add gccutils.sorted_callgraph() to get callgraph in topologically-sorted order

Author: davidmalcolm

gccutils.py

@@ -634,3 +634,45 @@ def check_isinstance(obj, types):
     """
     if not isinstance(obj, types):
         raise TypeError('%s / %r is not an instance of %s' % (obj, obj, types))
+
+def sorted_callgraph():
+    """
+    Return the callgraph, in topologically-sorted order
+    """
+    return topological_sort(gcc.get_callgraph_nodes(),
+                            get_srcs=lambda n: [edge.caller
+                                                for edge in n.callers
+                                                # Strip out recursive calls:
+                                                if edge.caller != n],
+                            get_dsts=lambda n: [edge.callee
+                                                for edge in n.callees
+                                                # Strip out recursive calls:
+                                                if edge.callee != n])
+
+def topological_sort(nodes, get_srcs, get_dsts):
+    """
+    Topological sort in O(n), based on depth-first traversal
+    """
+    result = []
+    visited = set()
+    debug = False
+    def visit(n):
+        if n not in visited:
+            if debug:
+                print('first visit to %s' % n.decl)
+            visited.add(n)
+            for m in get_srcs(n):
+                visit(m)
+            if debug:
+                print('adding to result: %s' % n.decl)
+            result.append(n)
+        else:
+            if debug:
+                print('already visited %s' % n.decl)
+
+    for n in nodes:
+        if not get_dsts(n):
+            visit(n)
+
+    return result
+

tests/gccutils/topological-sort/input.c

@@ -0,0 +1,95 @@
+/*
+   Copyright 2012 David Malcolm <dmalcolm@redhat.com>
+   Copyright 2012 Red Hat, Inc.
+
+   This is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+/*
+   Verify that the topological sort code in gccutils works
+*/
+
+int a(int);
+int b(int);
+int c(int);
+int d(int);
+int e(int);
+int f(int);
+int g(int);
+int h(int);
+int j(int);
+int k(int);
+
+int a(int i)
+{
+    return e(i) + c(i);
+}
+
+int b(int i)
+{
+    return 42 - i;
+}
+
+int c(int i)
+{
+    return i * i;
+}
+
+int d(int i)
+{
+    return a(i) + b(c(i));
+}
+
+/* Directly recursive (actually factorial) */
+int e(int i)
+{
+    if (i>1) {
+        return i * e(i-1);
+    } else {
+        return 1;
+    }
+}
+
+/* f and g are mutually recursive */
+int f(int i)
+{
+    return g(i) + b(i);
+}
+
+int g(int i)
+{
+    return f(i) + c(i) + k(i);
+}
+
+/* h is entirely disjoint from the rest of the graph */
+int h(int i)
+{
+    return i;
+}
+
+int j(int i)
+{
+    return 2 * f(i);
+}
+
+/* k is not defined */
+
+/*
+  PEP-7
+Local variables:
+c-basic-offset: 4
+indent-tabs-mode: nil
+End:
+*/

tests/gccutils/topological-sort/script.py

@@ -0,0 +1,29 @@
+# -*- coding: utf-8 -*-
+#   Copyright 2012 David Malcolm <dmalcolm@redhat.com>
+#   Copyright 2012 Red Hat, Inc.
+#
+#   This is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#   General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see
+#   <http://www.gnu.org/licenses/>.
+
+# Verify that the topological sort code in gccutils works
+import gcc
+
+def on_pass_execution(p, fn):
+    if p.name == '*free_lang_data':
+        from gccutils import sorted_callgraph
+        for cgn in sorted_callgraph():
+            print(cgn.decl)
+
+gcc.register_callback(gcc.PLUGIN_PASS_EXECUTION,
+                      on_pass_execution)

tests/gccutils/topological-sort/stdout.txt

@@ -0,0 +1,10 @@
+j
+f
+g
+k
+h
+d
+a
+e
+c
+b