Add explicit smi checks for unary smi operations.

runtime/vm/flow_graph_optimizer.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_optimizer.h"
 
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/hash_map.h"
 #include "vm/il_printer.h"
@@ skipping 400 matching lines @@
 bool FlowGraphOptimizer::TryReplaceWithUnaryOp(BindInstr* instr,
                                                InstanceCallComp* comp,
                                                Token::Kind op_kind) {
   if (comp->ic_data()->NumberOfChecks() != 1) {
     // TODO(srdjan): Not yet supported.
     return false;
   }
   ASSERT(comp->ArgumentCount() == 1);
   Computation* unary_op = NULL;
   if (HasOneSmi(*comp->ic_data())) {
-    unary_op = new UnarySmiOpComp(op_kind, comp, comp->ArgumentAt(0)->value());
+    Value* value = comp->ArgumentAt(0)->value();
+    InsertBefore(instr,
+                 new CheckSmiComp(value->CopyValue(), comp),
+                 instr->env(),
+                 BindInstr::kUnused);
+    unary_op = new UnarySmiOpComp(op_kind,
+                                  (op_kind == Token::kNEGATE) ? comp : NULL,
+                                  value);
   } else if (HasOneDouble(*comp->ic_data()) && (op_kind == Token::kNEGATE)) {
     unary_op = new NumberNegateComp(comp, comp->ArgumentAt(0)->value());
   }
   if (unary_op == NULL) return false;
 
   unary_op->set_ic_data(comp->ic_data());
   instr->set_computation(unary_op);
   RemovePushArguments(comp);
   return true;
 }
@@ skipping 620 matching lines @@
       DirectChainedHashMap<BindInstr*> child_map(*map);  // Copy map.
       OptimizeRecursive(child, &child_map);
     } else {
       OptimizeRecursive(child, map);  // Reuse map for the last child.
     }
   }
 }
 
 
 }  // namespace dart