Remember and reuse derived map for external arrays

src/objects.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 117 matching lines @@
 
 
 // PropertyDetails captures type and attributes for a property.
 // They are used both in property dictionaries and instance descriptors.
 class PropertyDetails BASE_EMBEDDED {
  public:
 
   PropertyDetails(PropertyAttributes attributes,
                   PropertyType type,
                   int index = 0) {
+    ASSERT(type != EXTERNAL_ARRAY_TRANSITION);
     ASSERT(TypeField::is_valid(type));
     ASSERT(AttributesField::is_valid(attributes));
-    ASSERT(IndexField::is_valid(index));
+    ASSERT(StorageField::is_valid(index));
 
     value_ = TypeField::encode(type)
         | AttributesField::encode(attributes)
-        | IndexField::encode(index);
+        | StorageField::encode(index);
 
     ASSERT(type == this->type());
     ASSERT(attributes == this->attributes());
     ASSERT(index == this->index());
   }
 
+  PropertyDetails(PropertyAttributes attributes,
+                  PropertyType type,
+                  ExternalArrayType array_type) {
+    ASSERT(type == EXTERNAL_ARRAY_TRANSITION);
+    ASSERT(TypeField::is_valid(type));
+    ASSERT(AttributesField::is_valid(attributes));
+    ASSERT(StorageField::is_valid(static_cast<int>(array_type)));
+
+    value_ = TypeField::encode(type)
+        | AttributesField::encode(attributes)
+        | StorageField::encode(static_cast<int>(array_type));
+
+    ASSERT(type == this->type());
+    ASSERT(attributes == this->attributes());
+    ASSERT(array_type == this->array_type());
+  }
+
   // Conversion for storing details as Object*.
   inline PropertyDetails(Smi* smi);
   inline Smi* AsSmi();
 
   PropertyType type() { return TypeField::decode(value_); }
 
   bool IsTransition() {
     PropertyType t = type();
     ASSERT(t != INTERCEPTOR);
-    return t == MAP_TRANSITION || t == CONSTANT_TRANSITION;
+    return t == MAP_TRANSITION || t == CONSTANT_TRANSITION ||
+        t == EXTERNAL_ARRAY_TRANSITION;
   }
 
   bool IsProperty() {
     return type() < FIRST_PHANTOM_PROPERTY_TYPE;
   }
 
   PropertyAttributes attributes() { return AttributesField::decode(value_); }
 
-  int index() { return IndexField::decode(value_); }
+  int index() { return StorageField::decode(value_); }
+
+  ExternalArrayType array_type() {
+    ASSERT(type() == EXTERNAL_ARRAY_TRANSITION);
+    return static_cast<ExternalArrayType>(StorageField::decode(value_));
+  }
 
   inline PropertyDetails AsDeleted();
 
-  static bool IsValidIndex(int index) { return IndexField::is_valid(index); }
+  static bool IsValidIndex(int index) {
+    return StorageField::is_valid(index);
+  }
 
   bool IsReadOnly() { return (attributes() & READ_ONLY) != 0; }
   bool IsDontDelete() { return (attributes() & DONT_DELETE) != 0; }
   bool IsDontEnum() { return (attributes() & DONT_ENUM) != 0; }
   bool IsDeleted() { return DeletedField::decode(value_) != 0;}
 
   // Bit fields in value_ (type, shift, size). Must be public so the
   // constants can be embedded in generated code.
-  class TypeField:       public BitField<PropertyType,       0, 3> {};
-  class AttributesField: public BitField<PropertyAttributes, 3, 3> {};
-  class DeletedField:    public BitField<uint32_t,           6, 1> {};
-  class IndexField:      public BitField<uint32_t,           7, 32-7> {};
+  class TypeField:       public BitField<PropertyType,       0, 4> {};
+  class AttributesField: public BitField<PropertyAttributes, 4, 3> {};
+  class DeletedField:    public BitField<uint32_t,           7, 1> {};
+  class StorageField:    public BitField<uint32_t,           8, 32-8> {};
 
   static const int kInitialIndex = 1;
  private:
   uint32_t value_;
 };
 
 
 // Setter that skips the write barrier if mode is SKIP_WRITE_BARRIER.
 enum WriteBarrierMode { SKIP_WRITE_BARRIER, UPDATE_WRITE_BARRIER };
 
@@ skipping 3299 matching lines @@
   static const int kAllowOSRAtLoopNestingLevelOffset =
       kHasDeoptimizationSupportOffset + 1;
 
   static const int kSafepointTableOffsetOffset = kStackSlotsOffset + kIntSize;
   static const int kStackCheckTableOffsetOffset = kStackSlotsOffset + kIntSize;
 
   // Flags layout.
   static const int kFlagsICStateShift        = 0;
   static const int kFlagsICInLoopShift       = 3;
   static const int kFlagsTypeShift           = 4;
-  static const int kFlagsKindShift           = 7;
-  static const int kFlagsICHolderShift       = 11;
-  static const int kFlagsExtraICStateShift   = 12;
-  static const int kFlagsArgumentsCountShift = 14;
+  static const int kFlagsKindShift           = 8;
+  static const int kFlagsICHolderShift       = 12;
+  static const int kFlagsExtraICStateShift   = 13;
+  static const int kFlagsArgumentsCountShift = 15;
 
   static const int kFlagsICStateMask        = 0x00000007;  // 00000000111
   static const int kFlagsICInLoopMask       = 0x00000008;  // 00000001000
-  static const int kFlagsTypeMask           = 0x00000070;  // 00001110000
-  static const int kFlagsKindMask           = 0x00000780;  // 11110000000
-  static const int kFlagsCacheInPrototypeMapMask = 0x00000800;
-  static const int kFlagsExtraICStateMask   = 0x00003000;
-  static const int kFlagsArgumentsCountMask = 0xFFFFC000;
+  static const int kFlagsTypeMask           = 0x000000F0;  // 00001110000
+  static const int kFlagsKindMask           = 0x00000F00;  // 11110000000
+  static const int kFlagsCacheInPrototypeMapMask = 0x00001000;
+  static const int kFlagsExtraICStateMask   = 0x00006000;
+  static const int kFlagsArgumentsCountMask = 0xFFFF8000;
 
   static const int kFlagsNotUsedInLookup =
       (kFlagsICInLoopMask | kFlagsTypeMask | kFlagsCacheInPrototypeMapMask);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Code);
 };
 
 
 // All heap objects have a Map that describes their structure.
@@ skipping 181 matching lines @@
   // descriptors and the fast elements bit set.
   MUST_USE_RESULT inline MaybeObject* GetFastElementsMap();
 
   // Returns this map if it has the fast elements bit cleared,
   // otherwise returns a copy of the map, with all transitions dropped
   // from the descriptors and the fast elements bit cleared.
   MUST_USE_RESULT inline MaybeObject* GetSlowElementsMap();
 
   // Returns a new map with all transitions dropped from the descriptors and the
   // external array elements bit set.
-  MUST_USE_RESULT inline MaybeObject* NewExternalArrayElementsMap();
+  MUST_USE_RESULT MaybeObject* GetExternalArrayElementsMap(
+      ExternalArrayType array_type,
+      bool safe_to_add_transition);
 
   // Returns the property index for name (only valid for FAST MODE).
   int PropertyIndexFor(String* name);
 
   // Returns the next free property index (only valid for FAST MODE).
   int NextFreePropertyIndex();
 
   // Returns the number of properties described in instance_descriptors.
   int NumberOfDescribedProperties();
 
@@ skipping 2889 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_