Add flag to disable string externalization

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 47 matching lines @@
     "instead of showing the corresponding interface names (e.g. \"String\")");
 DEFINE_FLAG(bool, use_lib_cache, true, "Use library name cache");
 DEFINE_FLAG(bool, ignore_patch_signature_mismatch, false,
             "Ignore patch file member signature mismatch.");
 
 DECLARE_FLAG(charp, coverage_dir);
 DECLARE_FLAG(bool, show_invisible_frames);
 DECLARE_FLAG(bool, trace_deoptimization);
 DECLARE_FLAG(bool, trace_deoptimization_verbose);
 DECLARE_FLAG(bool, write_protect_code);
+DECLARE_FLAG(bool, support_externalizable_strings);
 
 
 static const char* const kGetterPrefix = "get:";
 static const intptr_t kGetterPrefixLength = strlen(kGetterPrefix);
 static const char* const kSetterPrefix = "set:";
 static const intptr_t kSetterPrefixLength = strlen(kSetterPrefix);
 
 // A cache of VM heap allocated preinitialized empty ic data entry arrays.
 RawArray* ICData::cached_icdata_arrays_[kCachedICDataArrayCount];
 
@@ skipping 7730 matching lines @@
           guarded_list_length_in_object_offset());
     }
   }
 
   return Thread::Current()->zone()->PrintToString("<%s %s>",
     is_nullable() ? "nullable" : "not-nullable",
     class_name);
 }
 
 
+bool Field::IsExternalizableCid(intptr_t cid) {
+  if (FLAG_support_externalizable_strings) {
+    return (cid == kOneByteStringCid) || (cid == kTwoByteStringCid);
+  } else {
+    return false;
+  }
+}
+
+
 void Field::InitializeGuardedListLengthInObjectOffset() const {
   ASSERT(IsOriginal());
   if (needs_length_check() &&
       (guarded_list_length() != Field::kUnknownFixedLength)) {
     const intptr_t offset = GetListLengthOffset(guarded_cid());
     set_guarded_list_length_in_object_offset(offset);
     ASSERT(offset != Field::kUnknownLengthOffset);
   } else {
     set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
   }
@@ skipping 11766 matching lines @@
                                           peer,
                                           callback,
                                           external_size);
 }
 
 
 RawString* String::MakeExternal(void* array,
                                 intptr_t length,
                                 void* peer,
                                 Dart_PeerFinalizer cback) const {
+  ASSERT(FLAG_support_externalizable_strings);
   String& result = String::Handle();
   void* external_data;
   Dart_WeakPersistentHandleFinalizer finalizer;
   {
     NoSafepointScope no_safepoint;
     ASSERT(array != NULL);
     intptr_t str_length = this->Length();
     ASSERT(length >= (str_length * this->CharSize()));
     intptr_t class_id = raw()->GetClassId();
 
@@ skipping 2248 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart