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 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
ForPropertyIndex(Map * map,int property_index,bool is_double)29 inline 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.
ForLoadByFieldIndex(Map * map,int orig_index)50 inline 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.)
GetLoadByFieldIndex()75 inline 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
ForDescriptor(Map * map,int descriptor_index)94 inline 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
ForKeyedLookupCacheIndex(Map * map,int index)104 inline 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
FromFieldAccessStubKey(int key)113 inline FieldIndex FieldIndex::FromFieldAccessStubKey(int key) {
114 return FieldIndex(key);
115 }
116
117
GetKeyedLookupCacheIndex()118 inline 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