[runtime] Allocate space for computed property names

src/factory.cc

 // Copyright 2014 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/factory.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast.h"
 #include "src/base/bits.h"
@@ skipping 167 matching lines @@
       FixedArray);
 }
 
 Handle<FixedArray> Factory::NewUninitializedFixedArray(int size) {
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateUninitializedFixedArray(size),
       FixedArray);
 }
 
+Handle<BoilerplateDescription> Factory::NewBoilerplateDescription(
+    int boilerplate, int all_properties, bool has_seen_proto) {
+  DCHECK_GE(all_properties, boilerplate);
+
+  int backing_store_size = all_properties - (has_seen_proto ? 1 : 0);
+  DCHECK_GE(backing_store_size, 0);
+  bool has_different_size_backing_store = boilerplate != backing_store_size;
+
+  // Space for name and value for every boilerplate property.
+  int size = 2 * boilerplate;
+
+  if (has_different_size_backing_store) {
+    // An extra entry for the backing store size.
+    size++;
+  }
+
+  Handle<BoilerplateDescription> description =
+      Handle<BoilerplateDescription>::cast(NewFixedArray(size, TENURED));
+
+  if (has_different_size_backing_store) {
+    DCHECK((boilerplate != all_properties) || has_seen_proto);
+    description->set_backing_store_size(isolate(), backing_store_size);
+  }
+  return description;
+}
 
 Handle<FixedArrayBase> Factory::NewFixedDoubleArray(int size,
                                                     PretenureFlag pretenure) {
   DCHECK(0 <= size);
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateUninitializedFixedDoubleArray(size, pretenure),
       FixedArrayBase);
 }
 
@@ skipping 2588 matching lines @@
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), rw_attribs);
     Descriptor d = Descriptor::AccessorConstant(
         Handle<Name>(Name::cast(prototype->name())), prototype, rw_attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 }  // namespace internal
 }  // namespace v8