Revision: 4066
Author: [email protected]
Date: Tue Mar  9 02:49:41 2010
Log: Refactor the code cache to handle large number of properties on the global object (take 2).

A separate object type for the code cache have been added. This object has two different code caches. The first one (default_cache) is a fixed array organized in the same way as the as the code cache was before. The second cache (global_access_cache) is for code stubs to access the global object. This cache is organized as a hash table taking the property name and code flags as the key.

The reason for separating the global access stubs into a hash table representation is that the number of these is not bounded in the same was as the other types.

This is a remake of r3952 (http://codereview.chromium.org/652119) which have the additional ability to look for the index of code stubs for access to the global object.

BUG=http://code.google.com/p/v8/issues/detail?id=613

Review URL: http://codereview.chromium.org/717001
http://code.google.com/p/v8/source/detail?r=4066

Modified:
 /branches/bleeding_edge/src/heap.cc
 /branches/bleeding_edge/src/heap.h
 /branches/bleeding_edge/src/ic.cc
 /branches/bleeding_edge/src/ic.h
 /branches/bleeding_edge/src/objects-debug.cc
 /branches/bleeding_edge/src/objects-inl.h
 /branches/bleeding_edge/src/objects.cc
 /branches/bleeding_edge/src/objects.h

=======================================
--- /branches/bleeding_edge/src/heap.cc Tue Mar  9 01:41:58 2010
+++ /branches/bleeding_edge/src/heap.cc Tue Mar  9 02:49:41 2010
@@ -1214,6 +1214,16 @@
   }
   return map;
 }
+
+
+Object* Heap::AllocateCodeCache() {
+  Object* result = AllocateStruct(CODE_CACHE_TYPE);
+  if (result->IsFailure()) return result;
+  CodeCache* code_cache = CodeCache::cast(result);
+  code_cache->set_default_cache(empty_fixed_array());
+  code_cache->set_normal_type_cache(undefined_value());
+  return code_cache;
+}


 const Heap::StringTypeTable Heap::string_type_table[] = {
=======================================
--- /branches/bleeding_edge/src/heap.h  Mon Mar  8 22:38:33 2010
+++ /branches/bleeding_edge/src/heap.h  Tue Mar  9 02:49:41 2010
@@ -348,6 +348,9 @@
   // Allocate a map for the specified function
   static Object* AllocateInitialMap(JSFunction* fun);

+  // Allocates an empty code cache.
+  static Object* AllocateCodeCache();
+
   // Allocates and fully initializes a String.  There are two String
// encodings: ASCII and two byte. One should choose between the three string // allocation functions based on the encoding of the string buffer used to
=======================================
--- /branches/bleeding_edge/src/ic.cc   Mon Mar  1 08:24:05 2010
+++ /branches/bleeding_edge/src/ic.cc   Tue Mar  9 02:49:41 2010
@@ -63,7 +63,9 @@
                  Code* new_target,
                  const char* extra_info) {
   if (FLAG_trace_ic) {
-    State new_state = StateFrom(new_target, Heap::undefined_value());
+    State new_state = StateFrom(new_target,
+                                Heap::undefined_value(),
+                                Heap::undefined_value());
     PrintF("[%s (%c->%c)%s", type,
            TransitionMarkFromState(old_state),
            TransitionMarkFromState(new_state),
@@ -132,7 +134,7 @@
 }
 #endif

-IC::State IC::StateFrom(Code* target, Object* receiver) {
+IC::State IC::StateFrom(Code* target, Object* receiver, Object* name) {
   IC::State state = target->ic_state();

   if (state != MONOMORPHIC) return state;
@@ -148,7 +150,7 @@
   // the receiver map's code cache.  Therefore, if the current target
   // is in the receiver map's code cache, the inline cache failed due
   // to prototype check failure.
-  int index = map->IndexInCodeCache(target);
+  int index = map->IndexInCodeCache(String::cast(name), target);
   if (index >= 0) {
     // For keyed load/store, the most likely cause of cache failure is
     // that the key has changed.  We do not distinguish between
@@ -160,7 +162,7 @@

