Fixes a couple problems with GC of unoptimized code.

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 1490 matching lines @@
   // Parameter names are valid for all valid parameter indices, and are not
   // limited to named optional parameters.
   RawString* ParameterNameAt(intptr_t index) const;
   void SetParameterNameAt(intptr_t index, const String& value) const;
   RawArray* parameter_names() const { return raw_ptr()->parameter_names_; }
   void set_parameter_names(const Array& value) const;
 
   // Sets function's code and code's function.
   void SetCode(const Code& value) const;
 
-  // Detaches code from the function by setting the code to null, and patches
-  // the code to be non-entrant.
-  void DetachCode() const;
-
-  // Reattaches code to the function, and patches the code to be entrant.
-  void ReattachCode(const Code& code) const;
-
   // Disables optimized code and switches to unoptimized code.
   void SwitchToUnoptimizedCode() const;
 
   // Return the most recently compiled and installed code for this function.
   // It is not the only Code object that points to this function.
   RawCode* CurrentCode() const { return raw_ptr()->code_; }
 
   RawCode* unoptimized_code() const { return raw_ptr()->unoptimized_code_; }
   void set_unoptimized_code(const Code& value) const;
   static intptr_t code_offset() { return OFFSET_OF(RawFunction, code_); }
@@ skipping 467 matching lines @@
   bool TestParameterType(TypeTestKind test_kind,
                          intptr_t parameter_position,
                          intptr_t other_parameter_position,
                          const AbstractTypeArguments& type_arguments,
                          const Function& other,
                          const AbstractTypeArguments& other_type_arguments,
                          Error* bound_error) const;
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Function, Object);
   friend class Class;
+  // RawFunction::VisitFunctionPointers accesses the private constructor of
+  // Function.
+  friend class RawFunction;
 };
 
 
 class ClosureData: public Object {
  public:
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawClosureData));
   }
 
  private:
@@ skipping 1338 matching lines @@
   intptr_t BinarySearchInSCallTable(uword pc) const;
 
   // New is a private method as RawInstruction and RawCode objects should
   // only be created using the Code::FinalizeCode method. This method creates
   // the RawInstruction and RawCode objects, sets up the pointer offsets
   // and links the two in a GC safe manner.
   static RawCode* New(intptr_t pointer_offsets_length);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Code, Object);
   friend class Class;
+
+  // So that the RawFunction pointer visitor can determine whether code the
+  // function points to is optimized.
+  friend class RawFunction;
 };
 
 
 class Context : public Object {
  public:
   RawContext* parent() const { return raw_ptr()->parent_; }
   void set_parent(const Context& parent) const {
     ASSERT(parent.IsNull() || parent.isolate() == Isolate::Current());
     StorePointer(&raw_ptr()->parent_, parent.raw());
   }
@@ skipping 1640 matching lines @@
                            Snapshot::Kind kind);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(String, Instance);
 
   friend class Class;
   friend class Symbols;
   friend class OneByteString;
   friend class TwoByteString;
   friend class ExternalOneByteString;
   friend class ExternalTwoByteString;
+  // So that the MarkingVisitor can print a debug string from a NoHandleScope.
+  friend class MarkingVisitor;
 };
 
 
 class OneByteString : public AllStatic {
  public:
   static int32_t CharAt(const String& str, intptr_t index) {
     return *CharAddr(str, index);
   }
 
   static void SetCharAt(const String& str, intptr_t index, uint8_t code_point) {
@@ skipping 1396 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_