Fix smi-based math floor.

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 2412 matching lines @@
           return Representation::Double();
         case kMathAbs:
           return representation();
         default:
           UNREACHABLE();
           return Representation::None();
       }
     }
   }
 
+  virtual void UpdateRepresentation(Representation new_rep,
+                                    HInferRepresentationPhase* h_infer,
+                                    const char* reason) {
+    if (flexible_int() && !new_rep.IsSmi()) {
+      new_rep = Representation::Integer32();
+    }
+    HValue::UpdateRepresentation(new_rep, h_infer, reason);
+  }
+
+  virtual void RepresentationChanged(Representation new_rep) {
+    if (flexible_int() && new_rep.IsInteger32()) {
+      ClearFlag(kFlexibleRepresentation);
+    }
+  }
+
   virtual Range* InferRange(Zone* zone);
 
   virtual HValue* Canonicalize();
   virtual Representation RepresentationFromInputs();
 
   BuiltinFunctionId op() const { return op_; }
   const char* OpName() const;
 
   DECLARE_CONCRETE_INSTRUCTION(UnaryMathOperation)
 
  protected:
   virtual bool DataEquals(HValue* other) {
     HUnaryMathOperation* b = HUnaryMathOperation::cast(other);
     return op_ == b->op();
   }
 
  private:
+  bool flexible_int() {
+    return op_ == kMathFloor || op_ == kMathRound;
+  }
+
   HUnaryMathOperation(HValue* context, HValue* value, BuiltinFunctionId op)
       : HTemplateInstruction<2>(HType::TaggedNumber()), op_(op) {
     SetOperandAt(0, context);
     SetOperandAt(1, value);
     switch (op) {
       case kMathFloor:
       case kMathRound:
-        // TODO(verwaest): Set representation to flexible int starting as smi.
-        set_representation(Representation::Integer32());
+        set_representation(Representation::Smi());
+        SetFlag(kFlexibleRepresentation);
         break;
       case kMathAbs:
         // Not setting representation here: it is None intentionally.
         SetFlag(kFlexibleRepresentation);
         // TODO(svenpanne) This flag is actually only needed if representation()
         // is tagged, and not when it is an unboxed double or unboxed integer.
         SetGVNFlag(kChangesNewSpacePromotion);
         break;
       case kMathLog:
       case kMathSin:
@@ skipping 4309 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_