test rendering and fix non-determinism

numba_rvsdg/core/datastructures/scfg.py

@@ -1046,10 +1046,12 @@ def make_scfg(
 
         scfg_graph = {}
         seen = set()
-        queue = curr_heads
+        # The queue must be a sorted FIFO to maintain reproducible insertion
+        # order for the SCFG.
+        queue = deque(sorted(curr_heads))
 
         while queue:
-            current_name = queue.pop()
+            current_name = queue.popleft()
             if current_name in seen:
                 continue
             seen.add(current_name)
@@ -1083,7 +1085,7 @@ def make_scfg(
 
             scfg_graph[current_name] = block
             if current_name != exiting:
-                queue.update(edges[current_name])
+                queue.extend(edges[current_name])
 
         scfg = SCFG(scfg_graph, name_gen=name_gen)
         return scfg

numba_rvsdg/core/transformations.py

@@ -120,8 +120,10 @@ def reverse_lookup(d: Mapping[int, str], value: str) -> int:
     # All new blocks are recorded for later insertion into the loop set
     new_blocks = set()
     doms = _doms(scfg)
-    # For every block in the loop:
-    for name in loop:
+    # The loop is a set of blocks, but order matters for reproducibility when
+    # assigning synth blocks and so we iterate over the sorted blocks since
+    # sets in Python are unorderd.
+    for name in sorted(loop):
         # If the block is an exiting block or a backedge block
         if name in exiting_blocks or name in backedge_blocks:
             # Copy the jump targets, these will be modified
@@ -377,8 +379,10 @@ def extract_region(
 
     # Generate a new region name
     region_name = scfg.name_gen.new_region_name(region_kind)
+    # Create the subregion, make sure that blocks are inserted in a predictable
+    # order by sorting the set of region blocks.
     head_subgraph = SCFG(
-        {name: scfg.graph[name] for name in region_blocks},
+        {name: scfg.graph[name] for name in sorted(region_blocks)},
         name_gen=scfg.name_gen,
     )
 

numba_rvsdg/rendering/rendering.py

@@ -70,9 +70,9 @@ def render_block(
         """
         if type(block) == BasicBlock:  # noqa: E721
             self.render_basic_block(digraph, name, block)
-        if type(block) == PythonBytecodeBlock:  # noqa: E721
+        elif type(block) == PythonBytecodeBlock:  # noqa: E721
             self.render_basic_block(digraph, name, block)
-        if type(block) == PythonASTBlock:  # noqa: E721
+        elif type(block) == PythonASTBlock:  # noqa: E721
             self.render_python_ast_block(digraph, name, block)  # type: ignore
         elif type(block) == SyntheticAssignment:  # noqa: E721
             self.render_control_variable_block(digraph, name, block)
@@ -337,10 +337,7 @@ def render_branching_block(
         digraph.node(str(name), shape="rect", label=body)
 
     def render_scfg(self) -> "Digraph":
-        """Renders the provided SCFG object."""
-        for name, block in self.scfg.graph.items():  # type: ignore
-            self.render_block(self.g, name, block)
-        self.render_edges(self.scfg)  # type: ignore
+        """Return the graphviz Digraph that contains the rendered SCFG."""
         return self.g
 
     def view(self, name: Optional[str] = None) -> None:

