Use a dictionary-mode code cache on the map rather than a dual system.

src/objects-inl.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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 855 matching lines @@
         ->NormalizedMapCacheVerify();
   }
 #endif
   return true;
 }
 
 bool HeapObject::IsCompilationCacheTable() const { return IsHashTable(); }
 
 bool HeapObject::IsCodeCacheHashTable() const { return IsHashTable(); }
 
-bool HeapObject::IsPolymorphicCodeCacheHashTable() const {
-  return IsHashTable();
-}
-
 bool HeapObject::IsMapCache() const { return IsHashTable(); }
 
 bool HeapObject::IsObjectHashTable() const { return IsHashTable(); }
 
 bool HeapObject::IsOrderedHashTable() const {
   return map() == GetHeap()->ordered_hash_table_map();
 }
 
 
 bool Object::IsOrderedHashSet() const {
@@ skipping 2137 matching lines @@
 
 
 // Find entry for key otherwise return kNotFound.
 template <typename Derived, typename Shape, typename Key>
 int HashTable<Derived, Shape, Key>::FindEntry(Isolate* isolate, Key key,
                                               int32_t hash) {
   uint32_t capacity = Capacity();
   uint32_t entry = FirstProbe(hash, capacity);
   uint32_t count = 1;
   // EnsureCapacity will guarantee the hash table is never full.
+  Object* undefined = isolate->heap()->undefined_value();
+  Object* the_hole = isolate->heap()->the_hole_value();
   while (true) {
     Object* element = KeyAt(entry);
     // Empty entry. Uses raw unchecked accessors because it is called by the
     // string table during bootstrapping.
-    if (element == isolate->heap()->root(Heap::kUndefinedValueRootIndex)) break;
-    if (element != isolate->heap()->root(Heap::kTheHoleValueRootIndex) &&
-        Shape::IsMatch(key, element)) return entry;
+    if (element == undefined) break;
+    if (element != the_hole && Shape::IsMatch(key, element)) return entry;
     entry = NextProbe(entry, count++, capacity);
   }
   return kNotFound;
 }
 
 bool StringSetShape::IsMatch(String* key, Object* value) {
   return value->IsString() && key->Equals(String::cast(value));
 }
 
 uint32_t StringSetShape::Hash(String* key) { return key->Hash(); }
@@ skipping 85 matching lines @@
 CAST_ACCESSOR(LayoutDescriptor)
 CAST_ACCESSOR(Map)
 CAST_ACCESSOR(Name)
 CAST_ACCESSOR(NameDictionary)
 CAST_ACCESSOR(NormalizedMapCache)
 CAST_ACCESSOR(Object)
 CAST_ACCESSOR(ObjectHashTable)
 CAST_ACCESSOR(Oddball)
 CAST_ACCESSOR(OrderedHashMap)
 CAST_ACCESSOR(OrderedHashSet)
-CAST_ACCESSOR(PolymorphicCodeCacheHashTable)
 CAST_ACCESSOR(PropertyCell)
 CAST_ACCESSOR(ScopeInfo)
 CAST_ACCESSOR(SeededNumberDictionary)
 CAST_ACCESSOR(SeqOneByteString)
 CAST_ACCESSOR(SeqString)
 CAST_ACCESSOR(SeqTwoByteString)
 CAST_ACCESSOR(SharedFunctionInfo)
 CAST_ACCESSOR(Simd128Value)
 CAST_ACCESSOR(SlicedString)
 CAST_ACCESSOR(Smi)
@@ skipping 1454 matching lines @@
   set_bit_field3(IsUnstable::update(bit_field3(), true));
 }
 
 
 bool Map::is_stable() {
   return !IsUnstable::decode(bit_field3());
 }
 
 
 bool Map::has_code_cache() {
-  return code_cache() != GetIsolate()->heap()->empty_fixed_array();
+  // Code caches are always fixed arrays. The empty fixed array is used as a
+  // sentinel for an absent code cache.
+  return FixedArray::cast(code_cache())->length() != 0;
 }
 
 
 bool Map::CanBeDeprecated() {
   int descriptor = LastAdded();
   for (int i = 0; i <= descriptor; i++) {
     PropertyDetails details = instance_descriptors()->GetDetails(i);
     if (details.representation().IsNone()) return true;
     if (details.representation().IsSmi()) return true;
     if (details.representation().IsDouble()) return true;
@@ skipping 144 matching lines @@
   return result;
 }
 
 
 ExtraICState Code::extra_ic_state() {
   DCHECK(is_inline_cache_stub() || ic_state() == DEBUG_STUB);
   return ExtractExtraICStateFromFlags(flags());
 }
 
 
-Code::StubType Code::type() {
-  return ExtractTypeFromFlags(flags());
-}
-
 // For initialization.
 void Code::set_raw_kind_specific_flags1(int value) {
   WRITE_INT_FIELD(this, kKindSpecificFlags1Offset, value);
 }
 
 
 void Code::set_raw_kind_specific_flags2(int value) {
   WRITE_INT_FIELD(this, kKindSpecificFlags2Offset, value);
 }
 
@@ skipping 257 matching lines @@
   if (FLAG_enable_embedded_constant_pool) {
     int offset = constant_pool_offset();
     if (offset < instruction_size()) {
       constant_pool = FIELD_ADDR(this, kHeaderSize + offset);
     }
   }
   return constant_pool;
 }
 
