Compute preorder as well as postorder basic block orderings.

runtime/vm/flow_graph_builder.h

 // 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.
 
 #ifndef VM_FLOW_GRAPH_BUILDER_H_
 #define VM_FLOW_GRAPH_BUILDER_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
 #include "vm/intermediate_language.h"
 
 namespace dart {
 
 class Instruction;
 class ParsedFunction;
 
 // Build a flow graph from a parsed function's AST.
 class FlowGraphBuilder: public ValueObject {
  public:
   explicit FlowGraphBuilder(const ParsedFunction& parsed_function)
       : parsed_function_(parsed_function),
+        preorder_block_entries_(),
         postorder_block_entries_() { }
 
   void BuildGraph();
 
   const ParsedFunction& parsed_function() const { return parsed_function_; }
 
-  const GrowableArray<BlockEntryInstr*>* blocks() const {
-    return &postorder_block_entries_;
+  const GrowableArray<BlockEntryInstr*>& postorder_block_entries() const {
+    return postorder_block_entries_;
   }
 
   void Bailout(const char* reason);
 
   void set_context_level(intptr_t value) { context_level_ = value; }
   intptr_t context_level() const { return context_level_; }
 
  private:
   const ParsedFunction& parsed_function_;
+  GrowableArray<BlockEntryInstr*> preorder_block_entries_;
   GrowableArray<BlockEntryInstr*> postorder_block_entries_;
   intptr_t context_level_;
 };
 
 
 class TestGraphVisitor;
 
 // Translate an AstNode to a control-flow graph fragment for its effects
 // (e.g., a statement or an expression in an effect context).  Implements a
 // function from an AstNode and next temporary index to a graph fragment
@@ skipping 212 matching lines @@
   }
 
   // Output parameters.
   BlockEntryInstr** true_successor_address_;
   BlockEntryInstr** false_successor_address_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_BUILDER_H_