     // Remove the target from the code cache to avoid hitting the same
     // invalid stub again.
-    map->RemoveFromCodeCache(index);
+    map->RemoveFromCodeCache(String::cast(name), target, index);

     return MONOMORPHIC_PROTOTYPE_FAILURE;
   }
@@ -1300,7 +1302,7 @@
   NoHandleAllocation na;
   ASSERT(args.length() == 2);
   CallIC ic;
-  IC::State state = IC::StateFrom(ic.target(), args[0]);
+  IC::State state = IC::StateFrom(ic.target(), args[0], args[1]);
   Object* result =
       ic.LoadFunction(state, args.at<Object>(0), args.at<String>(1));

@@ -1333,7 +1335,7 @@
   NoHandleAllocation na;
   ASSERT(args.length() == 2);
   LoadIC ic;
-  IC::State state = IC::StateFrom(ic.target(), args[0]);
+  IC::State state = IC::StateFrom(ic.target(), args[0], args[1]);
   return ic.Load(state, args.at<Object>(0), args.at<String>(1));
 }

@@ -1343,7 +1345,7 @@
   NoHandleAllocation na;
   ASSERT(args.length() == 2);
   KeyedLoadIC ic;
-  IC::State state = IC::StateFrom(ic.target(), args[0]);
+  IC::State state = IC::StateFrom(ic.target(), args[0], args[1]);
   return ic.Load(state, args.at<Object>(0), args.at<Object>(1));
 }

@@ -1353,7 +1355,7 @@
   NoHandleAllocation na;
   ASSERT(args.length() == 3);
   StoreIC ic;
-  IC::State state = IC::StateFrom(ic.target(), args[0]);
+  IC::State state = IC::StateFrom(ic.target(), args[0], args[1]);
   return ic.Store(state, args.at<Object>(0), args.at<String>(1),
                   args.at<Object>(2));
 }
@@ -1411,7 +1413,7 @@
   NoHandleAllocation na;
   ASSERT(args.length() == 3);
   KeyedStoreIC ic;
-  IC::State state = IC::StateFrom(ic.target(), args[0]);
+  IC::State state = IC::StateFrom(ic.target(), args[0], args[1]);
   return ic.Store(state, args.at<Object>(0), args.at<Object>(1),
                   args.at<Object>(2));
 }
=======================================
--- /branches/bleeding_edge/src/ic.h    Mon Mar  1 08:24:05 2010
+++ /branches/bleeding_edge/src/ic.h    Tue Mar  9 02:49:41 2010
@@ -94,8 +94,8 @@
   Code* target() { return GetTargetAtAddress(address()); }
   inline Address address();

- // Compute the current IC state based on the target stub and the receiver.
-  static State StateFrom(Code* target, Object* receiver);
+ // Compute the current IC state based on the target stub, receiver and name.
+  static State StateFrom(Code* target, Object* receiver, Object* name);

   // Clear the inline cache to initial state.
   static void Clear(Address address);
=======================================
--- /branches/bleeding_edge/src/objects-debug.cc        Thu Feb 25 07:43:27 2010
+++ /branches/bleeding_edge/src/objects-debug.cc        Tue Mar  9 02:49:41 2010
@@ -642,6 +642,24 @@
   VerifyHeapPointer(prototype());
   VerifyHeapPointer(instance_descriptors());
 }
+
+
+void CodeCache::CodeCachePrint() {
+  HeapObject::PrintHeader("CodeCache");
+  PrintF("\n - default_cache: ");
+  default_cache()->ShortPrint();
+  PrintF("\n - normal_type_cache: ");
+  normal_type_cache()->ShortPrint();
+}
+
+
+void CodeCache::CodeCacheVerify() {
+  VerifyHeapPointer(default_cache());
+  VerifyHeapPointer(normal_type_cache());
+  ASSERT(default_cache()->IsFixedArray());
+  ASSERT(normal_type_cache()->IsUndefined()
+         || normal_type_cache()->IsCodeCacheHashTable());
+}


 void FixedArray::FixedArrayPrint() {
=======================================
--- /branches/bleeding_edge/src/objects-inl.h   Mon Mar  1 08:24:05 2010
+++ /branches/bleeding_edge/src/objects-inl.h   Tue Mar  9 02:49:41 2010
@@ -562,6 +562,11 @@
 bool Object::IsCompilationCacheTable() {
   return IsHashTable();
 }
+
+
+bool Object::IsCodeCacheHashTable() {
+  return IsHashTable();
+}


 bool Object::IsMapCache() {
@@ -1568,6 +1573,7 @@
 CAST_ACCESSOR(DescriptorArray)
 CAST_ACCESSOR(SymbolTable)
 CAST_ACCESSOR(CompilationCacheTable)
+CAST_ACCESSOR(CodeCacheHashTable)
 CAST_ACCESSOR(MapCache)
 CAST_ACCESSOR(String)
 CAST_ACCESSOR(SeqString)
@@ -2258,7 +2264,7 @@

