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 3143 matching lines @@
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
           // Canonicalization introduced more opportunities for constant
           // propagation.
           ConstantPropagator::Optimize(flow_graph);
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
         }
 
         // Optimistically convert loop phis that have a single non-smi input
         // coming from the loop pre-header into smi-phis.
         if (FLAG_loop_invariant_code_motion) {
+          flow_graph->FixupRedefinitions();
+          DEBUG_ASSERT(flow_graph->VerifyRedefinitions());
           LICM licm(flow_graph);
           licm.OptimisticallySpecializeSmiPhis();
           DEBUG_ASSERT(flow_graph->VerifyUseLists());
         }
 
         // Propagate types and eliminate even more type tests.
         // Recompute types after constant propagation to infer more precise
         // types for uses that were previously reached by now eliminated phis.
         FlowGraphTypePropagator::Propagate(flow_graph);
         DEBUG_ASSERT(flow_graph->VerifyUseLists());
@@ skipping 378 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