1// Copyright 2014 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_FIELD_INDEX_INL_H_
6#define V8_FIELD_INDEX_INL_H_
7
8#include "src/field-index.h"
9
10namespace v8 {
11namespace internal {
12
13
14inline FieldIndex FieldIndex::ForInObjectOffset(int offset, Map* map) {
15  DCHECK((offset % kPointerSize) == 0);
16  int index = offset / kPointerSize;
17  if (map == NULL) {
18    return FieldIndex(true, index, false, index + 1, 0, true);
19  }
20  int first_inobject_offset = map->GetInObjectPropertyOffset(0);
21  if (offset < first_inobject_offset) {
22    return FieldIndex(true, index, false, 0, 0, true);
23  } else {
24    return FieldIndex::ForPropertyIndex(map, offset / kPointerSize);
25  }
26}
27
28
29inline FieldIndex FieldIndex::ForPropertyIndex(Map* map,
30                                               int property_index,
31                                               bool is_double) {
32  DCHECK(map->instance_type() >= FIRST_NONSTRING_TYPE);
33  int inobject_properties = map->inobject_properties();
34  bool is_inobject = property_index < inobject_properties;
35  int first_inobject_offset;
36  if (is_inobject) {
37    first_inobject_offset = map->GetInObjectPropertyOffset(0);
38  } else {
39    first_inobject_offset = FixedArray::kHeaderSize;
40    property_index -= inobject_properties;
41  }
42  return FieldIndex(is_inobject,
43                    property_index + first_inobject_offset / kPointerSize,
44                    is_double, inobject_properties, first_inobject_offset);
45}
46
47
48// Takes an index as computed by GetLoadFieldByIndex and reconstructs a
49// FieldIndex object from it.
50inline FieldIndex FieldIndex::ForLoadByFieldIndex(Map* map, int orig_index) {
51  int field_index = orig_index;
52  int is_inobject = true;
53  bool is_double = field_index & 1;
54  int first_inobject_offset = 0;
55  field_index >>= 1;
56  if (field_index < 0) {
57    field_index = -(field_index + 1);
58    is_inobject = false;
59    first_inobject_offset = FixedArray::kHeaderSize;
60    field_index += FixedArray::kHeaderSize / kPointerSize;
61  } else {
62    first_inobject_offset = map->GetInObjectPropertyOffset(0);
63    field_index += JSObject::kHeaderSize / kPointerSize;
64  }
65  FieldIndex result(is_inobject, field_index, is_double,
66                    map->inobject_properties(), first_inobject_offset);
67  DCHECK(result.GetLoadByFieldIndex() == orig_index);
68  return result;
69}
70
71
72// Returns the index format accepted by the HLoadFieldByIndex instruction.
73// (In-object: zero-based from (object start + JSObject::kHeaderSize),
74// out-of-object: zero-based from FixedArray::kHeaderSize.)
75inline int FieldIndex::GetLoadByFieldIndex() const {
76  // For efficiency, the LoadByFieldIndex instruction takes an index that is
77  // optimized for quick access. If the property is inline, the index is
78  // positive. If it's out-of-line, the encoded index is -raw_index - 1 to
79  // disambiguate the zero out-of-line index from the zero inobject case.
80  // The index itself is shifted up by one bit, the lower-most bit
81  // signifying if the field is a mutable double box (1) or not (0).
82  int result = index();
83  if (is_inobject()) {
84    result -= JSObject::kHeaderSize / kPointerSize;
85  } else {
86    result -= FixedArray::kHeaderSize / kPointerSize;
87    result = -result - 1;
88  }
89  result <<= 1;
90  return is_double() ? (result | 1) : result;
91}
92
93
94inline FieldIndex FieldIndex::ForDescriptor(Map* map, int descriptor_index) {
95  PropertyDetails details =
96      map->instance_descriptors()->GetDetails(descriptor_index);
97  int field_index =
98      map->instance_descriptors()->GetFieldIndex(descriptor_index);
99  return ForPropertyIndex(map, field_index,
100                          details.representation().IsDouble());
101}
102
103
104inline FieldIndex FieldIndex::ForKeyedLookupCacheIndex(Map* map, int index) {
105  if (FLAG_compiled_keyed_generic_loads) {
106    return ForLoadByFieldIndex(map, index);
107  } else {
108    return ForPropertyIndex(map, index);
109  }
110}
111
112
113inline FieldIndex FieldIndex::FromFieldAccessStubKey(int key) {
114  return FieldIndex(key);
115}
116
117
118inline int FieldIndex::GetKeyedLookupCacheIndex() const {
119  if (FLAG_compiled_keyed_generic_loads) {
120    return GetLoadByFieldIndex();
121  } else {
122    return property_index();
123  }
124}
125
126
127} }  // namespace v8::internal
128
129#endif
130