PruneConnectors: Generalize to scoped NestedSDFGs

dace/transformation/dataflow/prune_connectors.py

@@ -46,7 +46,10 @@ def can_be_applied(self, graph: SDFGState, expr_index: int, sdfg: SDFG, permissi
         # Add WCR outputs to "do not prune" input list
         for e in graph.out_edges(nsdfg):
             if e.data.wcr is not None and e.src_conn in prune_in:
-                if (graph.in_degree(next(iter(graph.in_edges_by_connector(nsdfg, e.src_conn))).src) > 0):
+                # Find access node
+                in_edge = next(iter(graph.in_edges_by_connector(nsdfg, e.src_conn)))
+                access_node = graph.memlet_path(in_edge)[0].src
+                if graph.in_degree(access_node) > 0:
                     prune_in.remove(e.src_conn)
         has_before = all(
             graph.in_degree(graph.memlet_path(e)[0].src) > 0 for e in graph.in_edges(nsdfg) if e.dst_conn in prune_in)
@@ -73,7 +76,9 @@ def apply(self, state: SDFGState, sdfg: SDFG):
         # Add WCR outputs to "do not prune" input list
         for e in state.out_edges(nsdfg):
             if e.data.wcr is not None and e.src_conn in prune_in:
-                if (state.in_degree(next(iter(state.in_edges_by_connector(nsdfg, e.src_conn))).src) > 0):
+                in_edge = next(iter(state.in_edges_by_connector(nsdfg, e.src_conn)))
+                access_node = state.memlet_path(in_edge)[0].src
+                if state.in_degree(access_node) > 0:
                     prune_in.remove(e.src_conn)
         do_not_prune = set()
         for conn in prune_in:

tests/transformations/prune_connectors_test.py

@@ -4,7 +4,10 @@
 import os
 import pytest
 import dace
-from dace.transformation.dataflow import PruneConnectors
+
+from dace.sdfg.state import StateSubgraphView
+from dace.transformation.dataflow import PruneConnectors, AugAssignToWCR
+from dace.transformation import helpers
 
 
 def make_sdfg():
@@ -237,6 +240,83 @@ def test_unused_retval_2():
     assert np.allclose(a, 1)
 
 
+def test_prune_connectors_in_scope():
+
+    @dace.program
+    def sdfg_prune_connectors_in_scope(A: dace.float64[32], B: dace.float64[32]):
+        for i in dace.map[0:32]:
+            with dace.tasklet(language=dace.Language.CPP):
+                a << A[i]
+                c << B[i]
+                b >> A[i]
+                """
+                b = min(c, a);
+                """
+
+    sdfg = sdfg_prune_connectors_in_scope.to_sdfg()
+    sdfg.simplify()
+
+    state = sdfg.start_state
+    map_entry = None
+    for node in state.nodes():
+        if isinstance(node, dace.nodes.MapEntry):
+            map_entry = node
+            break
+
+    map_exit = state.exit_node(map_entry)
+    subgraph = StateSubgraphView(state, set(state.all_nodes_between(map_entry, map_exit)))
+    helpers.nest_state_subgraph(sdfg, state, subgraph)
+
+    # WCR Conversion
+    applied = sdfg.apply_transformations_repeated(AugAssignToWCR)
+    assert applied == 1
+
+    applied = sdfg.apply_transformations_repeated(PruneConnectors)
+    assert applied == 1
+
+
+def test_prune_connectors_in_scope_dependency():
+
+    @dace.program
+    def sdfg_prune_connectors_in_scope_dependency(A: dace.float64[32], B: dace.float64[32]):
+        for j in dace.map[0:32]:
+            with dace.tasklet(language=dace.Language.CPP):
+                a >> A[j]
+                """
+                a = 0;
+                """
+        for i in dace.map[0:32]:
+            with dace.tasklet(language=dace.Language.CPP):
+                a << A[i]
+                c << B[i]
+                b >> A[i]
+                """
+                b = min(c, a);
+                """
+
+    sdfg = sdfg_prune_connectors_in_scope_dependency.to_sdfg()
+    sdfg.simplify()
+
+    state = sdfg.start_state
+    map_entry = None
+    for node in state.nodes():
+        if isinstance(node, dace.nodes.MapEntry) and str(node.map.params[0]) == "i":
+            map_entry = node
+            break
+
+    # Create NestedSDFG inside map
+    map_exit = state.exit_node(map_entry)
+    subgraph = StateSubgraphView(state, set(state.all_nodes_between(map_entry, map_exit)))
+    helpers.nest_state_subgraph(sdfg, state, subgraph)
+
+    # WCR Conversion: A is no input of NestedSDFG
+    applied = sdfg.apply_transformations_repeated(AugAssignToWCR)
+    assert applied == 1
+
+    applied = sdfg.apply_transformations_repeated(PruneConnectors)
+    assert applied == 0
+
+
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
     parser.add_argument("--N", default=64)
@@ -248,3 +328,5 @@ def test_unused_retval_2():
     test_prune_connectors(True, n=n)
     test_unused_retval()
     test_unused_retval_2()
+    test_prune_connectors_in_scope()
+    test_prune_connectors_in_scope_dependency()