| // Copyright 2018 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. |
| |
| #ifndef V8_OBJECTS_FREE_SPACE_H_ |
| #define V8_OBJECTS_FREE_SPACE_H_ |
| |
| #include "src/objects/heap-object.h" |
| |
| // Has to be the last include (doesn't have include guards): |
| #include "src/objects/object-macros.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| #include "torque-generated/src/objects/free-space-tq.inc" |
| |
| // FreeSpace are fixed-size free memory blocks used by the heap and GC. |
| // They look like heap objects (are heap object tagged and have a map) so that |
| // the heap remains iterable. They have a size and a next pointer. |
| // The next pointer is the raw address of the next FreeSpace object (or NULL) |
| // in the free list. |
| // |
| // When external code space is enabled next pointer is stored as Smi values |
| // representing a diff from current FreeSpace object address in kObjectAlignment |
| // chunks. Terminating FreeSpace value is represented as Smi zero. |
| // Such a representation has the following properties: |
| // a) it can hold both positive an negative diffs for full pointer compression |
| // cage size (HeapObject address has only valuable 30 bits while Smis have |
| // 31 bits), |
| // b) it's independent of the pointer compression base and pointer compression |
| // scheme. |
| class FreeSpace : public TorqueGeneratedFreeSpace<FreeSpace, HeapObject> { |
| public: |
| // [size]: size of the free space including the header. |
| DECL_RELAXED_INT_ACCESSORS(size) |
| static inline void SetSize(const WritableFreeSpace& writable_free_space, |
| int size, RelaxedStoreTag); |
| inline int Size(); |
| |
| // Accessors for the next field. |
| inline Tagged<FreeSpace> next() const; |
| inline void SetNext(const WritableFreeSpace& writable_free_space, |
| Tagged<FreeSpace> next); |
| |
| inline static Tagged<FreeSpace> cast(Tagged<HeapObject> obj); |
| inline static Tagged<FreeSpace> unchecked_cast(const Tagged<Object> obj); |
| |
| // Dispatched behavior. |
| DECL_PRINTER(FreeSpace) |
| |
| class BodyDescriptor; |
| |
| private: |
| inline bool IsValid() const; |
| |
| TQ_OBJECT_CONSTRUCTORS(FreeSpace) |
| }; |
| |
| } // namespace internal |
| } // namespace v8 |
| |
| #include "src/objects/object-macros-undef.h" |
| |
| #endif // V8_OBJECTS_FREE_SPACE_H_ |