Request for comments on overall approach.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index b227e909c1face0575f73b1249bb677108c05bac..4d92512cc5e84fbb52b6f69adb59e1fcce0522b3 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -17,6 +17,7 @@
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
 #include "vm/debuginfo.h"
+#include "vm/disassembler.h"
 #include "vm/double_conversion.h"
 #include "vm/exceptions.h"
 #include "vm/growable_array.h"
@@ -273,12 +274,10 @@ void Object::InitOnce() {
     uword address = heap->Allocate(size, Heap::kOld);
     class_class_ = reinterpret_cast<RawClass*>(address + kHeapObjectTag);
     InitializeObject(address, Class::kInstanceKind, size);
-    // Make the class_ field point to itself.
-    class_class_->ptr()->class_ = class_class_;
 
     Class fake;
     // Initialization from Class::New<Class>.
-    cls = class_class_;
+    cls.ForceSetRaw(class_class_);
     cls.set_handle_vtable(fake.vtable());
     cls.set_instance_size(Class::InstanceSize());
     cls.set_next_field_offset(Class::InstanceSize());
@@ -299,10 +298,6 @@ void Object::InitOnce() {
   cls.set_is_finalized();
   null_class_ = cls.raw();
 
-  // Complete initialization of null_ instance, i.e. initialize its class_
-  // field.
-  null_->ptr()->class_ = null_class_;
-
   // Allocate and initialize the sentinel values of Null class.
   {
     cls = null_class_;
@@ -988,10 +983,7 @@ RawObject* Object::Allocate(const Class& cls,
   }
   NoGCScope no_gc;
   InitializeObject(address, cls.index(), size);
-  RawObject* raw_obj = reinterpret_cast<RawObject*>(address + kHeapObjectTag);
-  raw_obj->ptr()->class_ = cls.raw();
-  ASSERT(cls.index() == RawObject::ClassTag::decode(raw_obj->ptr()->tags_));
-  return raw_obj;
+  return reinterpret_cast<RawObject*>(address + kHeapObjectTag);
 }
 
 
@@ -6302,6 +6294,17 @@ RawCode* Code::LookupCode(uword pc) {
 }
 
 
+#ifdef DEBUG
+void Code::FindAndPrint(uword pc) {

[Ivan Posva, 2012/05/26 04:34:46]

?

[Vyacheslav Egorov (Google), 2012/05/26 16:48:22]

This is a very useful helper method for debugging. If you have a crash in native
code it is easy to do: 

p dart::Code::FindAndPrint($pc)

to get the whole function (with comments). saves a lot of typing. 

I will obviously submit it as an entirely separate CL.

or I can try to write GDB macros, but having it right in the C++ has the
benefit: if we change something in Code/Instructions we will most definitely
forget to update GDB macros, but this guy will always stay updated. 

+  const Code& code = Code::Handle(Code::LookupCode(pc));
+  const Instructions& instructions =
+        Instructions::Handle(code.instructions());
+  uword start = instructions.EntryPoint();
+  Disassembler::Disassemble(start, start + instructions.size());
+}
+#endif
+
+
 intptr_t Code::GetTokenIndexOfPC(uword pc) const {
   intptr_t token_index = -1;
   const PcDescriptors& descriptors = PcDescriptors::Handle(pc_descriptors());
@@ -8965,7 +8968,6 @@ void Array::MakeImmutable() const {
       isolate, isolate->object_store()->immutable_array_class());
   {
     NoGCScope no_gc;
-    raw_ptr()->class_ = cls.raw();
     uword tags = raw_ptr()->tags_;
     tags = RawObject::ClassTag::update(cls.index(), tags);
     raw_ptr()->tags_ = tags;
@@ -9036,21 +9038,18 @@ RawArray* Array::MakeArray(const GrowableObjectArray& growable_array) {
       // space as an Array object.
       RawArray* raw = reinterpret_cast<RawArray*>(RawObject::FromAddr(addr));
       const Class& cls = Class::Handle(isolate->object_store()->array_class());
-      raw->ptr()->class_ = cls.raw();
       tags = 0;
       tags = RawObject::SizeTag::update(leftover_size, tags);
       tags = RawObject::ClassTag::update(cls.index(), tags);
       raw->ptr()->tags_ = tags;
       intptr_t leftover_len =
           ((leftover_size - Array::InstanceSize(0)) / kWordSize);
-      raw->ptr()->tags_ = tags;
       raw->ptr()->length_ = Smi::New(leftover_len);
     } else {
       // Update the leftover space as a basic object.
       ASSERT(leftover_size == Object::InstanceSize());
       RawObject* raw = reinterpret_cast<RawObject*>(RawObject::FromAddr(addr));
       const Class& cls = Class::Handle(isolate->object_store()->object_class());
-      raw->ptr()->class_ = cls.raw();
       tags = 0;
       tags = RawObject::SizeTag::update(leftover_size, tags);
       tags = RawObject::ClassTag::update(cls.index(), tags);