Ensure that BoxInt32 input is correctly preserved on the slow-path.

runtime/vm/flow_graph_allocator.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/flow_graph_allocator.h"
 
 #include "vm/bit_vector.h"
 #include "vm/intermediate_language.h"
 #include "vm/il_printer.h"
 #include "vm/flow_graph.h"
@@ skipping 140 matching lines @@
     BitVector* kill = kill_[i];
     BitVector* live_in = live_in_[i];
 
     // Iterate backwards starting at the last instruction.
     for (BackwardInstructionIterator it(block); !it.Done(); it.Advance()) {
       Instruction* current = it.Current();
 
       // Initialize location summary for instruction.
       current->InitializeLocationSummary(Isolate::Current(), true);  // opt
       LocationSummary* locs = current->locs();
+#if DEBUG
+      locs->DiscoverWritableInputs();
+#endif
 
       // Handle definitions.
       Definition* current_def = current->AsDefinition();
       if ((current_def != NULL) && current_def->HasSSATemp()) {
         kill->Add(current_def->ssa_temp_index());
         live_in->Remove(current_def->ssa_temp_index());
         if (current_def->HasPairRepresentation()) {
           kill->Add(ToSecondPairVreg(current_def->ssa_temp_index()));
           live_in->Remove(ToSecondPairVreg(current_def->ssa_temp_index()));
         }
@@ skipping 2746 matching lines @@
     OS::Print("-- [after ssa allocator] ir [%s] -------------\n",
               function.ToFullyQualifiedCString());
     FlowGraphPrinter printer(flow_graph_, true);
     printer.PrintBlocks();
     OS::Print("----------------------------------------------\n");
   }
 }
 
 
 }  // namespace dart