Do not reuse tags_ field to store next_ pointer of FreeListElement.

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 20 matching lines @@
 #endif
 }
 
 
 intptr_t RawObject::SizeFromClass() const {
   NoHandleScope no_handles(Isolate::Current());
 
   // Only reasonable to be called on heap objects.
   ASSERT(IsHeapObject());
 
-  // 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(GetClassId());
   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_);
@@ skipping 170 matching lines @@
         const RawJSRegExp* raw_jsregexp =
             reinterpret_cast<const RawJSRegExp*>(this);
         intptr_t data_length = Smi::Value(raw_jsregexp->ptr()->data_length_);
         instance_size = JSRegExp::InstanceSize(data_length);
         break;
       }
       case kFreeListElement: {
         ASSERT(FreeBit::decode(ptr()->tags_));
         uword addr = RawObject::ToAddr(const_cast<RawObject*>(this));
         FreeListElement* element = reinterpret_cast<FreeListElement*>(addr);
-        instance_size = element->size();
+        instance_size = element->Size();
         break;
       }
       default:
         UNREACHABLE();
         break;
     }
   }
   ASSERT(instance_size != 0);
   uword tags = ptr()->tags_;
   ASSERT((instance_size == SizeTag::decode(tags)) ||
-         (SizeTag::decode(tags) == 0) ||
-         FreeBit::decode(tags));
+         (SizeTag::decode(tags) == 0));
   return instance_size;
 }
 
 
 intptr_t RawObject::VisitPointers(ObjectPointerVisitor* visitor) {
   intptr_t size = 0;
   NoHandleScope no_handles(visitor->isolate());
 
   // 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.
   intptr_t class_id = GetClassId();
   ObjectKind kind;
 
   if (class_id < kNumPredefinedKinds) {
     kind = static_cast<ObjectKind>(class_id);
   } else {
     RawClass* raw_class = Isolate::Current()->class_table()->At(class_id);
     kind = raw_class->ptr()->instance_kind_;
   }
 
   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: {
+      ASSERT(FreeBit::decode(ptr()->tags_));
+      uword addr = RawObject::ToAddr(const_cast<RawObject*>(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 636 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