 ACCESSORS(Map, instance_descriptors, DescriptorArray,
           kInstanceDescriptorsOffset)
-ACCESSORS(Map, code_cache, FixedArray, kCodeCacheOffset)
+ACCESSORS(Map, code_cache, Object, kCodeCacheOffset)
 ACCESSORS(Map, constructor, Object, kConstructorOffset)

ACCESSORS(JSFunction, shared, SharedFunctionInfo, kSharedFunctionInfoOffset)
@@ -2396,6 +2402,9 @@
               kThisPropertyAssignmentsCountOffset)


+ACCESSORS(CodeCache, default_cache, FixedArray, kDefaultCacheOffset)
+ACCESSORS(CodeCache, normal_type_cache, Object, kNormalTypeCacheOffset)
+
 bool Script::HasValidSource() {
   Object* src = this->source();
   if (!src->IsString()) return true;
=======================================
--- /branches/bleeding_edge/src/objects.cc      Thu Mar  4 03:27:28 2010
+++ /branches/bleeding_edge/src/objects.cc      Tue Mar  9 02:49:41 2010
@@ -3033,19 +3033,79 @@


 Object* Map::UpdateCodeCache(String* name, Code* code) {
+  // Allocate the code cache if not present.
+  if (code_cache()->IsFixedArray()) {
+    Object* result = Heap::AllocateCodeCache();
+    if (result->IsFailure()) return result;
+    set_code_cache(result);
+  }
+
+  // Update the code cache.
+  return CodeCache::cast(code_cache())->Update(name, code);
+}
+
+
+Object* Map::FindInCodeCache(String* name, Code::Flags flags) {
+  // Do a lookup if a code cache exists.
+  if (!code_cache()->IsFixedArray()) {
+    return CodeCache::cast(code_cache())->Lookup(name, flags);
+  } else {
+    return Heap::undefined_value();
+  }
+}
+
+
+int Map::IndexInCodeCache(String* name, Code* code) {
+  // Get the internal index if a code cache exists.
+  if (!code_cache()->IsFixedArray()) {
+    return CodeCache::cast(code_cache())->GetIndex(name, code);
+  }
+  return -1;
+}
+
+
+void Map::RemoveFromCodeCache(String* name, Code* code, int index) {
+  // No GC is supposed to happen between a call to IndexInCodeCache and
+  // RemoveFromCodeCache so the code cache must be there.
+  ASSERT(!code_cache()->IsFixedArray());
+  CodeCache::cast(code_cache())->RemoveByIndex(name, code, index);
+}
+
+
+Object* CodeCache::Update(String* name, Code* code) {
   ASSERT(code->ic_state() == MONOMORPHIC);
-  FixedArray* cache = code_cache();
-
-  // When updating the code cache we disregard the type encoded in the
+
+ // The number of monomorphic stubs for normal load/store/call IC's can grow to + // a large number and therefore they need to go into a hash table. They are
+  // used to load global properties from cells.
+  if (code->type() == NORMAL) {
+ // Make sure that a hash table is allocated for the normal load code cache.
+    if (normal_type_cache()->IsUndefined()) {
+      Object* result =
+          CodeCacheHashTable::Allocate(CodeCacheHashTable::kInitialSize);
+      if (result->IsFailure()) return result;
+      set_normal_type_cache(result);
+    }
+    return UpdateNormalTypeCache(name, code);
+  } else {
+    ASSERT(default_cache()->IsFixedArray());
+    return UpdateDefaultCache(name, code);
+  }
+}
+
+
+Object* CodeCache::UpdateDefaultCache(String* name, Code* code) {
+ // When updating the default code cache we disregard the type encoded in the
   // flags. This allows call constant stubs to overwrite call field
   // stubs, etc.
   Code::Flags flags = Code::RemoveTypeFromFlags(code->flags());

