Symbols for type cells.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index 6717dd5d6d4a8e85f3c13e83e11a5bfae7702de2..5345e9ee5483b4166d13b6ee7958fe9787b0f903 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -533,9 +533,9 @@ static void Generate_JSEntryTrampolineHelper(MacroAssembler* masm,
     // Invoke the code.
     if (is_construct) {
       // No type feedback cell is available
-      Handle<Object> undefined_sentinel(
-          masm->isolate()->factory()->undefined_value());
-      __ Move(rbx, undefined_sentinel);
+      Handle<Object> megamorphic_sentinel =
+          TypeFeedbackInfo::MegamorphicSentinel(masm->isolate());
+      __ Move(rbx, megamorphic_sentinel);
       // Expects rdi to hold function pointer.
       CallConstructStub stub(NO_CALL_FUNCTION_FLAGS);
       __ CallStub(&stub);
@@ -1128,10 +1128,9 @@ void Builtins::Generate_ArrayCode(MacroAssembler* masm) {
 
   // Run the native code for the Array function called as a normal function.
   // tail call a stub
-  Handle<Object> undefined_sentinel(
-      masm->isolate()->heap()->undefined_value(),
-      masm->isolate());
-  __ Move(rbx, undefined_sentinel);
+  Handle<Object> megamorphic_sentinel =
+      TypeFeedbackInfo::MegamorphicSentinel(masm->isolate());
+  __ Move(rbx, megamorphic_sentinel);
   ArrayConstructorStub stub(masm->isolate());
   __ TailCallStub(&stub);
 }