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