Avoid reading RawObject::class_ directly in the runtime.

runtime/vm/raw_object.cc

 // 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.
 
 #include "vm/raw_object.h"
 
 #include "vm/class_table.h"
 #include "vm/freelist.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
@@ skipping 30 matching lines @@
 #endif
 }
 
 
 intptr_t RawObject::SizeFromClass() const {
   NoHandleScope no_handles(Isolate::Current());
 
   // Only reasonable to be called on heap objects.
   ASSERT(IsHeapObject());
 
-  RawClass* raw_class = ptr()->class_;
+  // TODO(vegorov): this should be moved to fast path when class_ is eliminated.
+  if (FreeBit::decode(ptr()->tags_)) {
+    return reinterpret_cast<FreeListElement*>(ptr())->Size();
+  }
+
+  RawClass* raw_class = Isolate::Current()->class_table()->At(GetClassIndex());
   intptr_t instance_size = raw_class->ptr()->instance_size_;
   ObjectKind instance_kind = raw_class->ptr()->instance_kind_;
 
   if (instance_size == 0) {
     switch (instance_kind) {
       case kTokenStream: {
         const RawTokenStream* raw_tokens =
             reinterpret_cast<const RawTokenStream*>(this);
         intptr_t tokens_length = Smi::Value(raw_tokens->ptr()->length_);
         instance_size = TokenStream::InstanceSize(tokens_length);
@@ skipping 193 matching lines @@
 }
 
 
 intptr_t RawObject::VisitPointers(ObjectPointerVisitor* visitor) {
   intptr_t size = 0;
   NoHandleScope no_handles(Isolate::Current());
 
   // Only reasonable to be called on heap objects.
   ASSERT(IsHeapObject());
 
+  if (FreeBit::decode(ptr()->tags_)) {
+    // Nothing to visit for free list elements.
+    uword addr = RawObject::ToAddr(this);
+    FreeListElement* element = reinterpret_cast<FreeListElement*>(addr);
+    return element->Size();
+  }
+
   // Read the necessary data out of the class before visting the class itself.
-  RawClass* raw_class = ptr()->class_;
-  ObjectKind kind = raw_class->ptr()->instance_kind_;
+  intptr_t class_index = GetClassIndex();
+  ObjectKind kind;
+
+  if (class_index < kNumPredefinedKinds) {
+    kind = static_cast<ObjectKind>(class_index);
+  } else {
+    RawClass* raw_class = Isolate::Current()->class_table()->At(class_index);
+    kind = raw_class->ptr()->instance_kind_;
+  }
 
   // Visit the class before visting the fields.
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&ptr()->class_));
 
   switch (kind) {
 #define RAW_VISITPOINTERS(clazz) \
     case clazz::kInstanceKind: { \
       Raw##clazz* raw_obj = reinterpret_cast<Raw##clazz*>(this); \
       size = Raw##clazz::Visit##clazz##Pointers(raw_obj, visitor); \
       break; \
     }
     CLASS_LIST_NO_OBJECT(RAW_VISITPOINTERS)
 #undef RAW_VISITPOINTERS
-    case kFreeListElement: {

[Ivan Posva, 2012/05/31 13:06:24]

You do not handle kFreeListElements here, but I do not see a corresponding
change to set the FreeBit in this CL.

[Vyacheslav Egorov (Google), 2012/05/31 13:21:48]

But free bit is always set for FreeListElement is not it?

Take a look at FreeListElement::set_next

-      ASSERT(FreeBit::decode(ptr()->tags_));
-      // Nothing to visit for free list elements.
-      uword addr = RawObject::ToAddr(this);
-      FreeListElement* element = reinterpret_cast<FreeListElement*>(addr);
-      size = element->Size();
-      break;
-    }
     default:
       OS::Print("Kind: %d\n", kind);
       UNREACHABLE();
       break;
   }
 
   ASSERT(size != 0);
   ASSERT(size == Size());
   return size;
 }
@@ skipping 133 matching lines @@
 
 intptr_t RawInstructions::VisitInstructionsPointers(
     RawInstructions* raw_obj, ObjectPointerVisitor* visitor) {
   RawInstructions* obj = raw_obj->ptr();
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&obj->code_));
   return Instructions::InstanceSize(obj->size_);
 }
 
 
 bool RawInstructions::ContainsPC(RawObject* raw_obj, uword pc) {
-  RawClass* raw_class = raw_obj->ptr()->class_;
-  ObjectKind instance_kind = raw_class->ptr()->instance_kind_;
-  if (instance_kind == kInstructions) {
+  uword tags = raw_obj->ptr()->tags_;
+  if (RawObject::ClassTag::decode(tags) == kInstructions) {
     RawInstructions* raw_instr = reinterpret_cast<RawInstructions*>(raw_obj);
     uword start_pc =
         reinterpret_cast<uword>(raw_instr->ptr()) + Instructions::HeaderSize();
     uword end_pc = start_pc + raw_instr->ptr()->size_;
     ASSERT(end_pc > start_pc);
     if ((pc >= start_pc) && (pc < end_pc)) {
       return true;
     }
   }
   return false;
@@ skipping 102 matching lines @@
     RawUnwindError* raw_obj, ObjectPointerVisitor* visitor) {
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
   return UnwindError::InstanceSize();
 }
 
 
 intptr_t RawInstance::VisitInstancePointers(RawInstance* raw_obj,
                                             ObjectPointerVisitor* visitor) {
   // Make sure that we got here with the tagged pointer as this.
   ASSERT(raw_obj->IsHeapObject());
-  RawInstance* obj = raw_obj->ptr();
-  intptr_t instance_size = obj->class_->ptr()->instance_size_;
-  intptr_t num_native_fields = obj->class_->ptr()->num_native_fields_;
+  RawClass* cls = Isolate::Current()->class_table()->At(
+    raw_obj->GetClassIndex());
+  intptr_t instance_size = cls->ptr()->instance_size_;
+  intptr_t num_native_fields = cls->ptr()->num_native_fields_;
 
   // Calculate the first and last raw object pointer fields.
   uword obj_addr = RawObject::ToAddr(raw_obj);
   uword from = obj_addr + sizeof(RawObject) + num_native_fields * kWordSize;
   uword to = obj_addr + instance_size - kWordSize;
   visitor->VisitPointers(reinterpret_cast<RawObject**>(from),
                          reinterpret_cast<RawObject**>(to));
   return instance_size;
 }
 
@@ skipping 355 matching lines @@
 intptr_t RawJSRegExp::VisitJSRegExpPointers(RawJSRegExp* raw_obj,
                                             ObjectPointerVisitor* visitor) {
   // Make sure that we got here with the tagged pointer as this.
   ASSERT(raw_obj->IsHeapObject());
   intptr_t length = Smi::Value(raw_obj->ptr()->data_length_);
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
   return JSRegExp::InstanceSize(length);
 }
 
 }  // namespace dart