Add OptimizedCodeEntry as a new heap object type. An optimized code entry represents an association…

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 4685dc7d314cf4c4a99f6fcdd69b0c8455f35704..f380b7da4c5e381d0b68c7bd587d7b6ea3019f6b 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -131,6 +131,7 @@
 //       - Oddball
 //       - Foreign
 //       - SharedFunctionInfo
+//       - OptimizedCodeEntry
 //       - Struct
 //         - Box
 //         - DeclaredAccessorDescriptor
@@ -406,6 +407,7 @@ const int kStubMinorKeyBits = kBitsPerInt - kSmiTagSize - kStubMajorKeyBits;
   V(FIXED_ARRAY_TYPE)                                                          \
   V(FIXED_DOUBLE_ARRAY_TYPE)                                                   \
   V(SHARED_FUNCTION_INFO_TYPE)                                                 \
+  V(OPTIMIZED_CODE_ENTRY_TYPE)                                                 \
                                                                                \
   V(JS_MESSAGE_OBJECT_TYPE)                                                    \
                                                                                \
@@ -756,6 +758,7 @@ enum InstanceType {
 
   FIXED_ARRAY_TYPE,
   SHARED_FUNCTION_INFO_TYPE,
+  OPTIMIZED_CODE_ENTRY_TYPE,
 
   JS_MESSAGE_OBJECT_TYPE,
 
@@ -1017,6 +1020,7 @@ class MaybeObject BASE_EMBEDDED {
   V(Code)                                      \
   V(Oddball)                                   \
   V(SharedFunctionInfo)                        \
+  V(OptimizedCodeEntry)                        \
   V(JSValue)                                   \
   V(JSDate)                                    \
   V(JSMessageObject)                           \
@@ -6842,6 +6846,76 @@ class SharedFunctionInfo: public HeapObject {
 };
 
 
+// An optimized code entry represents an association between the native
+// context, a function, optimized code, and the literals. The entries
+// are linked into two lists for efficient lookup: by native context
+// (linked through next_by_native_context), or by shared function
+// info (linked through next_by_shared_info).
+// The references to the native context, function, and code are weak,
+// in order not to leak native contexts or functions through
+// SharedFunctionInfo. This means an entry can become "dead" through GC.
+// Entries are cleaned up lazily as each list is traversed.

[Michael Starzinger, 2013/08/28 14:59:47]

nit: s/cleaned up/removed from the list/ IIUC?

+class OptimizedCodeEntry: public HeapObject {
+ public:
+  // [native_context]: The native context of this entry. (WEAK)
+  DECL_ACCESSORS(native_context, Context)
+
+  // [function]: The JSFunction of this entry. (WEAK)
+  DECL_ACCESSORS(function, JSFunction)
+
+  // [code]: The optimized code of this entry. (WEAK)
+  DECL_ACCESSORS(code, Code)
+
+  // [literals]: Array of literals for this entry.
+  DECL_ACCESSORS(literals, FixedArray)
+
+  // [next_by_shared_info]: The next link in the list, when traversing
+  // starting with a SharedFunctionInfo. (NULL if none).
+  DECL_ACCESSORS(next_by_shared_info, OptimizedCodeEntry)
+
+  // [next_by_native_context]: The next link in the list, when traversing
+  // starting with a native context. (NULL if none)
+  DECL_ACCESSORS(next_by_native_context, OptimizedCodeEntry)
+
+  // Casting.
+  static inline OptimizedCodeEntry* cast(Object* obj);
+
+  DECLARE_PRINTER(OptimizedCodeEntry)
+  DECLARE_VERIFIER(OptimizedCodeEntry)
+
+  // Layout description.
+  static const int kNativeContextOffset = JSObject::kHeaderSize;
+  static const int kFunctionOffset = kNativeContextOffset + kPointerSize;
+  static const int kCodeOffset = kFunctionOffset + kPointerSize;
+  static const int kLiteralsOffset = kCodeOffset + kPointerSize;
+  static const int kNextBySharedInfoOffset =
+      kLiteralsOffset + kPointerSize;
+  static const int kNextByNativeContextOffset =
+      kNextBySharedInfoOffset + kPointerSize;
+  static const int kCacheableOffset = kNextByNativeContextOffset + kPointerSize;
+  static const int kSize = kCacheableOffset + kIntSize;
+  static const int kAlignedSize = OBJECT_POINTER_ALIGN(kSize);
+
+  typedef FixedBodyDescriptor<kLiteralsOffset,
+                              kNextByNativeContextOffset + kPointerSize,
+                              kSize> BodyDescriptor;
+
+  // Kills an entry, nulling out its references to native context, function,
+  // and code.

[Michael Starzinger, 2013/08/28 14:59:47]

nit: ... and literals.

+  void Kill();
+  inline bool cacheable();
+  inline void set_cacheable(bool val);
+
+ private:
+  // Used internally during traversal to skip dead entries.
+  inline bool IsDead() {
+    return function() == NULL || code() == NULL;
+  }
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(OptimizedCodeEntry);
+};
+
+
 class JSGeneratorObject: public JSObject {
  public:
   // [function]: The function corresponding to this generator object.