   // First check whether we can update existing code cache without
   // extending it.
+  FixedArray* cache = default_cache();
   int length = cache->length();
   int deleted_index = -1;
-  for (int i = 0; i < length; i += 2) {
+  for (int i = 0; i < length; i += kCodeCacheEntrySize) {
     Object* key = cache->get(i);
     if (key->IsNull()) {
       if (deleted_index < 0) deleted_index = i;
@@ -3053,14 +3113,15 @@
     }
     if (key->IsUndefined()) {
       if (deleted_index >= 0) i = deleted_index;
-      cache->set(i + 0, name);
-      cache->set(i + 1, code);
+      cache->set(i + kCodeCacheEntryNameOffset, name);
+      cache->set(i + kCodeCacheEntryCodeOffset, code);
       return this;
     }
     if (name->Equals(String::cast(key))) {
-      Code::Flags found = Code::cast(cache->get(i + 1))->flags();
+      Code::Flags found =
+          Code::cast(cache->get(i + kCodeCacheEntryCodeOffset))->flags();
       if (Code::RemoveTypeFromFlags(found) == flags) {
-        cache->set(i + 1, code);
+        cache->set(i + kCodeCacheEntryCodeOffset, code);
         return this;
       }
     }
@@ -3069,61 +3130,207 @@
   // Reached the end of the code cache.  If there were deleted
   // elements, reuse the space for the first of them.
   if (deleted_index >= 0) {
-    cache->set(deleted_index + 0, name);
-    cache->set(deleted_index + 1, code);
+    cache->set(deleted_index + kCodeCacheEntryNameOffset, name);
+    cache->set(deleted_index + kCodeCacheEntryCodeOffset, code);
     return this;
   }

-  // Extend the code cache with some new entries (at least one).
-  int new_length = length + ((length >> 1) & ~1) + 2;
-  ASSERT((new_length & 1) == 0);  // must be a multiple of two
+  // Extend the code cache with some new entries (at least one). Must be a
+  // multiple of the entry size.
+  int new_length = length + ((length >> 1)) + kCodeCacheEntrySize;
+  new_length = new_length - new_length % kCodeCacheEntrySize;
+  ASSERT((new_length % kCodeCacheEntrySize) == 0);
   Object* result = cache->CopySize(new_length);
   if (result->IsFailure()) return result;

   // Add the (name, code) pair to the new cache.
   cache = FixedArray::cast(result);
-  cache->set(length + 0, name);
-  cache->set(length + 1, code);
-  set_code_cache(cache);
+  cache->set(length + kCodeCacheEntryNameOffset, name);
+  cache->set(length + kCodeCacheEntryCodeOffset, code);
+  set_default_cache(cache);
   return this;
 }


-Object* Map::FindInCodeCache(String* name, Code::Flags flags) {
-  FixedArray* cache = code_cache();
+Object* CodeCache::UpdateNormalTypeCache(String* name, Code* code) {
+  // Adding a new entry can cause a new cache to be allocated.
+ CodeCacheHashTable* cache = CodeCacheHashTable::cast(normal_type_cache());
+  Object* new_cache = cache->Put(name, code);
+  if (new_cache->IsFailure()) return new_cache;
+  set_normal_type_cache(new_cache);
+  return this;
+}
+
+
+Object* CodeCache::Lookup(String* name, Code::Flags flags) {
+  if (Code::ExtractTypeFromFlags(flags) == NORMAL) {
+    return LookupNormalTypeCache(name, flags);
+  } else {
+    return LookupDefaultCache(name, flags);
+  }
+}
+
+
+Object* CodeCache::LookupDefaultCache(String* name, Code::Flags flags) {
+  FixedArray* cache = default_cache();
   int length = cache->length();
-  for (int i = 0; i < length; i += 2) {
-    Object* key = cache->get(i);
+  for (int i = 0; i < length; i += kCodeCacheEntrySize) {
+    Object* key = cache->get(i + kCodeCacheEntryNameOffset);
     // Skip deleted elements.
     if (key->IsNull()) continue;
     if (key->IsUndefined()) return key;
     if (name->Equals(String::cast(key))) {
-      Code* code = Code::cast(cache->get(i + 1));
-      if (code->flags() == flags) return code;
+      Code* code = Code::cast(cache->get(i + kCodeCacheEntryCodeOffset));
+      if (code->flags() == flags) {
+        return code;
+      }
     }
   }
   return Heap::undefined_value();
 }