 Code::Flags Code::ComputeFlags(Kind kind, InlineCacheState ic_state,
-                               ExtraICState extra_ic_state, StubType type,
+                               ExtraICState extra_ic_state,
                                CacheHolderFlag holder) {
   // Compute the bit mask.
   unsigned int bits = KindField::encode(kind) | ICStateField::encode(ic_state) |
-                      TypeField::encode(type) |
                       ExtraICStateField::encode(extra_ic_state) |
                       CacheHolderField::encode(holder);
   return static_cast<Flags>(bits);
 }
 
 Code::Flags Code::ComputeMonomorphicFlags(Kind kind,
                                           ExtraICState extra_ic_state,
-                                          CacheHolderFlag holder,
-                                          StubType type) {
-  return ComputeFlags(kind, MONOMORPHIC, extra_ic_state, type, holder);
+                                          CacheHolderFlag holder) {
+  return ComputeFlags(kind, MONOMORPHIC, extra_ic_state, holder);
+}
+
+Code::Flags Code::ComputeHandlerFlags(Kind handler_kind,
+                                      CacheHolderFlag holder) {
+  return ComputeFlags(Code::HANDLER, MONOMORPHIC, handler_kind, holder);
 }
 
 
-Code::Flags Code::ComputeHandlerFlags(Kind handler_kind, StubType type,
-                                      CacheHolderFlag holder) {
-  return ComputeFlags(Code::HANDLER, MONOMORPHIC, handler_kind, type, holder);
-}
-
-
 Code::Kind Code::ExtractKindFromFlags(Flags flags) {
   return KindField::decode(flags);
 }
 
 
 InlineCacheState Code::ExtractICStateFromFlags(Flags flags) {
   return ICStateField::decode(flags);
 }
 
 
 ExtraICState Code::ExtractExtraICStateFromFlags(Flags flags) {
   return ExtraICStateField::decode(flags);
 }
 
 
-Code::StubType Code::ExtractTypeFromFlags(Flags flags) {
-  return TypeField::decode(flags);
-}
-
 CacheHolderFlag Code::ExtractCacheHolderFromFlags(Flags flags) {
   return CacheHolderField::decode(flags);
 }
 
-
-Code::Flags Code::RemoveTypeFromFlags(Flags flags) {
-  int bits = flags & ~TypeField::kMask;
+Code::Flags Code::RemoveHolderFromFlags(Flags flags) {
+  int bits = flags & ~CacheHolderField::kMask;
   return static_cast<Flags>(bits);
 }
 
-
-Code::Flags Code::RemoveTypeAndHolderFromFlags(Flags flags) {
-  int bits = flags & ~TypeField::kMask & ~CacheHolderField::kMask;
-  return static_cast<Flags>(bits);
-}
-
 
 Code* Code::GetCodeFromTargetAddress(Address address) {
   HeapObject* code = HeapObject::FromAddress(address - Code::kHeaderSize);
   // GetCodeFromTargetAddress might be called when marking objects during mark
   // sweep. reinterpret_cast is therefore used instead of the more appropriate
   // Code::cast. Code::cast does not work when the object's map is
   // marked.
   Code* result = reinterpret_cast<Code*>(code);
   return result;
 }
@@ skipping 654 matching lines @@
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_generator, kIsGenerator)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_concise_method,
                kIsConciseMethod)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_getter_function,
                kIsGetterFunction)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_setter_function,
                kIsSetterFunction)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_default_constructor,
                kIsDefaultConstructor)
 
-ACCESSORS(CodeCache, default_cache, FixedArray, kDefaultCacheOffset)
-ACCESSORS(CodeCache, normal_type_cache, Object, kNormalTypeCacheOffset)
-
-ACCESSORS(PolymorphicCodeCache, cache, Object, kCacheOffset)
-
 bool Script::HasValidSource() {
   Object* src = this->source();
   if (!src->IsString()) return true;
   String* src_str = String::cast(src);
   if (!StringShape(src_str).IsExternal()) return true;
   if (src_str->IsOneByteRepresentation()) {
     return ExternalOneByteString::cast(src)->resource() != NULL;
   } else if (src_str->IsTwoByteRepresentation()) {
     return ExternalTwoByteString::cast(src)->resource() != NULL;
   }
@@ skipping 1691 matching lines @@
   }
 FOR_EACH_SCOPE_INFO_NUMERIC_FIELD(SCOPE_INFO_FIELD_ACCESSORS)
 #undef SCOPE_INFO_FIELD_ACCESSORS
 
 
 void Map::ClearCodeCache(Heap* heap) {
   // No write barrier is needed since empty_fixed_array is not in new space.
   // Please note this function is used during marking:
   //  - MarkCompactCollector::MarkUnmarkedObject
   //  - IncrementalMarking::Step
-  DCHECK(!heap->InNewSpace(heap->empty_fixed_array()));
   WRITE_FIELD(this, kCodeCacheOffset, heap->empty_fixed_array());
 }
 
 
 int Map::SlackForArraySize(int old_size, int size_limit) {
   const int max_slack = size_limit - old_size;
   CHECK_LE(0, max_slack);
   if (old_size < 4) {
     DCHECK_LE(1, max_slack);
     return 1;
@@ skipping 305 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_