Deprecate old code aging mechanism.

src/objects.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 4802 matching lines @@
 #define DECLARE_CODE_AGE_ENUM(X) k##X##CodeAge,
   enum Age {
     kNoAge = 0,
     CODE_AGE_LIST(DECLARE_CODE_AGE_ENUM)
     kAfterLastCodeAge,
     kLastCodeAge = kAfterLastCodeAge - 1,
     kCodeAgeCount = kAfterLastCodeAge - 1
   };
 #undef DECLARE_CODE_AGE_ENUM
 
-  // Code aging
+  // 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);
   void MakeOlder(MarkingParity);
   static bool IsYoungSequence(byte* sequence);
   bool IsOld();
   int GetAge();
 
   void PrintDeoptLocation(int bailout_id);
 
 #ifdef VERIFY_HEAP
   void VerifyEmbeddedMapsDependency();
@@ skipping 1298 matching lines @@
   // This is used to determine if we can safely flush code from a function
   // when doing GC if we expect that the function will no longer be used.
   DECL_BOOLEAN_ACCESSORS(allows_lazy_compilation)
 
   // Indicates if this function can be lazy compiled without a context.
   // This is used to determine if we can force compilation without reaching
   // the function through program execution but through other means (e.g. heap
   // iteration by the debugger).
   DECL_BOOLEAN_ACCESSORS(allows_lazy_compilation_without_context)
 
-  // Indicates how many full GCs this function has survived with assigned
-  // code object. Used to determine when it is relatively safe to flush
-  // this code object and replace it with lazy compilation stub.
-  // Age is reset when GC notices that the code object is referenced
-  // from the stack or compilation cache.
-  inline int code_age();
-  inline void set_code_age(int age);
-
   // Indicates whether optimizations have been disabled for this
   // shared function info. If a function is repeatedly optimized or if
   // we cannot optimize the function we disable optimization to avoid
   // spending time attempting to optimize it again.
   DECL_BOOLEAN_ACCESSORS(optimization_disabled)
 
   // Indicates the language mode of the function's code as defined by the
   // current harmony drafts for the next ES language standard. Possible
   // values are:
   // 1. CLASSIC_MODE - Unrestricted syntax and semantics, same as in ES5.
@@ skipping 223 matching lines @@
 
   // Bit positions in start_position_and_type.
   // The source code start position is in the 30 most significant bits of
   // the start_position_and_type field.
   static const int kIsExpressionBit    = 0;
   static const int kIsTopLevelBit      = 1;
   static const int kStartPositionShift = 2;
   static const int kStartPositionMask  = ~((1 << kStartPositionShift) - 1);
 
   // Bit positions in compiler_hints.
-  static const int kCodeAgeSize = 3;
-  static const int kCodeAgeMask = (1 << kCodeAgeSize) - 1;
-
   enum CompilerHints {
     kAllowLazyCompilation,
     kAllowLazyCompilationWithoutContext,
     kLiveObjectsMayExist,
-    kCodeAgeShift,
-    kOptimizationDisabled = kCodeAgeShift + kCodeAgeSize,
+    kOptimizationDisabled,
     kStrictModeFunction,
     kExtendedModeFunction,
     kUsesArguments,
     kHasDuplicateParameters,
     kNative,
     kBoundFunction,
     kIsAnonymous,
     kNameShouldPrintAsAnonymous,
     kIsFunction,
     kDontOptimize,
@@ skipping 3288 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_