-int Map::IndexInCodeCache(Code* code) {
-  FixedArray* array = code_cache();
+Object* CodeCache::LookupNormalTypeCache(String* name, Code::Flags flags) {
+  if (!normal_type_cache()->IsUndefined()) {
+ CodeCacheHashTable* cache = CodeCacheHashTable::cast(normal_type_cache());
+    return cache->Lookup(name, flags);
+  } else {
+    return Heap::undefined_value();
+  }
+}
+
+
+int CodeCache::GetIndex(String* name, Code* code) {
+  // This is not used for normal load/store/call IC's.
+  if (code->type() == NORMAL) {
+    if (normal_type_cache()->IsUndefined()) return -1;
+ CodeCacheHashTable* cache = CodeCacheHashTable::cast(normal_type_cache());
+    return cache->GetIndex(name, code->flags());
+  }
+
+  FixedArray* array = default_cache();
   int len = array->length();
-  for (int i = 0; i < len; i += 2) {
-    if (array->get(i + 1) == code) return i + 1;
+  for (int i = 0; i < len; i += kCodeCacheEntrySize) {
+    if (array->get(i + kCodeCacheEntryCodeOffset) == code) return i + 1;
   }
   return -1;
 }


-void Map::RemoveFromCodeCache(int index) {
-  FixedArray* array = code_cache();
-  ASSERT(array->length() >= index && array->get(index)->IsCode());
-  // Use null instead of undefined for deleted elements to distinguish
-  // deleted elements from unused elements.  This distinction is used
-  // when looking up in the cache and when updating the cache.
-  array->set_null(index - 1);  // key
-  array->set_null(index);  // code
+void CodeCache::RemoveByIndex(String* name, Code* code, int index) {
+  if (code->type() == NORMAL) {
+    ASSERT(!normal_type_cache()->IsUndefined());
+ CodeCacheHashTable* cache = CodeCacheHashTable::cast(normal_type_cache());
+    ASSERT(cache->GetIndex(name, code->flags()) == index);
+    cache->RemoveByIndex(index);
+  } else {
+    FixedArray* array = default_cache();
+    ASSERT(array->length() >= index && array->get(index)->IsCode());
+    // Use null instead of undefined for deleted elements to distinguish
+    // deleted elements from unused elements.  This distinction is used
+    // when looking up in the cache and when updating the cache.
+    ASSERT_EQ(1, kCodeCacheEntryCodeOffset - kCodeCacheEntryNameOffset);
+    array->set_null(index - 1);  // Name.
+    array->set_null(index);  // Code.
+  }
+}
+
+
+// The key in the code cache hash table consists of the property name and the +// code object. The actual match is on the name and the code flags. If a key
+// is created using the flags and not a code object it can only be used for
+// lookup not to create a new entry.
+class CodeCacheHashTableKey : public HashTableKey {
+ public:
+  CodeCacheHashTableKey(String* name, Code::Flags flags)
+      : name_(name), flags_(flags), code_(NULL) { }
+
+  CodeCacheHashTableKey(String* name, Code* code)
+      : name_(name),
+        flags_(code->flags()),
+        code_(code) { }
+
+
+  bool IsMatch(Object* other) {
+    if (!other->IsFixedArray()) return false;
+    FixedArray* pair = FixedArray::cast(other);
+    String* name = String::cast(pair->get(0));
+    Code::Flags flags = Code::cast(pair->get(1))->flags();
+    if (flags != flags_) {
+      return false;
+    }
+    return name_->Equals(name);
+  }
+
+  static uint32_t NameFlagsHashHelper(String* name, Code::Flags flags) {
+    return name->Hash() ^ flags;
+  }
+
+  uint32_t Hash() { return NameFlagsHashHelper(name_, flags_); }
+
+  uint32_t HashForObject(Object* obj) {
+    FixedArray* pair = FixedArray::cast(obj);
+    String* name = String::cast(pair->get(0));
+    Code* code = Code::cast(pair->get(1));
+    return NameFlagsHashHelper(name, code->flags());
+  }
+
+  Object* AsObject() {
+    ASSERT(code_ != NULL);
+    Object* obj = Heap::AllocateFixedArray(2);
+    if (obj->IsFailure()) return obj;
+    FixedArray* pair = FixedArray::cast(obj);
+    pair->set(0, name_);
+    pair->set(1, code_);
+    return pair;
+  }
+
+ private:
+  String* name_;
+  Code::Flags flags_;
+  Code* code_;
+};
+
+
+Object* CodeCacheHashTable::Lookup(String* name, Code::Flags flags) {
+  CodeCacheHashTableKey key(name, flags);
+  int entry = FindEntry(&key);
+  if (entry == kNotFound) return Heap::undefined_value();
+  return get(EntryToIndex(entry) + 1);
+}
+
+
+Object* CodeCacheHashTable::Put(String* name, Code* code) {
+  CodeCacheHashTableKey key(name, code);
+  Object* obj = EnsureCapacity(1, &key);
+  if (obj->IsFailure()) return obj;
+
+  // Don't use this, as the table might have grown.
+  CodeCacheHashTable* cache = reinterpret_cast<CodeCacheHashTable*>(obj);
+
+  int entry = cache->FindInsertionEntry(key.Hash());
+  Object* k = key.AsObject();
+  if (k->IsFailure()) return k;
+
+  cache->set(EntryToIndex(entry), k);
+  cache->set(EntryToIndex(entry) + 1, code);
+  cache->ElementAdded();
+  return cache;
+}
+
+
+int CodeCacheHashTable::GetIndex(String* name, Code::Flags flags) {
+  CodeCacheHashTableKey key(name, flags);
+  int entry = FindEntry(&key);
+  return (entry == kNotFound) ? -1 : entry;
+}
+
+
+void CodeCacheHashTable::RemoveByIndex(int index) {
+  ASSERT(index >= 0);
+  set(EntryToIndex(index), Heap::null_value());
+  set(EntryToIndex(index) + 1, Heap::null_value());
+  ElementRemoved();
 }


