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 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 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 // Takes an index as computed by GetLoadByFieldIndex and reconstructs a 43 // FieldIndex object from it. 44 inline FieldIndex FieldIndex::ForLoadByFieldIndex(Map* map, int orig_index) { 45 int field_index = orig_index; 46 int is_inobject = true; 47 bool is_double = field_index & 1; 48 int first_inobject_offset = 0; 49 field_index >>= 1; 50 if (field_index < 0) { 51 field_index = -(field_index + 1); 52 is_inobject = false; 53 first_inobject_offset = FixedArray::kHeaderSize; 54 field_index += FixedArray::kHeaderSize / kPointerSize; 55 } else { 56 first_inobject_offset = map->GetInObjectPropertyOffset(0); 57 field_index += JSObject::kHeaderSize / kPointerSize; 58 } 59 FieldIndex result(is_inobject, field_index, is_double, 60 map->GetInObjectProperties(), first_inobject_offset); 61 DCHECK(result.GetLoadByFieldIndex() == orig_index); 62 return result; 63 } 64 65 66 // Returns the index format accepted by the HLoadFieldByIndex instruction. 67 // (In-object: zero-based from (object start + JSObject::kHeaderSize), 68 // out-of-object: zero-based from FixedArray::kHeaderSize.) 69 inline int FieldIndex::GetLoadByFieldIndex() const { 70 // For efficiency, the LoadByFieldIndex instruction takes an index that is 71 // optimized for quick access. If the property is inline, the index is 72 // positive. If it's out-of-line, the encoded index is -raw_index - 1 to 73 // disambiguate the zero out-of-line index from the zero inobject case. 74 // The index itself is shifted up by one bit, the lower-most bit 75 // signifying if the field is a mutable double box (1) or not (0). 76 int result = index(); 77 if (is_inobject()) { 78 result -= JSObject::kHeaderSize / kPointerSize; 79 } else { 80 result -= FixedArray::kHeaderSize / kPointerSize; 81 result = -result - 1; 82 } 83 result <<= 1; 84 return is_double() ? (result | 1) : result; 85 } 86 87 inline FieldIndex FieldIndex::ForDescriptor(Map* map, int descriptor_index) { 88 PropertyDetails details = 89 map->instance_descriptors()->GetDetails(descriptor_index); 90 int field_index = details.field_index(); 91 return ForPropertyIndex(map, field_index, 92 details.representation().IsDouble()); 93 } 94 95 inline FieldIndex FieldIndex::FromFieldAccessStubKey(int key) { 96 return FieldIndex(key); 97 } 98 99 } // namespace internal 100 } // namespace v8 101 102 #endif 103
