[Heap] Remove concept of MarkingParity.

src/objects.h

 // Copyright 2015 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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 266 matching lines @@
 };
 
 
 // Indicates whether we are only interested in the descriptors of a particular
 // map, or in all descriptors in the descriptor array.
 enum DescriptorFlag {
   ALL_DESCRIPTORS,
   OWN_DESCRIPTORS
 };
 
-// The GC maintains a bit of information, the MarkingParity, which toggles
-// from odd to even and back every time marking is completed. Incremental
-// marking can visit an object twice during a marking phase, so algorithms that
-// that piggy-back on marking can use the parity to ensure that they only
-// perform an operation on an object once per marking phase: they record the
-// MarkingParity when they visit an object, and only re-visit the object when it
-// is marked again and the MarkingParity changes.
-enum MarkingParity {
-  NO_MARKING_PARITY,
-  ODD_MARKING_PARITY,
-  EVEN_MARKING_PARITY
-};
-
 // ICs store extra state in a Code object. The default extra state is
 // kNoExtraICState.
 typedef int ExtraICState;
 static const ExtraICState kNoExtraICState = 0;
 
 // Instance size sentinel for objects of variable size.
 const int kVariableSizeSentinel = 0;
 
 // We may store the unsigned bit field as signed Smi value and do not
 // use the sign bit.
@@ skipping 5424 matching lines @@
 
   // Code aging.  Indicates how many full GCs this code has survived without
   // being entered through the prologue.  Used to determine when it is
   // relatively safe to flush this code object and replace it with the lazy
   // compilation stub.
   static void MakeCodeAgeSequenceYoung(byte* sequence, Isolate* isolate);
   static void MarkCodeAsExecuted(byte* sequence, Isolate* isolate);
   void MakeYoung(Isolate* isolate);
   void PreAge(Isolate* isolate);
   void MarkToBeExecutedOnce(Isolate* isolate);
-  void MakeOlder(MarkingParity);
+  void MakeOlder();
   static bool IsYoungSequence(Isolate* isolate, byte* sequence);
   bool IsOld();
   Age GetAge();
   static inline Code* GetPreAgedCodeAgeStub(Isolate* isolate) {
-    return GetCodeAgeStub(isolate, kNotExecutedCodeAge, NO_MARKING_PARITY);
+    return GetCodeAgeStub(isolate, kNotExecutedCodeAge);
   }
 
   void PrintDeoptLocation(FILE* out, Address pc);
   bool CanDeoptAt(Address pc);
 
 #ifdef VERIFY_HEAP
   void VerifyEmbeddedObjectsDependency();
 #endif
 
 #ifdef DEBUG
@@ skipping 121 matching lines @@
 
   // This constant should be encodable in an ARM instruction.
   static const int kFlagsNotUsedInLookup = CacheHolderField::kMask;
 
  private:
   friend class RelocIterator;
   friend class Deoptimizer;  // For FindCodeAgeSequence.
 
   // Code aging
   byte* FindCodeAgeSequence();
-  static void GetCodeAgeAndParity(Code* code, Age* age,
-                                  MarkingParity* parity);
-  static void GetCodeAgeAndParity(Isolate* isolate, byte* sequence, Age* age,
-                                  MarkingParity* parity);
-  static Code* GetCodeAgeStub(Isolate* isolate, Age age, MarkingParity parity);
+  static Age GetCodeAge(Isolate* isolate, byte* sequence);
+  static Age GetAgeOfCodeAgeStub(Code* code);
+  static Code* GetCodeAgeStub(Isolate* isolate, Age age);
 
   // Code aging -- platform-specific
-  static void PatchPlatformCodeAge(Isolate* isolate,
-                                   byte* sequence, Age age,
-                                   MarkingParity parity);
+  static void PatchPlatformCodeAge(Isolate* isolate, byte* sequence, Age age);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Code);
 };
 
 class AbstractCode : public HeapObject {
  public:
   // All code kinds and INTERPRETED_FUNCTION.
   enum Kind {
 #define DEFINE_CODE_KIND_ENUM(name) name,
     CODE_KIND_LIST(DEFINE_CODE_KIND_ENUM)
@@ skipping 5966 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_