Use integer division in a certain case.

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 539 matching lines @@
     kUseGVN,
     // Track instructions that are dominating side effects. If an instruction
     // sets this flag, it must implement SetSideEffectDominator() and should
     // indicate which side effects to track by setting GVN flags.
     kTrackSideEffectDominators,
     kCanOverflow,
     kBailoutOnMinusZero,
     kCanBeDivByZero,
     kDeoptimizeOnUndefined,
     kIsArguments,
+    // This instruction truncates its inputs
     kTruncatingToInt32,
+    // All other instructions will truncate this instruction's output
+    kWillTruncateToInt32,
     kIsDead,
     kLastFlag = kIsDead
   };
 
   STATIC_ASSERT(kLastFlag < kBitsPerInt);
 
   static const int kChangesToDependsFlagsLeftShift = 1;
 
   static GVNFlag ChangesFlagFromInt(int x) {
     return static_cast<GVNFlag>(x * 2);
@@ skipping 87 matching lines @@
   virtual HValue* OperandAt(int index) = 0;
   void SetOperandAt(int index, HValue* value);
 
   void DeleteAndReplaceWith(HValue* other);
   void ReplaceAllUsesWith(HValue* other);
   bool HasNoUses() const { return use_list_ == NULL; }
   bool HasMultipleUses() const {
     return use_list_ != NULL && use_list_->tail() != NULL;
   }
   int UseCount() const;
+  int UseCountIgnoringInputsRequiringNone() const;
 
   // Mark this HValue as dead and to be removed from other HValues' use lists.
   void Kill();
 
   int flags() const { return flags_; }
   void SetFlag(Flag f) { flags_ |= (1 << f); }
   void ClearFlag(Flag f) { flags_ &= ~(1 << f); }
   bool CheckFlag(Flag f) const { return (flags_ & (1 << f)) != 0; }
 
   // Returns true if the flag specified is set for all uses, false otherwise.
@@ skipping 4506 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(LoadFieldByIndex);
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_