Introduce phantom weak handles in the API and use them internally for debug info

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 7461 matching lines @@
   FlagAndPersistent object_a, object_b;
 
   {
     v8::HandleScope handle_scope(iso);
     object_a.handle.Reset(iso, v8::Object::New(iso));
     object_b.handle.Reset(iso, v8::Object::New(iso));
   }
 
   object_a.flag = false;
   object_b.flag = false;
-  object_a.handle.SetWeak(&object_a, &DisposeAndSetFlag);
-  object_b.handle.SetWeak(&object_b, &DisposeAndSetFlag);
+  object_a.handle.SetPhantom(&object_a, &DisposeAndSetFlag);
+  object_b.handle.SetPhantom(&object_b, &DisposeAndSetFlag);
   CHECK(!object_b.handle.IsIndependent());
   object_a.handle.MarkIndependent();
   object_b.handle.MarkIndependent();
   CHECK(object_b.handle.IsIndependent());
   CcTest::heap()->CollectGarbage(i::NEW_SPACE);
   CHECK(object_a.flag);
   CHECK(object_b.flag);
 }
 

[ulan, 2014/10/20 14:26:02]

Could you please also test we don't mark through a dying phantom handle?
I mean that phantom handle and its value die in the same GC.

[Erik Corry, 2014/10/22 13:21:00]

I haven't done this yet.

 
 static void InvokeScavenge() {
   CcTest::heap()->CollectGarbage(i::NEW_SPACE);
 }
 
 
 static void InvokeMarkSweep() {
   CcTest::heap()->CollectAllGarbage(i::Heap::kNoGCFlags);
 }
 
@@ skipping 16290 matching lines @@
   char chunk2[] =
       "XXr = 13;\n"
       "  return foob\xeb\x91\x80\xeb\x91\x80r;\n"
       "}\n";
   chunk1[strlen(chunk1) - 1] = reference[0];
   chunk2[0] = reference[1];
   chunk2[1] = reference[2];
   const char* chunks[] = {chunk1, chunk2, "foo();", NULL};
   RunStreamingTest(chunks, v8::ScriptCompiler::StreamedSource::UTF8);
 }