added dataflow

Author: jsiek

dataflow_analysis.py

@@ -0,0 +1,22 @@
+from collections import deque
+from graph import transpose
+from functools import reduce
+from utils import trace
+
+def analyze_dataflow(G, transfer, bottom, join):
+    trans_G = transpose(G)
+    mapping = {}
+    for v in G.vertices():
+        mapping[v] = bottom
+    worklist = deque()
+    for v in G.vertices():
+        worklist.append(v)
+    while worklist:
+        node = worklist.pop()
+        input = reduce(join, [mapping[v] for v in trans_G.adjacent(node)], bottom)
+        output = transfer(node, input)
+        if output != mapping[node]:
+            mapping[node] = output
+            for v in G.adjacent(node):
+                worklist.append(v)
+