Fix the flag --reorder-basic-blocks so it works to disable reordering.

runtime/vm/flow_graph.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.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
 #include "vm/growable_array.h"
 
 namespace dart {
 
+DECLARE_FLAG(bool, reorder_basic_blocks);
 DECLARE_FLAG(bool, trace_optimization);
 DECLARE_FLAG(bool, verify_compiler);
 DEFINE_FLAG(bool, optimize_try_catch, true, "Optimization of try-catch");
 
 
 FlowGraph::FlowGraph(const FlowGraphBuilder& builder,
                      GraphEntryInstr* graph_entry,
                      intptr_t max_block_id)
   : parent_(),
     current_ssa_temp_index_(0),
     max_block_id_(max_block_id),
     parsed_function_(*builder.parsed_function()),
     num_copied_params_(builder.num_copied_params()),
     num_non_copied_params_(builder.num_non_copied_params()),
     num_stack_locals_(builder.num_stack_locals()),
     graph_entry_(graph_entry),
     preorder_(),
     postorder_(),
     reverse_postorder_(),
     optimized_block_order_(),
     block_effects_(NULL),
     licm_allowed_(true),
     use_far_branches_(false),
     loop_headers_(NULL),
     loop_invariant_loads_(NULL) {
   DiscoverBlocks();
 }
 
 
+GrowableArray<BlockEntryInstr*>* FlowGraph::codegen_block_order(
+    bool is_optimized) {
+  return (is_optimized && FLAG_reorder_basic_blocks)
+      ? &optimized_block_order_
+      : &reverse_postorder_;
+}
+
+
 ConstantInstr* FlowGraph::GetConstant(const Object& object) {
   // Check if the constant is already in the pool.
   GrowableArray<Definition*>* pool = graph_entry_->initial_definitions();
   for (intptr_t i = 0; i < pool->length(); ++i) {
     ConstantInstr* constant = (*pool)[i]->AsConstant();
     if ((constant != NULL) && (constant->value().raw() == object.raw())) {
       return constant;
     }
   }
   // Otherwise, allocate and add it to the pool.
@@ skipping 1091 matching lines @@
 }
 
 
 bool BlockEffects::IsSideEffectFreePath(BlockEntryInstr* from,
                                         BlockEntryInstr* to) const {
   return available_at_[to->postorder_number()]->Contains(
       from->postorder_number());
 }
 
 }  // namespace dart