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

runtime/vm/block_scheduler.cc

 // Copyright (c) 2013, 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/block_scheduler.h"
 
 #include "vm/allocation.h"
 #include "vm/code_patcher.h"
 #include "vm/flow_graph.h"
 
@@ skipping 62 matching lines @@
         double weight =
             static_cast<double>(count) / static_cast<double>(entry_count);
         jump->set_edge_weight(weight);
       }
     }
   }
 }
 
 
 void BlockScheduler::AssignEdgeWeights() const {
+  if (!FLAG_emit_edge_counters) {
+    return;
+  }
   const Code& unoptimized_code = flow_graph()->parsed_function().code();
   ASSERT(!unoptimized_code.IsNull());
 
   ZoneGrowableArray<uword>* deopt_id_pc_pairs = new ZoneGrowableArray<uword>();
   const PcDescriptors& descriptors =
       PcDescriptors::Handle(unoptimized_code.pc_descriptors());
   PcDescriptors::Iterator iter(descriptors, RawPcDescriptors::kDeopt);
   uword entry = unoptimized_code.EntryPoint();
   while (iter.MoveNext()) {
     intptr_t deopt_id = iter.DeoptId();
@@ skipping 146 matching lines @@
   for (intptr_t i = block_count - 1; i >= 0; --i) {
     if (chains[i]->first->block == flow_graph()->postorder()[i]) {
       for (Link* link = chains[i]->first; link != NULL; link = link->next) {
         flow_graph()->CodegenBlockOrder(true)->Add(link->block);
       }
     }
   }
 }
 
 }  // namespace dart