hole.h

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// Copyright 2023 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_HOLE_H_
#define V8_OBJECTS_HOLE_H_
 
#include "src/objects/heap-number.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/hole-tq.inc"
 
class Hole : public HeapObject {
 public:
  inline void set_raw_numeric_value(uint64_t bits);
 
  DECL_VERIFIER(Hole)
 
  static inline void Initialize(Isolate* isolate, DirectHandle<Hole> hole,
                                DirectHandle<HeapNumber> numeric_value);
 
  // Currently, we allow optimized code to treat holes as HeapNumbers to avoid
  // conditional branching. This works by making Hole::kRawNumericValueOffset
  // the same as offsetof(HeapNumber, value_) and storing NaN at that offset in
  // Holes. This way, a hole will look like a NaN HeapNumber to optimized code.
  DECL_FIELD_OFFSET_TQ(RawNumericValue, HeapObject::kHeaderSize, "float64")
  static constexpr int kSize = kRawNumericValueOffset + kDoubleSize;
 
  using BodyDescriptor = FixedBodyDescriptor<kSize, kSize, kSize>;
 
  DECL_PRINTER(Hole)
 
  OBJECT_CONSTRUCTORS(Hole, HeapObject);
};
 
}  // namespace internal
}  // namespace v8
 
#include "src/objects/object-macros-undef.h"
 
#endif  // V8_OBJECTS_HOLE_H_