Introduce safe interface to "copy and grow" FixedArray.

src/heap/heap.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 4408 matching lines @@
   int len = src->length();
   HeapObject* obj;
   {
     AllocationResult allocation = AllocateRawFixedArray(len, TENURED);
     if (!allocation.To(&obj)) return allocation;
   }
   obj->set_map_no_write_barrier(fixed_array_map());
   FixedArray* result = FixedArray::cast(obj);
   result->set_length(len);
 
-  // Copy the content
+  // Copy the content.
   DisallowHeapAllocation no_gc;
   WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
   for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
 
   // TODO(mvstanton): The map is set twice because of protection against calling
   // set() on a COW FixedArray. Issue v8:3221 created to track this, and
   // we might then be able to remove this whole method.
   HeapObject::cast(obj)->set_map_no_write_barrier(fixed_cow_array_map());
   return result;
 }
 
 
 AllocationResult Heap::AllocateEmptyFixedTypedArray(
     ExternalArrayType array_type) {
   return AllocateFixedTypedArray(0, array_type, false, TENURED);
 }
 
 
+AllocationResult Heap::CopyFixedArrayAndGrow(FixedArray* src, int grow_by) {
+  int old_len = src->length();
+  int new_len = old_len + grow_by;
+  HeapObject* obj;
+  {
+    AllocationResult allocation = AllocateRawFixedArray(new_len, NOT_TENURED);
+    if (!allocation.To(&obj)) return allocation;
+  }
+  obj->set_map_no_write_barrier(fixed_array_map());
+  FixedArray* result = FixedArray::cast(obj);
+  result->set_length(new_len);
+
+  // Copy the content.
+  DisallowHeapAllocation no_gc;
+  WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
+  for (int i = 0; i < old_len; i++) result->set(i, src->get(i), mode);
+  MemsetPointer(result->data_start() + old_len, undefined_value(), grow_by);
+  return result;
+}
+
+
 AllocationResult Heap::CopyFixedArrayWithMap(FixedArray* src, Map* map) {
   int len = src->length();
   HeapObject* obj;
   {
     AllocationResult allocation = AllocateRawFixedArray(len, NOT_TENURED);
     if (!allocation.To(&obj)) return allocation;
   }
   if (InNewSpace(obj)) {
     obj->set_map_no_write_barrier(map);
     CopyBlock(obj->address() + kPointerSize, src->address() + kPointerSize,
               FixedArray::SizeFor(len) - kPointerSize);
     return obj;
   }
   obj->set_map_no_write_barrier(map);
   FixedArray* result = FixedArray::cast(obj);
   result->set_length(len);
 
-  // Copy the content
+  // Copy the content.
   DisallowHeapAllocation no_gc;
   WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
   for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
   return result;
 }
 
 
 AllocationResult Heap::CopyFixedDoubleArrayWithMap(FixedDoubleArray* src,
                                                    Map* map) {
   int len = src->length();
@@ skipping 2382 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }  // namespace internal
 }  // namespace v8