With --noopt run unoptimized code through optimizer, more optimizations can be done later.

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/il_printer.h"
 #include "vm/intermediate_language.h"
 #include "vm/growable_array.h"
 #include "vm/object_store.h"
 #include "vm/report.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, prune_dead_locals, true, "optimize dead locals away");
+DECLARE_FLAG(bool, emit_edge_counters);
 DECLARE_FLAG(bool, reorder_basic_blocks);
 DECLARE_FLAG(bool, trace_optimization);
 DECLARE_FLAG(bool, verify_compiler);
 
 
 FlowGraph::FlowGraph(const ParsedFunction& parsed_function,
                      GraphEntryInstr* graph_entry,
                      intptr_t max_block_id)
   : thread_(Thread::Current()),
     parent_(),
@@ skipping 48 matching lines @@
         return;
       }
     }
     to->Add(prefix);
   }
 }
 
 
 bool FlowGraph::ShouldReorderBlocks(const Function& function,
                                     bool is_optimized) {
-  return is_optimized && FLAG_reorder_basic_blocks && !function.is_intrinsic();
+  return is_optimized && FLAG_reorder_basic_blocks &&
+      FLAG_emit_edge_counters && !function.is_intrinsic();
 }
 
 
 GrowableArray<BlockEntryInstr*>* FlowGraph::CodegenBlockOrder(
     bool is_optimized) {
   return ShouldReorderBlocks(function(), is_optimized)
       ? &optimized_block_order_
       : &reverse_postorder_;
 }
 
@@ skipping 1291 matching lines @@
 }
 
 
 bool BlockEffects::IsSideEffectFreePath(BlockEntryInstr* from,
                                         BlockEntryInstr* to) const {
   return available_at_[to->postorder_number()]->Contains(
       from->postorder_number());
 }
 
 }  // namespace dart