compiler: Add PhaseMarker

Author: FabioLuporini

devito/ir/clusters/cluster.py

@@ -16,7 +16,7 @@
 from devito.symbolics import estimate_cost
 from devito.tools import as_tuple, filter_ordered, flatten, infer_dtype
 from devito.types import (
-    CriticalRegion, Fence, Indexed, TensorMove, ThreadArrive, ThreadCommit,
+    CriticalRegion, Fence, Indexed, PhaseMarker, TensorMove, ThreadArrive, ThreadCommit,
     ThreadPoolSync, ThreadWait, WeakFence
 )
 
@@ -303,6 +303,10 @@ def is_fence(self):
     def is_weak_fence(self):
         return self._is_type(WeakFence)
 
+    @cached_property
+    def is_phase_marker(self):
+        return self._is_type(PhaseMarker)
+
     @cached_property
     def is_critical_region(self):
         return self._is_type(CriticalRegion)

devito/types/misc.py

@@ -24,6 +24,7 @@
     'Hyperplane',
     'Indirection',
     'Jump',
+    'PhaseMarker',
     'Pointer',
     'Temp',
     'TempArray',
@@ -332,6 +333,17 @@ class WeakFence(sympy.Function, Fence):
     pass
 
 
+class PhaseMarker(WeakFence):
+
+    """
+    A special WeakFence acting as a marker to logically separate different compute phases.
+    Thus, statements in different phases will not be reordered across the marker upon
+    topological sorting.
+    """
+
+    pass
+
+
 class CriticalRegion(sympy.Function, Fence):
 
     """