Fixup redefinitions before doing code motion

runtime/vm/precompiler.cc

 // Copyright (c) 2015, 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/precompiler.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
@@ skipping 3198 matching lines @@
                 flow_graph->Canonicalize();
               }
               DEBUG_ASSERT(flow_graph->VerifyUseLists());
             }
           }
 
           // Run loop-invariant code motion right after load elimination since
           // it depends on the numbering of loads from the previous
           // load-elimination.
           if (FLAG_loop_invariant_code_motion) {
+            flow_graph->RenameUsesDominatedByRedefinitions();
+            DEBUG_ASSERT(flow_graph->VerifyRedefinitions());
             LICM licm(flow_graph);
             licm.Optimize();
             DEBUG_ASSERT(flow_graph->VerifyUseLists());
           }
           flow_graph->RemoveRedefinitions();
         }
 
         // Optimize (a << b) & c patterns, merge operations.
         // Run after CSE in order to have more opportunity to merge
         // instructions that have same inputs.
@@ skipping 323 matching lines @@
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   DartPrecompilationPipeline pipeline(zone, field_type_map);
   return PrecompileFunctionHelper(precompiler, &pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart