[strong] Implement strong mode semantics for the count operation.

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HYDROGEN_INSTRUCTIONS_H_
 #define V8_HYDROGEN_INSTRUCTIONS_H_
 
 #include <cstring>
 #include <iosfwd>
 
@@ skipping 4133 matching lines @@
 };
 
 
 class HBitwiseBinaryOperation : public HBinaryOperation {
  public:
   HBitwiseBinaryOperation(HValue* context, HValue* left, HValue* right,
                           Strength strength, HType type = HType::TaggedNumber())
       : HBinaryOperation(context, left, right, strength, type) {
     SetFlag(kFlexibleRepresentation);
     SetFlag(kTruncatingToInt32);
-    SetFlag(kAllowUndefinedAsNaN);
+    if (!is_strong(strength)) SetFlag(kAllowUndefinedAsNaN);
     SetAllSideEffects();
   }
 
   void RepresentationChanged(Representation to) override {
     if (to.IsTagged() &&
         (left()->ToNumberCanBeObserved() || right()->ToNumberCanBeObserved())) {
       SetAllSideEffects();
       ClearFlag(kUseGVN);
     } else {
       ClearAllSideEffects();
@@ skipping 60 matching lines @@
 
 
 class HArithmeticBinaryOperation : public HBinaryOperation {
  public:
   HArithmeticBinaryOperation(HValue* context, HValue* left, HValue* right,
                              Strength strength)
       : HBinaryOperation(context, left, right, strength,
                          HType::TaggedNumber()) {
     SetAllSideEffects();
     SetFlag(kFlexibleRepresentation);
-    SetFlag(kAllowUndefinedAsNaN);
+    if (!is_strong(strength)) SetFlag(kAllowUndefinedAsNaN);
   }
 
   void RepresentationChanged(Representation to) override {
     if (to.IsTagged() &&
         (left()->ToNumberCanBeObserved() || right()->ToNumberCanBeObserved())) {
       SetAllSideEffects();
       ClearFlag(kUseGVN);
     } else {
       ClearAllSideEffects();
       SetFlag(kUseGVN);
@@ skipping 3688 matching lines @@
 };
 
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_