Revert 21720: "Introduce FieldIndex to unify and abstract property/field offset"

src/field-index.h

-// 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/utils.h"
-#include "src/property-details.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 V8_FINAL {
- public:
-  static FieldIndex ForPropertyIndex(Map* map,
-                                     int index,
-                                     bool is_double = false);
-  static FieldIndex ForInObjectOffset(int offset, Map* map = NULL);
-  static FieldIndex ForLookupResult(const LookupResult* result);
-  static FieldIndex ForDescriptor(Map* map, int descriptor_index);
-  static FieldIndex ForLoadByFieldIndex(Map* map, int index);
-  static FieldIndex ForKeyedLookupCacheIndex(Map* map, int index) {
-    return ForPropertyIndex(map, index);
-  }
-
-  bool is_inobject() const {
-    return IsInObjectBits::decode(bit_field_);
-  }
-
-  bool is_double() const {
-    return IsDoubleBits::decode(bit_field_);
-  }
-
-  int offset() const {
-    return index() * kPointerSize;
-  }
-
-  int index() const {
-    return IndexBits::decode(bit_field_);
-  }
-
-  int outobject_array_index() const {
-    ASSERT(!is_inobject());
-    return index() - first_inobject_property_offset() / kPointerSize;
-  }
-
-  int property_index() const {
-    ASSERT(!IsHiddenField::decode(bit_field_));
-    int result = index() - first_inobject_property_offset() / kPointerSize;
-    if (!is_inobject()) {
-      result += InObjectPropertyBits::decode(bit_field_);
-    }
-    return result;
-  }
-
-  int 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() - first_inobject_property_offset() / kPointerSize;
-    if (!is_inobject()) {
-      result = -result - 1;
-    }
-    result <<= 1;
-    return is_double() ? (result | 1) : result;
-  }
-
-  int GetKeyedLookupCacheIndex() const {
-    return property_index();
-  }
-
-  int GetLoadFieldStubKey() const {
-    return bit_field_ &
-        (IsInObjectBits::kMask | IsDoubleBits::kMask | IndexBits::kMask);
-  }
-
- private:
-  FieldIndex(bool is_inobject, int local_index, bool is_double,
-             int inobject_properties, int first_inobject_property_offset,
-             bool is_hidden = false) {
-    ASSERT((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);
-  }
-
-  int first_inobject_property_offset() const {
-    ASSERT(!IsHiddenField::decode(bit_field_));
-    return FirstInobjectPropertyOffsetBits::decode(bit_field_);
-  }
-
-  static const int kIndexBitsSize = kDescriptorIndexBitCount + 1;
-
-  class IndexBits: public BitField<int, 0, kIndexBitsSize> {};
-  class IsInObjectBits: public BitField<bool, IndexBits::kNext, 1> {};
-  class IsDoubleBits: public BitField<bool, IsInObjectBits::kNext, 1> {};
-  class InObjectPropertyBits: public BitField<int, IsDoubleBits::kNext,
-                                              kDescriptorIndexBitCount> {};
-  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 v8::internal
-
-#endif