Line data    Source code

       1             : // Copyright 2015 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_BODY_DESCRIPTORS_H_
       6             : #define V8_OBJECTS_BODY_DESCRIPTORS_H_
       7             : 
       8             : #include "src/objects.h"
       9             : 
      10             : namespace v8 {
      11             : namespace internal {
      12             : 
      13             : // This is the base class for object's body descriptors.
      14             : //
      15             : // Each BodyDescriptor subclass must provide the following methods:
      16             : //
      17             : // 1) Returns true if the object contains a tagged value at given offset.
      18             : //    It is used for invalid slots filtering. If the offset points outside
      19             : //    of the object or to the map word, the result is UNDEFINED (!!!).
      20             : //
      21             : //   static bool IsValidSlot(HeapObject* obj, int offset);
      22             : //
      23             : //
      24             : // 2) Iterate object's body using stateful object visitor.
      25             : //
      26             : //   template <typename ObjectVisitor>
      27             : //   static inline void IterateBody(HeapObject* obj, int object_size,
      28             : //                                  ObjectVisitor* v);
      29             : //
      30             : //
      31             : // 3) Iterate object's body using stateless object visitor.
      32             : //
      33             : //   template <typename StaticVisitor>
      34             : //   static inline void IterateBody(HeapObject* obj, int object_size);
      35             : //
      36             : class BodyDescriptorBase BASE_EMBEDDED {
      37             :  public:
      38             :   template <typename ObjectVisitor>
      39             :   static inline void IteratePointers(HeapObject* obj, int start_offset,
      40             :                                      int end_offset, ObjectVisitor* v);
      41             : 
      42             :   template <typename StaticVisitor>
      43             :   static inline void IteratePointers(Heap* heap, HeapObject* obj,
      44             :                                      int start_offset, int end_offset);
      45             : 
      46             :   template <typename ObjectVisitor>
      47             :   static inline void IteratePointer(HeapObject* obj, int offset,
      48             :                                     ObjectVisitor* v);
      49             : 
      50             :   template <typename StaticVisitor>
      51             :   static inline void IteratePointer(Heap* heap, HeapObject* obj, int offset);
      52             : 
      53             :  protected:
      54             :   // Returns true for all header and embedder fields.
      55             :   static inline bool IsValidSlotImpl(HeapObject* obj, int offset);
      56             : 
      57             :   // Treats all header and embedder fields in the range as tagged.
      58             :   template <typename ObjectVisitor>
      59             :   static inline void IterateBodyImpl(HeapObject* obj, int start_offset,
      60             :                                      int end_offset, ObjectVisitor* v);
      61             : 
      62             :   // Treats all header and embedder fields in the range as tagged.
      63             :   template <typename StaticVisitor>
      64             :   static inline void IterateBodyImpl(Heap* heap, HeapObject* obj,
      65             :                                      int start_offset, int end_offset);
      66             : };
      67             : 
      68             : 
      69             : // This class describes a body of an object of a fixed size
      70             : // in which all pointer fields are located in the [start_offset, end_offset)
      71             : // interval.
      72             : template <int start_offset, int end_offset, int size>
      73             : class FixedBodyDescriptor final : public BodyDescriptorBase {
      74             :  public:
      75             :   static const int kStartOffset = start_offset;
      76             :   static const int kEndOffset = end_offset;
      77             :   static const int kSize = size;
      78             : 
      79             :   static bool IsValidSlot(HeapObject* obj, int offset) {
      80           0 :     return offset >= kStartOffset && offset < kEndOffset;
      81             :   }
      82             : 
      83             :   template <typename ObjectVisitor>
      84             :   static inline void IterateBody(HeapObject* obj, ObjectVisitor* v) {
      85     2454238 :     IteratePointers(obj, start_offset, end_offset, v);
      86             :   }
      87             : 
      88             :   template <typename ObjectVisitor>
      89             :   static inline void IterateBody(HeapObject* obj, int object_size,
      90             :                                  ObjectVisitor* v) {
      91             :     IterateBody(obj, v);
      92             :   }
      93             : 
      94             :   template <typename StaticVisitor>
      95   158944839 :   static inline void IterateBody(HeapObject* obj) {
      96             :     Heap* heap = obj->GetHeap();
      97   126022231 :     IteratePointers<StaticVisitor>(heap, obj, start_offset, end_offset);
      98   158944864 :   }
      99             : 
     100             :   template <typename StaticVisitor>
     101             :   static inline void IterateBody(HeapObject* obj, int object_size) {
     102             :     IterateBody(obj);
     103             :   }
     104             : };
     105             : 
     106             : 
     107             : // This class describes a body of an object of a variable size
     108             : // in which all pointer fields are located in the [start_offset, object_size)
     109             : // interval.
     110             : template <int start_offset>
     111             : class FlexibleBodyDescriptor final : public BodyDescriptorBase {
     112             :  public:
     113             :   static const int kStartOffset = start_offset;
     114             : 
     115             :   static bool IsValidSlot(HeapObject* obj, int offset) {
     116           0 :     return (offset >= kStartOffset);
     117             :   }
     118             : 
     119             :   template <typename ObjectVisitor>
     120             :   static inline void IterateBody(HeapObject* obj, int object_size,
     121             :                                  ObjectVisitor* v) {
     122     2140912 :     IteratePointers(obj, start_offset, object_size, v);
     123             :   }
     124             : 
     125             :   template <typename StaticVisitor>
     126    84173849 :   static inline void IterateBody(HeapObject* obj, int object_size) {
     127             :     Heap* heap = obj->GetHeap();
     128    76580031 :     IteratePointers<StaticVisitor>(heap, obj, start_offset, object_size);
     129    84173853 :   }
     130             : 
     131             :   static inline int SizeOf(Map* map, HeapObject* object);
     132             : };
     133             : 
     134             : 
     135             : typedef FlexibleBodyDescriptor<HeapObject::kHeaderSize> StructBodyDescriptor;
     136             : 
     137             : }  // namespace internal
     138             : }  // namespace v8
     139             : 
     140             : #endif  // V8_OBJECTS_BODY_DESCRIPTORS_H_