Clear use lists for globals and definitions in start environment in release mode.

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"
@@ skipping 264 matching lines @@
         use->set_use_index(pred_index);
         use->AddToInputUseList();
       }
     }
   }
 }
 
 
 void FlowGraph::ComputeUseLists() {
   DEBUG_ASSERT(ResetUseLists());
+  // Clear global constants.
+  ClearUseLists(graph_entry_->constant_null());
+  // Clear definitions in the start environment.
+  for (intptr_t i = 0; i < graph_entry_->start_env()->values().length(); ++i) {

[srdjan, 2012/08/30 18:32:02]

You could cache  graph_entry_->start_env()->values() in a local variable.

+    ClearUseLists(graph_entry_->start_env()->values()[i]->definition());
+  }
   ComputeUseListsRecursive(graph_entry_);
   DEBUG_ASSERT(ValidateUseLists());
 }
 
 
 void FlowGraph::ComputeSSA(intptr_t next_virtual_register_number) {
   current_ssa_temp_index_ = next_virtual_register_number;
   GrowableArray<BitVector*> dominance_frontier;
   ComputeDominators(&preorder_, &parent_, &dominance_frontier);
   InsertPhis(preorder_, assigned_vars_, dominance_frontier);
@@ skipping 438 matching lines @@
   // Remove original arguments to the call.
   for (intptr_t i = 0; i < caller_comp->ArgumentCount(); ++i) {
     PushArgumentInstr* push = caller_comp->ArgumentAt(i);
     push->ReplaceUsesWith(push->value()->definition());
     push->RemoveFromGraph();
   }
 }
 
 
 }  // namespace dart