numba_rvsdg/tests/test_rendering.py

@@ -0,0 +1,198 @@
+# This file conatins expected dot output, which uses tabs for indentation.
+# Flake8 will fail, so we just ignore the whole file.
+# flake8: noqa
+# Also ignore types, since we don't type annotate tests.
+# mypy: ignore-errors
+
+from numba_rvsdg.core.datastructures.scfg import SCFG
+from numba_rvsdg.rendering.rendering import SCFGRenderer
+
+expected_original = r"""digraph {
+	0 [label="0\l
+jump targets: ('1', '2')
+back edges: ()" shape=rect]
+	1 [label="1\l
+jump targets: ('3',)
+back edges: ()" shape=rect]
+	2 [label="2\l
+jump targets: ('4',)
+back edges: ()" shape=rect]
+	3 [label="3\l
+jump targets: ('2', '5')
+back edges: ()" shape=rect]
+	4 [label="4\l
+jump targets: ('1',)
+back edges: ()" shape=rect]
+	5 [label="5\l
+jump targets: ()
+back edges: ()" shape=rect]
+	0 -> 1
+	0 -> 2
+	1 -> 3
+	2 -> 4
+	3 -> 2
+	3 -> 5
+	4 -> 1
+}"""
+
+expected_restructured = r"""digraph {
+	subgraph cluster_head_region_0 {
+		color=red label="head_region_0
+jump targets: ('branch_region_0', 'branch_region_1')
+back edges: ()"
+		0 [label="0\l
+jump targets: ('branch_region_0', 'branch_region_1')
+back edges: ()" shape=rect]
+	}
+	subgraph cluster_branch_region_0 {
+		color=green label="branch_region_0
+jump targets: ('tail_region_0',)
+back edges: ()"
+		synth_asign_block_0 [label="synth_asign_block_0\lcontrol_var_0 = 0
+jump targets: ('tail_region_0',)
+back edges: ()" shape=rect]
+	}
+	subgraph cluster_branch_region_1 {
+		color=green label="branch_region_1
+jump targets: ('tail_region_0',)
+back edges: ()"
+		synth_asign_block_1 [label="synth_asign_block_1\lcontrol_var_0 = 1
+jump targets: ('tail_region_0',)
+back edges: ()" shape=rect]
+	}
+	subgraph cluster_tail_region_0 {
+		color=purple label="tail_region_0
+jump targets: ()
+back edges: ()"
+		5 [label="5\l
+jump targets: ()
+back edges: ()" shape=rect]
+		subgraph cluster_loop_region_0 {
+			color=blue label="loop_region_0
+jump targets: ('5',)
+back edges: ()"
+			subgraph cluster_head_region_1 {
+				color=red label="head_region_1
+jump targets: ('branch_region_2', 'branch_region_3')
+back edges: ()"
+				synth_head_block_0 [label="synth_head_block_0\lvariable: control_var_0\l0=>branch_region_2\l1=>branch_region_3
+jump targets: ('branch_region_2', 'branch_region_3')
+back edges: ()" shape=rect]
+			}
+			subgraph cluster_branch_region_2 {
+				color=green label="branch_region_2
+jump targets: ('tail_region_1',)
+back edges: ()"
+				subgraph cluster_head_region_2 {
+					color=red label="head_region_2
+jump targets: ('branch_region_4', 'branch_region_5')
+back edges: ()"
+					1 [label="1\l
+jump targets: ('3',)
+back edges: ()" shape=rect]
+					3 [label="3\l
+jump targets: ('branch_region_4', 'branch_region_5')
+back edges: ()" shape=rect]
+				}
+				subgraph cluster_branch_region_4 {
+					color=green label="branch_region_4
+jump targets: ('tail_region_2',)
+back edges: ()"
+					synth_asign_block_2 [label="synth_asign_block_2\lbackedge_var_0 = 0\lcontrol_var_0 = 1
+jump targets: ('tail_region_2',)
+back edges: ()" shape=rect]
+				}
+				subgraph cluster_branch_region_5 {
+					color=green label="branch_region_5
+jump targets: ('tail_region_2',)
+back edges: ()"
+					synth_asign_block_3 [label="synth_asign_block_3\lbackedge_var_0 = 1
+jump targets: ('tail_region_2',)
+back edges: ()" shape=rect]
+				}
+				subgraph cluster_tail_region_2 {
+					color=purple label="tail_region_2
+jump targets: ('tail_region_1',)
+back edges: ()"
+					synth_tail_block_0 [label="synth_tail_block_0\l
+jump targets: ('tail_region_1',)
+back edges: ()" shape=rect]
+				}
+			}
+			subgraph cluster_branch_region_3 {
+				color=green label="branch_region_3
+jump targets: ('tail_region_1',)
+back edges: ()"
+				2 [label="2\l
+jump targets: ('4',)
+back edges: ()" shape=rect]
+				4 [label="4\l
+jump targets: ('synth_asign_block_4',)
+back edges: ()" shape=rect]
+				synth_asign_block_4 [label="synth_asign_block_4\lbackedge_var_0 = 0\lcontrol_var_0 = 0
+jump targets: ('tail_region_1',)
+back edges: ()" shape=rect]
+			}
+			subgraph cluster_tail_region_1 {
+				color=purple label="tail_region_1
+jump targets: ('5',)
+back edges: ()"
+				synth_exit_latch_block_0 [label="synth_exit_latch_block_0\lvariable: backedge_var_0\l1=>5\l0=>head_region_1
+jump targets: ('5',)
+back edges: ('head_region_1',)" shape=rect]
+			}
+		}
+	}
+	0 -> synth_asign_block_0
+	0 -> synth_asign_block_1
+	synth_asign_block_0 -> synth_head_block_0
+	synth_asign_block_1 -> synth_head_block_0
+	synth_head_block_0 -> 1
+	synth_head_block_0 -> 2
+	1 -> 3
+	3 -> synth_asign_block_2
+	3 -> synth_asign_block_3
+	synth_asign_block_2 -> synth_tail_block_0
+	synth_asign_block_3 -> synth_tail_block_0
+	synth_tail_block_0 -> synth_exit_latch_block_0
+	2 -> 4
+	4 -> synth_asign_block_4
+	synth_asign_block_4 -> synth_exit_latch_block_0
+	synth_exit_latch_block_0 -> 5
+	synth_exit_latch_block_0 -> synth_head_block_0 [color=grey constraint=0 style=dashed]
+}"""
+
+
+def test_simple():
+    original = """
+    blocks:
+        '0':
+            type: basic
+        '1':
+            type: basic
+        '2':
+            type: basic
+        '3':
+            type: basic
+        '4':
+            type: basic
+        '5':
+            type: basic
+    edges:
+        '0': ['1', '2']
+        '1': ['3']
+        '2': ['4']
+        '3': ['2', '5']
+        '4': ['1']
+        '5': []
+    backedges:
+    """
+    scfg, _ = SCFG.from_yaml(original)
+
+    dot_original = str(SCFGRenderer(scfg).render_scfg()).strip()
+    assert expected_original == dot_original
+
+    scfg.restructure()
+
+    dot_restructured = str(SCFGRenderer(scfg).render_scfg()).strip()
+    assert expected_restructured == dot_restructured