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// Copyright 2014 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_FIELD_INDEX_INL_H_
#define V8_FIELD_INDEX_INL_H_
#include "src/field-index.h"
#include "src/objects-inl.h"
#include "src/objects/descriptor-array.h"
namespace v8 {
namespace internal {
inline FieldIndex FieldIndex::ForInObjectOffset(int offset, Encoding encoding,
const Map* map) {
DCHECK(map == nullptr || offset < map->instance_size());
DCHECK(encoding == kWord32 ? (offset % kInt32Size) == 0
: (offset % kPointerSize) == 0);
return FieldIndex(true, offset, encoding, 0, 0);
}
inline FieldIndex FieldIndex::ForPropertyIndex(const Map* map,
int property_index,
Representation representation) {
DCHECK(map->instance_type() >= FIRST_NONSTRING_TYPE);
int inobject_properties = map->GetInObjectProperties();
bool is_inobject = property_index < inobject_properties;
int first_inobject_offset;
int offset;
if (is_inobject) {
first_inobject_offset = map->GetInObjectPropertyOffset(0);
offset = map->GetInObjectPropertyOffset(property_index);
} else {
first_inobject_offset = FixedArray::kHeaderSize;
property_index -= inobject_properties;
offset = FixedArray::kHeaderSize + property_index * kPointerSize;
}
Encoding encoding = FieldEncoding(representation);
return FieldIndex(is_inobject, offset, encoding, inobject_properties,
first_inobject_offset);
}
// Takes an index as computed by GetLoadByFieldIndex and reconstructs a
// FieldIndex object from it.
inline FieldIndex FieldIndex::ForLoadByFieldIndex(const Map* map,
int orig_index) {
int field_index = orig_index;
bool is_inobject = true;
int first_inobject_offset = 0;
Encoding encoding = field_index & 1 ? kDouble : kTagged;
field_index >>= 1;
int offset;
if (field_index < 0) {
first_inobject_offset = FixedArray::kHeaderSize;
field_index = -(field_index + 1);
is_inobject = false;
offset = FixedArray::kHeaderSize + field_index * kPointerSize;
} else {
first_inobject_offset = map->GetInObjectPropertyOffset(0);
offset = map->GetInObjectPropertyOffset(field_index);
}
FieldIndex result(is_inobject, offset, encoding, map->GetInObjectProperties(),
first_inobject_offset);
DCHECK_EQ(result.GetLoadByFieldIndex(), orig_index);
return result;
}
// Returns the index format accepted by the HLoadFieldByIndex instruction.
// (In-object: zero-based from (object start + JSObject::kHeaderSize),
// out-of-object: zero-based from FixedArray::kHeaderSize.)
inline int FieldIndex::GetLoadByFieldIndex() const {
// For efficiency, the LoadByFieldIndex instruction takes an index that is
// optimized for quick access. If the property is inline, the index is
// positive. If it's out-of-line, the encoded index is -raw_index - 1 to
// disambiguate the zero out-of-line index from the zero inobject case.
// The index itself is shifted up by one bit, the lower-most bit
// signifying if the field is a mutable double box (1) or not (0).
int result = index();
if (is_inobject()) {
result -= JSObject::kHeaderSize / kPointerSize;
} else {
result -= FixedArray::kHeaderSize / kPointerSize;
result = -result - 1;
}
result <<= 1;
return is_double() ? (result | 1) : result;
}
inline FieldIndex FieldIndex::ForDescriptor(const Map* map,
int descriptor_index) {
PropertyDetails details =
map->instance_descriptors()->GetDetails(descriptor_index);
int field_index = details.field_index();
return ForPropertyIndex(map, field_index, details.representation());
}
} // namespace internal
} // namespace v8
#endif // V8_FIELD_INDEX_INL_H_
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