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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_H_
#define V8_FIELD_INDEX_H_
#include "src/property-details.h"
#include "src/utils.h"
namespace v8 {
namespace internal {
class Map;
// Wrapper class to hold a field index, usually but not necessarily generated
// from a property index. When available, the wrapper class captures additional
// information to allow the field index to be translated back into the property
// index it was originally generated from.
class FieldIndex final {
public:
FieldIndex() : bit_field_(0) {}
static FieldIndex ForPropertyIndex(Map* map,
int index,
bool is_double = false);
static FieldIndex ForInObjectOffset(int offset, Map* map = NULL);
static FieldIndex ForDescriptor(Map* map, int descriptor_index);
static FieldIndex ForLoadByFieldIndex(Map* map, int index);
static FieldIndex FromFieldAccessStubKey(int key);
int GetLoadByFieldIndex() const;
bool is_inobject() const {
return IsInObjectBits::decode(bit_field_);
}
bool is_hidden_field() const { return IsHiddenField::decode(bit_field_); }
bool is_double() const {
return IsDoubleBits::decode(bit_field_);
}
int offset() const {
return index() * kPointerSize;
}
// Zero-indexed from beginning of the object.
int index() const {
return IndexBits::decode(bit_field_);
}
int outobject_array_index() const {
DCHECK(!is_inobject());
return index() - first_inobject_property_offset() / kPointerSize;
}
// Zero-based from the first inobject property. Overflows to out-of-object
// properties.
int property_index() const {
DCHECK(!is_hidden_field());
int result = index() - first_inobject_property_offset() / kPointerSize;
if (!is_inobject()) {
result += InObjectPropertyBits::decode(bit_field_);
}
return result;
}
int GetFieldAccessStubKey() const {
return bit_field_ &
(IsInObjectBits::kMask | IsDoubleBits::kMask | IndexBits::kMask);
}
bool operator==(FieldIndex const& other) const {
return bit_field_ == other.bit_field_;
}
bool operator!=(FieldIndex const& other) const { return !(*this == other); }
private:
FieldIndex(bool is_inobject, int local_index, bool is_double,
int inobject_properties, int first_inobject_property_offset,
bool is_hidden = false) {
DCHECK((first_inobject_property_offset & (kPointerSize - 1)) == 0);
bit_field_ = IsInObjectBits::encode(is_inobject) |
IsDoubleBits::encode(is_double) |
FirstInobjectPropertyOffsetBits::encode(first_inobject_property_offset) |
IsHiddenField::encode(is_hidden) |
IndexBits::encode(local_index) |
InObjectPropertyBits::encode(inobject_properties);
}
explicit FieldIndex(int bit_field) : bit_field_(bit_field) {}
int first_inobject_property_offset() const {
DCHECK(!is_hidden_field());
return FirstInobjectPropertyOffsetBits::decode(bit_field_);
}
static const int kIndexBitsSize = kDescriptorIndexBitCount + 1;
// Index from beginning of object.
class IndexBits: public BitField<int, 0, kIndexBitsSize> {};
class IsInObjectBits: public BitField<bool, IndexBits::kNext, 1> {};
class IsDoubleBits: public BitField<bool, IsInObjectBits::kNext, 1> {};
// Number of inobject properties.
class InObjectPropertyBits
: public BitField<int, IsDoubleBits::kNext, kDescriptorIndexBitCount> {};
// Offset of first inobject property from beginning of object.
class FirstInobjectPropertyOffsetBits
: public BitField<int, InObjectPropertyBits::kNext, 7> {};
class IsHiddenField
: public BitField<bool, FirstInobjectPropertyOffsetBits::kNext, 1> {};
STATIC_ASSERT(IsHiddenField::kNext <= 32);
int bit_field_;
};
} // namespace internal
} // namespace v8
#endif
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