Fixup redefinitions before doing code motion

runtime/vm/flow_graph.h

 // 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.
 
 #ifndef RUNTIME_VM_FLOW_GRAPH_H_
 #define RUNTIME_VM_FLOW_GRAPH_H_
 
 #include "vm/bit_vector.h"
 #include "vm/growable_array.h"
 #include "vm/hash_map.h"
@@ skipping 181 matching lines @@
                         Instruction* instr,
                         Environment* env,
                         UseKind use_kind);
 
   // Operations on the flow graph.
   void ComputeSSA(intptr_t next_virtual_register_number,
                   ZoneGrowableArray<Definition*>* inlining_parameters);
 
   // Verification methods for debugging.
   bool VerifyUseLists();
+  bool VerifyRedefinitions();
 
   void DiscoverBlocks();
 
   void MergeBlocks();
 
   // Compute information about effects occuring in different blocks and
   // discover side-effect free paths.
   void ComputeBlockEffects();
   BlockEffects* block_effects() const { return block_effects_; }
 
@@ skipping 72 matching lines @@
   // shift can be a truncating Smi shift-left and result is always Smi.
   // Merge instructions (only per basic-block).
   void TryOptimizePatterns();
 
   // Replaces uses that are dominated by dom of 'def' with 'other'.
   // Note: uses that occur at instruction dom itself are not dominated by it.
   static void RenameDominatedUses(Definition* def,
                                   Instruction* dom,
                                   Definition* other);
 
+  // Renames uses of redefined values to make sure that uses of redefined
+  // values that are dominated by a redefinition are renamed.
+  void RenameUsesDominatedByRedefinitions();
+
  private:
   friend class IfConverter;
   friend class BranchSimplifier;
   friend class ConstantPropagator;
   friend class DeadCodeElimination;
 
   // SSA transformation methods and fields.
   void ComputeDominators(GrowableArray<BitVector*>* dominance_frontier);
 
   void CompressPath(intptr_t start_index,
@@ skipping 229 matching lines @@
 
  private:
   GrowableArray<Definition*> defs_;
   BitVector* contains_vector_;
 };
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_FLOW_GRAPH_H_