Add flow graph printing into a .cfg file with flag --print-flow-graph-file.

vm/flow_graph_builder.cc

Index: vm/flow_graph_builder.cc
===================================================================
--- vm/flow_graph_builder.cc	(revision 8145)
+++ vm/flow_graph_builder.cc	(working copy)
@@ -2301,14 +2301,22 @@
     GrowableArray<BitVector*> dominance_frontier;
     ComputeDominators(&preorder_block_entries_, &parent, &dominance_frontier);
   }
-  if (FLAG_print_flow_graph) {
+  if (FLAG_print_flow_graph || (Dart::flow_graph_writer() != NULL)) {
     intptr_t length = postorder_block_entries_.length();
     GrowableArray<BlockEntryInstr*> reverse_postorder(length);
     for (intptr_t i = length - 1; i >= 0; --i) {
       reverse_postorder.Add(postorder_block_entries_[i]);
     }
-    FlowGraphPrinter printer(function, reverse_postorder);
-    printer.PrintBlocks();
+    if (FLAG_print_flow_graph) {
+      // Print flow graph to stdout.
+      FlowGraphPrinter printer(function, reverse_postorder);
+      printer.PrintBlocks();
+    }
+    if (Dart::flow_graph_writer() != NULL) {
+      // Write flow graph to file.
+      FlowGraphVisualizer printer(function, reverse_postorder);

[siva, 2012/06/04 18:23:57]

Over here this appears to be a per isolate object but when dumping out the
information, output from all isolates will get mixed up. Not sure how the
visualizer will handle that.

+      printer.PrintFunction();
+    }
   }
 }