Make embedded maps in optimized code weak.

src/lithium.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 411 matching lines @@
 
   if (generator.GenerateCode()) {
     if (FLAG_trace_codegen) {
       PrintF("Crankshaft Compiler - ");
     }
     CodeGenerator::MakeCodePrologue(info());
     Code::Flags flags = Code::ComputeFlags(kind);
     Handle<Code> code =
         CodeGenerator::MakeCodeEpilogue(&assembler, flags, info());
     generator.FinishCode(code);
+    RegisterDependentCodeForEmbeddedMaps(code);

[Michael Starzinger, 2013/01/21 10:49:46]

Let's move the call to this function into LCodeGen::FinishCode, I think it
belongs there.

[ulan, 2013/01/21 13:11:57]

As discussed offline, leaving this here, otherwise we'd have to duplicate it for
each platform.

     CodeGenerator::PrintCode(code, info());
     return code;
   }
   return Handle<Code>::null();
 }
 
 
+void LChunk::RegisterDependentCodeForEmbeddedMaps(Handle<Code> code) {
+  ZoneList<Handle<Map> > maps(1, zone());
+  int mode_mask = RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT);
+  for (RelocIterator it(*code, mode_mask); !it.done(); it.next()) {
+    RelocInfo::Mode mode = it.rinfo()->rmode();
+    if (mode == RelocInfo::EMBEDDED_OBJECT &&
+        it.rinfo()->target_object()->IsMap()) {
+      Handle<Map> map(Map::cast(it.rinfo()->target_object()));
+      if (map->CanTransition()) {
+        maps.Add(map, zone());
+      }
+    }
+  }
+  for (int i = 0; i < maps.length(); i++) {
+    maps.at(i)->AddDependentCode(code);
+  }
+}
+
 } }  // namespace v8::internal