@@ -6992,7 +7199,6 @@
   table->SetNumberOfDeletedElements(0);
   return table;
 }
-


 template<typename Shape, typename Key>
=======================================
--- /branches/bleeding_edge/src/objects.h       Mon Mar  8 03:58:33 2010
+++ /branches/bleeding_edge/src/objects.h       Tue Mar  9 02:49:41 2010
@@ -72,6 +72,7 @@
 //             - Dictionary
 //             - SymbolTable
 //             - CompilationCacheTable
+//             - CodeCacheHashTable
 //             - MapCache
 //           - Context
 //           - GlobalContext
@@ -102,6 +103,7 @@
 //         - TypeSwitchInfo
 //         - DebugInfo
 //         - BreakPointInfo
+//         - CodeCache
 //
 // Formats of Object*:
 //  Smi:        [31 bit signed int] 0
@@ -269,6 +271,7 @@
V(SIGNATURE_INFO_TYPE) \ V(TYPE_SWITCH_INFO_TYPE) \ V(SCRIPT_TYPE) \ + V(CODE_CACHE_TYPE) \ \ V(JS_VALUE_TYPE) \ V(JS_OBJECT_TYPE) \
@@ -364,7 +367,8 @@
V(OBJECT_TEMPLATE_INFO, ObjectTemplateInfo, object_template_info) \ V(SIGNATURE_INFO, SignatureInfo, signature_info) \ V(TYPE_SWITCH_INFO, TypeSwitchInfo, type_switch_info) \
-  V(SCRIPT, Script, script)
+ V(SCRIPT, Script, script) \
+  V(CODE_CACHE, CodeCache, code_cache)

 #ifdef ENABLE_DEBUGGER_SUPPORT
#define STRUCT_LIST_DEBUGGER(V) \
@@ -468,6 +472,7 @@
   SIGNATURE_INFO_TYPE,
   TYPE_SWITCH_INFO_TYPE,
   SCRIPT_TYPE,
+  CODE_CACHE_TYPE,
 #ifdef ENABLE_DEBUGGER_SUPPORT
   DEBUG_INFO_TYPE,
   BREAK_POINT_INFO_TYPE,
@@ -601,6 +606,7 @@
   inline bool IsDictionary();
   inline bool IsSymbolTable();
   inline bool IsCompilationCacheTable();
+  inline bool IsCodeCacheHashTable();
   inline bool IsMapCache();
   inline bool IsPrimitive();
   inline bool IsGlobalObject();
@@ -2929,7 +2935,7 @@
   DECL_ACCESSORS(instance_descriptors, DescriptorArray)

   // [stub cache]: contains stubs compiled for this map.
-  DECL_ACCESSORS(code_cache, FixedArray)
+  DECL_ACCESSORS(code_cache, Object)

