Maintain a FixedArray for the optimized code map.

src/objects.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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 6459 matching lines @@
 class SharedFunctionInfo: public HeapObject {
  public:
   // [name]: Function name.
   DECL_ACCESSORS(name, Object)
 
   // [code]: Function code.
   DECL_ACCESSORS(code, Code)
   inline void ReplaceCode(Code* code);
 
   // [optimized_code_map]: Map from native context to optimized code
-  // and a shared literals array or Smi(0) if none.
-  DECL_ACCESSORS(optimized_code_map, Object)
+  // and a shared literals array.
+  DECL_ACCESSORS(optimized_code_map, FixedArray)
 
   // Returns entry from optimized code map for specified context and OSR entry.
   // Note that {code == nullptr, literals == nullptr} indicates no matching
   // entry has been found, whereas {code, literals == nullptr} indicates that
   // code is context-independent.
   CodeAndLiterals SearchOptimizedCodeMap(Context* native_context,
                                          BailoutId osr_ast_id);
 
   // Clear optimized code map.
   void ClearOptimizedCodeMap();
 
+  // We have a special root FixedArray with the right shape and values
+  // to represent the cleared optimized code map. This predicate checks
+  // if that root is installed.
+  inline bool OptimizedCodeMapIsCleared() const;
+
   // Removes a specific optimized code object from the optimized code map.
   // In case of non-OSR the code reference is cleared from the cache entry but
   // the entry itself is left in the map in order to proceed sharing literals.
   void EvictFromOptimizedCodeMap(Code* optimized_code, const char* reason);
 
   // Trims the optimized code map after entries have been removed.
   void TrimOptimizedCodeMap(int shrink_by);
 
   // Add a new entry to the optimized code map for context-independent code.
   static void AddSharedCodeToOptimizedCodeMap(Handle<SharedFunctionInfo> shared,
@@ skipping 4203 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_