Line data    Source code

       1             : // Copyright 2017 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #ifndef V8_OBJECTS_DATA_HANDLER_H_
       6             : #define V8_OBJECTS_DATA_HANDLER_H_
       7             : 
       8             : #include "src/objects/struct.h"
       9             : 
      10             : // Has to be the last include (doesn't have include guards):
      11             : #include "src/objects/object-macros.h"
      12             : 
      13             : namespace v8 {
      14             : namespace internal {
      15             : 
      16             : // DataHandler is a base class for load and store handlers that can't be
      17             : // encoded in one Smi. Kind of a handler can be deduced from instance type.
      18             : class DataHandler : public Struct {
      19             :  public:
      20             :   // [smi_handler]: A Smi which encodes a handler or Code object (we still
      21             :   // use code handlers for accessing lexical environment variables, but soon
      22             :   // only smi handlers will remain). See LoadHandler and StoreHandler for
      23             :   // details about encoding.
      24             :   DECL_ACCESSORS(smi_handler, Object)
      25             : 
      26             :   // [validity_cell]: A validity Cell that guards prototype chain modifications.
      27             :   DECL_ACCESSORS(validity_cell, Object)
      28             : 
      29             :   // Returns number of optional data fields available in the object.
      30             :   inline int data_field_count() const;
      31             : 
      32             :   // [data1-3]: These are optional general-purpose fields whose content and
      33             :   // presence depends on the handler kind.
      34             :   DECL_ACCESSORS(data1, MaybeObject)
      35             :   DECL_ACCESSORS(data2, MaybeObject)
      36             :   DECL_ACCESSORS(data3, MaybeObject)
      37             : 
      38             : // Layout description.
      39             : #define DATA_HANDLER_FIELDS(V)        \
      40             :   V(kSmiHandlerOffset, kTaggedSize)   \
      41             :   V(kValidityCellOffset, kTaggedSize) \
      42             :   V(kSizeWithData0, 0)                \
      43             :   V(kData1Offset, kTaggedSize)        \
      44             :   V(kSizeWithData1, 0)                \
      45             :   V(kData2Offset, kTaggedSize)        \
      46             :   V(kSizeWithData2, 0)                \
      47             :   V(kData3Offset, kTaggedSize)        \
      48             :   V(kSizeWithData3, 0)
      49             : 
      50             :   DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, DATA_HANDLER_FIELDS)
      51             : #undef DATA_HANDLER_FIELDS
      52             : 
      53             :   DECL_CAST(DataHandler)
      54             : 
      55             :   DECL_VERIFIER(DataHandler)
      56             : 
      57             :   class BodyDescriptor;
      58             : 
      59      801028 :   OBJECT_CONSTRUCTORS(DataHandler, Struct)
      60             : };
      61             : 
      62             : }  // namespace internal
      63             : }  // namespace v8
      64             : 
      65             : #include "src/objects/object-macros-undef.h"
      66             : 
      67             : #endif  // V8_OBJECTS_DATA_HANDLER_H_