Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 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_H_ |
| 6 | #define V8_FIELD_INDEX_H_ |
| 7 | |
| 8 | #include "src/property-details.h" |
| 9 | #include "src/utils.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | class Map; |
| 15 | |
| 16 | // Wrapper class to hold a field index, usually but not necessarily generated |
| 17 | // from a property index. When available, the wrapper class captures additional |
| 18 | // information to allow the field index to be translated back into the property |
| 19 | // index it was originally generated from. |
| 20 | class FieldIndex FINAL { |
| 21 | public: |
| 22 | static FieldIndex ForPropertyIndex(Map* map, |
| 23 | int index, |
| 24 | bool is_double = false); |
| 25 | static FieldIndex ForInObjectOffset(int offset, Map* map = NULL); |
| 26 | static FieldIndex ForDescriptor(Map* map, int descriptor_index); |
| 27 | static FieldIndex ForLoadByFieldIndex(Map* map, int index); |
| 28 | static FieldIndex ForKeyedLookupCacheIndex(Map* map, int index); |
| 29 | static FieldIndex FromFieldAccessStubKey(int key); |
| 30 | |
| 31 | int GetLoadByFieldIndex() const; |
| 32 | |
| 33 | bool is_inobject() const { |
| 34 | return IsInObjectBits::decode(bit_field_); |
| 35 | } |
| 36 | |
| 37 | bool is_double() const { |
| 38 | return IsDoubleBits::decode(bit_field_); |
| 39 | } |
| 40 | |
| 41 | int offset() const { |
| 42 | return index() * kPointerSize; |
| 43 | } |
| 44 | |
| 45 | // Zero-indexed from beginning of the object. |
| 46 | int index() const { |
| 47 | return IndexBits::decode(bit_field_); |
| 48 | } |
| 49 | |
| 50 | int outobject_array_index() const { |
| 51 | DCHECK(!is_inobject()); |
| 52 | return index() - first_inobject_property_offset() / kPointerSize; |
| 53 | } |
| 54 | |
| 55 | // Zero-based from the first inobject property. Overflows to out-of-object |
| 56 | // properties. |
| 57 | int property_index() const { |
| 58 | DCHECK(!IsHiddenField::decode(bit_field_)); |
| 59 | int result = index() - first_inobject_property_offset() / kPointerSize; |
| 60 | if (!is_inobject()) { |
| 61 | result += InObjectPropertyBits::decode(bit_field_); |
| 62 | } |
| 63 | return result; |
| 64 | } |
| 65 | |
| 66 | int GetKeyedLookupCacheIndex() const; |
| 67 | |
| 68 | int GetFieldAccessStubKey() const { |
| 69 | return bit_field_ & |
| 70 | (IsInObjectBits::kMask | IsDoubleBits::kMask | IndexBits::kMask); |
| 71 | } |
| 72 | |
| 73 | private: |
| 74 | FieldIndex(bool is_inobject, int local_index, bool is_double, |
| 75 | int inobject_properties, int first_inobject_property_offset, |
| 76 | bool is_hidden = false) { |
| 77 | DCHECK((first_inobject_property_offset & (kPointerSize - 1)) == 0); |
| 78 | bit_field_ = IsInObjectBits::encode(is_inobject) | |
| 79 | IsDoubleBits::encode(is_double) | |
| 80 | FirstInobjectPropertyOffsetBits::encode(first_inobject_property_offset) | |
| 81 | IsHiddenField::encode(is_hidden) | |
| 82 | IndexBits::encode(local_index) | |
| 83 | InObjectPropertyBits::encode(inobject_properties); |
| 84 | } |
| 85 | |
| 86 | explicit FieldIndex(int bit_field) : bit_field_(bit_field) {} |
| 87 | |
| 88 | int first_inobject_property_offset() const { |
| 89 | DCHECK(!IsHiddenField::decode(bit_field_)); |
| 90 | return FirstInobjectPropertyOffsetBits::decode(bit_field_); |
| 91 | } |
| 92 | |
| 93 | static const int kIndexBitsSize = kDescriptorIndexBitCount + 1; |
| 94 | |
| 95 | // Index from beginning of object. |
| 96 | class IndexBits: public BitField<int, 0, kIndexBitsSize> {}; |
| 97 | class IsInObjectBits: public BitField<bool, IndexBits::kNext, 1> {}; |
| 98 | class IsDoubleBits: public BitField<bool, IsInObjectBits::kNext, 1> {}; |
| 99 | // Number of inobject properties. |
| 100 | class InObjectPropertyBits |
| 101 | : public BitField<int, IsDoubleBits::kNext, kDescriptorIndexBitCount> {}; |
| 102 | // Offset of first inobject property from beginning of object. |
| 103 | class FirstInobjectPropertyOffsetBits |
| 104 | : public BitField<int, InObjectPropertyBits::kNext, 7> {}; |
| 105 | class IsHiddenField |
| 106 | : public BitField<bool, FirstInobjectPropertyOffsetBits::kNext, 1> {}; |
| 107 | STATIC_ASSERT(IsHiddenField::kNext <= 32); |
| 108 | |
| 109 | int bit_field_; |
| 110 | }; |
| 111 | |
| 112 | } } // namespace v8::internal |
| 113 | |
| 114 | #endif |