   Object* CopyDropDescriptors();

@@ -2965,10 +2971,10 @@

   // Returns the non-negative index of the code object if it is in the
   // cache and -1 otherwise.
-  int IndexInCodeCache(Code* code);
+  int IndexInCodeCache(String* name, Code* code);

   // Removes a code object from the code cache at the given index.
-  void RemoveFromCodeCache(int index);
+  void RemoveFromCodeCache(String* name, Code* code, int index);

   // For every transition in this map, makes the transition's
   // target's prototype pointer point back to this map.
@@ -3033,6 +3039,11 @@
   static const int kNeedsLoading = 0;
   static const int kIsExtensible = 1;

+ // Layout of the default cache. It holds alternating name and code objects.
+  static const int kCodeCacheEntrySize = 2;
+  static const int kCodeCacheEntryNameOffset = 0;
+  static const int kCodeCacheEntryCodeOffset = 1;
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Map);
 };
@@ -3716,6 +3727,97 @@
 };


+class CodeCache: public Struct {
+ public:
+  DECL_ACCESSORS(default_cache, FixedArray)
+  DECL_ACCESSORS(normal_type_cache, Object)
+
+  // Add the code object to the cache.
+  Object* Update(String* name, Code* code);
+
+ // Lookup code object in the cache. Returns code object if found and undefined
+  // if not.
+  Object* Lookup(String* name, Code::Flags flags);
+
+ // Get the internal index of a code object in the cache. Returns -1 if the
+  // code object is not in that cache. This index can be used to later call
+ // RemoveByIndex. The cache cannot be modified between a call to GetIndex and
+  // RemoveByIndex.
+  int GetIndex(String* name, Code* code);
+
+  // Remove an object from the cache with the provided internal index.
+  void RemoveByIndex(String* name, Code* code, int index);
+
+  static inline CodeCache* cast(Object* obj);
+
+#ifdef DEBUG
+  void CodeCachePrint();
+  void CodeCacheVerify();
+#endif
+
+  static const int kDefaultCacheOffset = HeapObject::kHeaderSize;
+  static const int kNormalTypeCacheOffset =
+      kDefaultCacheOffset + kPointerSize;
+  static const int kSize = kNormalTypeCacheOffset + kPointerSize;
+
+ private:
+  Object* UpdateDefaultCache(String* name, Code* code);
+  Object* UpdateNormalTypeCache(String* name, Code* code);
+  Object* LookupDefaultCache(String* name, Code::Flags flags);
+  Object* LookupNormalTypeCache(String* name, Code::Flags flags);
+
+ // Code cache layout of the default cache. Elements are alternating name and
+  // code objects for non normal load/store/call IC's.
+  static const int kCodeCacheEntrySize = 2;
+  static const int kCodeCacheEntryNameOffset = 0;
+  static const int kCodeCacheEntryCodeOffset = 1;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(CodeCache);
+};
+
+
+class CodeCacheHashTableShape {
+ public:
+  static inline bool IsMatch(HashTableKey* key, Object* value) {
+    return key->IsMatch(value);
+  }
+
+  static inline uint32_t Hash(HashTableKey* key) {
+    return key->Hash();
+  }
+
+  static inline uint32_t HashForObject(HashTableKey* key, Object* object) {
+    return key->HashForObject(object);
+  }
+
+  static Object* AsObject(HashTableKey* key) {
+    return key->AsObject();
+  }
+
+  static const int kPrefixSize = 0;
+  static const int kEntrySize = 2;
+};
+
+
+class CodeCacheHashTable: public HashTable<CodeCacheHashTableShape,
+                                           HashTableKey*> {
+ public:
+  Object* Lookup(String* name, Code::Flags flags);
+  Object* Put(String* name, Code* code);
+
+  int GetIndex(String* name, Code::Flags flags);
+  void RemoveByIndex(int index);
+
+  static inline CodeCacheHashTable* cast(Object* obj);
+
+  // Initial size of the fixed array backing the hash table.
+  static const int kInitialSize = 64;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(CodeCacheHashTable);
+};
+
+
 enum AllowNullsFlag {ALLOW_NULLS, DISALLOW_NULLS};
 enum RobustnessFlag {ROBUST_STRING_TRAVERSAL, FAST_STRING_TRAVERSAL};

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