Maintain a FixedArray for the optimized code map.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 69053ee570135722593c303e96ff62192de3abcf..b80bf7465bf00fdc930d3585f938a7f9579ab671 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6519,8 +6519,8 @@ class SharedFunctionInfo: public HeapObject {
   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
@@ -6558,6 +6558,8 @@ class SharedFunctionInfo: public HeapObject {
   static void SetScript(Handle<SharedFunctionInfo> shared,
                         Handle<Object> script_object);
 
+  inline bool OptimizedCodeMapIsCleared() const;

[Michael Starzinger, 2015/11/13 12:14:22]

nit: Needs a comment explaining the nature of the "empty optimized code map".
Also move up the predicate to right after ClearOptimizedCodeMap to make it clear
that these things belong together.

[mvstanton, 2015/11/17 20:32:12]

Done.

+
   // Layout description of the optimized code map.
   static const int kSharedCodeIndex = 0;
   static const int kEntriesStart = 1;