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      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #include "v8.h"
     29 
     30 #include "objects.h"
     31 #include "transitions-inl.h"
     32 #include "utils.h"
     33 
     34 namespace v8 {
     35 namespace internal {
     36 
     37 
     38 static MaybeObject* AllocateRaw(int length) {
     39   Heap* heap = Isolate::Current()->heap();
     40 
     41   // Use FixedArray to not use TransitionArray::cast on incomplete object.
     42   FixedArray* array;
     43   MaybeObject* maybe_array = heap->AllocateFixedArray(length);
     44   if (!maybe_array->To(&array)) return maybe_array;
     45   return array;
     46 }
     47 
     48 
     49 MaybeObject* TransitionArray::Allocate(int number_of_transitions) {
     50   FixedArray* array;
     51   MaybeObject* maybe_array = AllocateRaw(ToKeyIndex(number_of_transitions));
     52   if (!maybe_array->To(&array)) return maybe_array;
     53   array->set(kPrototypeTransitionsIndex, Smi::FromInt(0));
     54   return array;
     55 }
     56 
     57 
     58 void TransitionArray::NoIncrementalWriteBarrierCopyFrom(TransitionArray* origin,
     59                                                         int origin_transition,
     60                                                         int target_transition) {
     61   NoIncrementalWriteBarrierSet(target_transition,
     62                                origin->GetKey(origin_transition),
     63                                origin->GetTarget(origin_transition));
     64 }
     65 
     66 
     67 static bool InsertionPointFound(Name* key1, Name* key2) {
     68   return key1->Hash() > key2->Hash();
     69 }
     70 
     71 
     72 MaybeObject* TransitionArray::NewWith(SimpleTransitionFlag flag,
     73                                       Name* key,
     74                                       Map* target,
     75                                       Object* back_pointer) {
     76   TransitionArray* result;
     77   MaybeObject* maybe_result;
     78 
     79   if (flag == SIMPLE_TRANSITION) {
     80     maybe_result = AllocateRaw(kSimpleTransitionSize);
     81     if (!maybe_result->To(&result)) return maybe_result;
     82     result->set(kSimpleTransitionTarget, target);
     83   } else {
     84     maybe_result = Allocate(1);
     85     if (!maybe_result->To(&result)) return maybe_result;
     86     result->NoIncrementalWriteBarrierSet(0, key, target);
     87   }
     88   result->set_back_pointer_storage(back_pointer);
     89   return result;
     90 }
     91 
     92 
     93 MaybeObject* TransitionArray::ExtendToFullTransitionArray() {
     94   ASSERT(!IsFullTransitionArray());
     95   int nof = number_of_transitions();
     96   TransitionArray* result;
     97   MaybeObject* maybe_result = Allocate(nof);
     98   if (!maybe_result->To(&result)) return maybe_result;
     99 
    100   if (nof == 1) {
    101     result->NoIncrementalWriteBarrierCopyFrom(this, kSimpleTransitionIndex, 0);
    102   }
    103 
    104   result->set_back_pointer_storage(back_pointer_storage());
    105   return result;
    106 }
    107 
    108 
    109 MaybeObject* TransitionArray::CopyInsert(Name* name, Map* target) {
    110   TransitionArray* result;
    111 
    112   int number_of_transitions = this->number_of_transitions();
    113   int new_size = number_of_transitions;
    114 
    115   int insertion_index = this->Search(name);
    116   if (insertion_index == kNotFound) ++new_size;
    117 
    118   MaybeObject* maybe_array;
    119   maybe_array = TransitionArray::Allocate(new_size);
    120   if (!maybe_array->To(&result)) return maybe_array;
    121 
    122   if (HasPrototypeTransitions()) {
    123     result->SetPrototypeTransitions(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(this, i, i);
    130       }
    131     }
    132     result->NoIncrementalWriteBarrierSet(insertion_index, name, target);
    133     result->set_back_pointer_storage(back_pointer_storage());
    134     return result;
    135   }
    136 
    137   insertion_index = 0;
    138   for (; insertion_index < number_of_transitions; ++insertion_index) {
    139     if (InsertionPointFound(GetKey(insertion_index), name)) break;
    140     result->NoIncrementalWriteBarrierCopyFrom(
    141         this, 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         this, insertion_index, insertion_index + 1);
    149   }
    150 
    151   result->set_back_pointer_storage(back_pointer_storage());
    152   return result;
    153 }
    154 
    155 
    156 } }  // namespace v8::internal
    157