Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2012 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 | #include "src/v8.h" |
| 6 | |
| 7 | #include "src/objects.h" |
| 8 | #include "src/transitions-inl.h" |
| 9 | #include "src/utils.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | |
| 15 | Handle<TransitionArray> TransitionArray::Allocate(Isolate* isolate, |
| 16 | int number_of_transitions) { |
| 17 | Handle<FixedArray> array = |
| 18 | isolate->factory()->NewFixedArray(ToKeyIndex(number_of_transitions)); |
| 19 | array->set(kPrototypeTransitionsIndex, Smi::FromInt(0)); |
| 20 | return Handle<TransitionArray>::cast(array); |
| 21 | } |
| 22 | |
| 23 | |
| 24 | Handle<TransitionArray> TransitionArray::AllocateSimple(Isolate* isolate, |
| 25 | Handle<Map> target) { |
| 26 | Handle<FixedArray> array = |
| 27 | isolate->factory()->NewFixedArray(kSimpleTransitionSize); |
| 28 | array->set(kSimpleTransitionTarget, *target); |
| 29 | return Handle<TransitionArray>::cast(array); |
| 30 | } |
| 31 | |
| 32 | |
| 33 | void TransitionArray::NoIncrementalWriteBarrierCopyFrom(TransitionArray* origin, |
| 34 | int origin_transition, |
| 35 | int target_transition) { |
| 36 | NoIncrementalWriteBarrierSet(target_transition, |
| 37 | origin->GetKey(origin_transition), |
| 38 | origin->GetTarget(origin_transition)); |
| 39 | } |
| 40 | |
| 41 | |
| 42 | static bool InsertionPointFound(Name* key1, Name* key2) { |
| 43 | return key1->Hash() > key2->Hash(); |
| 44 | } |
| 45 | |
| 46 | |
| 47 | Handle<TransitionArray> TransitionArray::NewWith(Handle<Map> map, |
| 48 | Handle<Name> name, |
| 49 | Handle<Map> target, |
| 50 | SimpleTransitionFlag flag) { |
| 51 | Handle<TransitionArray> result; |
| 52 | Isolate* isolate = name->GetIsolate(); |
| 53 | |
| 54 | if (flag == SIMPLE_TRANSITION) { |
| 55 | result = AllocateSimple(isolate, target); |
| 56 | } else { |
| 57 | result = Allocate(isolate, 1); |
| 58 | result->NoIncrementalWriteBarrierSet(0, *name, *target); |
| 59 | } |
| 60 | result->set_back_pointer_storage(map->GetBackPointer()); |
| 61 | return result; |
| 62 | } |
| 63 | |
| 64 | |
| 65 | Handle<TransitionArray> TransitionArray::ExtendToFullTransitionArray( |
| 66 | Handle<Map> containing_map) { |
| 67 | DCHECK(!containing_map->transitions()->IsFullTransitionArray()); |
| 68 | int nof = containing_map->transitions()->number_of_transitions(); |
| 69 | |
| 70 | // A transition array may shrink during GC. |
| 71 | Handle<TransitionArray> result = Allocate(containing_map->GetIsolate(), nof); |
| 72 | DisallowHeapAllocation no_gc; |
| 73 | int new_nof = containing_map->transitions()->number_of_transitions(); |
| 74 | if (new_nof != nof) { |
| 75 | DCHECK(new_nof == 0); |
| 76 | result->Shrink(ToKeyIndex(0)); |
| 77 | } else if (nof == 1) { |
| 78 | result->NoIncrementalWriteBarrierCopyFrom( |
| 79 | containing_map->transitions(), kSimpleTransitionIndex, 0); |
| 80 | } |
| 81 | |
| 82 | result->set_back_pointer_storage( |
| 83 | containing_map->transitions()->back_pointer_storage()); |
| 84 | return result; |
| 85 | } |
| 86 | |
| 87 | |
| 88 | Handle<TransitionArray> TransitionArray::CopyInsert(Handle<Map> map, |
| 89 | Handle<Name> name, |
| 90 | Handle<Map> target, |
| 91 | SimpleTransitionFlag flag) { |
| 92 | if (!map->HasTransitionArray()) { |
| 93 | return TransitionArray::NewWith(map, name, target, flag); |
| 94 | } |
| 95 | |
| 96 | int number_of_transitions = map->transitions()->number_of_transitions(); |
| 97 | int new_size = number_of_transitions; |
| 98 | |
| 99 | int insertion_index = map->transitions()->Search(*name); |
| 100 | if (insertion_index == kNotFound) ++new_size; |
| 101 | |
| 102 | Handle<TransitionArray> result = Allocate(map->GetIsolate(), new_size); |
| 103 | |
| 104 | // The map's transition array may grown smaller during the allocation above as |
| 105 | // it was weakly traversed, though it is guaranteed not to disappear. Trim the |
| 106 | // result copy if needed, and recompute variables. |
| 107 | DCHECK(map->HasTransitionArray()); |
| 108 | DisallowHeapAllocation no_gc; |
| 109 | TransitionArray* array = map->transitions(); |
| 110 | if (array->number_of_transitions() != number_of_transitions) { |
| 111 | DCHECK(array->number_of_transitions() < number_of_transitions); |
| 112 | |
| 113 | number_of_transitions = array->number_of_transitions(); |
| 114 | new_size = number_of_transitions; |
| 115 | |
| 116 | insertion_index = array->Search(*name); |
| 117 | if (insertion_index == kNotFound) ++new_size; |
| 118 | |
| 119 | result->Shrink(ToKeyIndex(new_size)); |
| 120 | } |
| 121 | |
| 122 | if (array->HasPrototypeTransitions()) { |
| 123 | result->SetPrototypeTransitions(array->GetPrototypeTransitions()); |
| 124 | } |
| 125 | |
| 126 | if (insertion_index != kNotFound) { |
| 127 | for (int i = 0; i < number_of_transitions; ++i) { |
| 128 | if (i != insertion_index) { |
| 129 | result->NoIncrementalWriteBarrierCopyFrom(array, i, i); |
| 130 | } |
| 131 | } |
| 132 | result->NoIncrementalWriteBarrierSet(insertion_index, *name, *target); |
| 133 | result->set_back_pointer_storage(array->back_pointer_storage()); |
| 134 | return result; |
| 135 | } |
| 136 | |
| 137 | insertion_index = 0; |
| 138 | for (; insertion_index < number_of_transitions; ++insertion_index) { |
| 139 | if (InsertionPointFound(array->GetKey(insertion_index), *name)) break; |
| 140 | result->NoIncrementalWriteBarrierCopyFrom( |
| 141 | array, insertion_index, insertion_index); |
| 142 | } |
| 143 | |
| 144 | result->NoIncrementalWriteBarrierSet(insertion_index, *name, *target); |
| 145 | |
| 146 | for (; insertion_index < number_of_transitions; ++insertion_index) { |
| 147 | result->NoIncrementalWriteBarrierCopyFrom( |
| 148 | array, insertion_index, insertion_index + 1); |
| 149 | } |
| 150 | |
| 151 | result->set_back_pointer_storage(array->back_pointer_storage()); |
| 152 | return result; |
| 153 | } |
| 154 | |
| 155 | |
| 156 | } } // namespace v8::internal |