Index: utils/extract_vplan.py
===================================================================
--- /dev/null
+++ utils/extract_vplan.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+
+# This script extracts the VPlan digraphs from the vectoriser debug messages
+# and saves them in individual dot files (one for each plan). Optionally, and
+# providing 'dot' is installed, it can also render the dot into a PNG file.
+
+import sys
+import re
+import argparse
+import shutil
+import subprocess
+
+parser = argparse.ArgumentParser()
+parser.add_argument('--png', action='store_true')
+args = parser.parse_args()
+
+dot = shutil.which('dot')
+if args.png and not dot:
+    raise RuntimeError("Can't export to PNG without 'dot' in the system")
+
+VPlans = list()
+Names = list()
+CurVPlan = ''
+for line in sys.stdin:
+    if not CurVPlan and re.match("digraph VPlan {", line):
+        CurVPlan = line
+    elif CurVPlan:
+        if re.match("}", line):
+            CurVPlan += line
+            VPlans.append(CurVPlan)
+            CurVPlan = ''
+        else:
+            m = re.search("(VF.*,UF.*), ", line)
+            if m:
+                name = re.sub('[^a-zA-Z0-9]', '', m.group(1))
+                Names.append(name)
+                print("Found VPlan for " + name)
+            CurVPlan += line
+
+if len(VPlans) != len(Names):
+    raise RuntimeError("Incongruent number of VPlans and respective names")
+
+for i in range(len(VPlans)):
+    if args.png:
+        filename = 'VPlan' + Names[i] + '.png'
+        print("Exporting " + Names[i] + " to PNG via dot: " + filename)
+        p = subprocess.Popen([dot, '-Tpng', '-o', filename], encoding='utf-8',
+                              stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        out, err = p.communicate(input=VPlans[i])
+        if err:
+            raise RuntimeError("Error running dot: " + err)
+
+    else:
+        filename = 'VPlan' + Names[i] + '.dot'
+        print("No visualisation requested, saving to file: " + filename)
+        out = open(filename, 'w')
+        out.write(VPlans[i])
+        out.close()