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// 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_MAYBE_OBJECT_INL_H_
#define V8_OBJECTS_MAYBE_OBJECT_INL_H_
#include "src/objects/maybe-object.h"
#ifdef V8_COMPRESS_POINTERS
#include "src/isolate.h"
#endif
#include "src/objects/heap-object-inl.h"
#include "src/objects/slots-inl.h"
#include "src/objects/smi-inl.h"
namespace v8 {
namespace internal {
bool MaybeObject::ToSmi(Smi* value) {
if (HAS_SMI_TAG(ptr_)) {
*value = Smi::cast(Object(ptr_));
return true;
}
return false;
}
Smi MaybeObject::ToSmi() const {
DCHECK(HAS_SMI_TAG(ptr_));
return Smi::cast(Object(ptr_));
}
bool MaybeObject::IsStrongOrWeak() const {
if (IsSmi() || IsCleared()) {
return false;
}
return true;
}
bool MaybeObject::GetHeapObject(HeapObject* result) const {
if (IsSmi() || IsCleared()) {
return false;
}
*result = GetHeapObject();
return true;
}
bool MaybeObject::GetHeapObject(HeapObject* result,
HeapObjectReferenceType* reference_type) const {
if (IsSmi() || IsCleared()) {
return false;
}
*reference_type = HasWeakHeapObjectTag(ptr_)
? HeapObjectReferenceType::WEAK
: HeapObjectReferenceType::STRONG;
*result = GetHeapObject();
return true;
}
bool MaybeObject::IsStrong() const {
return !HasWeakHeapObjectTag(ptr_) && !IsSmi();
}
bool MaybeObject::GetHeapObjectIfStrong(HeapObject* result) const {
if (!HasWeakHeapObjectTag(ptr_) && !IsSmi()) {
*result = HeapObject::cast(Object(ptr_));
return true;
}
return false;
}
HeapObject MaybeObject::GetHeapObjectAssumeStrong() const {
DCHECK(IsStrong());
return HeapObject::cast(Object(ptr_));
}
bool MaybeObject::IsWeak() const {
return HasWeakHeapObjectTag(ptr_) && !IsCleared();
}
bool MaybeObject::IsWeakOrCleared() const { return HasWeakHeapObjectTag(ptr_); }
bool MaybeObject::GetHeapObjectIfWeak(HeapObject* result) const {
if (IsWeak()) {
*result = GetHeapObject();
return true;
}
return false;
}
HeapObject MaybeObject::GetHeapObjectAssumeWeak() const {
DCHECK(IsWeak());
return GetHeapObject();
}
HeapObject MaybeObject::GetHeapObject() const {
DCHECK(!IsSmi());
DCHECK(!IsCleared());
return HeapObject::cast(Object(ptr_ & ~kWeakHeapObjectMask));
}
Object MaybeObject::GetHeapObjectOrSmi() const {
if (IsSmi()) {
return Object(ptr_);
}
return GetHeapObject();
}
bool MaybeObject::IsObject() const { return IsSmi() || IsStrong(); }
MaybeObject MaybeObject::MakeWeak(MaybeObject object) {
DCHECK(object.IsStrongOrWeak());
return MaybeObject(object.ptr_ | kWeakHeapObjectMask);
}
// static
HeapObjectReference HeapObjectReference::ClearedValue(Isolate* isolate) {
// Construct cleared weak ref value.
Address raw_value = kClearedWeakHeapObjectLower32;
#ifdef V8_COMPRESS_POINTERS
// This is necessary to make pointer decompression computation also
// suitable for cleared weak references.
Address isolate_root = isolate->isolate_root();
raw_value |= isolate_root;
DCHECK_EQ(raw_value & (~static_cast<Address>(kClearedWeakHeapObjectLower32)),
isolate_root);
#endif
// The rest of the code will check only the lower 32-bits.
DCHECK_EQ(kClearedWeakHeapObjectLower32, static_cast<uint32_t>(raw_value));
return HeapObjectReference(raw_value);
}
template <typename THeapObjectSlot>
void HeapObjectReference::Update(THeapObjectSlot slot, HeapObject value) {
static_assert(std::is_same<THeapObjectSlot, FullHeapObjectSlot>::value ||
std::is_same<THeapObjectSlot, HeapObjectSlot>::value,
"Only FullHeapObjectSlot and HeapObjectSlot are expected here");
Address old_value = (*slot).ptr();
DCHECK(!HAS_SMI_TAG(old_value));
Address new_value = value->ptr();
DCHECK(Internals::HasHeapObjectTag(new_value));
#ifdef DEBUG
bool weak_before = HasWeakHeapObjectTag(old_value);
#endif
slot.store(
HeapObjectReference(new_value | (old_value & kWeakHeapObjectMask)));
#ifdef DEBUG
bool weak_after = HasWeakHeapObjectTag((*slot).ptr());
DCHECK_EQ(weak_before, weak_after);
#endif
}
} // namespace internal
} // namespace v8
#endif // V8_OBJECTS_MAYBE_OBJECT_INL_H_
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