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

vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
@@ skipping 2283 matching lines @@
                                variable_count);
   // Number blocks in reverse postorder.
   intptr_t block_count = postorder_block_entries_.length();
   for (intptr_t i = 0; i < block_count; ++i) {
     postorder_block_entries_[i]->set_block_id(block_count - i - 1);
   }
   if (for_optimized) {
     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();
+    }
   }
 }
 
 
 // Compute immediate dominators and the dominance frontier for each basic
 // block.  As a side effect of the algorithm, sets the immediate dominator
 // of each basic block.
 //
 // preorder: an input list of basic block entries in preorder.  The
 //     algorithm relies on the block ordering.
@@ skipping 121 matching lines @@
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart