@ -309,10 +312,15 @@ def expr_symbols(self):
                     retval.extend(i.free_symbols)
                 except AttributeError:
                     pass
+
         if self.base is not None:
             retval.append(self.base)
-        if self.retobj is not None:
+
+        if isinstance(self.retobj, Indexed):
+            retval.extend(self.retobj.free_symbols)
+        elif self.retobj is not None:
             retval.append(self.retobj)
+
         return tuple(filter_ordered(retval))
 
     @property
@@ -744,6 +752,8 @@ class CallableBody(Node):
     maps : Transfer or list of Transfer, optional
         Data maps for `body` (a data map may e.g. trigger a data transfer from
         host to device).
+    strides : list of Nodes, optional
+        Statements defining symbols used to access linearized arrays.
     objs : list of Definitions, optional
         Object definitions for `body`.
     unmaps : Transfer or list of Transfer, optional
@@ -756,19 +766,21 @@ class CallableBody(Node):
 
     is_CallableBody = True
 
-    _traversable = ['unpacks', 'init', 'allocs', 'casts', 'bundles', 'maps', 'objs',
-                    'body', 'unmaps', 'unbundles', 'frees']
+    _traversable = ['unpacks', 'init', 'allocs', 'casts', 'bundles', 'maps',
+                    'strides', 'objs', 'body', 'unmaps', 'unbundles', 'frees']
 
-    def __init__(self, body, init=(), unpacks=(), allocs=(), casts=(),
+    def __init__(self, body, init=(), unpacks=(), strides=(), allocs=(), casts=(),
                  bundles=(), objs=(), maps=(), unmaps=(), unbundles=(), frees=()):
         # Sanity check
         assert not isinstance(body, CallableBody), "CallableBody's cannot be nested"
 
         self.body = as_tuple(body)
-        self.init = as_tuple(init)
+
         self.unpacks = as_tuple(unpacks)
+        self.init = as_tuple(init)
         self.allocs = as_tuple(allocs)
         self.casts = as_tuple(casts)
+        self.strides = as_tuple(strides)
         self.bundles = as_tuple(bundles)
         self.maps = as_tuple(maps)
         self.objs = as_tuple(objs)
@@ -1201,6 +1213,10 @@ def __getattr__(self, name):
     def functions(self):
         return as_tuple(self.nthreads)
 
+    @property
+    def expr_symbols(self):
+        return as_tuple(self.nthreads)
+
     @property
     def root(self):
         return self.body[0]