First cut at constructing a call graph.

bin/sixtypical

@@ -50,6 +50,13 @@ def process_input_files(filenames, options):
             sys.stdout.write(json.dumps(analyzer.exit_contexts_map, indent=4, sort_keys=True, separators=(',', ':')))
             sys.stdout.write("\n")
 
+    if options.dump_callgraph:
+        for routine in program.routines:
+            sys.stdout.write('-----------\n')
+            sys.stdout.write('{}\n'.format(routine.name))
+            for called_routine in routine.called_routines:
+                sys.stdout.write('    {}\n'.format(called_routine.name))
+
     compilation_roster = None
     if options.optimize_fallthru:
         from sixtypical.fallthru import FallthruAnalyzer
@@ -161,6 +168,11 @@ if __name__ == '__main__':
         action="store_true",
         help="Dump the ordered fallthru map, in JSON, to stdout after analyzing the program."
     )
+    argparser.add_argument(
+        "--dump-callgraph",
+        action="store_true",
+        help="Dump the call graph, in JSON, to stdout after analyzing the program."
+    )
     argparser.add_argument(
         "--parse-only",
         action="store_true",

src/sixtypical/analyzer.py

@@ -143,6 +143,7 @@ class Analyzer(object):
         for routine in program.routines:
             context = self.analyze_routine(routine)
             routine.encountered_gotos = list(context.encountered_gotos()) if context else []
+            routine.called_routines = list(context.called_routines) if context else []
 
     def analyze_routine(self, routine):
         assert isinstance(routine, Routine)
@@ -515,6 +516,7 @@ class Analyzer(object):
         type = self.get_type(instr.location)
         if not isinstance(type, (RoutineType, VectorType)):
             raise TypeMismatchError(instr, instr.location.name)
+        context.mark_as_called(instr.location)
         if isinstance(type, VectorType):
             type = type.of_type
         for ref in type.inputs:

src/sixtypical/context.py

@@ -35,6 +35,7 @@ class AnalysisContext(object):
         self._terminated = False
         self._gotos_encountered = set()
         self._pointer_assoc = dict()
+        self.called_routines = set()
 
         for ref in inputs:
             if self.is_constant(ref):
@@ -79,6 +80,7 @@ class AnalysisContext(object):
         c._writeable = set(self._writeable)
         c._pointer_assoc = dict(self._pointer_assoc)
         c._gotos_encountered = set(self._gotos_encountered)
+        c.called_routines = set(self.called_routines)
         return c
 
     def update_from(self, other):
@@ -94,6 +96,7 @@ class AnalysisContext(object):
         self._writeable = set(other._writeable)
         self._terminated = other._terminated
         self._pointer_assoc = dict(other._pointer_assoc)
+        self.called_routines = set(other.called_routines)
 
     def each_meaningful(self):
         for ref in self._range.keys():
@@ -326,3 +329,6 @@ class AnalysisContext(object):
             return self.symtab.fetch_local_type(self.routine.name, ref.name).max_range
         else:
             return self.symtab.fetch_global_type(ref.name).max_range
+
+    def mark_as_called(self, routine):
+        self.called_routines.add(routine)