Implement flooring division by a constant via truncating division by a constant.

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 606 matching lines @@
     kUseGVN,
     // Track instructions that are dominating side effects. If an instruction
     // sets this flag, it must implement HandleSideEffectDominator() and should
     // indicate which side effects to track by setting GVN flags.
     kTrackSideEffectDominators,
     kCanOverflow,
     kBailoutOnMinusZero,
     kCanBeDivByZero,
     kLeftCanBeMinInt,
     kLeftCanBeNegative,
+    kLeftCanBePositive,
     kAllowUndefinedAsNaN,
     kIsArguments,
     kTruncatingToInt32,
     kAllUsesTruncatingToInt32,
     kTruncatingToSmi,
     kAllUsesTruncatingToSmi,
     // Set after an instruction is killed.
     kIsDead,
     // Instructions that are allowed to produce full range unsigned integer
     // values are marked with kUint32 flag. If arithmetic shift or a load from
@@ skipping 3461 matching lines @@
   virtual bool DataEquals(HValue* other) V8_OVERRIDE { return true; }
 
  private:
   HMathFloorOfDiv(HValue* context, HValue* left, HValue* right)
       : HBinaryOperation(context, left, right) {
     set_representation(Representation::Integer32());
     SetFlag(kUseGVN);
     SetFlag(kCanOverflow);
     SetFlag(kCanBeDivByZero);
     SetFlag(kLeftCanBeMinInt);
+    SetFlag(kLeftCanBeNegative);
+    SetFlag(kLeftCanBePositive);
     SetFlag(kAllowUndefinedAsNaN);
   }
 
   virtual Range* InferRange(Zone* zone) V8_OVERRIDE;
 
   virtual bool IsDeletable() const V8_OVERRIDE { return true; }
 };
 
 
 class HArithmeticBinaryOperation : public HBinaryOperation {
@@ skipping 3396 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_