Ensure constant truncation is only done when it is safe.

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3255 matching lines @@
   // Replay effects of this instruction on the given environment.
   void ReplayEnvironment(HEnvironment* env);
 
   DECLARE_CONCRETE_INSTRUCTION(CapturedObject)
 
  private:
   int capture_id_;
 };
 
 
+class HGraphBuilder;
 class HConstant V8_FINAL : public HTemplateInstruction<0> {
  public:
   DECLARE_INSTRUCTION_FACTORY_P1(HConstant, int32_t);
   DECLARE_INSTRUCTION_FACTORY_P2(HConstant, int32_t, Representation);
   DECLARE_INSTRUCTION_FACTORY_P1(HConstant, double);
   DECLARE_INSTRUCTION_FACTORY_P1(HConstant, Handle<Object>);
   DECLARE_INSTRUCTION_FACTORY_P2(HConstant, Handle<Map>, UniqueValueId);
   DECLARE_INSTRUCTION_FACTORY_P1(HConstant, ExternalReference);
 
   static HConstant* CreateAndInsertAfter(Zone* zone,
@@ skipping 86 matching lines @@
     if (HasInteger32Value()) return Representation::Integer32();
     if (HasNumberValue()) return Representation::Double();
     if (HasExternalReferenceValue()) return Representation::External();
     return Representation::Tagged();
   }
 
   virtual bool EmitAtUses() V8_OVERRIDE;
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
   HConstant* CopyToRepresentation(Representation r, Zone* zone) const;
   Maybe<HConstant*> CopyToTruncatedInt32(Zone* zone);
-  Maybe<HConstant*> CopyToTruncatedNumber(Zone* zone);
+  Maybe<HConstant*> CopyToTruncatedNumberAndAdd(Zone* zone,
+                                                HGraphBuilder* builder);
   bool HasInteger32Value() const { return has_int32_value_; }
   int32_t Integer32Value() const {
     ASSERT(HasInteger32Value());
     return int32_value_;
   }
   bool HasSmiValue() const { return has_smi_value_; }
   bool HasDoubleValue() const { return has_double_value_; }
   double DoubleValue() const {
     ASSERT(HasDoubleValue());
     return double_value_;
@@ skipping 3582 matching lines @@
   virtual bool IsDeletable() const V8_OVERRIDE { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_