Internalize strings in-place

src/heap/spaces.cc

 // Copyright 2011 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/heap/spaces.h"
 
 #include <utility>
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
@@ skipping 3138 matching lines @@
     CHECK(object->address() == page->area_start());
 
     // The first word should be a map, and we expect all map pointers to be
     // in map space.
     Map* map = object->map();
     CHECK(map->IsMap());
     CHECK(heap()->map_space()->Contains(map));
 
     // We have only code, sequential strings, external strings
     // (sequential strings that have been morphed into external
-    // strings), fixed arrays, byte arrays, and constant pool arrays in the
-    // large object space.
+    // strings), thin strings (sequential strings that have been
+    // morphed into thin strings), fixed arrays, byte arrays, and
+    // constant pool arrays in the large object space.
     CHECK(object->IsAbstractCode() || object->IsSeqString() ||
-          object->IsExternalString() || object->IsFixedArray() ||
-          object->IsFixedDoubleArray() || object->IsByteArray());
+          object->IsExternalString() || object->IsThinString() ||
+          object->IsFixedArray() || object->IsFixedDoubleArray() ||
+          object->IsByteArray());
 
     // The object itself should look OK.
     object->ObjectVerify();
 
     // Byte arrays and strings don't have interior pointers.
     if (object->IsAbstractCode()) {
       VerifyPointersVisitor code_visitor;
       object->IterateBody(map->instance_type(), object->Size(), &code_visitor);
     } else if (object->IsFixedArray()) {
       FixedArray* array = FixedArray::cast(object);
@@ skipping 55 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8