[runtime] Allocate space for computed property names

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 9809 matching lines @@
 
 
 void FixedArray::CopyTo(int pos, FixedArray* dest, int dest_pos, int len) {
   DisallowHeapAllocation no_gc;
   WriteBarrierMode mode = dest->GetWriteBarrierMode(no_gc);
   for (int index = 0; index < len; index++) {
     dest->set(dest_pos+index, get(pos+index), mode);
   }
 }
 
+Object* BoilerplateDescription::name(int index) const {
+  // get() already checks for out of bounds access, but we do not want to allow
+  // access to the last element, if it is the number of properties.
+  DCHECK_NE(size(), index);
+  return get(2 * index);
+}
+
+Object* BoilerplateDescription::value(int index) const {
+  return get(2 * index + 1);
+}
+
+int BoilerplateDescription::size() const {
+  DCHECK_EQ(0, (length() - (this->has_number_of_properties() ? 1 : 0)) % 2);
+  // Rounding is intended.
+  return length() / 2;
+}
+
+int BoilerplateDescription::backing_store_size() const {
+  if (has_number_of_properties()) {
+    // If present, the last entry contains the number of properties.
+    return Smi::cast(this->get(length() - 1))->value();
+  }
+  // If the number is not given explicitly, we assume there are no
+  // properties with computed names.
+  return size();
+}
+
+void BoilerplateDescription::set_backing_store_size(Isolate* isolate,
+                                                    int backing_store_size) {
+  DCHECK(has_number_of_properties());
+  DCHECK_NE(size(), backing_store_size);
+  Handle<Object> backing_store_size_obj =
+      isolate->factory()->NewNumberFromInt(backing_store_size);
+  set(length() - 1, *backing_store_size_obj);
+}
+
+bool BoilerplateDescription::has_number_of_properties() const {
+  return length() % 2 != 0;
+}
 
 #ifdef DEBUG
 bool FixedArray::IsEqualTo(FixedArray* other) {
   if (length() != other->length()) return false;
   for (int i = 0 ; i < length(); ++i) {
     if (get(i) != other->get(i)) return false;
   }
   return true;
 }
 #endif
@@ skipping 10076 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8