Enable weak embedded maps in optimized code.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 0501ccf5805a0c752a01c4876895ba2b7863bf53..43ad7e99f14a22dd5cb29d71ca91ec43d01854b2 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -2055,6 +2055,17 @@ void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) {
   // etc., and all objects reachable from them.
   heap()->IterateStrongRoots(visitor, VISIT_ONLY_STRONG);
 
+  // If the call-site of the top optimized code was not prepared for
+  // deoptimization, then treat the maps in the code as strong pointers,
+  // otherwise a map can die and deoptimize the code.

[Michael Starzinger, 2013/07/02 14:20:54]

Can we move this into MarkCompactCollector::MarkLiveObjects? It is not actually
part of the root-set, it is just a requirement from the mark-compact collector
(e.g. similar to PrepareForCodeFlushing).

[ulan, 2013/07/02 14:45:41]

Done.

+  StackFrame* frame = isolate()->TopOptimizedFrame();
+  if (frame) {
+    Code* code = frame->LookupCode();
+    if (!code->CanDeoptAt(frame->pc())) {
+      code->CodeIterateBody(visitor);
+    }
+  }
+
   // Handle the string table specially.
   MarkStringTable();