Mark null and undefined as undetectable, and use it to handle abstract equality comparison in the g…

src/crankshaft/x64/lithium-codegen-x64.cc

 // Copyright 2013 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/crankshaft/x64/lithium-codegen-x64.h"
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 5301 matching lines @@
     __ CmpObjectType(input, SYMBOL_TYPE, input);
     final_branch_condition = equal;
 
   } else if (String::Equals(type_name, factory->boolean_string())) {
     __ CompareRoot(input, Heap::kTrueValueRootIndex);
     __ j(equal, true_label, true_distance);
     __ CompareRoot(input, Heap::kFalseValueRootIndex);
     final_branch_condition = equal;
 
   } else if (String::Equals(type_name, factory->undefined_string())) {
-    __ CompareRoot(input, Heap::kUndefinedValueRootIndex);
-    __ j(equal, true_label, true_distance);
+    __ CompareRoot(input, Heap::kNullValueRootIndex);
+    __ j(equal, false_label, false_distance);
     __ JumpIfSmi(input, false_label, false_distance);
     // Check for undetectable objects => true.
     __ movp(input, FieldOperand(input, HeapObject::kMapOffset));
     __ testb(FieldOperand(input, Map::kBitFieldOffset),
              Immediate(1 << Map::kIsUndetectable));
     final_branch_condition = not_zero;
 
   } else if (String::Equals(type_name, factory->function_string())) {
     __ JumpIfSmi(input, false_label, false_distance);
     // Check for callable and not undetectable objects => true.
@@ skipping 285 matching lines @@
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64