Implement prologue weak persistent handles.

runtime/vm/verifier.cc

Index: runtime/vm/verifier.cc
diff --git a/runtime/vm/verifier.cc b/runtime/vm/verifier.cc
index adb53fa8df6176be2bef0f246d64c2c0eb2964d9..f1cd7f47d275a76e922ad087095684893430394a 100644
--- a/runtime/vm/verifier.cc
+++ b/runtime/vm/verifier.cc
@@ -41,7 +41,8 @@ void VerifyPointersVisitor::VisitPointers(RawObject** first, RawObject** last) {
 
 
 void VerifyWeakPointersVisitor::VisitHandle(uword addr) {
-  WeakPersistentHandle* handle = reinterpret_cast<WeakPersistentHandle*>(addr);
+  FinalizablePersistentHandle* handle =
+      reinterpret_cast<FinalizablePersistentHandle*>(addr);
   RawObject* raw_obj = handle->raw();
   visitor_->VisitPointer(&raw_obj);
 }
@@ -51,10 +52,14 @@ void VerifyPointersVisitor::VerifyPointers() {
   NoGCScope no_gc;
   Isolate* isolate = Isolate::Current();
   VerifyPointersVisitor visitor;
+  // Visit all strongly reachable objects.
   isolate->VisitObjectPointers(&visitor,
+                               false,  // skip prologue weak handles

[siva, 2012/03/09 21:48:41]

Why do we want to skip verification of prolog weak handles?

They are potentially reachable right.

[cshapiro, 2012/03/13 23:06:43]

We don't.  We just defer the visit until later.  More specifically, during the
visit of WeakPersistentHandles on line 61.  I'll add a matching comment next to
the "true" on line 62.

                                StackFrameIterator::kValidateFrames);
   VerifyWeakPointersVisitor weak_visitor(&visitor);
-  isolate->VisitWeakPersistentHandles(&weak_visitor);
+  // Visit weak handles and prologue weak handles.
+  isolate->VisitWeakPersistentHandles(&weak_visitor,
+                                      true);
 }
 
 }  // namespace dart